From 7f566621e1a8db3898100c4c814ecf3bcb6c9197 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 6 Aug 2024 13:44:49 -0400
Subject: [PATCH 01/86] clear out getters on new scope

---
 .../3-transform/client/transform-client.js       | 16 +++++++++++++++-
 packages/svelte/src/compiler/phases/scope.js     |  1 -
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 82d49f0ad7e6..1400c5cccd0f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -58,7 +58,21 @@ import { VariableDeclaration } from './visitors/VariableDeclaration.js';
 
 /** @type {Visitors} */
 const visitors = {
-	_: set_scope,
+	_: function set_scope(node, { next, state }) {
+		const scope = state.scopes.get(node);
+
+		if (scope && scope !== state.scope) {
+			const getters = { ...state.getters };
+
+			for (const name of scope.declarations.keys()) {
+				delete getters[name];
+			}
+
+			next({ ...state, getters, scope });
+		} else {
+			next();
+		}
+	},
 	AnimateDirective,
 	ArrowFunctionExpression,
 	AssignmentExpression,
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index 5eba0d3cf267..0d63a0381ce3 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -532,7 +532,6 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 					references_within.add(id);
 				}
 			}
-			scopes.set(node.expression, state.scope);
 
 			// context and children are a new scope
 			const scope = state.scope.child();

From d36d9c47057cf6ba872d8ebeab0155a4c9a0545e Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 6 Aug 2024 13:55:44 -0400
Subject: [PATCH 02/86] fix

---
 .../phases/3-transform/client/visitors/EachBlock.js   | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index a82677817a6e..665522683b2b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -1,6 +1,7 @@
 /** @import { AssignmentExpression, BlockStatement, Expression, Identifier, MemberExpression, Pattern, Statement } from 'estree' */
 /** @import { Binding, EachBlock } from '#compiler' */
 /** @import { ComponentContext, Context } from '../types' */
+/** @import { Scope } from '../../../scope' */
 import {
 	EACH_INDEX_REACTIVE,
 	EACH_IS_ANIMATED,
@@ -20,7 +21,15 @@ import { get_assignment_value, build_getter, build_setter, with_loc } from '../u
  */
 export function EachBlock(node, context) {
 	const each_node_meta = node.metadata;
-	const collection = /** @type {Expression} */ (context.visit(node.expression));
+
+	// expression should be evaluated in the parent scope, not the scope
+	// created by the each block itself
+	const collection = /** @type {Expression} */ (
+		context.visit(node.expression, {
+			...context.state,
+			scope: /** @type {Scope} */ (context.state.scope.parent)
+		})
+	);
 
 	if (!each_node_meta.is_controlled) {
 		context.state.template.push('<!>');

From ffedcf764c505ceb2c13997541fab022b2c07a38 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 6 Aug 2024 14:56:35 -0400
Subject: [PATCH 03/86] fix

---
 .../compiler/phases/2-analyze/visitors/EachBlock.js   | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/EachBlock.js
index 2e09c756e3b9..ebf20d5aa612 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/EachBlock.js
@@ -1,5 +1,6 @@
 /** @import { EachBlock } from '#compiler' */
 /** @import { Context } from '../types' */
+/** @import { Scope } from '../../scope' */
 import * as e from '../../../errors.js';
 import { validate_block_not_empty, validate_opening_tag } from './shared/utils.js';
 
@@ -25,5 +26,13 @@ export function EachBlock(node, context) {
 			node.key.type !== 'Identifier' || !node.index || node.key.name !== node.index;
 	}
 
-	context.next();
+	// evaluate expression in parent scope
+	context.visit(node.expression, {
+		...context.state,
+		scope: /** @type {Scope} */ (context.state.scope.parent)
+	});
+
+	context.visit(node.body);
+	if (node.key) context.visit(node.key);
+	if (node.fallback) context.visit(node.fallback);
 }

From 002b7f77ae8a274d09a6ab1686b48f556de55110 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 6 Aug 2024 15:36:24 -0400
Subject: [PATCH 04/86] fix

---
 .../src/compiler/phases/3-transform/client/transform-client.js  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 1400c5cccd0f..ae7fcf60ae1f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -62,7 +62,7 @@ const visitors = {
 		const scope = state.scopes.get(node);
 
 		if (scope && scope !== state.scope) {
-			const getters = { ...state.getters };
+			const getters = node.type === 'LetDirective' ? state.getters : { ...state.getters };
 
 			for (const name of scope.declarations.keys()) {
 				delete getters[name];

From 4fd80f807344a8152a144d70e271c7613593ef6d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 6 Aug 2024 15:56:47 -0400
Subject: [PATCH 05/86] fix

---
 .../compiler/phases/3-transform/client/transform-client.js  | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index ae7fcf60ae1f..131fca5cc6a4 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -64,8 +64,10 @@ const visitors = {
 		if (scope && scope !== state.scope) {
 			const getters = node.type === 'LetDirective' ? state.getters : { ...state.getters };
 
-			for (const name of scope.declarations.keys()) {
-				delete getters[name];
+			if (node.type !== 'LetDirective') {
+				for (const name of scope.declarations.keys()) {
+					delete getters[name];
+				}
 			}
 
 			next({ ...state, getters, scope });

From cfa5419b2b06d139ca929b7634300d399638250c Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 6 Aug 2024 17:03:15 -0400
Subject: [PATCH 06/86] consolidate legacy_reactive_import logic

---
 .../phases/2-analyze/visitors/Attribute.js    |  4 +-
 .../phases/2-analyze/visitors/Identifier.js   | 12 +-----
 .../3-transform/client/transform-client.js    | 37 ++++++++++++++-----
 .../phases/3-transform/client/utils.js        | 15 --------
 .../client/visitors/LabeledStatement.js       |  2 +-
 packages/svelte/src/compiler/types/index.d.ts |  4 +-
 6 files changed, 32 insertions(+), 42 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/Attribute.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/Attribute.js
index 85dfc6c67ec3..5d9a4383fa48 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/Attribute.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Attribute.js
@@ -187,9 +187,7 @@ function get_delegated_event(event_name, handler, context) {
 				// Bail out if we reference anything from the EachBlock (for now) that mutates in non-runes mode,
 				(((!context.state.analysis.runes && binding.kind === 'each') ||
 					// or any normal not reactive bindings that are mutated.
-					binding.kind === 'normal' ||
-					// or any reactive imports (those are rewritten) (can only happen in legacy mode)
-					binding.kind === 'legacy_reactive_import') &&
+					binding.kind === 'normal') &&
 					binding.mutated))
 		) {
 			return unhoisted;
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js
index c00d5216107f..2e4595ec0852 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js
@@ -80,16 +80,8 @@ export function Identifier(node, context) {
 				binding.declaration_kind !== 'function') ||
 				binding.declaration_kind === 'import')
 		) {
-			if (binding.declaration_kind === 'import') {
-				if (
-					binding.mutated &&
-					// TODO could be more fine-grained - not every mention in the template implies a state binding
-					(context.state.reactive_statement || context.state.ast_type === 'template') &&
-					parent.type === 'MemberExpression'
-				) {
-					binding.kind = 'legacy_reactive_import';
-				}
-			} else if (
+			if (
+				binding.declaration_kind !== 'import' &&
 				binding.mutated &&
 				// TODO could be more fine-grained - not every mention in the template implies a state binding
 				(context.state.reactive_statement || context.state.ast_type === 'template')
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 131fca5cc6a4..c5c91466dd65 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -165,6 +165,32 @@ export function client_component(analysis, options) {
 		locations: /** @type {any} */ (null)
 	};
 
+	/** @type {ESTree.Statement[]} */
+	const legacy_reactive_imports = [];
+
+	// Very very dirty way of making import statements reactive in legacy mode if needed
+	if (!analysis.runes) {
+		for (const [name, binding] of state.scope.declarations) {
+			if (binding.declaration_kind === 'import' && binding.mutated) {
+				state.getters[name] = (node) => b.call('$$_import_' + node.name);
+
+				state.setters[name] = (node, context) =>
+					b.call(
+						'$$_import_' + binding.node.name,
+						b.assignment(
+							node.operator,
+							/** @type {ESTree.Pattern} */ (context.visit(node.left)),
+							/** @type {ESTree.Expression} */ (context.visit(node.right))
+						)
+					);
+
+				legacy_reactive_imports.push(
+					b.var('$$_import_' + name, b.call('$.reactive_import', b.thunk(b.id(name))))
+				);
+			}
+		}
+	}
+
 	const module = /** @type {ESTree.Program} */ (
 		walk(/** @type {SvelteNode} */ (analysis.module.ast), state, visitors)
 	);
@@ -188,16 +214,7 @@ export function client_component(analysis, options) {
 		)
 	);
 
-	// Very very dirty way of making import statements reactive in legacy mode if needed
-	if (!analysis.runes) {
-		for (const [name, binding] of analysis.module.scope.declarations) {
-			if (binding.kind === 'legacy_reactive_import') {
-				instance.body.unshift(
-					b.var('$$_import_' + name, b.call('$.reactive_import', b.thunk(b.id(name))))
-				);
-			}
-		}
-	}
+	instance.body.unshift(...legacy_reactive_imports);
 
 	/** @type {ESTree.Statement[]} */
 	const store_setup = [];
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 57ede67bb317..efffbecba271 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -106,10 +106,6 @@ export function build_getter(node, state) {
 		return b.member(b.id('$$props'), node);
 	}
 
-	if (binding.kind === 'legacy_reactive_import') {
-		return b.call('$$_import_' + node.name);
-	}
-
 	if (
 		is_state_source(binding, state) ||
 		binding.kind === 'derived' ||
@@ -271,17 +267,6 @@ export function build_setter(node, context, fallback, prefix, options) {
 		return setter(node, context);
 	}
 
-	if (binding.kind === 'legacy_reactive_import') {
-		return b.call(
-			'$$_import_' + binding.node.name,
-			b.assignment(
-				node.operator,
-				/** @type {Pattern} */ (visit(node.left)),
-				/** @type {Expression} */ (visit(node.right))
-			)
-		);
-	}
-
 	/**
 	 * @param {any} serialized
 	 * @returns
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LabeledStatement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LabeledStatement.js
index 262e44dfcbd9..87f56262a8ba 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LabeledStatement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LabeledStatement.js
@@ -34,7 +34,7 @@ export function LabeledStatement(node, context) {
 	const sequence = [];
 
 	for (const binding of reactive_statement.dependencies) {
-		if (binding.kind === 'normal') continue;
+		if (binding.kind === 'normal' && binding.declaration_kind !== 'import') continue;
 
 		const name = binding.node.name;
 		let serialized = build_getter(b.id(name), context.state);
diff --git a/packages/svelte/src/compiler/types/index.d.ts b/packages/svelte/src/compiler/types/index.d.ts
index 47dc9d7eb607..f7d111a267d6 100644
--- a/packages/svelte/src/compiler/types/index.d.ts
+++ b/packages/svelte/src/compiler/types/index.d.ts
@@ -271,7 +271,6 @@ export interface Binding {
 	 * - `snippet`: A snippet parameter
 	 * - `store_sub`: A $store value
 	 * - `legacy_reactive`: A `$:` declaration
-	 * - `legacy_reactive_import`: An imported binding that is mutated inside the component
 	 */
 	kind:
 		| 'normal'
@@ -284,8 +283,7 @@ export interface Binding {
 		| 'each'
 		| 'snippet'
 		| 'store_sub'
-		| 'legacy_reactive'
-		| 'legacy_reactive_import';
+		| 'legacy_reactive';
 	declaration_kind: DeclarationKind;
 	/**
 	 * What the value was initialized with.

From f4ccd6b865dae9f35f552a02f8bcb14c0d11bead Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 6 Aug 2024 17:03:44 -0400
Subject: [PATCH 07/86] unused

---
 .../src/compiler/phases/3-transform/client/transform-client.js   | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index c5c91466dd65..a0fc0650c22c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -4,7 +4,6 @@
 /** @import { Visitors, ComponentClientTransformState, ClientTransformState } from './types' */
 import { walk } from 'zimmerframe';
 import * as b from '../../../utils/builders.js';
-import { set_scope } from '../../scope.js';
 import { build_getter } from './utils.js';
 import { render_stylesheet } from '../css/index.js';
 import { dev, filename } from '../../../state.js';

From 0e7884fa533242f771cb456448913b6c17d616aa Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 6 Aug 2024 17:07:23 -0400
Subject: [PATCH 08/86] $$sanitized_props

---
 .../compiler/phases/3-transform/client/transform-client.js   | 4 +++-
 .../svelte/src/compiler/phases/3-transform/client/utils.js   | 5 -----
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index a0fc0650c22c..13e8f60ae4e2 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -167,9 +167,11 @@ export function client_component(analysis, options) {
 	/** @type {ESTree.Statement[]} */
 	const legacy_reactive_imports = [];
 
-	// Very very dirty way of making import statements reactive in legacy mode if needed
 	if (!analysis.runes) {
+		state.getters['$$props'] = (node) => ({ ...node, name: '$$sanitized_props' });
+
 		for (const [name, binding] of state.scope.declarations) {
+			// Very very dirty way of making import statements reactive in legacy mode if needed
 			if (binding.declaration_kind === 'import' && binding.mutated) {
 				state.getters[name] = (node) => b.call('$$_import_' + node.name);
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index efffbecba271..39f9e6b2cf9d 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -85,11 +85,6 @@ export function build_getter(node, state) {
 		return typeof getter === 'function' ? getter(node) : getter;
 	}
 
-	if (binding.node.name === '$$props') {
-		// Special case for $$props which only exists in the old world
-		return b.id('$$sanitized_props');
-	}
-
 	if (binding.kind === 'store_sub') {
 		return b.call(node);
 	}

From 20f1e662f1706a0cfe3e55da7d7b72d9ec29bbd2 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 6 Aug 2024 18:39:57 -0400
Subject: [PATCH 09/86] use getters mechanism for store_sub

---
 .../phases/3-transform/client/transform-client.js  | 14 +++++++++++++-
 .../compiler/phases/3-transform/client/utils.js    |  4 ----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 13e8f60ae4e2..3a263c3ab313 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -198,11 +198,18 @@ export function client_component(analysis, options) {
 
 	const instance_state = {
 		...state,
+		getters: { ...state.getters },
 		scope: analysis.instance.scope,
 		scopes: analysis.instance.scopes,
 		is_instance: true
 	};
 
+	for (const [name, binding] of instance_state.scope.declarations) {
+		if (binding.kind === 'store_sub') {
+			instance_state.getters[name] = (node) => b.call(node);
+		}
+	}
+
 	const instance = /** @type {ESTree.Program} */ (
 		walk(/** @type {SvelteNode} */ (analysis.instance.ast), instance_state, visitors)
 	);
@@ -210,7 +217,12 @@ export function client_component(analysis, options) {
 	const template = /** @type {ESTree.Program} */ (
 		walk(
 			/** @type {SvelteNode} */ (analysis.template.ast),
-			{ ...state, scope: analysis.instance.scope, scopes: analysis.template.scopes },
+			{
+				...state,
+				getters: instance_state.getters,
+				scope: analysis.instance.scope,
+				scopes: analysis.template.scopes
+			},
 			visitors
 		)
 	);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 39f9e6b2cf9d..88f064834aca 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -85,10 +85,6 @@ export function build_getter(node, state) {
 		return typeof getter === 'function' ? getter(node) : getter;
 	}
 
-	if (binding.kind === 'store_sub') {
-		return b.call(node);
-	}
-
 	if (binding.kind === 'prop' || binding.kind === 'bindable_prop') {
 		if (is_prop_source(binding, state)) {
 			return b.call(node);

From 4315ac3242f7ddf1a878254c8ef15059248c1478 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 7 Aug 2024 14:31:19 -0400
Subject: [PATCH 10/86] snapshot

---
 .../2-analyze/visitors/shared/attribute.js    |   2 +-
 .../2-analyze/visitors/shared/component.js    |  73 +++++++++-
 .../3-transform/client/transform-client.js    |  13 +-
 .../client/visitors/BlockStatement.js         |  10 ++
 .../client/visitors/LetDirective.js           |   2 +
 .../3-transform/client/visitors/Program.js    |  32 +++++
 .../client/visitors/shared/component.js       |  26 +++-
 .../server/visitors/shared/component.js       |  35 ++++-
 packages/svelte/src/compiler/phases/scope.js  | 134 +++++++++++++-----
 playgrounds/sandbox/run.js                    |   5 +
 10 files changed, 273 insertions(+), 59 deletions(-)
 create mode 100644 packages/svelte/src/compiler/phases/3-transform/client/visitors/BlockStatement.js
 create mode 100644 packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/attribute.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/attribute.js
index 8f60a67c62b0..4102460cbaa2 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/attribute.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/attribute.js
@@ -1,4 +1,4 @@
-/** @import { Attribute, ElementLike } from '#compiler' */
+/** @import { Attribute, ElementLike, SvelteNode } from '#compiler' */
 /** @import { Context } from '../../types' */
 import * as e from '../../../../errors.js';
 import { is_text_attribute } from '../../../../utils/ast.js';
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index 347a59488a57..01ecbee33402 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -1,7 +1,12 @@
 /** @import { Component, SvelteComponent, SvelteSelf } from '#compiler' */
 /** @import { Context } from '../../types' */
 import * as e from '../../../../errors.js';
-import { get_attribute_expression, is_expression_attribute } from '../../../../utils/ast.js';
+import {
+	get_attribute_expression,
+	is_expression_attribute,
+	is_text_attribute
+} from '../../../../utils/ast.js';
+import { is_element_node } from '../../../nodes.js';
 import {
 	validate_attribute,
 	validate_attribute_name,
@@ -60,9 +65,69 @@ export function visit_component(node, context) {
 		}
 	}
 
-	context.next({
+	const component_slots = new Set();
+
+	const default_state = {
+		...context.state,
+		scope: node.metadata.default_scope,
+		parent_element: null,
+		component_slots
+	};
+
+	const named_state = {
 		...context.state,
 		parent_element: null,
-		component_slots: new Set()
-	});
+		component_slots
+	};
+
+	for (const attribute of node.attributes) {
+		context.visit(attribute, attribute.type === 'LetDirective' ? default_state : named_state);
+	}
+
+	const default_slot_nodes = [];
+	const named_slot_nodes = [];
+
+	for (const child of node.fragment.nodes) {
+		const is_slotted_content =
+			is_element_node(child) &&
+			child.attributes.some(
+				(a) => a.type === 'Attribute' && a.name === 'slot' && is_text_attribute(a)
+			);
+
+		if (child.type === 'Comment') {
+			// ensure svelte-ignore comments are preserved in both cases
+			// TODO this is brittle
+			named_slot_nodes.push(child);
+			default_slot_nodes.push(child);
+		} else if (is_slotted_content) {
+			named_slot_nodes.push(child);
+		} else {
+			default_slot_nodes.push(child);
+		}
+	}
+
+	context.visit({ ...node.fragment, nodes: default_slot_nodes }, default_state);
+	context.visit({ ...node.fragment, nodes: named_slot_nodes }, named_state);
+
+	// context.visit(child, is_slotted_content ? named_state : default_state);
+
+	// if (
+	// 	is_element_node(child) &&
+	// 	child.attributes.some(
+	// 		(a) => a.type === 'Attribute' && a.name === 'slot' && is_text_attribute(a)
+	// 	)
+	// ) {
+	// 	context.visit(child);
+	// } else {
+	// 	context.visit(child, { scope });
+	// }
+
+	// context.visit(node, attribute.type === 'LetDirective' ? default_state : named_state);
+	// }
+
+	// context.next({
+	// 	...context.state,
+	// 	parent_element: null,
+	// 	component_slots: new Set()
+	// });
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 3a263c3ab313..2755357bcb83 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -14,6 +14,7 @@ import { Attribute } from './visitors/Attribute.js';
 import { AwaitBlock } from './visitors/AwaitBlock.js';
 import { BinaryExpression } from './visitors/BinaryExpression.js';
 import { BindDirective } from './visitors/BindDirective.js';
+import { BlockStatement } from './visitors/BlockStatement.js';
 import { BreakStatement } from './visitors/BreakStatement.js';
 import { CallExpression } from './visitors/CallExpression.js';
 import { ClassBody } from './visitors/ClassBody.js';
@@ -36,6 +37,7 @@ import { LabeledStatement } from './visitors/LabeledStatement.js';
 import { LetDirective } from './visitors/LetDirective.js';
 import { MemberExpression } from './visitors/MemberExpression.js';
 import { OnDirective } from './visitors/OnDirective.js';
+import { Program } from './visitors/Program.js';
 import { RegularElement } from './visitors/RegularElement.js';
 import { RenderTag } from './visitors/RenderTag.js';
 import { SlotElement } from './visitors/SlotElement.js';
@@ -61,10 +63,11 @@ const visitors = {
 		const scope = state.scopes.get(node);
 
 		if (scope && scope !== state.scope) {
-			const getters = node.type === 'LetDirective' ? state.getters : { ...state.getters };
+			const getters = { ...state.getters };
 
-			if (node.type !== 'LetDirective') {
-				for (const name of scope.declarations.keys()) {
+			for (const [name, binding] of scope.declarations) {
+				// if (binding.kind === 'normal') {
+				if (binding.kind !== 'each') {
 					delete getters[name];
 				}
 			}
@@ -81,6 +84,7 @@ const visitors = {
 	AwaitBlock,
 	BinaryExpression,
 	BindDirective,
+	BlockStatement,
 	BreakStatement,
 	CallExpression,
 	ClassBody,
@@ -103,6 +107,7 @@ const visitors = {
 	LetDirective,
 	MemberExpression,
 	OnDirective,
+	Program,
 	RegularElement,
 	RenderTag,
 	SlotElement,
@@ -206,7 +211,7 @@ export function client_component(analysis, options) {
 
 	for (const [name, binding] of instance_state.scope.declarations) {
 		if (binding.kind === 'store_sub') {
-			instance_state.getters[name] = (node) => b.call(node);
+			// instance_state.getters[name] = (node) => b.call(node);
 		}
 	}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/BlockStatement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/BlockStatement.js
new file mode 100644
index 000000000000..d5f15ebdf156
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/BlockStatement.js
@@ -0,0 +1,10 @@
+/** @import { BlockStatement, Expression } from 'estree' */
+/** @import { ComponentContext } from '../types' */
+
+/**
+ * @param {BlockStatement} node
+ * @param {ComponentContext} context
+ */
+export function BlockStatement(node, context) {
+	context.next();
+}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
index 2423c6e50e01..ba100bb689fa 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
@@ -42,6 +42,8 @@ export function LetDirective(node, context) {
 			)
 		);
 	} else {
+		context.state.getters[node.name] = (node) => b.call('$.get', node);
+
 		return b.const(
 			node.expression === null ? node.name : node.expression.name,
 			create_derived(context.state, b.thunk(b.member(b.id('$$slotProps'), b.id(node.name))))
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
new file mode 100644
index 000000000000..1d850528c566
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -0,0 +1,32 @@
+/** @import { Program, Expression } from 'estree' */
+/** @import { ComponentContext } from '../types' */
+import { is_prop_source } from '../utils.js';
+import * as b from '../../../../utils/builders.js';
+
+/**
+ * @param {Program} node
+ * @param {ComponentContext} context
+ */
+export function Program(node, context) {
+	if (context.state.is_instance) {
+		for (const [name, binding] of context.state.scope.declarations) {
+			if (binding.kind === 'store_sub') {
+				context.state.getters[name] = (node) => b.call(node);
+			}
+
+			if (binding.kind === 'prop' || binding.kind === 'bindable_prop') {
+				if (is_prop_source(binding, context.state)) {
+					context.state.getters[name] = (node) => b.call(node);
+				} else if (binding.prop_alias) {
+					const key = b.key(binding.prop_alias);
+					context.state.getters[name] = (node) =>
+						b.member(b.id('$$props'), key, key.type === 'Literal');
+				} else {
+					context.state.getters[name] = (node) => b.member(b.id('$$props'), node);
+				}
+			}
+		}
+	}
+
+	context.next();
+}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index 6416e26318c6..9418ed2a404e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -24,6 +24,16 @@ export function build_component(node, component_name, context, anchor = context.
 	/** @type {ExpressionStatement[]} */
 	const lets = [];
 
+	/**
+	 * Children in the default slot are evaluated in the component scope,
+	 * children in named slots are evaluated in the parent scope
+	 */
+	const child_state = {
+		...context.state,
+		scope: node.metadata.default_scope,
+		getters: { ...context.state.getters }
+	};
+
 	/** @type {Record<string, TemplateNode[]>} */
 	const children = {};
 
@@ -66,9 +76,10 @@ export function build_component(node, component_name, context, anchor = context.
 			props_and_spreads.push(props);
 		}
 	}
+
 	for (const attribute of node.attributes) {
 		if (attribute.type === 'LetDirective') {
-			lets.push(/** @type {ExpressionStatement} */ (context.visit(attribute)));
+			lets.push(/** @type {ExpressionStatement} */ (context.visit(attribute, child_state)));
 		} else if (attribute.type === 'OnDirective') {
 			if (!attribute.expression) {
 				context.state.analysis.needs_props = true;
@@ -242,12 +253,13 @@ export function build_component(node, component_name, context, anchor = context.
 					// @ts-expect-error
 					nodes: children[slot_name]
 				},
-				{
-					...context.state,
-					scope:
-						context.state.scopes.get(slot_name === 'default' ? children[slot_name][0] : node) ??
-						context.state.scope
-				}
+				slot_name === 'default' ? child_state : context.state
+				// {
+				// 	...context.state,
+				// 	scope:
+				// 		context.state.scopes.get(slot_name === 'default' ? children[slot_name][0] : node) ??
+				// 		context.state.scope
+				// }
 			)
 		);
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
index 60b3498510de..cf604ad9568b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
@@ -20,6 +20,15 @@ export function build_inline_component(node, expression, context) {
 	/** @type {Record<string, LetDirective[]>} */
 	const lets = { default: [] };
 
+	/**
+	 * Children in the default slot are evaluated in the component scope,
+	 * children in named slots are evaluated in the parent scope
+	 */
+	const child_state = {
+		...context.state,
+		scope: node.metadata.default_scope
+	};
+
 	/** @type {Record<string, TemplateNode[]>} */
 	const children = {};
 
@@ -144,13 +153,27 @@ export function build_inline_component(node, expression, context) {
 					// @ts-expect-error
 					nodes: children[slot_name]
 				},
-				{
-					...context.state,
-					scope:
-						context.state.scopes.get(slot_name === 'default' ? children[slot_name][0] : node) ??
-						context.state.scope
-				}
+				slot_name === 'default' ? child_state : context.state
+				// {
+				// 	...context.state,
+				// 	scope:
+				// 		context.state.scopes.get(slot_name === 'default' ? children[slot_name][0] : node) ??
+				// 		context.state.scope
+				// }
 			)
+			// context.visit(
+			// 	{
+			// 		...node.fragment,
+			// 		// @ts-expect-error
+			// 		nodes: children[slot_name]
+			// 	},
+			// 	{
+			// 		...context.state,
+			// 		scope:
+			// 			context.state.scopes.get(slot_name === 'default' ? children[slot_name][0] : node) ??
+			// 			context.state.scope
+			// 	}
+			// )
 		);
 
 		if (block.body.length === 0) continue;
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index 0d63a0381ce3..e181e2e0f730 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -9,6 +9,7 @@ import * as e from '../errors.js';
 import {
 	extract_identifiers,
 	extract_identifiers_from_destructuring,
+	is_text_attribute,
 	object,
 	unwrap_pattern
 } from '../utils/ast.js';
@@ -290,11 +291,81 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 	 * @type {Visitor<ElementLike, State, SvelteNode>}
 	 */
 	const SvelteFragment = (node, { state, next }) => {
-		const [scope] = analyze_let_directives(node, state.scope);
+		// const [scope] = analyze_let_directives(node, state.scope);
+		const scope = state.scope.child();
 		scopes.set(node, scope);
 		next({ scope });
 	};
 
+	/**
+	 * @type {Visitor<ElementLike, State, SvelteNode>}
+	 */
+	const Component = (node, context) => {
+		const scope = context.state.scope.child();
+		node.metadata.default_scope = scope;
+		// scopes.set(node, scope);
+
+		for (const attribute of node.attributes) {
+			if (attribute.type === 'LetDirective') {
+				context.visit(attribute, { scope });
+			} else {
+				context.visit(attribute);
+			}
+		}
+
+		for (const child of node.fragment.nodes) {
+			if (
+				is_element_node(child) &&
+				child.attributes.some(
+					(a) => a.type === 'Attribute' && a.name === 'slot' && is_text_attribute(a)
+				)
+			) {
+				context.visit(child);
+			} else {
+				context.visit(child, { scope });
+			}
+		}
+
+		// // let:x is super weird:
+		// // - for the default slot, its scope only applies to children that are not slots themselves
+		// // - for named slots, its scope applies to the component itself, too
+		// const [scope, is_default_slot] = analyze_let_directives(node, state.scope);
+		// if (is_default_slot) {
+		// 	for (const attribute of node.attributes) {
+		// 		visit(attribute);
+		// 	}
+		// } else {
+		// 	scopes.set(node, scope);
+
+		// 	for (const attribute of node.attributes) {
+		// 		visit(attribute, { ...state, scope });
+		// 	}
+		// }
+
+		// for (const child of node.fragment.nodes) {
+		// 	if (
+		// 		is_element_node(child) &&
+		// 		child.attributes.some(
+		// 			(attribute) => attribute.type === 'Attribute' && attribute.name === 'slot'
+		// 		)
+		// 	) {
+		// 		// <div slot="..."> inherits the scope above the component unless the component is a named slot itself, because slots are hella weird
+		// 		scopes.set(child, is_default_slot ? state.scope : scope);
+		// 		visit(child, { scope: is_default_slot ? state.scope : scope });
+		// 	} else {
+		// 		if (child.type === 'ExpressionTag') {
+		// 			// expression tag is a special case — we don't visit it directly, but via process_children,
+		// 			// so we need to set the scope on the expression rather than the tag itself
+		// 			scopes.set(child.expression, scope);
+		// 		} else {
+		// 			scopes.set(child, scope);
+		// 		}
+
+		// 		visit(child, { scope });
+		// 	}
+		// }
+	};
+
 	/**
 	 * @param {ElementLike} node
 	 * @param {Scope} parent
@@ -384,48 +455,37 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 		SvelteElement: SvelteFragment,
 		RegularElement: SvelteFragment,
 
-		Component(node, { state, visit, path }) {
-			state.scope.reference(b.id(node.name), path);
+		LetDirective(node, context) {
+			const scope = context.state.scope;
 
-			// let:x is super weird:
-			// - for the default slot, its scope only applies to children that are not slots themselves
-			// - for named slots, its scope applies to the component itself, too
-			const [scope, is_default_slot] = analyze_let_directives(node, state.scope);
-			if (is_default_slot) {
-				for (const attribute of node.attributes) {
-					visit(attribute);
-				}
-			} else {
-				scopes.set(node, scope);
+			/** @type {Binding[]} */
+			const bindings = [];
+			scope.declarators.set(node, bindings);
 
-				for (const attribute of node.attributes) {
-					visit(attribute, { ...state, scope });
+			if (node.expression) {
+				for (const id of extract_identifiers_from_destructuring(node.expression)) {
+					const binding = scope.declare(id, 'derived', 'const');
+					bindings.push(binding);
 				}
+			} else {
+				/** @type {Identifier} */
+				const id = {
+					name: node.name,
+					type: 'Identifier',
+					start: node.start,
+					end: node.end
+				};
+				const binding = scope.declare(id, 'derived', 'const');
+				bindings.push(binding);
 			}
+		},
 
-			for (const child of node.fragment.nodes) {
-				if (
-					is_element_node(child) &&
-					child.attributes.some(
-						(attribute) => attribute.type === 'Attribute' && attribute.name === 'slot'
-					)
-				) {
-					// <div slot="..."> inherits the scope above the component unless the component is a named slot itself, because slots are hella weird
-					scopes.set(child, is_default_slot ? state.scope : scope);
-					visit(child, { scope: is_default_slot ? state.scope : scope });
-				} else {
-					if (child.type === 'ExpressionTag') {
-						// expression tag is a special case — we don't visit it directly, but via process_children,
-						// so we need to set the scope on the expression rather than the tag itself
-						scopes.set(child.expression, scope);
-					} else {
-						scopes.set(child, scope);
-					}
-
-					visit(child, { scope });
-				}
-			}
+		Component: (node, context) => {
+			context.state.scope.reference(b.id(node.name), context.path);
+			Component(node, context);
 		},
+		SvelteSelf: Component,
+		SvelteComponent: Component,
 
 		// updates
 		AssignmentExpression(node, { state, next }) {
diff --git a/playgrounds/sandbox/run.js b/playgrounds/sandbox/run.js
index 0b72c18f46fe..bbeacb3e85f6 100644
--- a/playgrounds/sandbox/run.js
+++ b/playgrounds/sandbox/run.js
@@ -63,6 +63,11 @@ for (const generate of /** @type {const} */ (['client', 'server'])) {
 			runes: argv.values.runes
 		});
 
+		for (const warning of compiled.warnings) {
+			console.warn(warning.code);
+			console.warn(warning.frame);
+		}
+
 		fs.writeFileSync(
 			output_js,
 			compiled.js.code + '\n//# sourceMappingURL=' + path.basename(output_map)

From 4c6120a55b9f9cb245eb951fa1e5fb0c1cf77f4a Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 7 Aug 2024 17:47:00 -0400
Subject: [PATCH 11/86] fix

---
 .../2-analyze/visitors/shared/component.js    | 67 +++++++++++--------
 .../client/visitors/LetDirective.js           |  5 +-
 .../client/visitors/shared/component.js       | 56 +++++++++-------
 .../client/visitors/shared/element.js         |  2 +-
 .../server/visitors/shared/component.js       |  9 ++-
 packages/svelte/src/compiler/phases/scope.js  | 35 ++++++----
 packages/svelte/src/compiler/utils/slot.js    | 20 ++++++
 7 files changed, 123 insertions(+), 71 deletions(-)
 create mode 100644 packages/svelte/src/compiler/utils/slot.js

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index 01ecbee33402..67b5a6d4ff38 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -6,6 +6,7 @@ import {
 	is_expression_attribute,
 	is_text_attribute
 } from '../../../../utils/ast.js';
+import { determine_slot } from '../../../../utils/slot.js';
 import { is_element_node } from '../../../nodes.js';
 import {
 	validate_attribute,
@@ -67,47 +68,55 @@ export function visit_component(node, context) {
 
 	const component_slots = new Set();
 
-	const default_state = {
-		...context.state,
-		scope: node.metadata.default_scope,
-		parent_element: null,
-		component_slots
-	};
+	const slot_scope_applies_to_itself = !!determine_slot(node);
 
-	const named_state = {
-		...context.state,
-		parent_element: null,
-		component_slots
-	};
+	const default_state = slot_scope_applies_to_itself
+		? context.state
+		: {
+				...context.state,
+				scope: node.metadata.scopes.default,
+				parent_element: null,
+				component_slots
+			};
 
 	for (const attribute of node.attributes) {
-		context.visit(attribute, attribute.type === 'LetDirective' ? default_state : named_state);
+		context.visit(attribute, attribute.type === 'LetDirective' ? default_state : context.state);
 	}
 
-	const default_slot_nodes = [];
-	const named_slot_nodes = [];
+	const comments = [];
+	const nodes = {
+		default: []
+	};
 
 	for (const child of node.fragment.nodes) {
-		const is_slotted_content =
-			is_element_node(child) &&
-			child.attributes.some(
-				(a) => a.type === 'Attribute' && a.name === 'slot' && is_text_attribute(a)
-			);
-
 		if (child.type === 'Comment') {
-			// ensure svelte-ignore comments are preserved in both cases
-			// TODO this is brittle
-			named_slot_nodes.push(child);
-			default_slot_nodes.push(child);
-		} else if (is_slotted_content) {
-			named_slot_nodes.push(child);
+			comments.push(child);
+			continue;
+		}
+
+		let slot_name = determine_slot(child);
+
+		if (slot_name) {
+			nodes[slot_name] = [...comments, child];
 		} else {
-			default_slot_nodes.push(child);
+			nodes.default.push(...comments, child);
 		}
 	}
 
-	context.visit({ ...node.fragment, nodes: default_slot_nodes }, default_state);
-	context.visit({ ...node.fragment, nodes: named_slot_nodes }, named_state);
+	for (const slot_name in nodes) {
+		context.visit(
+			{ ...node.fragment, nodes: nodes[slot_name] },
+			{
+				...context.state,
+				scope: node.metadata.scopes[slot_name],
+				parent_element: null,
+				component_slots
+			}
+		);
+	}
+
+	// context.visit({ ...node.fragment, nodes: default_slot_nodes }, default_state);
+	// context.visit({ ...node.fragment, nodes: named_slot_nodes }, named_state);
 
 	// context.visit(child, is_slotted_content ? named_state : default_state);
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
index ba100bb689fa..9d42317bda46 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
@@ -42,10 +42,11 @@ export function LetDirective(node, context) {
 			)
 		);
 	} else {
-		context.state.getters[node.name] = (node) => b.call('$.get', node);
+		const name = node.expression === null ? node.name : node.expression.name;
+		context.state.getters[name] = (node) => b.call('$.get', node);
 
 		return b.const(
-			node.expression === null ? node.name : node.expression.name,
+			name,
 			create_derived(context.state, b.thunk(b.member(b.id('$$slotProps'), b.id(node.name))))
 		);
 	}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index 9418ed2a404e..3d729431fb04 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -9,6 +9,7 @@ import { create_derived, build_setter } from '../../utils.js';
 import { build_bind_this, validate_binding } from '../shared/utils.js';
 import { build_attribute_value } from '../shared/element.js';
 import { build_event_handler } from './events.js';
+import { determine_slot } from '../../../../../utils/slot.js';
 
 /**
  * @param {Component | SvelteComponent | SvelteSelf} node
@@ -24,14 +25,13 @@ export function build_component(node, component_name, context, anchor = context.
 	/** @type {ExpressionStatement[]} */
 	const lets = [];
 
-	/**
-	 * Children in the default slot are evaluated in the component scope,
-	 * children in named slots are evaluated in the parent scope
-	 */
-	const child_state = {
-		...context.state,
-		scope: node.metadata.default_scope,
-		getters: { ...context.state.getters }
+	/** @type {Record<string, typeof context.state>} */
+	const states = {
+		default: {
+			...context.state,
+			scope: node.metadata.scopes.default,
+			getters: { ...context.state.getters }
+		}
 	};
 
 	/** @type {Record<string, TemplateNode[]>} */
@@ -51,11 +51,13 @@ export function build_component(node, component_name, context, anchor = context.
 	 */
 	const binding_initializers = [];
 
+	const self_slot = determine_slot(node);
+
 	/**
 	 * If this component has a slot property, it is a named slot within another component. In this case
 	 * the slot scope applies to the component itself, too, and not just its children.
 	 */
-	let slot_scope_applies_to_itself = false;
+	let slot_scope_applies_to_itself = !!self_slot;
 
 	/**
 	 * Components may have a children prop and also have child nodes. In this case, we assume
@@ -77,9 +79,19 @@ export function build_component(node, component_name, context, anchor = context.
 		}
 	}
 
+	if (slot_scope_applies_to_itself) {
+		for (const attribute of node.attributes) {
+			if (attribute.type === 'LetDirective') {
+				lets.push(/** @type {ExpressionStatement} */ (context.visit(attribute)));
+			}
+		}
+	}
+
 	for (const attribute of node.attributes) {
 		if (attribute.type === 'LetDirective') {
-			lets.push(/** @type {ExpressionStatement} */ (context.visit(attribute, child_state)));
+			if (!slot_scope_applies_to_itself) {
+				lets.push(/** @type {ExpressionStatement} */ (context.visit(attribute, states.default)));
+			}
 		} else if (attribute.type === 'OnDirective') {
 			if (!attribute.expression) {
 				context.state.analysis.needs_props = true;
@@ -225,19 +237,7 @@ export function build_component(node, component_name, context, anchor = context.
 			continue;
 		}
 
-		let slot_name = 'default';
-
-		if (is_element_node(child)) {
-			const attribute = /** @type {Attribute | undefined} */ (
-				child.attributes.find(
-					(attribute) => attribute.type === 'Attribute' && attribute.name === 'slot'
-				)
-			);
-
-			if (attribute !== undefined) {
-				slot_name = /** @type {Text[]} */ (attribute.value)[0].data;
-			}
-		}
+		let slot_name = determine_slot(child) ?? 'default';
 
 		(children[slot_name] ||= []).push(child);
 	}
@@ -253,7 +253,15 @@ export function build_component(node, component_name, context, anchor = context.
 					// @ts-expect-error
 					nodes: children[slot_name]
 				},
-				slot_name === 'default' ? child_state : context.state
+				slot_name === 'default'
+					? slot_scope_applies_to_itself
+						? context.state
+						: states.default
+					: {
+							...context.state,
+							scope: node.metadata.scopes[slot_name],
+							getters: { ...context.state.getters }
+						}
 				// {
 				// 	...context.state,
 				// 	scope:
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/element.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/element.js
index 28d6684a576c..7d5c61c05602 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/element.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/element.js
@@ -101,7 +101,7 @@ export function build_attribute_value(value, context) {
 		}
 
 		return {
-			has_state: chunk.metadata.expression.has_call,
+			has_state: chunk.metadata.expression.has_state,
 			has_call: chunk.metadata.expression.has_call,
 			value: /** @type {Expression} */ (context.visit(chunk.expression))
 		};
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
index cf604ad9568b..ce2eb246ee61 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
@@ -26,7 +26,7 @@ export function build_inline_component(node, expression, context) {
 	 */
 	const child_state = {
 		...context.state,
-		scope: node.metadata.default_scope
+		scope: node.metadata.scopes.default
 	};
 
 	/** @type {Record<string, TemplateNode[]>} */
@@ -153,7 +153,12 @@ export function build_inline_component(node, expression, context) {
 					// @ts-expect-error
 					nodes: children[slot_name]
 				},
-				slot_name === 'default' ? child_state : context.state
+				slot_name === 'default'
+					? child_state
+					: {
+							...context.state,
+							scope: node.metadata.scopes[slot_name]
+						}
 				// {
 				// 	...context.state,
 				// 	scope:
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index e181e2e0f730..1d3876203d9d 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -1,6 +1,6 @@
 /** @import { ClassDeclaration, Expression, FunctionDeclaration, Identifier, ImportDeclaration, MemberExpression, Node, Pattern, VariableDeclarator } from 'estree' */
 /** @import { Context, Visitor } from 'zimmerframe' */
-/** @import { AnimateDirective, Binding, DeclarationKind, EachBlock, ElementLike, LetDirective, SvelteNode, TransitionDirective, UseDirective } from '#compiler' */
+/** @import { AnimateDirective, Attribute, Binding, DeclarationKind, EachBlock, ElementLike, LetDirective, SvelteNode, TransitionDirective, UseDirective } from '#compiler' */
 import is_reference from 'is-reference';
 import { walk } from 'zimmerframe';
 import { is_element_node } from './nodes.js';
@@ -14,6 +14,7 @@ import {
 	unwrap_pattern
 } from '../utils/ast.js';
 import { is_reserved, is_rune } from '../../utils.js';
+import { determine_slot } from '../utils/slot.js';
 
 export class Scope {
 	/** @type {ScopeRoot} */
@@ -301,29 +302,37 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 	 * @type {Visitor<ElementLike, State, SvelteNode>}
 	 */
 	const Component = (node, context) => {
-		const scope = context.state.scope.child();
-		node.metadata.default_scope = scope;
+		node.metadata.scopes = {
+			default: context.state.scope.child()
+		};
+
+		const default_state = !!determine_slot(node)
+			? context.state
+			: { scope: node.metadata.scopes.default };
 		// scopes.set(node, scope);
 
 		for (const attribute of node.attributes) {
 			if (attribute.type === 'LetDirective') {
-				context.visit(attribute, { scope });
+				context.visit(attribute, default_state);
 			} else {
 				context.visit(attribute);
 			}
 		}
 
 		for (const child of node.fragment.nodes) {
-			if (
-				is_element_node(child) &&
-				child.attributes.some(
-					(a) => a.type === 'Attribute' && a.name === 'slot' && is_text_attribute(a)
-				)
-			) {
-				context.visit(child);
-			} else {
-				context.visit(child, { scope });
+			let state = default_state;
+
+			const slot_name = determine_slot(child);
+
+			if (slot_name !== null) {
+				node.metadata.scopes[slot_name] = context.state.scope.child();
+
+				state = {
+					scope: node.metadata.scopes[slot_name]
+				};
 			}
+
+			context.visit(child, state);
 		}
 
 		// // let:x is super weird:
diff --git a/packages/svelte/src/compiler/utils/slot.js b/packages/svelte/src/compiler/utils/slot.js
new file mode 100644
index 000000000000..1c05ec8ee6c3
--- /dev/null
+++ b/packages/svelte/src/compiler/utils/slot.js
@@ -0,0 +1,20 @@
+/** @import { SvelteNode } from '#compiler' */
+import { is_element_node } from '../phases/nodes.js';
+import { is_text_attribute } from './ast.js';
+
+/**
+ * @param {SvelteNode} node
+ */
+export function determine_slot(node) {
+	if (!is_element_node(node)) return null;
+
+	for (const attribute of node.attributes) {
+		if (attribute.type !== 'Attribute') continue;
+		if (attribute.name !== 'slot') continue;
+		if (!is_text_attribute(attribute)) continue;
+
+		return /** @type {string} */ (attribute.value[0].data);
+	}
+
+	return null;
+}

From 6b55ee1cb1519cd16d6e7dcb5b3758c96b211f2d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 7 Aug 2024 23:12:48 -0400
Subject: [PATCH 12/86] tests passing

---
 .../phases/2-analyze/visitors/shared/component.js         | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index 67b5a6d4ff38..cfa3aadbcd56 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -94,13 +94,9 @@ export function visit_component(node, context) {
 			continue;
 		}
 
-		let slot_name = determine_slot(child);
+		let slot_name = determine_slot(child) ?? 'default';
 
-		if (slot_name) {
-			nodes[slot_name] = [...comments, child];
-		} else {
-			nodes.default.push(...comments, child);
-		}
+		(nodes[slot_name] ??= []).push(...comments, child);
 	}
 
 	for (const slot_name in nodes) {

From c74ba5a2529ae342773fdc43a6e102c47022518c Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 07:40:51 -0400
Subject: [PATCH 13/86] remove some stuff

---
 .../src/compiler/phases/3-transform/client/utils.js  | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 88f064834aca..c1cf822e3b6a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -85,18 +85,6 @@ export function build_getter(node, state) {
 		return typeof getter === 'function' ? getter(node) : getter;
 	}
 
-	if (binding.kind === 'prop' || binding.kind === 'bindable_prop') {
-		if (is_prop_source(binding, state)) {
-			return b.call(node);
-		}
-
-		if (binding.prop_alias) {
-			const key = b.key(binding.prop_alias);
-			return b.member(b.id('$$props'), key, key.type === 'Literal');
-		}
-		return b.member(b.id('$$props'), node);
-	}
-
 	if (
 		is_state_source(binding, state) ||
 		binding.kind === 'derived' ||

From 8e7e95b32bf9345caebe4ac46af53d0c14110b0b Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 09:31:03 -0400
Subject: [PATCH 14/86] more

---
 .../3-transform/client/transform-client.js    |  4 +--
 .../phases/3-transform/client/utils.js        | 12 +++----
 .../3-transform/client/visitors/AwaitBlock.js | 36 +++++++------------
 .../client/visitors/BlockStatement.js         |  4 ++-
 .../3-transform/client/visitors/Program.js    |  3 ++
 .../client/visitors/shared/declarations.js    | 27 ++++++++++++++
 6 files changed, 52 insertions(+), 34 deletions(-)
 create mode 100644 packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 2755357bcb83..ff3fd23346f1 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -65,9 +65,9 @@ const visitors = {
 		if (scope && scope !== state.scope) {
 			const getters = { ...state.getters };
 
+			// TODO do this in add_state_transformers and visit_function etc?
 			for (const [name, binding] of scope.declarations) {
-				// if (binding.kind === 'normal') {
-				if (binding.kind !== 'each') {
+				if (binding.kind === 'normal') {
 					delete getters[name];
 				}
 			}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index c1cf822e3b6a..2d9d9bff8801 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -17,6 +17,7 @@ import {
 	PROPS_IS_UPDATED
 } from '../../../../constants.js';
 import { is_ignored, dev } from '../../../state.js';
+import { get_value } from './visitors/shared/declarations.js';
 
 /**
  * @template {ClientTransformState} State
@@ -85,14 +86,6 @@ export function build_getter(node, state) {
 		return typeof getter === 'function' ? getter(node) : getter;
 	}
 
-	if (
-		is_state_source(binding, state) ||
-		binding.kind === 'derived' ||
-		binding.kind === 'legacy_reactive'
-	) {
-		return b.call('$.get', node);
-	}
-
 	return node;
 }
 
@@ -670,6 +663,7 @@ export function with_loc(target, source) {
  */
 export function create_derived_block_argument(node, context) {
 	if (node.type === 'Identifier') {
+		context.state.getters[node.name] = get_value;
 		return { id: node, declarations: null };
 	}
 
@@ -687,6 +681,8 @@ export function create_derived_block_argument(node, context) {
 	const declarations = [b.var(value, create_derived(context.state, b.thunk(block)))];
 
 	for (const id of identifiers) {
+		context.state.getters[id.name] = get_value;
+
 		declarations.push(
 			b.var(id, create_derived(context.state, b.thunk(b.member(b.call('$.get', value), id))))
 		);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
index 21f16f3449bf..f956a5cf3044 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
@@ -1,4 +1,4 @@
-/** @import { BlockStatement, Expression, Pattern } from 'estree' */
+/** @import { BlockStatement, Expression, Pattern, Statement } from 'estree' */
 /** @import { AwaitBlock } from '#compiler' */
 /** @import { ComponentContext } from '../types' */
 import * as b from '../../../../utils/builders.js';
@@ -15,39 +15,29 @@ export function AwaitBlock(node, context) {
 	let catch_block;
 
 	if (node.then) {
+		const argument = node.value && create_derived_block_argument(node.value, context);
+
 		/** @type {Pattern[]} */
 		const args = [b.id('$$anchor')];
-		const block = /** @type {BlockStatement} */ (context.visit(node.then));
-
-		if (node.value) {
-			const argument = create_derived_block_argument(node.value, context);
+		if (argument) args.push(argument.id);
 
-			args.push(argument.id);
-
-			if (argument.declarations !== null) {
-				block.body.unshift(...argument.declarations);
-			}
-		}
+		const declarations = argument?.declarations ?? [];
+		const block = /** @type {BlockStatement} */ (context.visit(node.then));
 
-		then_block = b.arrow(args, block);
+		then_block = b.arrow(args, b.block([...declarations, ...block.body]));
 	}
 
 	if (node.catch) {
+		const argument = node.error && create_derived_block_argument(node.error, context);
+
 		/** @type {Pattern[]} */
 		const args = [b.id('$$anchor')];
-		const block = /** @type {BlockStatement} */ (context.visit(node.catch));
-
-		if (node.error) {
-			const argument = create_derived_block_argument(node.error, context);
+		if (argument) args.push(argument.id);
 
-			args.push(argument.id);
-
-			if (argument.declarations !== null) {
-				block.body.unshift(...argument.declarations);
-			}
-		}
+		const declarations = argument?.declarations ?? [];
+		const block = /** @type {BlockStatement} */ (context.visit(node.catch));
 
-		catch_block = b.arrow(args, block);
+		catch_block = b.arrow(args, b.block([...declarations, ...block.body]));
 	}
 
 	context.state.init.push(
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/BlockStatement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/BlockStatement.js
index d5f15ebdf156..502fbd471e6a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/BlockStatement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/BlockStatement.js
@@ -1,10 +1,12 @@
-/** @import { BlockStatement, Expression } from 'estree' */
+/** @import { BlockStatement } from 'estree' */
 /** @import { ComponentContext } from '../types' */
+import { add_state_transformers } from './shared/declarations.js';
 
 /**
  * @param {BlockStatement} node
  * @param {ComponentContext} context
  */
 export function BlockStatement(node, context) {
+	add_state_transformers(context);
 	context.next();
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index 1d850528c566..6954f052831a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -2,6 +2,7 @@
 /** @import { ComponentContext } from '../types' */
 import { is_prop_source } from '../utils.js';
 import * as b from '../../../../utils/builders.js';
+import { add_state_transformers } from './shared/declarations.js';
 
 /**
  * @param {Program} node
@@ -28,5 +29,7 @@ export function Program(node, context) {
 		}
 	}
 
+	add_state_transformers(context);
+
 	context.next();
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
new file mode 100644
index 000000000000..80627fd8f3f8
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
@@ -0,0 +1,27 @@
+/** @import { Identifier } from 'estree' */
+/** @import { ComponentContext, Context } from '../../types' */
+import { is_state_source } from '../../utils.js';
+import * as b from '../../../../../utils/builders.js';
+
+/**
+ * @param {Identifier} node
+ */
+export function get_value(node) {
+	return b.call('$.get', node);
+}
+
+/**
+ *
+ * @param {Context | ComponentContext} context
+ */
+export function add_state_transformers(context) {
+	for (const [name, binding] of context.state.scope.declarations) {
+		if (
+			is_state_source(binding, context.state) ||
+			binding.kind === 'derived' ||
+			binding.kind === 'legacy_reactive'
+		) {
+			context.state.getters[name] = get_value;
+		}
+	}
+}

From 690f012b644ec21ac7d9f4bb81e5bf5c0bc5c08b Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 11:17:15 -0400
Subject: [PATCH 15/86] fix

---
 .../phases/3-transform/client/transform-client.js     |  6 ------
 .../3-transform/client/visitors/RegularElement.js     | 11 ++++++++---
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index ff3fd23346f1..068788477a66 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -209,12 +209,6 @@ export function client_component(analysis, options) {
 		is_instance: true
 	};
 
-	for (const [name, binding] of instance_state.scope.declarations) {
-		if (binding.kind === 'store_sub') {
-			// instance_state.getters[name] = (node) => b.call(node);
-		}
-	}
-
 	const instance = /** @type {ESTree.Program} */ (
 		walk(/** @type {SvelteNode} */ (analysis.instance.ast), instance_state, visitors)
 	);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
index 20630277821a..92c3e6071f6a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
@@ -100,6 +100,13 @@ export function RegularElement(node, context) {
 		metadata.context.template_needs_import_node = true;
 	}
 
+	// visit let directives first, to set state
+	for (const attribute of node.attributes) {
+		if (attribute.type === 'LetDirective') {
+			lets.push(/** @type {ExpressionStatement} */ (context.visit(attribute)));
+		}
+	}
+
 	for (const attribute of node.attributes) {
 		if (attribute.type === 'Attribute') {
 			attributes.push(attribute);
@@ -136,8 +143,6 @@ export function RegularElement(node, context) {
 			class_directives.push(attribute);
 		} else if (attribute.type === 'StyleDirective') {
 			style_directives.push(attribute);
-		} else if (attribute.type === 'LetDirective') {
-			lets.push(/** @type {ExpressionStatement} */ (context.visit(attribute)));
 		} else if (attribute.type === 'OnDirective') {
 			const handler = /** @type {Expression} */ (context.visit(attribute));
 			const has_action_directive = node.attributes.find((a) => a.type === 'UseDirective');
@@ -145,7 +150,7 @@ export function RegularElement(node, context) {
 			context.state.after_update.push(
 				b.stmt(has_action_directive ? b.call('$.effect', b.thunk(handler)) : handler)
 			);
-		} else {
+		} else if (attribute.type !== 'LetDirective') {
 			if (attribute.type === 'BindDirective') {
 				if (attribute.name === 'group' || attribute.name === 'checked') {
 					needs_special_value_handling = true;

From 7192ece1debb1c328311ed8041c0ddc5d89329d7 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 11:24:02 -0400
Subject: [PATCH 16/86] tidy up

---
 .../phases/2-analyze/visitors/shared/component.js     | 11 ++++-------
 packages/svelte/src/compiler/phases/scope.js          |  4 ++--
 packages/svelte/src/compiler/types/template.d.ts      |  8 ++++++++
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index cfa3aadbcd56..27e2ea561d9b 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -1,13 +1,8 @@
-/** @import { Component, SvelteComponent, SvelteSelf } from '#compiler' */
+/** @import { Component, Fragment, SvelteComponent, SvelteSelf } from '#compiler' */
 /** @import { Context } from '../../types' */
 import * as e from '../../../../errors.js';
-import {
-	get_attribute_expression,
-	is_expression_attribute,
-	is_text_attribute
-} from '../../../../utils/ast.js';
+import { get_attribute_expression, is_expression_attribute } from '../../../../utils/ast.js';
 import { determine_slot } from '../../../../utils/slot.js';
-import { is_element_node } from '../../../nodes.js';
 import {
 	validate_attribute,
 	validate_attribute_name,
@@ -84,6 +79,8 @@ export function visit_component(node, context) {
 	}
 
 	const comments = [];
+
+	/** @type {Record<string, Fragment['nodes']>} */
 	const nodes = {
 		default: []
 	};
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index 1d3876203d9d..9a04b8761c28 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -1,6 +1,6 @@
 /** @import { ClassDeclaration, Expression, FunctionDeclaration, Identifier, ImportDeclaration, MemberExpression, Node, Pattern, VariableDeclarator } from 'estree' */
 /** @import { Context, Visitor } from 'zimmerframe' */
-/** @import { AnimateDirective, Attribute, Binding, DeclarationKind, EachBlock, ElementLike, LetDirective, SvelteNode, TransitionDirective, UseDirective } from '#compiler' */
+/** @import { AnimateDirective, Attribute, Binding, Component, DeclarationKind, EachBlock, ElementLike, LetDirective, SvelteComponent, SvelteNode, SvelteSelf, TransitionDirective, UseDirective } from '#compiler' */
 import is_reference from 'is-reference';
 import { walk } from 'zimmerframe';
 import { is_element_node } from './nodes.js';
@@ -299,7 +299,7 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 	};
 
 	/**
-	 * @type {Visitor<ElementLike, State, SvelteNode>}
+	 * @type {Visitor<Component | SvelteComponent | SvelteSelf, State, SvelteNode>}
 	 */
 	const Component = (node, context) => {
 		node.metadata.scopes = {
diff --git a/packages/svelte/src/compiler/types/template.d.ts b/packages/svelte/src/compiler/types/template.d.ts
index 86341d07d007..20fdb25ee418 100644
--- a/packages/svelte/src/compiler/types/template.d.ts
+++ b/packages/svelte/src/compiler/types/template.d.ts
@@ -16,6 +16,7 @@ import type {
 	ChainExpression,
 	SimpleCallExpression
 } from 'estree';
+import type { Scope } from '../phases/scope';
 
 export interface BaseNode {
 	type: string;
@@ -275,6 +276,7 @@ interface BaseElement extends BaseNode {
 export interface Component extends BaseElement {
 	type: 'Component';
 	metadata: {
+		scopes: Record<string, Scope>;
 		dynamic: boolean;
 	};
 }
@@ -311,6 +313,9 @@ export interface SvelteComponent extends BaseElement {
 	type: 'SvelteComponent';
 	name: 'svelte:component';
 	expression: Expression;
+	metadata: {
+		scopes: Record<string, Scope>;
+	};
 }
 
 interface SvelteDocument extends BaseElement {
@@ -356,6 +361,9 @@ export interface SvelteOptionsRaw extends BaseElement {
 export interface SvelteSelf extends BaseElement {
 	type: 'SvelteSelf';
 	name: 'svelte:self';
+	metadata: {
+		scopes: Record<string, Scope>;
+	};
 }
 
 interface SvelteWindow extends BaseElement {

From e8ec10d98d56a187b49fb471f1d5189882a52502 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 12:24:10 -0400
Subject: [PATCH 17/86] simplify

---
 .../compiler/phases/3-transform/client/types.d.ts   |  2 +-
 .../src/compiler/phases/3-transform/client/utils.js |  2 +-
 .../phases/3-transform/client/visitors/ConstTag.js  |  7 ++++---
 .../phases/3-transform/client/visitors/EachBlock.js | 11 ++++++-----
 .../3-transform/client/visitors/LetDirective.js     |  6 ++----
 .../3-transform/client/visitors/SnippetBlock.js     |  7 ++++---
 .../client/visitors/shared/declarations.js          |  1 +
 .../3-transform/client/visitors/shared/utils.js     | 13 ++++++++-----
 8 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index 0284c82d1ee6..251c4a15bdd2 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -28,7 +28,7 @@ export interface ClientTransformState extends TransformState {
 	 * A map of `[name, node]` pairs, where `Identifier` nodes matching `name`
 	 * will be replaced with `node` (e.g. `x` -> `$.get(x)`)
 	 */
-	readonly getters: Record<string, Expression | ((id: Identifier) => Expression)>;
+	readonly getters: Record<string, (id: Identifier) => Expression>;
 	/**
 	 * Counterpart to `getters`
 	 */
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 2d9d9bff8801..00131991e2de 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -464,7 +464,7 @@ function get_hoisted_params(node, context) {
 				binding = /** @type {Binding} */ (scope.get(binding.node.name.slice(1)));
 			}
 
-			const expression = context.state.getters[reference];
+			let expression = context.state.getters[reference]?.(b.id(binding.node.name));
 
 			if (
 				// If it's a destructured derived binding, then we can extract the derived signal reference and use that.
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
index 10623ce3f5c0..d93bdc2c2f69 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
@@ -5,6 +5,7 @@ import { dev } from '../../../../state.js';
 import { extract_identifiers } from '../../../../utils/ast.js';
 import * as b from '../../../../utils/builders.js';
 import { create_derived } from '../utils.js';
+import { get_value } from './shared/declarations.js';
 
 /**
  * @param {ConstTag} node
@@ -24,7 +25,7 @@ export function ConstTag(node, context) {
 			)
 		);
 
-		context.state.getters[declaration.id.name] = b.call('$.get', declaration.id);
+		context.state.getters[declaration.id.name] = get_value;
 
 		// we need to eagerly evaluate the expression in order to hit any
 		// 'Cannot access x before initialization' errors
@@ -40,7 +41,7 @@ export function ConstTag(node, context) {
 		// Make all identifiers that are declared within the following computed regular
 		// variables, as they are not signals in that context yet
 		for (const node of identifiers) {
-			getters[node.name] = node;
+			delete getters[node.name];
 		}
 
 		const child_state = { ...context.state, getters };
@@ -67,7 +68,7 @@ export function ConstTag(node, context) {
 		}
 
 		for (const node of identifiers) {
-			context.state.getters[node.name] = b.member(b.call('$.get', tmp), node);
+			context.state.getters[node.name] = (node) => b.member(b.call('$.get', tmp), node);
 		}
 	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index 665522683b2b..5db5d646ac20 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -14,6 +14,7 @@ import { dev } from '../../../../state.js';
 import { extract_paths, object } from '../../../../utils/ast.js';
 import * as b from '../../../../utils/builders.js';
 import { get_assignment_value, build_getter, build_setter, with_loc } from '../utils.js';
+import { get_value } from './shared/declarations.js';
 
 /**
  * @param {EachBlock} node
@@ -187,7 +188,7 @@ export function EachBlock(node, context) {
 			return (flags & EACH_INDEX_REACTIVE) === 0 ? index_with_loc : b.call('$.get', index_with_loc);
 		};
 
-		key_state.getters[node.index] = b.id(node.index);
+		delete key_state.getters[node.index];
 	}
 
 	/** @type {Statement[]} */
@@ -202,7 +203,7 @@ export function EachBlock(node, context) {
 			)
 		);
 
-		key_state.getters[node.context.name] = node.context;
+		delete key_state.getters[node.context.name];
 	} else {
 		const unwrapped = getter(binding.node);
 		const paths = extract_paths(node.context);
@@ -217,7 +218,7 @@ export function EachBlock(node, context) {
 
 			declarations.push(b.let(path.node, needs_derived ? b.call('$.derived_safe_equal', fn) : fn));
 
-			const getter = needs_derived ? b.call('$.get', b.id(name)) : b.call(name);
+			const getter = needs_derived ? get_value : b.call;
 			child_state.getters[name] = getter;
 			child_state.setters[name] = create_mutation(
 				/** @type {Pattern} */ (path.update_expression(unwrapped))
@@ -226,10 +227,10 @@ export function EachBlock(node, context) {
 			// we need to eagerly evaluate the expression in order to hit any
 			// 'Cannot access x before initialization' errors
 			if (dev) {
-				declarations.push(b.stmt(getter));
+				declarations.push(b.stmt(getter(b.id(name))));
 			}
 
-			key_state.getters[name] = path.node;
+			key_state.getters[name] = () => path.node;
 		}
 	}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
index 9d42317bda46..0772dd9948d5 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
@@ -16,10 +16,8 @@ export function LetDirective(node, context) {
 		const bindings = context.state.scope.get_bindings(node);
 
 		for (const binding of bindings) {
-			context.state.getters[binding.node.name] = b.member(
-				b.call('$.get', b.id(name)),
-				b.id(binding.node.name)
-			);
+			context.state.getters[binding.node.name] = (node) =>
+				b.member(b.call('$.get', b.id(name)), node);
 		}
 
 		return b.const(
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
index cdb745544744..62b99bbe0b31 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
@@ -4,6 +4,7 @@
 import { dev } from '../../../../state.js';
 import { extract_paths } from '../../../../utils/ast.js';
 import * as b from '../../../../utils/builders.js';
+import { get_value } from './shared/declarations.js';
 
 /**
  * @param {SnippetBlock} node
@@ -35,7 +36,7 @@ export function SnippetBlock(node, context) {
 				right: b.id('$.noop')
 			});
 
-			getters[argument.name] = b.call(argument);
+			getters[argument.name] = b.call;
 			continue;
 		}
 
@@ -53,12 +54,12 @@ export function SnippetBlock(node, context) {
 
 			declarations.push(b.let(path.node, needs_derived ? b.call('$.derived_safe_equal', fn) : fn));
 
-			getters[name] = needs_derived ? b.call('$.get', b.id(name)) : b.call(name);
+			getters[name] = needs_derived ? get_value : b.call;
 
 			// we need to eagerly evaluate the expression in order to hit any
 			// 'Cannot access x before initialization' errors
 			if (dev) {
-				declarations.push(b.stmt(getters[name]));
+				declarations.push(b.stmt(getters[name](b.id(name))));
 			}
 		}
 	}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
index 80627fd8f3f8..2f368d7d33b8 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
@@ -4,6 +4,7 @@ import { is_state_source } from '../../utils.js';
 import * as b from '../../../../../utils/builders.js';
 
 /**
+ * Turns `foo` into `$.get(foo)`
  * @param {Identifier} node
  */
 export function get_value(node) {
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
index 874ebe31314b..3c6a06f504d7 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
@@ -145,8 +145,10 @@ export function build_bind_this(expression, value, { state, visit }) {
 	/** @type {Expression[]} */
 	const values = [];
 
-	/** @type {typeof state.getters} */
-	const getters = {};
+	/** @type {string[]} */
+	const seen = [];
+
+	const getters = { ...state.getters };
 
 	// Pass in each context variables to the get/set functions, so that we can null out old values on teardown.
 	// Note that we only do this for each context variables, the consequence is that the value might be stale in
@@ -154,7 +156,8 @@ export function build_bind_this(expression, value, { state, visit }) {
 	// variables, but that was the same case in Svelte 4, too. Once legacy mode is gone completely, we can revisit this.
 	walk(expression, null, {
 		Identifier(node, { path }) {
-			if (Object.hasOwn(getters, node.name)) return;
+			if (seen.includes(node.name)) return;
+			seen.push(node.name);
 
 			const parent = /** @type {Expression} */ (path.at(-1));
 			if (!is_reference(node, parent)) return;
@@ -166,14 +169,14 @@ export function build_bind_this(expression, value, { state, visit }) {
 				if (owner.type === 'EachBlock' && scope === binding.scope) {
 					ids.push(node);
 					values.push(/** @type {Expression} */ (visit(node)));
-					getters[node.name] = node;
+					delete getters[node.name];
 					break;
 				}
 			}
 		}
 	});
 
-	const child_state = { ...state, getters: { ...state.getters, ...getters } };
+	const child_state = { ...state, getters };
 
 	const get = /** @type {Expression} */ (visit(expression, child_state));
 	const set = /** @type {Expression} */ (

From 804772f6d4dc697f187f2463988a3a8b35e97319 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 13:26:33 -0400
Subject: [PATCH 18/86] simplify

---
 .../compiler/phases/3-transform/client/utils.js   | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 00131991e2de..ee094a1fcd3f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -74,16 +74,13 @@ export function is_state_source(binding, state) {
  * @returns {Expression}
  */
 export function build_getter(node, state) {
-	const binding = state.scope.get(node.name);
-
-	if (binding === null || node === binding.node) {
-		// No associated binding or the declaration itself which shouldn't be transformed
-		return node;
-	}
-
 	if (Object.hasOwn(state.getters, node.name)) {
-		const getter = state.getters[node.name];
-		return typeof getter === 'function' ? getter(node) : getter;
+		const binding = state.scope.get(node.name);
+
+		// don't transform the declaration itself
+		if (node !== binding?.node) {
+			return state.getters[node.name](node);
+		}
 	}
 
 	return node;

From 8b3832685865dd50afab6bb3f084133a38182652 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 13:44:26 -0400
Subject: [PATCH 19/86] getters -> transformers

---
 .../3-transform/client/transform-client.js    | 22 ++++++++-----
 .../phases/3-transform/client/types.d.ts      | 12 ++++---
 .../phases/3-transform/client/utils.js        | 13 +++++---
 .../3-transform/client/visitors/ConstTag.js   | 14 +++++---
 .../3-transform/client/visitors/EachBlock.js  | 33 +++++++++++--------
 .../3-transform/client/visitors/Fragment.js   |  2 +-
 .../client/visitors/LetDirective.js           |  9 +++--
 .../3-transform/client/visitors/Program.js    | 15 +++++----
 .../client/visitors/SnippetBlock.js           | 15 ++++++---
 .../client/visitors/shared/component.js       |  4 +--
 .../client/visitors/shared/declarations.js    |  4 ++-
 .../client/visitors/shared/utils.js           |  6 ++--
 12 files changed, 91 insertions(+), 58 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 068788477a66..594a7144ca26 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -63,16 +63,16 @@ const visitors = {
 		const scope = state.scopes.get(node);
 
 		if (scope && scope !== state.scope) {
-			const getters = { ...state.getters };
+			const transformers = { ...state.transformers };
 
 			// TODO do this in add_state_transformers and visit_function etc?
 			for (const [name, binding] of scope.declarations) {
 				if (binding.kind === 'normal') {
-					delete getters[name];
+					delete transformers[name];
 				}
 			}
 
-			next({ ...state, getters, scope });
+			next({ ...state, transformers, scope });
 		} else {
 			next();
 		}
@@ -156,7 +156,7 @@ export function client_component(analysis, options) {
 		preserve_whitespace: options.preserveWhitespace,
 		public_state: new Map(),
 		private_state: new Map(),
-		getters: {},
+		transformers: {},
 		setters: {},
 		in_constructor: false,
 
@@ -173,12 +173,16 @@ export function client_component(analysis, options) {
 	const legacy_reactive_imports = [];
 
 	if (!analysis.runes) {
-		state.getters['$$props'] = (node) => ({ ...node, name: '$$sanitized_props' });
+		state.transformers['$$props'] = {
+			read: (node) => ({ ...node, name: '$$sanitized_props' })
+		};
 
 		for (const [name, binding] of state.scope.declarations) {
 			// Very very dirty way of making import statements reactive in legacy mode if needed
 			if (binding.declaration_kind === 'import' && binding.mutated) {
-				state.getters[name] = (node) => b.call('$$_import_' + node.name);
+				state.transformers[name] = {
+					read: (node) => b.call('$$_import_' + node.name)
+				};
 
 				state.setters[name] = (node, context) =>
 					b.call(
@@ -203,7 +207,7 @@ export function client_component(analysis, options) {
 
 	const instance_state = {
 		...state,
-		getters: { ...state.getters },
+		transformers: { ...state.transformers },
 		scope: analysis.instance.scope,
 		scopes: analysis.instance.scopes,
 		is_instance: true
@@ -218,7 +222,7 @@ export function client_component(analysis, options) {
 			/** @type {SvelteNode} */ (analysis.template.ast),
 			{
 				...state,
-				getters: instance_state.getters,
+				transformers: instance_state.transformers,
 				scope: analysis.instance.scope,
 				scopes: analysis.template.scopes
 			},
@@ -669,7 +673,7 @@ export function client_module(analysis, options) {
 		legacy_reactive_statements: new Map(),
 		public_state: new Map(),
 		private_state: new Map(),
-		getters: {},
+		transformers: {},
 		setters: {},
 		in_constructor: false
 	};
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index 251c4a15bdd2..b2ce9655be55 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -24,11 +24,13 @@ export interface ClientTransformState extends TransformState {
 
 	/** The $: calls, which will be ordered in the end */
 	readonly legacy_reactive_statements: Map<LabeledStatement, Statement>;
-	/**
-	 * A map of `[name, node]` pairs, where `Identifier` nodes matching `name`
-	 * will be replaced with `node` (e.g. `x` -> `$.get(x)`)
-	 */
-	readonly getters: Record<string, (id: Identifier) => Expression>;
+	readonly transformers: Record<
+		string,
+		{
+			/** a function that turns `foo` into e.g. `$.get(foo)` */
+			read: (id: Identifier) => Expression;
+		}
+	>;
 	/**
 	 * Counterpart to `getters`
 	 */
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index ee094a1fcd3f..f1a0f3c7f080 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -74,12 +74,12 @@ export function is_state_source(binding, state) {
  * @returns {Expression}
  */
 export function build_getter(node, state) {
-	if (Object.hasOwn(state.getters, node.name)) {
+	if (Object.hasOwn(state.transformers, node.name)) {
 		const binding = state.scope.get(node.name);
 
 		// don't transform the declaration itself
 		if (node !== binding?.node) {
-			return state.getters[node.name](node);
+			return state.transformers[node.name].read(node);
 		}
 	}
 
@@ -461,7 +461,7 @@ function get_hoisted_params(node, context) {
 				binding = /** @type {Binding} */ (scope.get(binding.node.name.slice(1)));
 			}
 
-			let expression = context.state.getters[reference]?.(b.id(binding.node.name));
+			let expression = context.state.transformers[reference]?.read(b.id(binding.node.name));
 
 			if (
 				// If it's a destructured derived binding, then we can extract the derived signal reference and use that.
@@ -660,7 +660,10 @@ export function with_loc(target, source) {
  */
 export function create_derived_block_argument(node, context) {
 	if (node.type === 'Identifier') {
-		context.state.getters[node.name] = get_value;
+		context.state.transformers[node.name] = {
+			read: get_value
+		};
+
 		return { id: node, declarations: null };
 	}
 
@@ -678,7 +681,7 @@ export function create_derived_block_argument(node, context) {
 	const declarations = [b.var(value, create_derived(context.state, b.thunk(block)))];
 
 	for (const id of identifiers) {
-		context.state.getters[id.name] = get_value;
+		context.state.transformers[id.name] = { read: get_value };
 
 		declarations.push(
 			b.var(id, create_derived(context.state, b.thunk(b.member(b.call('$.get', value), id))))
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
index d93bdc2c2f69..8d8a8beb0f1b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
@@ -25,7 +25,9 @@ export function ConstTag(node, context) {
 			)
 		);
 
-		context.state.getters[declaration.id.name] = get_value;
+		context.state.transformers[declaration.id.name] = {
+			read: get_value
+		};
 
 		// we need to eagerly evaluate the expression in order to hit any
 		// 'Cannot access x before initialization' errors
@@ -36,15 +38,15 @@ export function ConstTag(node, context) {
 		const identifiers = extract_identifiers(declaration.id);
 		const tmp = b.id(context.state.scope.generate('computed_const'));
 
-		const getters = { ...context.state.getters };
+		const transformers = { ...context.state.transformers };
 
 		// Make all identifiers that are declared within the following computed regular
 		// variables, as they are not signals in that context yet
 		for (const node of identifiers) {
-			delete getters[node.name];
+			delete transformers[node.name];
 		}
 
-		const child_state = { ...context.state, getters };
+		const child_state = { ...context.state, transformers };
 
 		// TODO optimise the simple `{ x } = y` case — we can just return `y`
 		// instead of destructuring it only to return a new object
@@ -68,7 +70,9 @@ export function ConstTag(node, context) {
 		}
 
 		for (const node of identifiers) {
-			context.state.getters[node.name] = (node) => b.member(b.call('$.get', tmp), node);
+			context.state.transformers[node.name] = {
+				read: (node) => b.member(b.call('$.get', tmp), node)
+			};
 		}
 	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index 5db5d646ac20..c82a95f5902e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -120,14 +120,14 @@ export function EachBlock(node, context) {
 
 	const child_state = {
 		...context.state,
-		getters: { ...context.state.getters },
+		transformers: { ...context.state.transformers },
 		setters: { ...context.state.setters }
 	};
 
 	/** The state used when generating the key function, if necessary */
 	const key_state = {
 		...context.state,
-		getters: { ...context.state.getters }
+		transformers: { ...context.state.transformers }
 	};
 
 	/**
@@ -180,15 +180,21 @@ export function EachBlock(node, context) {
 		const item_with_loc = with_loc(item, id);
 		return b.call('$.unwrap', item_with_loc);
 	};
-	child_state.getters[item.name] = getter;
+	child_state.transformers[item.name] = {
+		read: getter
+	};
 
 	if (node.index) {
-		child_state.getters[node.index] = (id) => {
-			const index_with_loc = with_loc(index, id);
-			return (flags & EACH_INDEX_REACTIVE) === 0 ? index_with_loc : b.call('$.get', index_with_loc);
+		child_state.transformers[node.index] = {
+			read: (id) => {
+				const index_with_loc = with_loc(index, id);
+				return (flags & EACH_INDEX_REACTIVE) === 0
+					? index_with_loc
+					: b.call('$.get', index_with_loc);
+			}
 		};
 
-		delete key_state.getters[node.index];
+		delete key_state.transformers[node.index];
 	}
 
 	/** @type {Statement[]} */
@@ -203,14 +209,13 @@ export function EachBlock(node, context) {
 			)
 		);
 
-		delete key_state.getters[node.context.name];
+		delete key_state.transformers[node.context.name];
 	} else {
 		const unwrapped = getter(binding.node);
 		const paths = extract_paths(node.context);
 
 		for (const path of paths) {
 			const name = /** @type {Identifier} */ (path.node).name;
-			const binding = /** @type {Binding} */ (context.state.scope.get(name));
 			const needs_derived = path.has_default_value; // to ensure that default value is only called once
 			const fn = b.thunk(
 				/** @type {Expression} */ (context.visit(path.expression?.(unwrapped), child_state))
@@ -218,8 +223,8 @@ export function EachBlock(node, context) {
 
 			declarations.push(b.let(path.node, needs_derived ? b.call('$.derived_safe_equal', fn) : fn));
 
-			const getter = needs_derived ? get_value : b.call;
-			child_state.getters[name] = getter;
+			const read = needs_derived ? get_value : b.call;
+			child_state.transformers[name] = { read };
 			child_state.setters[name] = create_mutation(
 				/** @type {Pattern} */ (path.update_expression(unwrapped))
 			);
@@ -227,10 +232,12 @@ export function EachBlock(node, context) {
 			// we need to eagerly evaluate the expression in order to hit any
 			// 'Cannot access x before initialization' errors
 			if (dev) {
-				declarations.push(b.stmt(getter(b.id(name))));
+				declarations.push(b.stmt(read(b.id(name))));
 			}
 
-			key_state.getters[name] = () => path.node;
+			key_state.transformers[name] = {
+				read: () => path.node
+			};
 		}
 	}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
index 1696d9213eaf..a842ba07ee52 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
@@ -66,7 +66,7 @@ export function Fragment(node, context) {
 		after_update: [],
 		template: [],
 		locations: [],
-		getters: { ...context.state.getters },
+		transformers: { ...context.state.transformers },
 		metadata: {
 			context: {
 				template_needs_import_node: false,
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
index 0772dd9948d5..e4d6d06acf6f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
@@ -16,8 +16,9 @@ export function LetDirective(node, context) {
 		const bindings = context.state.scope.get_bindings(node);
 
 		for (const binding of bindings) {
-			context.state.getters[binding.node.name] = (node) =>
-				b.member(b.call('$.get', b.id(name)), node);
+			context.state.transformers[binding.node.name] = {
+				read: (node) => b.member(b.call('$.get', b.id(name)), node)
+			};
 		}
 
 		return b.const(
@@ -41,7 +42,9 @@ export function LetDirective(node, context) {
 		);
 	} else {
 		const name = node.expression === null ? node.name : node.expression.name;
-		context.state.getters[name] = (node) => b.call('$.get', node);
+		context.state.transformers[name] = {
+			read: (node) => b.call('$.get', node)
+		};
 
 		return b.const(
 			name,
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index 6954f052831a..a2c967edb75b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -1,4 +1,4 @@
-/** @import { Program, Expression } from 'estree' */
+/** @import { Program } from 'estree' */
 /** @import { ComponentContext } from '../types' */
 import { is_prop_source } from '../utils.js';
 import * as b from '../../../../utils/builders.js';
@@ -12,18 +12,21 @@ export function Program(node, context) {
 	if (context.state.is_instance) {
 		for (const [name, binding] of context.state.scope.declarations) {
 			if (binding.kind === 'store_sub') {
-				context.state.getters[name] = (node) => b.call(node);
+				context.state.transformers[name] = { read: b.call };
 			}
 
 			if (binding.kind === 'prop' || binding.kind === 'bindable_prop') {
 				if (is_prop_source(binding, context.state)) {
-					context.state.getters[name] = (node) => b.call(node);
+					context.state.transformers[name] = { read: b.call };
 				} else if (binding.prop_alias) {
 					const key = b.key(binding.prop_alias);
-					context.state.getters[name] = (node) =>
-						b.member(b.id('$$props'), key, key.type === 'Literal');
+					context.state.transformers[name] = {
+						read: (node) => b.member(b.id('$$props'), key, key.type === 'Literal')
+					};
 				} else {
-					context.state.getters[name] = (node) => b.member(b.id('$$props'), node);
+					context.state.transformers[name] = {
+						read: (node) => b.member(b.id('$$props'), node)
+					};
 				}
 			}
 		}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
index 62b99bbe0b31..d0ac1641be97 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
@@ -21,8 +21,8 @@ export function SnippetBlock(node, context) {
 	/** @type {Statement[]} */
 	const declarations = [];
 
-	const getters = { ...context.state.getters };
-	const child_state = { ...context.state, getters };
+	const transformers = { ...context.state.transformers };
+	const child_state = { ...context.state, transformers };
 
 	for (let i = 0; i < node.parameters.length; i++) {
 		const argument = node.parameters[i];
@@ -36,7 +36,10 @@ export function SnippetBlock(node, context) {
 				right: b.id('$.noop')
 			});
 
-			getters[argument.name] = b.call;
+			transformers[argument.name] = {
+				read: b.call
+			};
+
 			continue;
 		}
 
@@ -54,12 +57,14 @@ export function SnippetBlock(node, context) {
 
 			declarations.push(b.let(path.node, needs_derived ? b.call('$.derived_safe_equal', fn) : fn));
 
-			getters[name] = needs_derived ? get_value : b.call;
+			transformers[name] = {
+				read: needs_derived ? get_value : b.call
+			};
 
 			// we need to eagerly evaluate the expression in order to hit any
 			// 'Cannot access x before initialization' errors
 			if (dev) {
-				declarations.push(b.stmt(getters[name](b.id(name))));
+				declarations.push(b.stmt(transformers[name].read(b.id(name))));
 			}
 		}
 	}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index 3d729431fb04..baf9918b975b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -30,7 +30,7 @@ export function build_component(node, component_name, context, anchor = context.
 		default: {
 			...context.state,
 			scope: node.metadata.scopes.default,
-			getters: { ...context.state.getters }
+			transformers: { ...context.state.transformers }
 		}
 	};
 
@@ -260,7 +260,7 @@ export function build_component(node, component_name, context, anchor = context.
 					: {
 							...context.state,
 							scope: node.metadata.scopes[slot_name],
-							getters: { ...context.state.getters }
+							transformers: { ...context.state.transformers }
 						}
 				// {
 				// 	...context.state,
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
index 2f368d7d33b8..7e51b1ce963e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
@@ -22,7 +22,9 @@ export function add_state_transformers(context) {
 			binding.kind === 'derived' ||
 			binding.kind === 'legacy_reactive'
 		) {
-			context.state.getters[name] = get_value;
+			context.state.transformers[name] = {
+				read: get_value
+			};
 		}
 	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
index 3c6a06f504d7..4f865e387efc 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
@@ -148,7 +148,7 @@ export function build_bind_this(expression, value, { state, visit }) {
 	/** @type {string[]} */
 	const seen = [];
 
-	const getters = { ...state.getters };
+	const transformers = { ...state.transformers };
 
 	// Pass in each context variables to the get/set functions, so that we can null out old values on teardown.
 	// Note that we only do this for each context variables, the consequence is that the value might be stale in
@@ -169,14 +169,14 @@ export function build_bind_this(expression, value, { state, visit }) {
 				if (owner.type === 'EachBlock' && scope === binding.scope) {
 					ids.push(node);
 					values.push(/** @type {Expression} */ (visit(node)));
-					delete getters[node.name];
+					delete transformers[node.name];
 					break;
 				}
 			}
 		}
 	});
 
-	const child_state = { ...state, getters };
+	const child_state = { ...state, transformers };
 
 	const get = /** @type {Expression} */ (visit(expression, child_state));
 	const set = /** @type {Expression} */ (

From 099cb880f55dc2b128571fb3b2a4547dfa9474f0 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 14:06:54 -0400
Subject: [PATCH 20/86] update

---
 .../src/compiler/phases/3-transform/client/types.d.ts    | 9 +++++++--
 .../3-transform/client/visitors/UpdateExpression.js      | 6 ++++++
 .../3-transform/client/visitors/shared/declarations.js   | 9 ++++++++-
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index b2ce9655be55..de0d438be51f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -5,7 +5,8 @@ import type {
 	Identifier,
 	PrivateIdentifier,
 	Expression,
-	AssignmentExpression
+	AssignmentExpression,
+	UpdateExpression
 } from 'estree';
 import type { Namespace, SvelteNode, ValidatedCompileOptions } from '#compiler';
 import type { TransformState } from '../types.js';
@@ -27,8 +28,12 @@ export interface ClientTransformState extends TransformState {
 	readonly transformers: Record<
 		string,
 		{
-			/** a function that turns `foo` into e.g. `$.get(foo)` */
+			/** turn `foo` into e.g. `$.get(foo)` */
 			read: (id: Identifier) => Expression;
+			/** turn `foo++` into e.g. `$.update(foo)` */
+			update?: (node: UpdateExpression) => Expression;
+			/** turn `foo.bar++` into e.g. `$.mutate(foo, $.get(foo).bar += 1)` */
+			update_property?: (id: Identifier) => Expression;
 		}
 	>;
 	/**
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
index 5f8685eb3bfb..aeb948c547fd 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
@@ -10,8 +10,14 @@ import { build_getter, build_setter } from '../utils.js';
  */
 export function UpdateExpression(node, context) {
 	const argument = node.argument;
+	const transformers = context.state.transformers;
 
 	if (argument.type === 'Identifier') {
+		if (Object.hasOwn(transformers, argument.name) && transformers[argument.name].update) {
+			const transformer = transformers[argument.name].update;
+			if (transformer) return transformer(node);
+		}
+
 		const binding = context.state.scope.get(argument.name);
 		const is_store = binding?.kind === 'store_sub';
 		const name = is_store ? argument.name.slice(1) : argument.name;
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
index 7e51b1ce963e..5acb2e67410a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
@@ -23,7 +23,14 @@ export function add_state_transformers(context) {
 			binding.kind === 'legacy_reactive'
 		) {
 			context.state.transformers[name] = {
-				read: get_value
+				read: get_value,
+				update: (node) => {
+					return b.call(
+						node.prefix ? '$.update_pre' : '$.update',
+						node.argument,
+						node.operator === '--' && b.literal(-1)
+					);
+				}
 			};
 		}
 	}

From 65f125ea2c13930cc1f9b6fab96b3ca3272dfc2e Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 14:19:18 -0400
Subject: [PATCH 21/86] use update transformers

---
 .../3-transform/client/visitors/Program.js    | 25 +++++++++++--
 .../client/visitors/UpdateExpression.js       | 35 -------------------
 2 files changed, 22 insertions(+), 38 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index a2c967edb75b..fa4af03a5fab 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -1,6 +1,6 @@
 /** @import { Program } from 'estree' */
 /** @import { ComponentContext } from '../types' */
-import { is_prop_source } from '../utils.js';
+import { build_getter, is_prop_source } from '../utils.js';
 import * as b from '../../../../utils/builders.js';
 import { add_state_transformers } from './shared/declarations.js';
 
@@ -12,12 +12,31 @@ export function Program(node, context) {
 	if (context.state.is_instance) {
 		for (const [name, binding] of context.state.scope.declarations) {
 			if (binding.kind === 'store_sub') {
-				context.state.transformers[name] = { read: b.call };
+				context.state.transformers[name] = {
+					read: b.call,
+					update: (node) => {
+						return b.call(
+							node.prefix ? '$.update_pre_store' : '$.update_store',
+							build_getter(b.id(name.slice(1)), context.state),
+							b.call(node.argument),
+							node.operator === '--' && b.literal(-1)
+						);
+					}
+				};
 			}
 
 			if (binding.kind === 'prop' || binding.kind === 'bindable_prop') {
 				if (is_prop_source(binding, context.state)) {
-					context.state.transformers[name] = { read: b.call };
+					context.state.transformers[name] = {
+						read: b.call,
+						update: (node) => {
+							return b.call(
+								node.prefix ? '$.update_pre_prop' : '$.update_prop',
+								node.argument,
+								node.operator === '--' && b.literal(-1)
+							);
+						}
+					};
 				} else if (binding.prop_alias) {
 					const key = b.key(binding.prop_alias);
 					context.state.transformers[name] = {
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
index aeb948c547fd..384b9caa27d6 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
@@ -18,41 +18,6 @@ export function UpdateExpression(node, context) {
 			if (transformer) return transformer(node);
 		}
 
-		const binding = context.state.scope.get(argument.name);
-		const is_store = binding?.kind === 'store_sub';
-		const name = is_store ? argument.name.slice(1) : argument.name;
-
-		// use runtime functions for smaller output
-		if (
-			binding?.kind === 'state' ||
-			binding?.kind === 'frozen_state' ||
-			binding?.kind === 'each' ||
-			binding?.kind === 'legacy_reactive' ||
-			binding?.kind === 'prop' ||
-			binding?.kind === 'bindable_prop' ||
-			is_store
-		) {
-			/** @type {Expression[]} */
-			const args = [];
-
-			let fn = '$.update';
-			if (node.prefix) fn += '_pre';
-
-			if (is_store) {
-				fn += '_store';
-				args.push(build_getter(b.id(name), context.state), b.call('$' + name));
-			} else {
-				if (binding.kind === 'prop' || binding.kind === 'bindable_prop') fn += '_prop';
-				args.push(b.id(name));
-			}
-
-			if (node.operator === '--') {
-				args.push(b.literal(-1));
-			}
-
-			return b.call(fn, ...args);
-		}
-
 		return context.next();
 	}
 

From c4683eaa5e9219b82b6d666749cccb8db87faf92 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 16:50:14 -0400
Subject: [PATCH 22/86] add assign transformer

---
 .../phases/3-transform/client/types.d.ts      |  2 ++
 .../client/visitors/AssignmentExpression.js   | 10 ++++++
 .../client/visitors/shared/declarations.js    | 32 +++++++++++++++++--
 3 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index de0d438be51f..559197c359fd 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -30,6 +30,8 @@ export interface ClientTransformState extends TransformState {
 		{
 			/** turn `foo` into e.g. `$.get(foo)` */
 			read: (id: Identifier) => Expression;
+			/** turn `foo = bar` into e.g. `$.set(foo, bar)` */
+			assign?: (node: AssignmentExpression, visit: (node: SvelteNode) => SvelteNode) => Expression;
 			/** turn `foo++` into e.g. `$.update(foo)` */
 			update?: (node: UpdateExpression) => Expression;
 			/** turn `foo.bar++` into e.g. `$.mutate(foo, $.get(foo).bar += 1)` */
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index fefc11bf1f34..208b5bedb0c0 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -7,5 +7,15 @@ import { build_setter } from '../utils.js';
  * @param {Context} context
  */
 export function AssignmentExpression(node, context) {
+	if (node.left.type === 'Identifier') {
+		if (Object.hasOwn(context.state.transformers, node.left.name)) {
+			const transformer = context.state.transformers[node.left.name]?.assign;
+
+			if (transformer) {
+				return transformer(node, context.visit);
+			}
+		}
+	}
+
 	return build_setter(node, context, context.next);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
index 5acb2e67410a..b0884acb8d95 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
@@ -1,6 +1,6 @@
-/** @import { Identifier } from 'estree' */
+/** @import { BinaryOperator, Expression, Identifier } from 'estree' */
 /** @import { ComponentContext, Context } from '../../types' */
-import { is_state_source } from '../../utils.js';
+import { build_proxy_reassignment, is_state_source, should_proxy_or_freeze } from '../../utils.js';
 import * as b from '../../../../../utils/builders.js';
 
 /**
@@ -24,6 +24,34 @@ export function add_state_transformers(context) {
 		) {
 			context.state.transformers[name] = {
 				read: get_value,
+				assign: (node, visit) => {
+					let left = /** @type {Identifier} */ (node.left);
+					let value = /** @type {Expression} */ (visit(node.right));
+
+					if (node.operator !== '=') {
+						value = b.binary(
+							/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
+							/** @type {Expression} */ (visit(left)),
+							value
+						);
+					}
+
+					if (context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)) {
+						if (binding.kind === 'frozen_state') {
+							value = b.call('$.freeze', value);
+						} else {
+							value = build_proxy_reassignment(value, left.name);
+						}
+					}
+
+					let call = b.call('$.set', left, value);
+
+					if (context.state.scope.get(`$${left.name}`)?.kind === 'store_sub') {
+						call = b.call('$.store_unsub', call, b.literal(`$${left.name}`), b.id('$$stores'));
+					}
+
+					return call;
+				},
 				update: (node) => {
 					return b.call(
 						node.prefix ? '$.update_pre' : '$.update',

From 6c8a8f44995e9ad3d4f4a18b7e40bb2c236f5df2 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 20:35:54 -0400
Subject: [PATCH 23/86] more

---
 .../phases/3-transform/client/types.d.ts      |  6 +++-
 .../phases/3-transform/client/utils.js        |  8 +++++
 .../client/visitors/AssignmentExpression.js   | 10 ------
 .../3-transform/client/visitors/Program.js    | 31 +++++++++++++++++--
 .../client/visitors/shared/declarations.js    |  8 +++--
 5 files changed, 48 insertions(+), 15 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index 559197c359fd..1a640fd1f975 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -31,7 +31,11 @@ export interface ClientTransformState extends TransformState {
 			/** turn `foo` into e.g. `$.get(foo)` */
 			read: (id: Identifier) => Expression;
 			/** turn `foo = bar` into e.g. `$.set(foo, bar)` */
-			assign?: (node: AssignmentExpression, visit: (node: SvelteNode) => SvelteNode) => Expression;
+			assign?: (
+				node: AssignmentExpression,
+				visit: (node: SvelteNode) => SvelteNode,
+				is_primitive: boolean
+			) => Expression;
 			/** turn `foo++` into e.g. `$.update(foo)` */
 			update?: (node: UpdateExpression) => Expression;
 			/** turn `foo.bar++` into e.g. `$.mutate(foo, $.get(foo).bar += 1)` */
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index f1a0f3c7f080..00fb0089e871 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -272,6 +272,14 @@ export function build_setter(node, context, fallback, prefix, options) {
 
 	const serialize = () => {
 		if (left === node.left) {
+			if (Object.hasOwn(context.state.transformers, left.name)) {
+				const transformer = context.state.transformers[left.name]?.assign;
+
+				if (transformer) {
+					return transformer(node, context.visit, !!options?.skip_proxy_and_freeze);
+				}
+			}
+
 			const is_initial_proxy =
 				binding.initial !== null &&
 				should_proxy_or_freeze(/**@type {Expression}*/ (binding.initial), context.state.scope);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 208b5bedb0c0..fefc11bf1f34 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -7,15 +7,5 @@ import { build_setter } from '../utils.js';
  * @param {Context} context
  */
 export function AssignmentExpression(node, context) {
-	if (node.left.type === 'Identifier') {
-		if (Object.hasOwn(context.state.transformers, node.left.name)) {
-			const transformer = context.state.transformers[node.left.name]?.assign;
-
-			if (transformer) {
-				return transformer(node, context.visit);
-			}
-		}
-	}
-
 	return build_setter(node, context, context.next);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index fa4af03a5fab..3fa935260241 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -1,6 +1,11 @@
-/** @import { Program } from 'estree' */
+/** @import { BinaryOperator, Expression, Identifier, Program } from 'estree' */
 /** @import { ComponentContext } from '../types' */
-import { build_getter, is_prop_source } from '../utils.js';
+import {
+	build_getter,
+	build_proxy_reassignment,
+	is_prop_source,
+	should_proxy_or_freeze
+} from '../utils.js';
 import * as b from '../../../../utils/builders.js';
 import { add_state_transformers } from './shared/declarations.js';
 
@@ -29,6 +34,28 @@ export function Program(node, context) {
 				if (is_prop_source(binding, context.state)) {
 					context.state.transformers[name] = {
 						read: b.call,
+						assign: (node, visit) => {
+							let left = /** @type {Identifier} */ (node.left);
+							let value = /** @type {Expression} */ (visit(node.right));
+
+							if (node.operator !== '=') {
+								value = b.binary(
+									/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
+									/** @type {Expression} */ (visit(left)),
+									value
+								);
+							}
+
+							if (
+								context.state.analysis.runes &&
+								binding.kind === 'bindable_prop' &&
+								should_proxy_or_freeze(value, context.state.scope)
+							) {
+								value = build_proxy_reassignment(value, left.name);
+							}
+
+							return b.call(left, value);
+						},
 						update: (node) => {
 							return b.call(
 								node.prefix ? '$.update_pre_prop' : '$.update_prop',
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
index b0884acb8d95..978f680497c8 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
@@ -24,7 +24,7 @@ export function add_state_transformers(context) {
 		) {
 			context.state.transformers[name] = {
 				read: get_value,
-				assign: (node, visit) => {
+				assign: (node, visit, is_primitive) => {
 					let left = /** @type {Identifier} */ (node.left);
 					let value = /** @type {Expression} */ (visit(node.right));
 
@@ -36,7 +36,11 @@ export function add_state_transformers(context) {
 						);
 					}
 
-					if (context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)) {
+					if (
+						!is_primitive &&
+						context.state.analysis.runes &&
+						should_proxy_or_freeze(value, context.state.scope)
+					) {
 						if (binding.kind === 'frozen_state') {
 							value = b.call('$.freeze', value);
 						} else {

From 433141d56330c776ba30fe4b601a47864034c7d2 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 21:11:39 -0400
Subject: [PATCH 24/86] tweak

---
 .../phases/3-transform/client/types.d.ts      |  6 +---
 .../phases/3-transform/client/utils.js        | 25 ++++++++++++++-
 .../3-transform/client/visitors/Program.js    | 30 ++++++------------
 .../client/visitors/shared/declarations.js    | 31 +++----------------
 4 files changed, 38 insertions(+), 54 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index 1a640fd1f975..304abc621f2a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -31,11 +31,7 @@ export interface ClientTransformState extends TransformState {
 			/** turn `foo` into e.g. `$.get(foo)` */
 			read: (id: Identifier) => Expression;
 			/** turn `foo = bar` into e.g. `$.set(foo, bar)` */
-			assign?: (
-				node: AssignmentExpression,
-				visit: (node: SvelteNode) => SvelteNode,
-				is_primitive: boolean
-			) => Expression;
+			assign?: (node: Identifier, value: Expression) => Expression;
 			/** turn `foo++` into e.g. `$.update(foo)` */
 			update?: (node: UpdateExpression) => Expression;
 			/** turn `foo.bar++` into e.g. `$.mutate(foo, $.get(foo).bar += 1)` */
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 00fb0089e871..cc904456fc51 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -276,7 +276,30 @@ export function build_setter(node, context, fallback, prefix, options) {
 				const transformer = context.state.transformers[left.name]?.assign;
 
 				if (transformer) {
-					return transformer(node, context.visit, !!options?.skip_proxy_and_freeze);
+					let value = /** @type {Expression} */ (visit(node.right));
+
+					if (node.operator !== '=') {
+						value = b.binary(
+							/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
+							/** @type {Expression} */ (visit(left)),
+							value
+						);
+					}
+
+					if (
+						!options?.skip_proxy_and_freeze &&
+						binding.kind !== 'prop' &&
+						context.state.analysis.runes &&
+						should_proxy_or_freeze(value, context.state.scope)
+					) {
+						if (binding.kind === 'frozen_state') {
+							value = b.call('$.freeze', value);
+						} else {
+							value = build_proxy_reassignment(value, left.name);
+						}
+					}
+
+					return transformer(left, value);
 				}
 			}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index 3fa935260241..f3f88a9bb51f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -19,6 +19,13 @@ export function Program(node, context) {
 			if (binding.kind === 'store_sub') {
 				context.state.transformers[name] = {
 					read: b.call,
+					assign: (node, value) => {
+						return b.call(
+							'$.store_set',
+							/** @type {Expression} */ (context.visit(b.id(node.name.slice(1)))),
+							value
+						);
+					},
 					update: (node) => {
 						return b.call(
 							node.prefix ? '$.update_pre_store' : '$.update_store',
@@ -34,27 +41,8 @@ export function Program(node, context) {
 				if (is_prop_source(binding, context.state)) {
 					context.state.transformers[name] = {
 						read: b.call,
-						assign: (node, visit) => {
-							let left = /** @type {Identifier} */ (node.left);
-							let value = /** @type {Expression} */ (visit(node.right));
-
-							if (node.operator !== '=') {
-								value = b.binary(
-									/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
-									/** @type {Expression} */ (visit(left)),
-									value
-								);
-							}
-
-							if (
-								context.state.analysis.runes &&
-								binding.kind === 'bindable_prop' &&
-								should_proxy_or_freeze(value, context.state.scope)
-							) {
-								value = build_proxy_reassignment(value, left.name);
-							}
-
-							return b.call(left, value);
+						assign: (node, value) => {
+							return b.call(node, value);
 						},
 						update: (node) => {
 							return b.call(
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
index 978f680497c8..1c25cd6a9d80 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
@@ -24,34 +24,11 @@ export function add_state_transformers(context) {
 		) {
 			context.state.transformers[name] = {
 				read: get_value,
-				assign: (node, visit, is_primitive) => {
-					let left = /** @type {Identifier} */ (node.left);
-					let value = /** @type {Expression} */ (visit(node.right));
+				assign: (node, value) => {
+					let call = b.call('$.set', node, value);
 
-					if (node.operator !== '=') {
-						value = b.binary(
-							/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
-							/** @type {Expression} */ (visit(left)),
-							value
-						);
-					}
-
-					if (
-						!is_primitive &&
-						context.state.analysis.runes &&
-						should_proxy_or_freeze(value, context.state.scope)
-					) {
-						if (binding.kind === 'frozen_state') {
-							value = b.call('$.freeze', value);
-						} else {
-							value = build_proxy_reassignment(value, left.name);
-						}
-					}
-
-					let call = b.call('$.set', left, value);
-
-					if (context.state.scope.get(`$${left.name}`)?.kind === 'store_sub') {
-						call = b.call('$.store_unsub', call, b.literal(`$${left.name}`), b.id('$$stores'));
+					if (context.state.scope.get(`$${node.name}`)?.kind === 'store_sub') {
+						call = b.call('$.store_unsub', call, b.literal(`$${node.name}`), b.id('$$stores'));
 					}
 
 					return call;

From c4d4052c36fffa451b40982cb27a89a8637104a3 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 21:14:18 -0400
Subject: [PATCH 25/86] remove junk

---
 .../phases/3-transform/client/utils.js        | 53 +------------------
 1 file changed, 1 insertion(+), 52 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index cc904456fc51..0477ef2e2d39 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -303,58 +303,7 @@ export function build_setter(node, context, fallback, prefix, options) {
 				}
 			}
 
-			const is_initial_proxy =
-				binding.initial !== null &&
-				should_proxy_or_freeze(/**@type {Expression}*/ (binding.initial), context.state.scope);
-			if ((binding.kind === 'prop' || binding.kind === 'bindable_prop') && !is_initial_proxy) {
-				return b.call(left, value);
-			} else if (is_store) {
-				return b.call('$.store_set', build_getter(b.id(left_name), state), value);
-			} else {
-				let call;
-				if (binding.kind === 'state') {
-					call = b.call(
-						'$.set',
-						b.id(left_name),
-						context.state.analysis.runes &&
-							!options?.skip_proxy_and_freeze &&
-							should_proxy_or_freeze(value, context.state.scope)
-							? build_proxy_reassignment(value, left_name)
-							: value
-					);
-				} else if (binding.kind === 'frozen_state') {
-					call = b.call(
-						'$.set',
-						b.id(left_name),
-						context.state.analysis.runes &&
-							!options?.skip_proxy_and_freeze &&
-							should_proxy_or_freeze(value, context.state.scope)
-							? b.call('$.freeze', value)
-							: value
-					);
-				} else if (
-					(binding.kind === 'prop' || binding.kind === 'bindable_prop') &&
-					is_initial_proxy
-				) {
-					call = b.call(
-						left,
-						context.state.analysis.runes &&
-							!options?.skip_proxy_and_freeze &&
-							should_proxy_or_freeze(value, context.state.scope) &&
-							binding.kind === 'bindable_prop'
-							? build_proxy_reassignment(value, left_name)
-							: value
-					);
-				} else {
-					call = b.call('$.set', b.id(left_name), value);
-				}
-
-				if (state.scope.get(`$${left.name}`)?.kind === 'store_sub') {
-					return b.call('$.store_unsub', call, b.literal(`$${left.name}`), b.id('$$stores'));
-				} else {
-					return call;
-				}
-			}
+			return node;
 		} else {
 			if (is_store) {
 				// If we are assigning to a store property, we need to ensure we don't

From 37be909c340f528f4afcc0703063be36c8a4d845 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 21:19:09 -0400
Subject: [PATCH 26/86] unused

---
 .../compiler/phases/3-transform/client/visitors/EachBlock.js   | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index c82a95f5902e..faabbb52c57c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -120,8 +120,7 @@ export function EachBlock(node, context) {
 
 	const child_state = {
 		...context.state,
-		transformers: { ...context.state.transformers },
-		setters: { ...context.state.setters }
+		transformers: { ...context.state.transformers }
 	};
 
 	/** The state used when generating the key function, if necessary */

From e5b17399a1db999283487a86362aa3240fdf0765 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 21:34:24 -0400
Subject: [PATCH 27/86] simplify

---
 .../src/compiler/phases/3-transform/client/utils.js  |  6 +++++-
 .../3-transform/client/visitors/BindDirective.js     | 12 ++----------
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 0477ef2e2d39..2e31baed903f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -286,8 +286,12 @@ export function build_setter(node, context, fallback, prefix, options) {
 						);
 					}
 
+					// special case — if an element binding, we know it's a primitive
+					const path = context.path.map((node) => node.type);
+					const is_primitive = path.at(-1) === 'BindDirective' && path.at(-2) === 'RegularElement';
+
 					if (
-						!options?.skip_proxy_and_freeze &&
+						!is_primitive &&
 						binding.kind !== 'prop' &&
 						context.state.analysis.runes &&
 						should_proxy_or_freeze(value, context.state.scope)
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/BindDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/BindDirective.js
index 8b9064d59aec..e0a40835bba7 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/BindDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/BindDirective.js
@@ -38,18 +38,10 @@ export function BindDirective(node, context) {
 	}
 
 	const getter = b.thunk(/** @type {Expression} */ (context.visit(expression)));
-	const assignment = b.assignment('=', expression, b.id('$$value'));
+
 	const setter = b.arrow(
 		[b.id('$$value')],
-		build_setter(
-			assignment,
-			context,
-			() => /** @type {Expression} */ (context.visit(assignment)),
-			null,
-			{
-				skip_proxy_and_freeze: true
-			}
-		)
+		/** @type {Expression} */ (context.visit(b.assignment('=', expression, b.id('$$value'))))
 	);
 
 	/** @type {CallExpression} */

From 75d1350c155643410a57d42d38ba1cf8487b6cb6 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 21:42:45 -0400
Subject: [PATCH 28/86] tidy up

---
 .../phases/3-transform/client/visitors/shared/component.js    | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index baf9918b975b..226a9965fe19 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -197,9 +197,7 @@ export function build_component(node, component_name, context, anchor = context.
 
 				const assignment = b.assignment('=', attribute.expression, b.id('$$value'));
 				push_prop(
-					b.set(attribute.name, [
-						b.stmt(build_setter(assignment, context, () => context.visit(assignment)))
-					])
+					b.set(attribute.name, [b.stmt(/** @type {Expression} */ (context.visit(assignment)))])
 				);
 			}
 		}

From 361da4939c9717c0bc3de87bf76b7a7079fb73e1 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 8 Aug 2024 21:52:31 -0400
Subject: [PATCH 29/86] tweak

---
 .../phases/3-transform/client/utils.js        | 60 +++++++++----------
 1 file changed, 30 insertions(+), 30 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 2e31baed903f..21c35fc74ffa 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -271,40 +271,40 @@ export function build_setter(node, context, fallback, prefix, options) {
 	const value = get_assignment_value(node, context);
 
 	const serialize = () => {
-		if (left === node.left) {
-			if (Object.hasOwn(context.state.transformers, left.name)) {
-				const transformer = context.state.transformers[left.name]?.assign;
-
-				if (transformer) {
-					let value = /** @type {Expression} */ (visit(node.right));
-
-					if (node.operator !== '=') {
-						value = b.binary(
-							/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
-							/** @type {Expression} */ (visit(left)),
-							value
-						);
-					}
+		const transformers = Object.hasOwn(context.state.transformers, left.name)
+			? context.state.transformers[left.name]
+			: null;
 
-					// special case — if an element binding, we know it's a primitive
-					const path = context.path.map((node) => node.type);
-					const is_primitive = path.at(-1) === 'BindDirective' && path.at(-2) === 'RegularElement';
+		if (left === node.left) {
+			if (transformers?.assign) {
+				let value = /** @type {Expression} */ (visit(node.right));
+
+				if (node.operator !== '=') {
+					value = b.binary(
+						/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
+						/** @type {Expression} */ (visit(left)),
+						value
+					);
+				}
 
-					if (
-						!is_primitive &&
-						binding.kind !== 'prop' &&
-						context.state.analysis.runes &&
-						should_proxy_or_freeze(value, context.state.scope)
-					) {
-						if (binding.kind === 'frozen_state') {
-							value = b.call('$.freeze', value);
-						} else {
-							value = build_proxy_reassignment(value, left.name);
-						}
+				// special case — if an element binding, we know it's a primitive
+				const path = context.path.map((node) => node.type);
+				const is_primitive = path.at(-1) === 'BindDirective' && path.at(-2) === 'RegularElement';
+
+				if (
+					!is_primitive &&
+					binding.kind !== 'prop' &&
+					context.state.analysis.runes &&
+					should_proxy_or_freeze(value, context.state.scope)
+				) {
+					if (binding.kind === 'frozen_state') {
+						value = b.call('$.freeze', value);
+					} else {
+						value = build_proxy_reassignment(value, left.name);
 					}
-
-					return transformer(left, value);
 				}
+
+				return transformers.assign(left, value);
 			}
 
 			return node;

From 690d3dcb88ac732db9bd66edaef4c302b8c2b657 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 08:08:04 -0400
Subject: [PATCH 30/86] assign_property

---
 .../src/compiler/phases/3-transform/client/types.d.ts  |  2 ++
 .../src/compiler/phases/3-transform/client/utils.js    | 10 ++++++++++
 .../3-transform/client/visitors/shared/declarations.js |  7 +++++++
 3 files changed, 19 insertions(+)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index 304abc621f2a..f910308a133d 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -32,6 +32,8 @@ export interface ClientTransformState extends TransformState {
 			read: (id: Identifier) => Expression;
 			/** turn `foo = bar` into e.g. `$.set(foo, bar)` */
 			assign?: (node: Identifier, value: Expression) => Expression;
+			/** turn `foo.bar = baz` into e.g. `$.mutate(foo, $.get(foo).bar = baz);` */
+			assign_property?: (node: Identifier, mutation: Expression) => Expression;
 			/** turn `foo++` into e.g. `$.update(foo)` */
 			update?: (node: UpdateExpression) => Expression;
 			/** turn `foo.bar++` into e.g. `$.mutate(foo, $.get(foo).bar += 1)` */
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 21c35fc74ffa..b37dbce1e998 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -309,6 +309,16 @@ export function build_setter(node, context, fallback, prefix, options) {
 
 			return node;
 		} else {
+			if (transformers?.assign_property) {
+				const mutation = b.assignment(
+					node.operator,
+					/** @type {Pattern} */ (context.visit(node.left)),
+					/** @type {Expression} */ (context.visit(node.right))
+				);
+
+				return transformers.assign_property(left, mutation);
+			}
+
 			if (is_store) {
 				// If we are assigning to a store property, we need to ensure we don't
 				// capture the read for the store as part of the member expression to
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
index 1c25cd6a9d80..ae158ba8dbca 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
@@ -33,6 +33,13 @@ export function add_state_transformers(context) {
 
 					return call;
 				},
+				assign_property: (node, mutation) => {
+					if (context.state.analysis.runes) {
+						return mutation;
+					}
+
+					return b.call('$.mutate', node, mutation);
+				},
 				update: (node) => {
 					return b.call(
 						node.prefix ? '$.update_pre' : '$.update',

From 5189d8005e52fbc3eee5cdf8a98b7efd2b61840d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 08:13:30 -0400
Subject: [PATCH 31/86] fix

---
 packages/svelte/src/compiler/phases/3-transform/client/utils.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index b37dbce1e998..9a5cbc6ebdd4 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -316,7 +316,7 @@ export function build_setter(node, context, fallback, prefix, options) {
 					/** @type {Expression} */ (context.visit(node.right))
 				);
 
-				return transformers.assign_property(left, mutation);
+				return maybe_skip_ownership_validation(transformers.assign_property(left, mutation));
 			}
 
 			if (is_store) {

From 1acc3c5fbe0f6a4579143f38e5407d5de9389187 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 08:24:36 -0400
Subject: [PATCH 32/86] tidy up

---
 .../phases/3-transform/client/utils.js        | 22 -------------------
 .../3-transform/client/visitors/Program.js    |  8 +++++++
 2 files changed, 8 insertions(+), 22 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 9a5cbc6ebdd4..a6be8929db1e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -354,28 +354,6 @@ export function build_setter(node, context, fallback, prefix, options) {
 						b.call('$.untrack', b.id('$' + left_name))
 					)
 				);
-			} else if (
-				!state.analysis.runes ||
-				// this condition can go away once legacy mode is gone; only necessary for interop with legacy parent bindings
-				(binding.mutated && binding.kind === 'bindable_prop')
-			) {
-				if (binding.kind === 'bindable_prop') {
-					return maybe_skip_ownership_validation(
-						b.call(
-							left,
-							b.assignment(node.operator, /** @type {Pattern} */ (visit(node.left)), value),
-							b.true
-						)
-					);
-				} else {
-					return maybe_skip_ownership_validation(
-						b.call(
-							'$.mutate',
-							b.id(left_name),
-							b.assignment(node.operator, /** @type {Pattern} */ (visit(node.left)), value)
-						)
-					);
-				}
 			} else if (
 				node.right.type === 'Literal' &&
 				prefix != null &&
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index f3f88a9bb51f..21d7249ac84e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -44,6 +44,14 @@ export function Program(node, context) {
 						assign: (node, value) => {
 							return b.call(node, value);
 						},
+						assign_property: (node, value) => {
+							if (binding.kind === 'bindable_prop') {
+								// only necessary for interop with legacy parent bindings
+								return b.call(node, value, b.true);
+							}
+
+							return value;
+						},
 						update: (node) => {
 							return b.call(
 								node.prefix ? '$.update_pre_prop' : '$.update_prop',

From e9635a5d9a558bfc94759d880b630728c045bca5 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 08:47:43 -0400
Subject: [PATCH 33/86] tidy up

---
 .../phases/3-transform/client/visitors/UpdateExpression.js      | 2 +-
 packages/svelte/src/compiler/phases/3-transform/utils.js        | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
index 384b9caa27d6..dd483f2ea3dd 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
@@ -2,7 +2,7 @@
 /** @import { Context } from '../types' */
 import { is_ignored } from '../../../../state.js';
 import * as b from '../../../../utils/builders.js';
-import { build_getter, build_setter } from '../utils.js';
+import { build_setter } from '../utils.js';
 
 /**
  * @param {UpdateExpression} node
diff --git a/packages/svelte/src/compiler/phases/3-transform/utils.js b/packages/svelte/src/compiler/phases/3-transform/utils.js
index 188ae6739f5c..38626b504fcb 100644
--- a/packages/svelte/src/compiler/phases/3-transform/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/utils.js
@@ -424,7 +424,7 @@ export function transform_inspect_rune(node, context) {
 	const { state, visit } = context;
 	const as_fn = state.options.generate === 'client';
 
-	if (!dev) return b.unary('void', b.literal(0));
+	if (!dev) return b.empty;
 
 	if (node.callee.type === 'MemberExpression') {
 		const raw_inspect_args = /** @type {CallExpression} */ (node.callee.object).arguments;

From e239d235b1bea5829848f11d4f8ca53151e177bb Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 10:33:30 -0400
Subject: [PATCH 34/86] move store code

---
 .../phases/3-transform/client/types.d.ts      |  2 +-
 .../phases/3-transform/client/utils.js        | 37 +--------------
 .../3-transform/client/visitors/Program.js    | 47 +++++++++++++++----
 3 files changed, 39 insertions(+), 47 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index f910308a133d..e4d0ee23aa11 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -33,7 +33,7 @@ export interface ClientTransformState extends TransformState {
 			/** turn `foo = bar` into e.g. `$.set(foo, bar)` */
 			assign?: (node: Identifier, value: Expression) => Expression;
 			/** turn `foo.bar = baz` into e.g. `$.mutate(foo, $.get(foo).bar = baz);` */
-			assign_property?: (node: Identifier, mutation: Expression) => Expression;
+			assign_property?: (node: Identifier, mutation: AssignmentExpression) => Expression;
 			/** turn `foo++` into e.g. `$.update(foo)` */
 			update?: (node: UpdateExpression) => Expression;
 			/** turn `foo.bar++` into e.g. `$.mutate(foo, $.get(foo).bar += 1)` */
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index a6be8929db1e..7874dfaf4e3c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -319,42 +319,7 @@ export function build_setter(node, context, fallback, prefix, options) {
 				return maybe_skip_ownership_validation(transformers.assign_property(left, mutation));
 			}
 
-			if (is_store) {
-				// If we are assigning to a store property, we need to ensure we don't
-				// capture the read for the store as part of the member expression to
-				// keep consistency with how store $ shorthand reads work in Svelte 4.
-				/**
-				 *
-				 * @param {Expression | Pattern} node
-				 * @returns {Expression}
-				 */
-				function visit_node(node) {
-					if (node.type === 'MemberExpression') {
-						return {
-							...node,
-							object: visit_node(/** @type {Expression} */ (node.object)),
-							property: /** @type {MemberExpression} */ (visit(node)).property
-						};
-					}
-					if (node.type === 'Identifier') {
-						const binding = state.scope.get(node.name);
-
-						if (binding !== null && binding.kind === 'store_sub') {
-							return b.call('$.untrack', b.thunk(/** @type {Expression} */ (visit(node))));
-						}
-					}
-					return /** @type {Expression} */ (visit(node));
-				}
-
-				return maybe_skip_ownership_validation(
-					b.call(
-						'$.store_mutate',
-						build_getter(b.id(left_name), state),
-						b.assignment(node.operator, /** @type {Pattern}} */ (visit_node(node.left)), value),
-						b.call('$.untrack', b.id('$' + left_name))
-					)
-				);
-			} else if (
+			if (
 				node.right.type === 'Literal' &&
 				prefix != null &&
 				(node.operator === '+=' || node.operator === '-=')
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index 21d7249ac84e..fa74e8abbb4b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -1,11 +1,6 @@
-/** @import { BinaryOperator, Expression, Identifier, Program } from 'estree' */
+/** @import { Expression, MemberExpression, Program } from 'estree' */
 /** @import { ComponentContext } from '../types' */
-import {
-	build_getter,
-	build_proxy_reassignment,
-	is_prop_source,
-	should_proxy_or_freeze
-} from '../utils.js';
+import { build_getter, is_prop_source } from '../utils.js';
 import * as b from '../../../../utils/builders.js';
 import { add_state_transformers } from './shared/declarations.js';
 
@@ -17,13 +12,45 @@ export function Program(node, context) {
 	if (context.state.is_instance) {
 		for (const [name, binding] of context.state.scope.declarations) {
 			if (binding.kind === 'store_sub') {
+				const store = /** @type {Expression} */ (context.visit(b.id(name.slice(1))));
+
 				context.state.transformers[name] = {
 					read: b.call,
 					assign: (node, value) => {
+						return b.call('$.store_set', store, value);
+					},
+					assign_property: (node, mutation) => {
+						// We need to untrack the store read, for consistency with Svelte 4
+						const untracked = b.call('$.untrack', node);
+
+						/**
+						 *
+						 * @param {Expression} n
+						 * @returns {Expression}
+						 */
+						function replace(n) {
+							if (n.type === 'MemberExpression') {
+								return {
+									...n,
+									object: replace(/** @type {Expression} */ (n.object)),
+									property: n.property
+								};
+							}
+
+							return untracked;
+						}
+
 						return b.call(
-							'$.store_set',
-							/** @type {Expression} */ (context.visit(b.id(node.name.slice(1)))),
-							value
+							'$.store_mutate',
+							store,
+							b.assignment(
+								mutation.operator,
+								/** @type {MemberExpression} */ (
+									replace(/** @type {MemberExpression} */ (mutation.left))
+								),
+								mutation.right
+							),
+							untracked
 						);
 					},
 					update: (node) => {

From 549a48873491b4e04776b1139ad8986dfac513c9 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 10:38:46 -0400
Subject: [PATCH 35/86] this appears to be unused

---
 .../phases/3-transform/client/utils.js        | 132 ++++++++----------
 1 file changed, 61 insertions(+), 71 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 7874dfaf4e3c..455705322c1b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -268,86 +268,76 @@ export function build_setter(node, context, fallback, prefix, options) {
 		return fallback();
 	}
 
-	const value = get_assignment_value(node, context);
-
-	const serialize = () => {
-		const transformers = Object.hasOwn(context.state.transformers, left.name)
-			? context.state.transformers[left.name]
-			: null;
-
-		if (left === node.left) {
-			if (transformers?.assign) {
-				let value = /** @type {Expression} */ (visit(node.right));
-
-				if (node.operator !== '=') {
-					value = b.binary(
-						/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
-						/** @type {Expression} */ (visit(left)),
-						value
-					);
-				}
-
-				// special case — if an element binding, we know it's a primitive
-				const path = context.path.map((node) => node.type);
-				const is_primitive = path.at(-1) === 'BindDirective' && path.at(-2) === 'RegularElement';
-
-				if (
-					!is_primitive &&
-					binding.kind !== 'prop' &&
-					context.state.analysis.runes &&
-					should_proxy_or_freeze(value, context.state.scope)
-				) {
-					if (binding.kind === 'frozen_state') {
-						value = b.call('$.freeze', value);
-					} else {
-						value = build_proxy_reassignment(value, left.name);
-					}
-				}
-
-				return transformers.assign(left, value);
-			}
-
-			return node;
-		} else {
-			if (transformers?.assign_property) {
-				const mutation = b.assignment(
-					node.operator,
-					/** @type {Pattern} */ (context.visit(node.left)),
-					/** @type {Expression} */ (context.visit(node.right))
+	const transformers = Object.hasOwn(context.state.transformers, left.name)
+		? context.state.transformers[left.name]
+		: null;
+
+	if (left === node.left) {
+		if (transformers?.assign) {
+			let value = /** @type {Expression} */ (visit(node.right));
+
+			if (node.operator !== '=') {
+				value = b.binary(
+					/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
+					/** @type {Expression} */ (visit(left)),
+					value
 				);
-
-				return maybe_skip_ownership_validation(transformers.assign_property(left, mutation));
 			}
 
+			// special case — if an element binding, we know it's a primitive
+			const path = context.path.map((node) => node.type);
+			const is_primitive = path.at(-1) === 'BindDirective' && path.at(-2) === 'RegularElement';
+
 			if (
-				node.right.type === 'Literal' &&
-				prefix != null &&
-				(node.operator === '+=' || node.operator === '-=')
+				!is_primitive &&
+				binding.kind !== 'prop' &&
+				context.state.analysis.runes &&
+				should_proxy_or_freeze(value, context.state.scope)
 			) {
-				return maybe_skip_ownership_validation(
-					b.update(
-						node.operator === '+=' ? '++' : '--',
-						/** @type {Expression} */ (visit(node.left)),
-						prefix
-					)
-				);
-			} else {
-				return maybe_skip_ownership_validation(
-					b.assignment(
-						node.operator,
-						/** @type {Pattern} */ (visit(node.left)),
-						/** @type {Expression} */ (visit(node.right))
-					)
-				);
+				if (binding.kind === 'frozen_state') {
+					value = b.call('$.freeze', value);
+				} else {
+					value = build_proxy_reassignment(value, left.name);
+				}
 			}
+
+			return transformers.assign(left, value);
 		}
-	};
 
-	if (value.type === 'BinaryExpression' && /** @type {any} */ (value.operator) === '??') {
-		return b.logical('??', build_getter(b.id(left_name), state), serialize());
-	}
+		return node;
+	} else {
+		if (transformers?.assign_property) {
+			const mutation = b.assignment(
+				node.operator,
+				/** @type {Pattern} */ (context.visit(node.left)),
+				/** @type {Expression} */ (context.visit(node.right))
+			);
+
+			return maybe_skip_ownership_validation(transformers.assign_property(left, mutation));
+		}
 
-	return serialize();
+		if (
+			node.right.type === 'Literal' &&
+			prefix != null &&
+			(node.operator === '+=' || node.operator === '-=')
+		) {
+			return maybe_skip_ownership_validation(
+				b.update(
+					node.operator === '+=' ? '++' : '--',
+					/** @type {Expression} */ (visit(node.left)),
+					prefix
+				)
+			);
+		} else {
+			return maybe_skip_ownership_validation(
+				b.assignment(
+					node.operator,
+					/** @type {Pattern} */ (visit(node.left)),
+					/** @type {Expression} */ (visit(node.right))
+				)
+			);
+		}
+	}
 }
 
 /**

From 5d1ea4cb56fc59bfd9d2226a970646dd6ac26e49 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 10:40:23 -0400
Subject: [PATCH 36/86] tidy up

---
 .../src/compiler/phases/3-transform/client/utils.js  | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 455705322c1b..92a910a7bc38 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -222,12 +222,7 @@ export function build_setter(node, context, fallback, prefix, options) {
 
 	const left = object(assignee);
 
-	if (left === null) {
-		return fallback();
-	}
-
-	const binding = state.scope.get(left.name);
-
+	const binding = left && state.scope.get(left.name);
 	if (!binding) return fallback();
 
 	if (Object.hasOwn(state.setters, left.name)) {
@@ -252,9 +247,6 @@ export function build_setter(node, context, fallback, prefix, options) {
 		return maybe_skip_ownership_validation(fallback());
 	}
 
-	const is_store = binding.kind === 'store_sub';
-	const left_name = is_store ? left.name.slice(1) : left.name;
-
 	if (
 		binding.kind !== 'state' &&
 		binding.kind !== 'frozen_state' &&
@@ -262,7 +254,7 @@ export function build_setter(node, context, fallback, prefix, options) {
 		binding.kind !== 'bindable_prop' &&
 		binding.kind !== 'each' &&
 		binding.kind !== 'legacy_reactive' &&
-		!is_store
+		binding.kind !== 'store_sub'
 	) {
 		// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
 		return fallback();

From dc6879dfaf4f4a583f69177746aab3b79c4202d1 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 10:47:49 -0400
Subject: [PATCH 37/86] tweak

---
 .../svelte/src/compiler/phases/3-transform/client/utils.js | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 92a910a7bc38..c6bfc6792645 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -243,10 +243,6 @@ export function build_setter(node, context, fallback, prefix, options) {
 		return serialized;
 	}
 
-	if (binding.kind === 'derived') {
-		return maybe_skip_ownership_validation(fallback());
-	}
-
 	if (
 		binding.kind !== 'state' &&
 		binding.kind !== 'frozen_state' &&
@@ -254,7 +250,8 @@ export function build_setter(node, context, fallback, prefix, options) {
 		binding.kind !== 'bindable_prop' &&
 		binding.kind !== 'each' &&
 		binding.kind !== 'legacy_reactive' &&
-		binding.kind !== 'store_sub'
+		binding.kind !== 'store_sub' &&
+		binding.kind !== 'derived'
 	) {
 		// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
 		return fallback();

From 2769d36579f782fac8fd7c04997b2e3b767c09d0 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 10:50:27 -0400
Subject: [PATCH 38/86] simplify

---
 .../phases/3-transform/client/utils.js        | 114 +++++++++---------
 1 file changed, 56 insertions(+), 58 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index c6bfc6792645..54f1d8ec7aec 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -261,71 +261,69 @@ export function build_setter(node, context, fallback, prefix, options) {
 		? context.state.transformers[left.name]
 		: null;
 
-	if (left === node.left) {
-		if (transformers?.assign) {
-			let value = /** @type {Expression} */ (visit(node.right));
-
-			if (node.operator !== '=') {
-				value = b.binary(
-					/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
-					/** @type {Expression} */ (visit(left)),
-					value
-				);
-			}
+	// reassignment
+	if (left === node.left && transformers?.assign) {
+		let value = /** @type {Expression} */ (visit(node.right));
+
+		if (node.operator !== '=') {
+			value = b.binary(
+				/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
+				/** @type {Expression} */ (visit(left)),
+				value
+			);
+		}
 
-			// special case — if an element binding, we know it's a primitive
-			const path = context.path.map((node) => node.type);
-			const is_primitive = path.at(-1) === 'BindDirective' && path.at(-2) === 'RegularElement';
+		// special case — if an element binding, we know it's a primitive
+		const path = context.path.map((node) => node.type);
+		const is_primitive = path.at(-1) === 'BindDirective' && path.at(-2) === 'RegularElement';
 
-			if (
-				!is_primitive &&
-				binding.kind !== 'prop' &&
-				context.state.analysis.runes &&
-				should_proxy_or_freeze(value, context.state.scope)
-			) {
-				if (binding.kind === 'frozen_state') {
-					value = b.call('$.freeze', value);
-				} else {
-					value = build_proxy_reassignment(value, left.name);
-				}
+		if (
+			!is_primitive &&
+			binding.kind !== 'prop' &&
+			context.state.analysis.runes &&
+			should_proxy_or_freeze(value, context.state.scope)
+		) {
+			if (binding.kind === 'frozen_state') {
+				value = b.call('$.freeze', value);
+			} else {
+				value = build_proxy_reassignment(value, left.name);
 			}
-
-			return transformers.assign(left, value);
 		}
 
-		return node;
-	} else {
-		if (transformers?.assign_property) {
-			const mutation = b.assignment(
-				node.operator,
-				/** @type {Pattern} */ (context.visit(node.left)),
-				/** @type {Expression} */ (context.visit(node.right))
-			);
+		return transformers.assign(left, value);
+	}
 
-			return maybe_skip_ownership_validation(transformers.assign_property(left, mutation));
-		}
+	// mutation
+	if (transformers?.assign_property) {
+		const mutation = b.assignment(
+			node.operator,
+			/** @type {Pattern} */ (context.visit(node.left)),
+			/** @type {Expression} */ (context.visit(node.right))
+		);
 
-		if (
-			node.right.type === 'Literal' &&
-			prefix != null &&
-			(node.operator === '+=' || node.operator === '-=')
-		) {
-			return maybe_skip_ownership_validation(
-				b.update(
-					node.operator === '+=' ? '++' : '--',
-					/** @type {Expression} */ (visit(node.left)),
-					prefix
-				)
-			);
-		} else {
-			return maybe_skip_ownership_validation(
-				b.assignment(
-					node.operator,
-					/** @type {Pattern} */ (visit(node.left)),
-					/** @type {Expression} */ (visit(node.right))
-				)
-			);
-		}
+		return maybe_skip_ownership_validation(transformers.assign_property(left, mutation));
+	}
+
+	if (
+		node.right.type === 'Literal' &&
+		prefix != null &&
+		(node.operator === '+=' || node.operator === '-=')
+	) {
+		return maybe_skip_ownership_validation(
+			b.update(
+				node.operator === '+=' ? '++' : '--',
+				/** @type {Expression} */ (visit(node.left)),
+				prefix
+			)
+		);
+	} else {
+		return maybe_skip_ownership_validation(
+			b.assignment(
+				node.operator,
+				/** @type {Pattern} */ (visit(node.left)),
+				/** @type {Expression} */ (visit(node.right))
+			)
+		);
 	}
 }
 

From 420fc63da32cc17a6e146aff555c31f55e5f68b5 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 10:52:14 -0400
Subject: [PATCH 39/86] move code

---
 .../phases/3-transform/client/utils.js        | 24 +++++++++----------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 54f1d8ec7aec..30d70521908d 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -231,18 +231,6 @@ export function build_setter(node, context, fallback, prefix, options) {
 		return setter(node, context);
 	}
 
-	/**
-	 * @param {any} serialized
-	 * @returns
-	 */
-	function maybe_skip_ownership_validation(serialized) {
-		if (is_ignored(node, 'ownership_invalid_mutation')) {
-			return b.call('$.skip_ownership_validation', b.thunk(serialized));
-		}
-
-		return serialized;
-	}
-
 	if (
 		binding.kind !== 'state' &&
 		binding.kind !== 'frozen_state' &&
@@ -293,6 +281,18 @@ export function build_setter(node, context, fallback, prefix, options) {
 		return transformers.assign(left, value);
 	}
 
+	/**
+	 * @param {any} serialized
+	 * @returns
+	 */
+	const maybe_skip_ownership_validation = (serialized) => {
+		if (is_ignored(node, 'ownership_invalid_mutation')) {
+			return b.call('$.skip_ownership_validation', b.thunk(serialized));
+		}
+
+		return serialized;
+	};
+
 	// mutation
 	if (transformers?.assign_property) {
 		const mutation = b.assignment(

From 2f1bcb177c67ad3da2a0223f2fced7228f7771de Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 11:01:14 -0400
Subject: [PATCH 40/86] move stuff

---
 .../3-transform/client/transform-client.js    | 22 ++++++---------
 .../phases/3-transform/client/utils.js        | 27 +++++++++----------
 2 files changed, 21 insertions(+), 28 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 594a7144ca26..00e26afb661c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -179,24 +179,18 @@ export function client_component(analysis, options) {
 
 		for (const [name, binding] of state.scope.declarations) {
 			// Very very dirty way of making import statements reactive in legacy mode if needed
+			// TODO move this into the Program visitor
 			if (binding.declaration_kind === 'import' && binding.mutated) {
+				const id = b.id('$$_import_' + name);
+
 				state.transformers[name] = {
-					read: (node) => b.call('$$_import_' + node.name)
+					read: (node) => b.call(id),
+					assign_property: (node, mutation) => {
+						return b.call(id, mutation);
+					}
 				};
 
-				state.setters[name] = (node, context) =>
-					b.call(
-						'$$_import_' + binding.node.name,
-						b.assignment(
-							node.operator,
-							/** @type {ESTree.Pattern} */ (context.visit(node.left)),
-							/** @type {ESTree.Expression} */ (context.visit(node.right))
-						)
-					);
-
-				legacy_reactive_imports.push(
-					b.var('$$_import_' + name, b.call('$.reactive_import', b.thunk(b.id(name))))
-				);
+				legacy_reactive_imports.push(b.var(id, b.call('$.reactive_import', b.thunk(b.id(name)))));
 			}
 		}
 	}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 30d70521908d..024420134c5a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -231,20 +231,6 @@ export function build_setter(node, context, fallback, prefix, options) {
 		return setter(node, context);
 	}
 
-	if (
-		binding.kind !== 'state' &&
-		binding.kind !== 'frozen_state' &&
-		binding.kind !== 'prop' &&
-		binding.kind !== 'bindable_prop' &&
-		binding.kind !== 'each' &&
-		binding.kind !== 'legacy_reactive' &&
-		binding.kind !== 'store_sub' &&
-		binding.kind !== 'derived'
-	) {
-		// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
-		return fallback();
-	}
-
 	const transformers = Object.hasOwn(context.state.transformers, left.name)
 		? context.state.transformers[left.name]
 		: null;
@@ -317,6 +303,19 @@ export function build_setter(node, context, fallback, prefix, options) {
 			)
 		);
 	} else {
+		if (
+			binding.kind !== 'state' &&
+			binding.kind !== 'frozen_state' &&
+			binding.kind !== 'prop' &&
+			binding.kind !== 'bindable_prop' &&
+			binding.kind !== 'each' &&
+			binding.kind !== 'legacy_reactive' &&
+			binding.kind !== 'store_sub' &&
+			binding.kind !== 'derived'
+		) {
+			// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
+			return fallback();
+		}
 		return maybe_skip_ownership_validation(
 			b.assignment(
 				node.operator,

From 2d99cf735817f7280327f4984865a27e7d300b6d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 11:19:03 -0400
Subject: [PATCH 41/86] note to self

---
 .../compiler/phases/3-transform/client/visitors/EachBlock.js    | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index faabbb52c57c..54bcec9c4631 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -208,6 +208,8 @@ export function EachBlock(node, context) {
 			)
 		);
 
+		// TODO handle `item++` (currently we don't invalidate inner signals)
+
 		delete key_state.transformers[node.context.name];
 	} else {
 		const unwrapped = getter(binding.node);

From 7a846acb8108ab3ec2d17738d40513d899413142 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 11:37:01 -0400
Subject: [PATCH 42/86] move stuff

---
 .../phases/3-transform/client/visitors/EachBlock.js        | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index 54bcec9c4631..303244b815cd 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -179,9 +179,6 @@ export function EachBlock(node, context) {
 		const item_with_loc = with_loc(item, id);
 		return b.call('$.unwrap', item_with_loc);
 	};
-	child_state.transformers[item.name] = {
-		read: getter
-	};
 
 	if (node.index) {
 		child_state.transformers[node.index] = {
@@ -200,6 +197,10 @@ export function EachBlock(node, context) {
 	const declarations = [];
 
 	if (node.context.type === 'Identifier') {
+		child_state.transformers[item.name] = {
+			read: getter
+		};
+
 		child_state.setters[node.context.name] = create_mutation(
 			b.member(
 				each_node_meta.array_name ? b.call(each_node_meta.array_name) : collection,

From c7990ef4227738a04a7940e8c1519e42bcc16577 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 12:22:34 -0400
Subject: [PATCH 43/86] each blocks

---
 .../phases/3-transform/client/utils.js        | 12 ++++----
 .../3-transform/client/visitors/EachBlock.js  | 28 ++++++++++++++++++-
 2 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 024420134c5a..d62a94a85754 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -225,12 +225,6 @@ export function build_setter(node, context, fallback, prefix, options) {
 	const binding = left && state.scope.get(left.name);
 	if (!binding) return fallback();
 
-	if (Object.hasOwn(state.setters, left.name)) {
-		const setter = state.setters[left.name];
-		// @ts-expect-error
-		return setter(node, context);
-	}
-
 	const transformers = Object.hasOwn(context.state.transformers, left.name)
 		? context.state.transformers[left.name]
 		: null;
@@ -267,6 +261,12 @@ export function build_setter(node, context, fallback, prefix, options) {
 		return transformers.assign(left, value);
 	}
 
+	if (Object.hasOwn(state.setters, left.name)) {
+		const setter = state.setters[left.name];
+		// @ts-expect-error
+		return setter(node, context);
+	}
+
 	/**
 	 * @param {any} serialized
 	 * @returns
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index 303244b815cd..af4e5092d3ee 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -196,9 +196,35 @@ export function EachBlock(node, context) {
 	/** @type {Statement[]} */
 	const declarations = [];
 
+	const invalidate = b.call(
+		'$.invalidate_inner_signals',
+		b.thunk(b.sequence(indirect_dependencies))
+	);
+
+	const invalidate_store = store_to_invalidate
+		? b.call('$.invalidate_store', b.id('$$stores'), b.literal(store_to_invalidate))
+		: undefined;
+
+	/** @type {Expression[]} */
+	const sequence = [];
+	if (!context.state.analysis.runes) sequence.push(invalidate);
+	if (invalidate_store) sequence.push(invalidate_store);
+
 	if (node.context.type === 'Identifier') {
 		child_state.transformers[item.name] = {
-			read: getter
+			read: getter,
+			assign: (node, value) => {
+				const left = b.member(
+					each_node_meta.array_name ? b.call(each_node_meta.array_name) : collection,
+					index,
+					true
+				);
+
+				return b.sequence([b.assignment('=', left, value), ...sequence]);
+			},
+			assign_property: (node, mutation) => {
+				return b.sequence([mutation, ...sequence]);
+			}
 		};
 
 		child_state.setters[node.context.name] = create_mutation(

From cdd2f24b821f6fe58ce4e74dda38fab28ac13bdf Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 12:55:00 -0400
Subject: [PATCH 44/86] note to self

---
 .../compiler/phases/3-transform/client/visitors/EachBlock.js   | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index af4e5092d3ee..de8c772ab499 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -225,6 +225,7 @@ export function EachBlock(node, context) {
 			assign_property: (node, mutation) => {
 				return b.sequence([mutation, ...sequence]);
 			}
+			// TODO update (`item++`) and update_property — these were unaccounted for previously
 		};
 
 		child_state.setters[node.context.name] = create_mutation(
@@ -235,8 +236,6 @@ export function EachBlock(node, context) {
 			)
 		);
 
-		// TODO handle `item++` (currently we don't invalidate inner signals)
-
 		delete key_state.transformers[node.context.name];
 	} else {
 		const unwrapped = getter(binding.node);

From c7060fd878a57846ea2aab9499e9e787122a88d4 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 13:31:24 -0400
Subject: [PATCH 45/86] lengthen stack trace

---
 .vscode/launch.json | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/.vscode/launch.json b/.vscode/launch.json
index 41d8017ce29f..fc593c0d0653 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -21,7 +21,10 @@
 			"type": "node",
 			"request": "launch",
 			"name": "Run sandbox",
-			"program": "${workspaceFolder}/playgrounds/sandbox/run.js"
+			"program": "${workspaceFolder}/playgrounds/sandbox/run.js",
+			"env": {
+				"NODE_OPTIONS": "--stack-trace-limit=10000"
+			}
 		}
 	],
 	"compounds": [

From fc7fdb664aafb7fbfe342bd9e2d13a0b496ff55a Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 14:15:10 -0400
Subject: [PATCH 46/86] tweak

---
 .../compiler/phases/3-transform/client/visitors/EachBlock.js    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index de8c772ab499..964858247556 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -211,7 +211,7 @@ export function EachBlock(node, context) {
 	if (invalidate_store) sequence.push(invalidate_store);
 
 	if (node.context.type === 'Identifier') {
-		child_state.transformers[item.name] = {
+		child_state.transformers[node.context.name] = {
 			read: getter,
 			assign: (node, value) => {
 				const left = b.member(

From ace6134fa7658ff4406edaa6a4045862b0535bd3 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 14:33:01 -0400
Subject: [PATCH 47/86] more

---
 .../phases/3-transform/client/visitors/EachBlock.js      | 8 --------
 .../phases/3-transform/client/visitors/shared/utils.js   | 9 ++++++++-
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index 964858247556..09afa0a2a1fe 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -228,14 +228,6 @@ export function EachBlock(node, context) {
 			// TODO update (`item++`) and update_property — these were unaccounted for previously
 		};
 
-		child_state.setters[node.context.name] = create_mutation(
-			b.member(
-				each_node_meta.array_name ? b.call(each_node_meta.array_name) : collection,
-				index,
-				true
-			)
-		);
-
 		delete key_state.transformers[node.context.name];
 	} else {
 		const unwrapped = getter(binding.node);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
index 4f865e387efc..8adea214e67f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
@@ -169,7 +169,14 @@ export function build_bind_this(expression, value, { state, visit }) {
 				if (owner.type === 'EachBlock' && scope === binding.scope) {
 					ids.push(node);
 					values.push(/** @type {Expression} */ (visit(node)));
-					delete transformers[node.name];
+
+					if (transformers[node.name]) {
+						transformers[node.name] = {
+							...transformers[node.name],
+							read: (node) => node
+						};
+					}
+
 					break;
 				}
 			}

From 81544e02873d23ab7744ab0aa32f7a15c3cfd890 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 14:40:39 -0400
Subject: [PATCH 48/86] tidy up

---
 .../3-transform/client/transform-client.js    |  2 -
 .../phases/3-transform/client/types.d.ts      |  7 ---
 .../phases/3-transform/client/utils.js        |  6 --
 .../3-transform/client/visitors/EachBlock.js  | 56 ++++---------------
 4 files changed, 12 insertions(+), 59 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 00e26afb661c..2fe79569401f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -157,7 +157,6 @@ export function client_component(analysis, options) {
 		public_state: new Map(),
 		private_state: new Map(),
 		transformers: {},
-		setters: {},
 		in_constructor: false,
 
 		// these are set inside the `Fragment` visitor, and cannot be used until then
@@ -668,7 +667,6 @@ export function client_module(analysis, options) {
 		public_state: new Map(),
 		private_state: new Map(),
 		transformers: {},
-		setters: {},
 		in_constructor: false
 	};
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index e4d0ee23aa11..c5e5da97a807 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -40,13 +40,6 @@ export interface ClientTransformState extends TransformState {
 			update_property?: (id: Identifier) => Expression;
 		}
 	>;
-	/**
-	 * Counterpart to `getters`
-	 */
-	readonly setters: Record<
-		string,
-		(assignment: AssignmentExpression, context: Context) => Expression
-	>;
 }
 
 export interface ComponentClientTransformState extends ClientTransformState {
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index d62a94a85754..efd895f3524e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -261,12 +261,6 @@ export function build_setter(node, context, fallback, prefix, options) {
 		return transformers.assign(left, value);
 	}
 
-	if (Object.hasOwn(state.setters, left.name)) {
-		const setter = state.setters[left.name];
-		// @ts-expect-error
-		return setter(node, context);
-	}
-
 	/**
 	 * @param {any} serialized
 	 * @returns
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index 09afa0a2a1fe..c65fac786156 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -129,46 +129,6 @@ export function EachBlock(node, context) {
 		transformers: { ...context.state.transformers }
 	};
 
-	/**
-	 * @param {Pattern} expression_for_id
-	 * @returns {(assignment: AssignmentExpression, context: Context) => Expression}
-	 */
-	const create_mutation = (expression_for_id) => {
-		return (assignment, context) => {
-			if (assignment.left.type !== 'Identifier' && assignment.left.type !== 'MemberExpression') {
-				// build_setter turns other patterns into IIFEs and separates the assignments
-				// into separate expressions, at which point this is called again with an identifier or member expression
-				return build_setter(assignment, context, () => assignment);
-			}
-
-			const left = object(assignment.left);
-			const value = get_assignment_value(assignment, context);
-			const invalidate = b.call(
-				'$.invalidate_inner_signals',
-				b.thunk(b.sequence(indirect_dependencies))
-			);
-			const invalidate_store = store_to_invalidate
-				? b.call('$.invalidate_store', b.id('$$stores'), b.literal(store_to_invalidate))
-				: undefined;
-
-			const sequence = [];
-			if (!context.state.analysis.runes) sequence.push(invalidate);
-			if (invalidate_store) sequence.push(invalidate_store);
-
-			if (left === assignment.left) {
-				const assign = b.assignment('=', expression_for_id, value);
-				sequence.unshift(assign);
-				return b.sequence(sequence);
-			} else {
-				const original_left = /** @type {MemberExpression} */ (assignment.left);
-				const left = /** @type {Pattern} */ (context.visit(original_left));
-				const assign = b.assignment(assignment.operator, left, value);
-				sequence.unshift(assign);
-				return b.sequence(sequence);
-			}
-		};
-	};
-
 	// We need to generate a unique identifier in case there's a bind:group below
 	// which needs a reference to the index
 	const index =
@@ -243,10 +203,18 @@ export function EachBlock(node, context) {
 			declarations.push(b.let(path.node, needs_derived ? b.call('$.derived_safe_equal', fn) : fn));
 
 			const read = needs_derived ? get_value : b.call;
-			child_state.transformers[name] = { read };
-			child_state.setters[name] = create_mutation(
-				/** @type {Pattern} */ (path.update_expression(unwrapped))
-			);
+
+			child_state.transformers[name] = {
+				read,
+				assign: (node, value) => {
+					const left = /** @type {Pattern} */ (path.update_expression(unwrapped));
+					return b.sequence([b.assignment('=', left, value), ...sequence]);
+				},
+				assign_property: (node, mutation) => {
+					return b.sequence([mutation, ...sequence]);
+				}
+				// TODO update (`item++`) and update_property — these were unaccounted for previously
+			};
 
 			// we need to eagerly evaluate the expression in order to hit any
 			// 'Cannot access x before initialization' errors

From e29bee5632f9132c9c6de02ae6bb372cceec0031 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 14:42:05 -0400
Subject: [PATCH 49/86] tidy up

---
 .../phases/3-transform/client/visitors/BindDirective.js     | 1 -
 .../phases/3-transform/client/visitors/EachBlock.js         | 6 +++---
 .../phases/3-transform/client/visitors/shared/component.js  | 5 ++---
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/BindDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/BindDirective.js
index e0a40835bba7..81bafcc18a09 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/BindDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/BindDirective.js
@@ -5,7 +5,6 @@ import { dev, is_ignored } from '../../../../state.js';
 import { is_text_attribute } from '../../../../utils/ast.js';
 import * as b from '../../../../utils/builders.js';
 import { binding_properties } from '../../../bindings.js';
-import { build_setter } from '../utils.js';
 import { build_attribute_value } from './shared/element.js';
 import { build_bind_this, validate_binding } from './shared/utils.js';
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index c65fac786156..e5a2620fb43b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -1,6 +1,6 @@
-/** @import { AssignmentExpression, BlockStatement, Expression, Identifier, MemberExpression, Pattern, Statement } from 'estree' */
+/** @import { BlockStatement, Expression, Identifier, Pattern, Statement } from 'estree' */
 /** @import { Binding, EachBlock } from '#compiler' */
-/** @import { ComponentContext, Context } from '../types' */
+/** @import { ComponentContext } from '../types' */
 /** @import { Scope } from '../../../scope' */
 import {
 	EACH_INDEX_REACTIVE,
@@ -13,7 +13,7 @@ import {
 import { dev } from '../../../../state.js';
 import { extract_paths, object } from '../../../../utils/ast.js';
 import * as b from '../../../../utils/builders.js';
-import { get_assignment_value, build_getter, build_setter, with_loc } from '../utils.js';
+import { build_getter, with_loc } from '../utils.js';
 import { get_value } from './shared/declarations.js';
 
 /**
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index 226a9965fe19..5eb3367ad591 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -1,11 +1,10 @@
 /** @import { BlockStatement, Expression, ExpressionStatement, Identifier, MemberExpression, Property, Statement } from 'estree' */
-/** @import { Attribute, Component, SvelteComponent, SvelteSelf, TemplateNode, Text } from '#compiler' */
+/** @import { Component, SvelteComponent, SvelteSelf, TemplateNode } from '#compiler' */
 /** @import { ComponentContext } from '../../types.js' */
 import { dev, is_ignored } from '../../../../../state.js';
 import { get_attribute_chunks } from '../../../../../utils/ast.js';
 import * as b from '../../../../../utils/builders.js';
-import { is_element_node } from '../../../../nodes.js';
-import { create_derived, build_setter } from '../../utils.js';
+import { create_derived } from '../../utils.js';
 import { build_bind_this, validate_binding } from '../shared/utils.js';
 import { build_attribute_value } from '../shared/element.js';
 import { build_event_handler } from './events.js';

From c649da8ab263069c8750e0105ab626f51a45e612 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 14:44:42 -0400
Subject: [PATCH 50/86] remove some junk

---
 .../compiler/phases/3-transform/client/utils.js  | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index efd895f3524e..d0204d321daa 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -92,10 +92,9 @@ export function build_getter(node, state) {
  * @param {import('zimmerframe').Context<SvelteNode, State>} context
  * @param {() => any} fallback
  * @param {boolean | null} [prefix] - If the assignment is a transformed update expression, set this. Else `null`
- * @param {{skip_proxy_and_freeze?: boolean}} [options]
  * @returns {Expression}
  */
-export function build_setter(node, context, fallback, prefix, options) {
+export function build_setter(node, context, fallback, prefix) {
 	const { state, visit } = context;
 
 	const assignee = node.left;
@@ -119,7 +118,7 @@ export function build_setter(node, context, fallback, prefix, options) {
 			const value = path.expression?.(b.id(tmp_id));
 			const assignment = b.assignment('=', path.node, value);
 			original_assignments.push(assignment);
-			assignments.push(build_setter(assignment, context, () => assignment, prefix, options));
+			assignments.push(build_setter(assignment, context, () => assignment, prefix));
 		}
 
 		if (assignments.every((assignment, i) => assignment === original_assignments[i])) {
@@ -166,11 +165,7 @@ export function build_setter(node, context, fallback, prefix, options) {
 			if (private_state !== undefined) {
 				if (state.in_constructor) {
 					// See if we should wrap value in $.proxy
-					if (
-						context.state.analysis.runes &&
-						!options?.skip_proxy_and_freeze &&
-						should_proxy_or_freeze(value, context.state.scope)
-					) {
+					if (context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)) {
 						const assignment = fallback();
 						if (assignment.type === 'AssignmentExpression') {
 							assignment.right =
@@ -184,9 +179,7 @@ export function build_setter(node, context, fallback, prefix, options) {
 					return b.call(
 						'$.set',
 						assignee,
-						context.state.analysis.runes &&
-							!options?.skip_proxy_and_freeze &&
-							should_proxy_or_freeze(value, context.state.scope)
+						context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)
 							? private_state.kind === 'frozen_state'
 								? b.call('$.freeze', value)
 								: build_proxy_reassignment(value, private_state.id)
@@ -205,7 +198,6 @@ export function build_setter(node, context, fallback, prefix, options) {
 			if (
 				context.state.analysis.runes &&
 				public_state !== undefined &&
-				!options?.skip_proxy_and_freeze &&
 				should_proxy_or_freeze(value, context.state.scope)
 			) {
 				const assignment = fallback();

From 3d6afdf3c9a1459095eedebd8e887c140a18189b Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 15:27:09 -0400
Subject: [PATCH 51/86] tidy up

---
 .../3-transform/client/transform-client.js    | 20 ++---
 .../phases/3-transform/client/types.d.ts      |  6 +-
 .../phases/3-transform/client/utils.js        | 22 +++---
 .../3-transform/client/visitors/ConstTag.js   | 10 +--
 .../3-transform/client/visitors/EachBlock.js  | 24 +++---
 .../3-transform/client/visitors/Fragment.js   |  2 +-
 .../client/visitors/LetDirective.js           |  4 +-
 .../3-transform/client/visitors/Program.js    | 12 +--
 .../client/visitors/SnippetBlock.js           | 10 +--
 .../client/visitors/UpdateExpression.js       | 74 ++++++++-----------
 .../client/visitors/shared/component.js       |  4 +-
 .../client/visitors/shared/declarations.js    |  4 +-
 .../client/visitors/shared/utils.js           | 10 +--
 13 files changed, 94 insertions(+), 108 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 2fe79569401f..6aa45ad40f00 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -63,16 +63,16 @@ const visitors = {
 		const scope = state.scopes.get(node);
 
 		if (scope && scope !== state.scope) {
-			const transformers = { ...state.transformers };
+			const transform = { ...state.transform };
 
 			// TODO do this in add_state_transformers and visit_function etc?
 			for (const [name, binding] of scope.declarations) {
 				if (binding.kind === 'normal') {
-					delete transformers[name];
+					delete transform[name];
 				}
 			}
 
-			next({ ...state, transformers, scope });
+			next({ ...state, transform, scope });
 		} else {
 			next();
 		}
@@ -156,7 +156,7 @@ export function client_component(analysis, options) {
 		preserve_whitespace: options.preserveWhitespace,
 		public_state: new Map(),
 		private_state: new Map(),
-		transformers: {},
+		transform: {},
 		in_constructor: false,
 
 		// these are set inside the `Fragment` visitor, and cannot be used until then
@@ -172,7 +172,7 @@ export function client_component(analysis, options) {
 	const legacy_reactive_imports = [];
 
 	if (!analysis.runes) {
-		state.transformers['$$props'] = {
+		state.transform['$$props'] = {
 			read: (node) => ({ ...node, name: '$$sanitized_props' })
 		};
 
@@ -182,9 +182,9 @@ export function client_component(analysis, options) {
 			if (binding.declaration_kind === 'import' && binding.mutated) {
 				const id = b.id('$$_import_' + name);
 
-				state.transformers[name] = {
+				state.transform[name] = {
 					read: (node) => b.call(id),
-					assign_property: (node, mutation) => {
+					mutate: (node, mutation) => {
 						return b.call(id, mutation);
 					}
 				};
@@ -200,7 +200,7 @@ export function client_component(analysis, options) {
 
 	const instance_state = {
 		...state,
-		transformers: { ...state.transformers },
+		transform: { ...state.transform },
 		scope: analysis.instance.scope,
 		scopes: analysis.instance.scopes,
 		is_instance: true
@@ -215,7 +215,7 @@ export function client_component(analysis, options) {
 			/** @type {SvelteNode} */ (analysis.template.ast),
 			{
 				...state,
-				transformers: instance_state.transformers,
+				transform: instance_state.transform,
 				scope: analysis.instance.scope,
 				scopes: analysis.template.scopes
 			},
@@ -666,7 +666,7 @@ export function client_module(analysis, options) {
 		legacy_reactive_statements: new Map(),
 		public_state: new Map(),
 		private_state: new Map(),
-		transformers: {},
+		transform: {},
 		in_constructor: false
 	};
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index c5e5da97a807..b576ddeecaed 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -25,7 +25,7 @@ export interface ClientTransformState extends TransformState {
 
 	/** The $: calls, which will be ordered in the end */
 	readonly legacy_reactive_statements: Map<LabeledStatement, Statement>;
-	readonly transformers: Record<
+	readonly transform: Record<
 		string,
 		{
 			/** turn `foo` into e.g. `$.get(foo)` */
@@ -33,11 +33,9 @@ export interface ClientTransformState extends TransformState {
 			/** turn `foo = bar` into e.g. `$.set(foo, bar)` */
 			assign?: (node: Identifier, value: Expression) => Expression;
 			/** turn `foo.bar = baz` into e.g. `$.mutate(foo, $.get(foo).bar = baz);` */
-			assign_property?: (node: Identifier, mutation: AssignmentExpression) => Expression;
+			mutate?: (node: Identifier, mutation: AssignmentExpression) => Expression;
 			/** turn `foo++` into e.g. `$.update(foo)` */
 			update?: (node: UpdateExpression) => Expression;
-			/** turn `foo.bar++` into e.g. `$.mutate(foo, $.get(foo).bar += 1)` */
-			update_property?: (id: Identifier) => Expression;
 		}
 	>;
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index d0204d321daa..487f75057a55 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -74,12 +74,12 @@ export function is_state_source(binding, state) {
  * @returns {Expression}
  */
 export function build_getter(node, state) {
-	if (Object.hasOwn(state.transformers, node.name)) {
+	if (Object.hasOwn(state.transform, node.name)) {
 		const binding = state.scope.get(node.name);
 
 		// don't transform the declaration itself
 		if (node !== binding?.node) {
-			return state.transformers[node.name].read(node);
+			return state.transform[node.name].read(node);
 		}
 	}
 
@@ -217,12 +217,12 @@ export function build_setter(node, context, fallback, prefix) {
 	const binding = left && state.scope.get(left.name);
 	if (!binding) return fallback();
 
-	const transformers = Object.hasOwn(context.state.transformers, left.name)
-		? context.state.transformers[left.name]
+	const transform = Object.hasOwn(context.state.transform, left.name)
+		? context.state.transform[left.name]
 		: null;
 
 	// reassignment
-	if (left === node.left && transformers?.assign) {
+	if (left === node.left && transform?.assign) {
 		let value = /** @type {Expression} */ (visit(node.right));
 
 		if (node.operator !== '=') {
@@ -250,7 +250,7 @@ export function build_setter(node, context, fallback, prefix) {
 			}
 		}
 
-		return transformers.assign(left, value);
+		return transform.assign(left, value);
 	}
 
 	/**
@@ -266,14 +266,14 @@ export function build_setter(node, context, fallback, prefix) {
 	};
 
 	// mutation
-	if (transformers?.assign_property) {
+	if (transform?.mutate) {
 		const mutation = b.assignment(
 			node.operator,
 			/** @type {Pattern} */ (context.visit(node.left)),
 			/** @type {Expression} */ (context.visit(node.right))
 		);
 
-		return maybe_skip_ownership_validation(transformers.assign_property(left, mutation));
+		return maybe_skip_ownership_validation(transform.mutate(left, mutation));
 	}
 
 	if (
@@ -360,7 +360,7 @@ function get_hoisted_params(node, context) {
 				binding = /** @type {Binding} */ (scope.get(binding.node.name.slice(1)));
 			}
 
-			let expression = context.state.transformers[reference]?.read(b.id(binding.node.name));
+			let expression = context.state.transform[reference]?.read(b.id(binding.node.name));
 
 			if (
 				// If it's a destructured derived binding, then we can extract the derived signal reference and use that.
@@ -559,7 +559,7 @@ export function with_loc(target, source) {
  */
 export function create_derived_block_argument(node, context) {
 	if (node.type === 'Identifier') {
-		context.state.transformers[node.name] = {
+		context.state.transform[node.name] = {
 			read: get_value
 		};
 
@@ -580,7 +580,7 @@ export function create_derived_block_argument(node, context) {
 	const declarations = [b.var(value, create_derived(context.state, b.thunk(block)))];
 
 	for (const id of identifiers) {
-		context.state.transformers[id.name] = { read: get_value };
+		context.state.transform[id.name] = { read: get_value };
 
 		declarations.push(
 			b.var(id, create_derived(context.state, b.thunk(b.member(b.call('$.get', value), id))))
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
index 8d8a8beb0f1b..1a7b2904d920 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
@@ -25,7 +25,7 @@ export function ConstTag(node, context) {
 			)
 		);
 
-		context.state.transformers[declaration.id.name] = {
+		context.state.transform[declaration.id.name] = {
 			read: get_value
 		};
 
@@ -38,15 +38,15 @@ export function ConstTag(node, context) {
 		const identifiers = extract_identifiers(declaration.id);
 		const tmp = b.id(context.state.scope.generate('computed_const'));
 
-		const transformers = { ...context.state.transformers };
+		const transform = { ...context.state.transform };
 
 		// Make all identifiers that are declared within the following computed regular
 		// variables, as they are not signals in that context yet
 		for (const node of identifiers) {
-			delete transformers[node.name];
+			delete transform[node.name];
 		}
 
-		const child_state = { ...context.state, transformers };
+		const child_state = { ...context.state, transform };
 
 		// TODO optimise the simple `{ x } = y` case — we can just return `y`
 		// instead of destructuring it only to return a new object
@@ -70,7 +70,7 @@ export function ConstTag(node, context) {
 		}
 
 		for (const node of identifiers) {
-			context.state.transformers[node.name] = {
+			context.state.transform[node.name] = {
 				read: (node) => b.member(b.call('$.get', tmp), node)
 			};
 		}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index e5a2620fb43b..8491850de896 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -120,13 +120,13 @@ export function EachBlock(node, context) {
 
 	const child_state = {
 		...context.state,
-		transformers: { ...context.state.transformers }
+		transform: { ...context.state.transform }
 	};
 
 	/** The state used when generating the key function, if necessary */
 	const key_state = {
 		...context.state,
-		transformers: { ...context.state.transformers }
+		transform: { ...context.state.transform }
 	};
 
 	// We need to generate a unique identifier in case there's a bind:group below
@@ -141,7 +141,7 @@ export function EachBlock(node, context) {
 	};
 
 	if (node.index) {
-		child_state.transformers[node.index] = {
+		child_state.transform[node.index] = {
 			read: (id) => {
 				const index_with_loc = with_loc(index, id);
 				return (flags & EACH_INDEX_REACTIVE) === 0
@@ -150,7 +150,7 @@ export function EachBlock(node, context) {
 			}
 		};
 
-		delete key_state.transformers[node.index];
+		delete key_state.transform[node.index];
 	}
 
 	/** @type {Statement[]} */
@@ -171,7 +171,7 @@ export function EachBlock(node, context) {
 	if (invalidate_store) sequence.push(invalidate_store);
 
 	if (node.context.type === 'Identifier') {
-		child_state.transformers[node.context.name] = {
+		child_state.transform[node.context.name] = {
 			read: getter,
 			assign: (node, value) => {
 				const left = b.member(
@@ -182,13 +182,13 @@ export function EachBlock(node, context) {
 
 				return b.sequence([b.assignment('=', left, value), ...sequence]);
 			},
-			assign_property: (node, mutation) => {
+			mutate: (node, mutation) => {
 				return b.sequence([mutation, ...sequence]);
 			}
-			// TODO update (`item++`) and update_property — these were unaccounted for previously
+			// TODO update (`item++`) — this was unaccounted for previously
 		};
 
-		delete key_state.transformers[node.context.name];
+		delete key_state.transform[node.context.name];
 	} else {
 		const unwrapped = getter(binding.node);
 		const paths = extract_paths(node.context);
@@ -204,16 +204,16 @@ export function EachBlock(node, context) {
 
 			const read = needs_derived ? get_value : b.call;
 
-			child_state.transformers[name] = {
+			child_state.transform[name] = {
 				read,
 				assign: (node, value) => {
 					const left = /** @type {Pattern} */ (path.update_expression(unwrapped));
 					return b.sequence([b.assignment('=', left, value), ...sequence]);
 				},
-				assign_property: (node, mutation) => {
+				mutate: (node, mutation) => {
 					return b.sequence([mutation, ...sequence]);
 				}
-				// TODO update (`item++`) and update_property — these were unaccounted for previously
+				// TODO update (`item++`) — this was unaccounted for previously
 			};
 
 			// we need to eagerly evaluate the expression in order to hit any
@@ -222,7 +222,7 @@ export function EachBlock(node, context) {
 				declarations.push(b.stmt(read(b.id(name))));
 			}
 
-			key_state.transformers[name] = {
+			key_state.transform[name] = {
 				read: () => path.node
 			};
 		}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
index a842ba07ee52..e7312d15aaf3 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
@@ -66,7 +66,7 @@ export function Fragment(node, context) {
 		after_update: [],
 		template: [],
 		locations: [],
-		transformers: { ...context.state.transformers },
+		transform: { ...context.state.transform },
 		metadata: {
 			context: {
 				template_needs_import_node: false,
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
index e4d6d06acf6f..c455ea32193e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
@@ -16,7 +16,7 @@ export function LetDirective(node, context) {
 		const bindings = context.state.scope.get_bindings(node);
 
 		for (const binding of bindings) {
-			context.state.transformers[binding.node.name] = {
+			context.state.transform[binding.node.name] = {
 				read: (node) => b.member(b.call('$.get', b.id(name)), node)
 			};
 		}
@@ -42,7 +42,7 @@ export function LetDirective(node, context) {
 		);
 	} else {
 		const name = node.expression === null ? node.name : node.expression.name;
-		context.state.transformers[name] = {
+		context.state.transform[name] = {
 			read: (node) => b.call('$.get', node)
 		};
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index fa74e8abbb4b..07fb459f3eb5 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -14,12 +14,12 @@ export function Program(node, context) {
 			if (binding.kind === 'store_sub') {
 				const store = /** @type {Expression} */ (context.visit(b.id(name.slice(1))));
 
-				context.state.transformers[name] = {
+				context.state.transform[name] = {
 					read: b.call,
 					assign: (node, value) => {
 						return b.call('$.store_set', store, value);
 					},
-					assign_property: (node, mutation) => {
+					mutate: (node, mutation) => {
 						// We need to untrack the store read, for consistency with Svelte 4
 						const untracked = b.call('$.untrack', node);
 
@@ -66,12 +66,12 @@ export function Program(node, context) {
 
 			if (binding.kind === 'prop' || binding.kind === 'bindable_prop') {
 				if (is_prop_source(binding, context.state)) {
-					context.state.transformers[name] = {
+					context.state.transform[name] = {
 						read: b.call,
 						assign: (node, value) => {
 							return b.call(node, value);
 						},
-						assign_property: (node, value) => {
+						mutate: (node, value) => {
 							if (binding.kind === 'bindable_prop') {
 								// only necessary for interop with legacy parent bindings
 								return b.call(node, value, b.true);
@@ -89,11 +89,11 @@ export function Program(node, context) {
 					};
 				} else if (binding.prop_alias) {
 					const key = b.key(binding.prop_alias);
-					context.state.transformers[name] = {
+					context.state.transform[name] = {
 						read: (node) => b.member(b.id('$$props'), key, key.type === 'Literal')
 					};
 				} else {
-					context.state.transformers[name] = {
+					context.state.transform[name] = {
 						read: (node) => b.member(b.id('$$props'), node)
 					};
 				}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
index d0ac1641be97..750b1b6a3b0d 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
@@ -21,8 +21,8 @@ export function SnippetBlock(node, context) {
 	/** @type {Statement[]} */
 	const declarations = [];
 
-	const transformers = { ...context.state.transformers };
-	const child_state = { ...context.state, transformers };
+	const transform = { ...context.state.transform };
+	const child_state = { ...context.state, transform };
 
 	for (let i = 0; i < node.parameters.length; i++) {
 		const argument = node.parameters[i];
@@ -36,7 +36,7 @@ export function SnippetBlock(node, context) {
 				right: b.id('$.noop')
 			});
 
-			transformers[argument.name] = {
+			transform[argument.name] = {
 				read: b.call
 			};
 
@@ -57,14 +57,14 @@ export function SnippetBlock(node, context) {
 
 			declarations.push(b.let(path.node, needs_derived ? b.call('$.derived_safe_equal', fn) : fn));
 
-			transformers[name] = {
+			transform[name] = {
 				read: needs_derived ? get_value : b.call
 			};
 
 			// we need to eagerly evaluate the expression in order to hit any
 			// 'Cannot access x before initialization' errors
 			if (dev) {
-				declarations.push(b.stmt(transformers[name].read(b.id(name))));
+				declarations.push(b.stmt(transform[name].read(b.id(name))));
 			}
 		}
 	}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
index dd483f2ea3dd..91383a56793c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/UpdateExpression.js
@@ -1,8 +1,8 @@
-/** @import { Expression, Pattern, Statement, UpdateExpression } from 'estree' */
+/** @import { Expression, Node, Pattern, Statement, UpdateExpression } from 'estree' */
 /** @import { Context } from '../types' */
 import { is_ignored } from '../../../../state.js';
+import { object } from '../../../../utils/ast.js';
 import * as b from '../../../../utils/builders.js';
-import { build_setter } from '../utils.js';
 
 /**
  * @param {UpdateExpression} node
@@ -10,16 +10,6 @@ import { build_setter } from '../utils.js';
  */
 export function UpdateExpression(node, context) {
 	const argument = node.argument;
-	const transformers = context.state.transformers;
-
-	if (argument.type === 'Identifier') {
-		if (Object.hasOwn(transformers, argument.name) && transformers[argument.name].update) {
-			const transformer = transformers[argument.name].update;
-			if (transformer) return transformer(node);
-		}
-
-		return context.next();
-	}
 
 	if (
 		argument.type === 'MemberExpression' &&
@@ -39,43 +29,41 @@ export function UpdateExpression(node, context) {
 		return b.call(fn, ...args);
 	}
 
-	/** @param {any} serialized */
-	function maybe_skip_ownership_validation(serialized) {
-		if (is_ignored(node, 'ownership_invalid_mutation')) {
-			return b.call('$.skip_ownership_validation', b.thunk(serialized));
-		}
-
-		return serialized;
+	if (argument.type !== 'Identifier' && argument.type !== 'MemberExpression') {
+		throw new Error('An impossible state was reached');
 	}
 
-	// turn it into an IIFE assignment expression: i++ -> (() => { const $$value = i; i+=1; return $$value; })
-	const assignment = b.assignment(
-		node.operator === '++' ? '+=' : '-=',
-		/** @type {Pattern} */ (argument),
-		b.literal(1)
-	);
+	const left = object(argument);
+	if (left === null) return context.next();
 
-	const serialized_assignment = build_setter(assignment, context, () => assignment, node.prefix);
+	if (left === argument) {
+		const transform = context.state.transform;
+		const update = transform[left.name]?.update;
 
-	const value = /** @type {Expression} */ (context.visit(argument));
-
-	if (serialized_assignment === assignment) {
-		// No change to output -> nothing to transform -> we can keep the original update expression
-		return maybe_skip_ownership_validation(context.next());
+		if (update && Object.hasOwn(transform, left.name)) {
+			return update(node);
+		}
 	}
 
-	if (context.state.analysis.runes) {
-		return maybe_skip_ownership_validation(serialized_assignment);
-	}
+	const assignment = /** @type {Expression} */ (
+		context.visit(
+			b.assignment(
+				node.operator === '++' ? '+=' : '-=',
+				/** @type {Pattern} */ (argument),
+				b.literal(1)
+			)
+		)
+	);
 
-	/** @type {Statement[]} */
-	let statements;
-	if (node.prefix) {
-		statements = [b.stmt(serialized_assignment), b.return(value)];
-	} else {
-		const tmp_id = context.state.scope.generate('$$value');
-		statements = [b.const(tmp_id, value), b.stmt(serialized_assignment), b.return(b.id(tmp_id))];
-	}
+	const parent = /** @type {Node} */ (context.path.at(-1));
+	const is_standalone = parent.type === 'ExpressionStatement'; // TODO and possibly others, but not e.g. the `test` of a WhileStatement
+
+	const update =
+		node.prefix || is_standalone
+			? assignment
+			: b.binary(node.operator === '++' ? '-' : '+', assignment, b.literal(1));
 
-	return maybe_skip_ownership_validation(b.call(b.thunk(b.block(statements))));
+	return is_ignored(node, 'ownership_invalid_mutation')
+		? b.call('$.skip_ownership_validation', b.thunk(update))
+		: update;
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index 5eb3367ad591..aaf2b024bd74 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -29,7 +29,7 @@ export function build_component(node, component_name, context, anchor = context.
 		default: {
 			...context.state,
 			scope: node.metadata.scopes.default,
-			transformers: { ...context.state.transformers }
+			transform: { ...context.state.transform }
 		}
 	};
 
@@ -257,7 +257,7 @@ export function build_component(node, component_name, context, anchor = context.
 					: {
 							...context.state,
 							scope: node.metadata.scopes[slot_name],
-							transformers: { ...context.state.transformers }
+							transform: { ...context.state.transform }
 						}
 				// {
 				// 	...context.state,
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
index ae158ba8dbca..5a03fd9be4d9 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/declarations.js
@@ -22,7 +22,7 @@ export function add_state_transformers(context) {
 			binding.kind === 'derived' ||
 			binding.kind === 'legacy_reactive'
 		) {
-			context.state.transformers[name] = {
+			context.state.transform[name] = {
 				read: get_value,
 				assign: (node, value) => {
 					let call = b.call('$.set', node, value);
@@ -33,7 +33,7 @@ export function add_state_transformers(context) {
 
 					return call;
 				},
-				assign_property: (node, mutation) => {
+				mutate: (node, mutation) => {
 					if (context.state.analysis.runes) {
 						return mutation;
 					}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
index 8adea214e67f..b11c2ed22407 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
@@ -148,7 +148,7 @@ export function build_bind_this(expression, value, { state, visit }) {
 	/** @type {string[]} */
 	const seen = [];
 
-	const transformers = { ...state.transformers };
+	const transform = { ...state.transform };
 
 	// Pass in each context variables to the get/set functions, so that we can null out old values on teardown.
 	// Note that we only do this for each context variables, the consequence is that the value might be stale in
@@ -170,9 +170,9 @@ export function build_bind_this(expression, value, { state, visit }) {
 					ids.push(node);
 					values.push(/** @type {Expression} */ (visit(node)));
 
-					if (transformers[node.name]) {
-						transformers[node.name] = {
-							...transformers[node.name],
+					if (transform[node.name]) {
+						transform[node.name] = {
+							...transform[node.name],
 							read: (node) => node
 						};
 					}
@@ -183,7 +183,7 @@ export function build_bind_this(expression, value, { state, visit }) {
 		}
 	});
 
-	const child_state = { ...state, transformers };
+	const child_state = { ...state, transform };
 
 	const get = /** @type {Expression} */ (visit(expression, child_state));
 	const set = /** @type {Expression} */ (

From 84cc1e7599cb0230dade6885d727f9a59989532c Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 15:30:38 -0400
Subject: [PATCH 52/86] move stuff

---
 .../phases/3-transform/client/utils.js        | 275 +-----------------
 .../client/visitors/AssignmentExpression.js   | 273 ++++++++++++++++-
 2 files changed, 273 insertions(+), 275 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 487f75057a55..ce9825ad018f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -1,61 +1,18 @@
-/** @import { ArrowFunctionExpression, AssignmentExpression, BinaryOperator, Expression, FunctionDeclaration, FunctionExpression, Identifier, MemberExpression, Node, Pattern, PrivateIdentifier, Statement } from 'estree' */
+/** @import { ArrowFunctionExpression, Expression, FunctionDeclaration, FunctionExpression, Identifier, Pattern, PrivateIdentifier, Statement } from 'estree' */
 /** @import { Binding, SvelteNode } from '#compiler' */
 /** @import { ClientTransformState, ComponentClientTransformState, ComponentContext } from './types.js' */
 /** @import { Scope } from '../../scope.js' */
 import * as b from '../../../utils/builders.js';
-import {
-	extract_identifiers,
-	extract_paths,
-	is_expression_async,
-	is_simple_expression,
-	object
-} from '../../../utils/ast.js';
+import { extract_identifiers, is_simple_expression } from '../../../utils/ast.js';
 import {
 	PROPS_IS_LAZY_INITIAL,
 	PROPS_IS_IMMUTABLE,
 	PROPS_IS_RUNES,
 	PROPS_IS_UPDATED
 } from '../../../../constants.js';
-import { is_ignored, dev } from '../../../state.js';
+import { dev } from '../../../state.js';
 import { get_value } from './visitors/shared/declarations.js';
 
-/**
- * @template {ClientTransformState} State
- * @param {AssignmentExpression} node
- * @param {import('zimmerframe').Context<SvelteNode, State>} context
- * @returns
- */
-export function get_assignment_value(node, { state, visit }) {
-	if (node.left.type === 'Identifier') {
-		const operator = node.operator;
-		return operator === '='
-			? /** @type {Expression} */ (visit(node.right))
-			: // turn something like x += 1 into x = x + 1
-				b.binary(
-					/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-					build_getter(node.left, state),
-					/** @type {Expression} */ (visit(node.right))
-				);
-	} else if (
-		node.left.type === 'MemberExpression' &&
-		node.left.object.type === 'ThisExpression' &&
-		node.left.property.type === 'PrivateIdentifier' &&
-		state.private_state.has(node.left.property.name)
-	) {
-		const operator = node.operator;
-		return operator === '='
-			? /** @type {Expression} */ (visit(node.right))
-			: // turn something like x += 1 into x = x + 1
-				b.binary(
-					/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-					/** @type {Expression} */ (visit(node.left)),
-					/** @type {Expression} */ (visit(node.right))
-				);
-	} else {
-		return /** @type {Expression} */ (visit(node.right));
-	}
-}
-
 /**
  * @param {Binding} binding
  * @param {ClientTransformState} state
@@ -86,232 +43,6 @@ export function build_getter(node, state) {
 	return node;
 }
 
-/**
- * @template {ClientTransformState} State
- * @param {AssignmentExpression} node
- * @param {import('zimmerframe').Context<SvelteNode, State>} context
- * @param {() => any} fallback
- * @param {boolean | null} [prefix] - If the assignment is a transformed update expression, set this. Else `null`
- * @returns {Expression}
- */
-export function build_setter(node, context, fallback, prefix) {
-	const { state, visit } = context;
-
-	const assignee = node.left;
-	if (
-		assignee.type === 'ArrayPattern' ||
-		assignee.type === 'ObjectPattern' ||
-		assignee.type === 'RestElement'
-	) {
-		// Turn assignment into an IIFE, so that `$.set` calls etc don't produce invalid code
-		const tmp_id = context.state.scope.generate('tmp');
-
-		/** @type {AssignmentExpression[]} */
-		const original_assignments = [];
-
-		/** @type {Expression[]} */
-		const assignments = [];
-
-		const paths = extract_paths(assignee);
-
-		for (const path of paths) {
-			const value = path.expression?.(b.id(tmp_id));
-			const assignment = b.assignment('=', path.node, value);
-			original_assignments.push(assignment);
-			assignments.push(build_setter(assignment, context, () => assignment, prefix));
-		}
-
-		if (assignments.every((assignment, i) => assignment === original_assignments[i])) {
-			// No change to output -> nothing to transform -> we can keep the original assignment
-			return fallback();
-		}
-
-		const rhs_expression = /** @type {Expression} */ (visit(node.right));
-
-		const iife_is_async =
-			is_expression_async(rhs_expression) ||
-			assignments.some((assignment) => is_expression_async(assignment));
-
-		const iife = b.arrow(
-			[],
-			b.block([
-				b.const(tmp_id, rhs_expression),
-				b.stmt(b.sequence(assignments)),
-				// return because it could be used in a nested expression where the value is needed.
-				// example: { foo: ({ bar } = { bar: 1 })}
-				b.return(b.id(tmp_id))
-			])
-		);
-
-		if (iife_is_async) {
-			return b.await(b.call(b.async(iife)));
-		} else {
-			return b.call(iife);
-		}
-	}
-
-	if (assignee.type !== 'Identifier' && assignee.type !== 'MemberExpression') {
-		throw new Error(`Unexpected assignment type ${assignee.type}`);
-	}
-
-	// Handle class private/public state assignment cases
-	if (assignee.type === 'MemberExpression') {
-		if (
-			assignee.object.type === 'ThisExpression' &&
-			assignee.property.type === 'PrivateIdentifier'
-		) {
-			const private_state = context.state.private_state.get(assignee.property.name);
-			const value = get_assignment_value(node, context);
-			if (private_state !== undefined) {
-				if (state.in_constructor) {
-					// See if we should wrap value in $.proxy
-					if (context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)) {
-						const assignment = fallback();
-						if (assignment.type === 'AssignmentExpression') {
-							assignment.right =
-								private_state.kind === 'frozen_state'
-									? b.call('$.freeze', value)
-									: build_proxy_reassignment(value, private_state.id);
-							return assignment;
-						}
-					}
-				} else {
-					return b.call(
-						'$.set',
-						assignee,
-						context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)
-							? private_state.kind === 'frozen_state'
-								? b.call('$.freeze', value)
-								: build_proxy_reassignment(value, private_state.id)
-							: value
-					);
-				}
-			}
-		} else if (
-			assignee.object.type === 'ThisExpression' &&
-			assignee.property.type === 'Identifier' &&
-			state.in_constructor
-		) {
-			const public_state = context.state.public_state.get(assignee.property.name);
-			const value = get_assignment_value(node, context);
-			// See if we should wrap value in $.proxy
-			if (
-				context.state.analysis.runes &&
-				public_state !== undefined &&
-				should_proxy_or_freeze(value, context.state.scope)
-			) {
-				const assignment = fallback();
-				if (assignment.type === 'AssignmentExpression') {
-					assignment.right =
-						public_state.kind === 'frozen_state'
-							? b.call('$.freeze', value)
-							: build_proxy_reassignment(value, public_state.id);
-					return assignment;
-				}
-			}
-		}
-	}
-
-	const left = object(assignee);
-
-	const binding = left && state.scope.get(left.name);
-	if (!binding) return fallback();
-
-	const transform = Object.hasOwn(context.state.transform, left.name)
-		? context.state.transform[left.name]
-		: null;
-
-	// reassignment
-	if (left === node.left && transform?.assign) {
-		let value = /** @type {Expression} */ (visit(node.right));
-
-		if (node.operator !== '=') {
-			value = b.binary(
-				/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
-				/** @type {Expression} */ (visit(left)),
-				value
-			);
-		}
-
-		// special case — if an element binding, we know it's a primitive
-		const path = context.path.map((node) => node.type);
-		const is_primitive = path.at(-1) === 'BindDirective' && path.at(-2) === 'RegularElement';
-
-		if (
-			!is_primitive &&
-			binding.kind !== 'prop' &&
-			context.state.analysis.runes &&
-			should_proxy_or_freeze(value, context.state.scope)
-		) {
-			if (binding.kind === 'frozen_state') {
-				value = b.call('$.freeze', value);
-			} else {
-				value = build_proxy_reassignment(value, left.name);
-			}
-		}
-
-		return transform.assign(left, value);
-	}
-
-	/**
-	 * @param {any} serialized
-	 * @returns
-	 */
-	const maybe_skip_ownership_validation = (serialized) => {
-		if (is_ignored(node, 'ownership_invalid_mutation')) {
-			return b.call('$.skip_ownership_validation', b.thunk(serialized));
-		}
-
-		return serialized;
-	};
-
-	// mutation
-	if (transform?.mutate) {
-		const mutation = b.assignment(
-			node.operator,
-			/** @type {Pattern} */ (context.visit(node.left)),
-			/** @type {Expression} */ (context.visit(node.right))
-		);
-
-		return maybe_skip_ownership_validation(transform.mutate(left, mutation));
-	}
-
-	if (
-		node.right.type === 'Literal' &&
-		prefix != null &&
-		(node.operator === '+=' || node.operator === '-=')
-	) {
-		return maybe_skip_ownership_validation(
-			b.update(
-				node.operator === '+=' ? '++' : '--',
-				/** @type {Expression} */ (visit(node.left)),
-				prefix
-			)
-		);
-	} else {
-		if (
-			binding.kind !== 'state' &&
-			binding.kind !== 'frozen_state' &&
-			binding.kind !== 'prop' &&
-			binding.kind !== 'bindable_prop' &&
-			binding.kind !== 'each' &&
-			binding.kind !== 'legacy_reactive' &&
-			binding.kind !== 'store_sub' &&
-			binding.kind !== 'derived'
-		) {
-			// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
-			return fallback();
-		}
-		return maybe_skip_ownership_validation(
-			b.assignment(
-				node.operator,
-				/** @type {Pattern} */ (visit(node.left)),
-				/** @type {Expression} */ (visit(node.right))
-			)
-		);
-	}
-}
-
 /**
  * @param {Expression} value
  * @param {PrivateIdentifier | string} proxy_reference
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index fefc11bf1f34..5967065b79b8 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -1,6 +1,10 @@
-/** @import { AssignmentExpression } from 'estree' */
-/** @import { Context } from '../types' */
-import { build_setter } from '../utils.js';
+/** @import { AssignmentExpression, BinaryOperator, Expression, Pattern } from 'estree' */
+/** @import { SvelteNode } from '#compiler' */
+/** @import { ClientTransformState, Context } from '../types.js' */
+import * as b from '../../../../utils/builders.js';
+import { extract_paths, is_expression_async, object } from '../../../../utils/ast.js';
+import { is_ignored } from '../../../../state.js';
+import { build_getter, build_proxy_reassignment, should_proxy_or_freeze } from '../utils.js';
 
 /**
  * @param {AssignmentExpression} node
@@ -9,3 +13,266 @@ import { build_setter } from '../utils.js';
 export function AssignmentExpression(node, context) {
 	return build_setter(node, context, context.next);
 }
+
+/**
+ * @template {ClientTransformState} State
+ * @param {AssignmentExpression} node
+ * @param {import('zimmerframe').Context<SvelteNode, State>} context
+ * @param {() => any} fallback
+ * @param {boolean | null} [prefix] - If the assignment is a transformed update expression, set this. Else `null`
+ * @returns {Expression}
+ */
+export function build_setter(node, context, fallback, prefix) {
+	const { state, visit } = context;
+
+	const assignee = node.left;
+	if (
+		assignee.type === 'ArrayPattern' ||
+		assignee.type === 'ObjectPattern' ||
+		assignee.type === 'RestElement'
+	) {
+		// Turn assignment into an IIFE, so that `$.set` calls etc don't produce invalid code
+		const tmp_id = context.state.scope.generate('tmp');
+
+		/** @type {AssignmentExpression[]} */
+		const original_assignments = [];
+
+		/** @type {Expression[]} */
+		const assignments = [];
+
+		const paths = extract_paths(assignee);
+
+		for (const path of paths) {
+			const value = path.expression?.(b.id(tmp_id));
+			const assignment = b.assignment('=', path.node, value);
+			original_assignments.push(assignment);
+			assignments.push(build_setter(assignment, context, () => assignment, prefix));
+		}
+
+		if (assignments.every((assignment, i) => assignment === original_assignments[i])) {
+			// No change to output -> nothing to transform -> we can keep the original assignment
+			return fallback();
+		}
+
+		const rhs_expression = /** @type {Expression} */ (visit(node.right));
+
+		const iife_is_async =
+			is_expression_async(rhs_expression) ||
+			assignments.some((assignment) => is_expression_async(assignment));
+
+		const iife = b.arrow(
+			[],
+			b.block([
+				b.const(tmp_id, rhs_expression),
+				b.stmt(b.sequence(assignments)),
+				// return because it could be used in a nested expression where the value is needed.
+				// example: { foo: ({ bar } = { bar: 1 })}
+				b.return(b.id(tmp_id))
+			])
+		);
+
+		if (iife_is_async) {
+			return b.await(b.call(b.async(iife)));
+		} else {
+			return b.call(iife);
+		}
+	}
+
+	if (assignee.type !== 'Identifier' && assignee.type !== 'MemberExpression') {
+		throw new Error(`Unexpected assignment type ${assignee.type}`);
+	}
+
+	// Handle class private/public state assignment cases
+	if (assignee.type === 'MemberExpression') {
+		if (
+			assignee.object.type === 'ThisExpression' &&
+			assignee.property.type === 'PrivateIdentifier'
+		) {
+			const private_state = context.state.private_state.get(assignee.property.name);
+			const value = get_assignment_value(node, context);
+			if (private_state !== undefined) {
+				if (state.in_constructor) {
+					// See if we should wrap value in $.proxy
+					if (context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)) {
+						const assignment = fallback();
+						if (assignment.type === 'AssignmentExpression') {
+							assignment.right =
+								private_state.kind === 'frozen_state'
+									? b.call('$.freeze', value)
+									: build_proxy_reassignment(value, private_state.id);
+							return assignment;
+						}
+					}
+				} else {
+					return b.call(
+						'$.set',
+						assignee,
+						context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)
+							? private_state.kind === 'frozen_state'
+								? b.call('$.freeze', value)
+								: build_proxy_reassignment(value, private_state.id)
+							: value
+					);
+				}
+			}
+		} else if (
+			assignee.object.type === 'ThisExpression' &&
+			assignee.property.type === 'Identifier' &&
+			state.in_constructor
+		) {
+			const public_state = context.state.public_state.get(assignee.property.name);
+			const value = get_assignment_value(node, context);
+			// See if we should wrap value in $.proxy
+			if (
+				context.state.analysis.runes &&
+				public_state !== undefined &&
+				should_proxy_or_freeze(value, context.state.scope)
+			) {
+				const assignment = fallback();
+				if (assignment.type === 'AssignmentExpression') {
+					assignment.right =
+						public_state.kind === 'frozen_state'
+							? b.call('$.freeze', value)
+							: build_proxy_reassignment(value, public_state.id);
+					return assignment;
+				}
+			}
+		}
+	}
+
+	const left = object(assignee);
+
+	const binding = left && state.scope.get(left.name);
+	if (!binding) return fallback();
+
+	const transform = Object.hasOwn(context.state.transform, left.name)
+		? context.state.transform[left.name]
+		: null;
+
+	// reassignment
+	if (left === node.left && transform?.assign) {
+		let value = /** @type {Expression} */ (visit(node.right));
+
+		if (node.operator !== '=') {
+			value = b.binary(
+				/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
+				/** @type {Expression} */ (visit(left)),
+				value
+			);
+		}
+
+		// special case — if an element binding, we know it's a primitive
+		const path = context.path.map((node) => node.type);
+		const is_primitive = path.at(-1) === 'BindDirective' && path.at(-2) === 'RegularElement';
+
+		if (
+			!is_primitive &&
+			binding.kind !== 'prop' &&
+			context.state.analysis.runes &&
+			should_proxy_or_freeze(value, context.state.scope)
+		) {
+			if (binding.kind === 'frozen_state') {
+				value = b.call('$.freeze', value);
+			} else {
+				value = build_proxy_reassignment(value, left.name);
+			}
+		}
+
+		return transform.assign(left, value);
+	}
+
+	/**
+	 * @param {any} serialized
+	 * @returns
+	 */
+	const maybe_skip_ownership_validation = (serialized) => {
+		if (is_ignored(node, 'ownership_invalid_mutation')) {
+			return b.call('$.skip_ownership_validation', b.thunk(serialized));
+		}
+
+		return serialized;
+	};
+
+	// mutation
+	if (transform?.mutate) {
+		const mutation = b.assignment(
+			node.operator,
+			/** @type {Pattern} */ (context.visit(node.left)),
+			/** @type {Expression} */ (context.visit(node.right))
+		);
+
+		return maybe_skip_ownership_validation(transform.mutate(left, mutation));
+	}
+
+	if (
+		node.right.type === 'Literal' &&
+		prefix != null &&
+		(node.operator === '+=' || node.operator === '-=')
+	) {
+		return maybe_skip_ownership_validation(
+			b.update(
+				node.operator === '+=' ? '++' : '--',
+				/** @type {Expression} */ (visit(node.left)),
+				prefix
+			)
+		);
+	} else {
+		if (
+			binding.kind !== 'state' &&
+			binding.kind !== 'frozen_state' &&
+			binding.kind !== 'prop' &&
+			binding.kind !== 'bindable_prop' &&
+			binding.kind !== 'each' &&
+			binding.kind !== 'legacy_reactive' &&
+			binding.kind !== 'store_sub' &&
+			binding.kind !== 'derived'
+		) {
+			// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
+			return fallback();
+		}
+		return maybe_skip_ownership_validation(
+			b.assignment(
+				node.operator,
+				/** @type {Pattern} */ (visit(node.left)),
+				/** @type {Expression} */ (visit(node.right))
+			)
+		);
+	}
+}
+
+/**
+ * @template {ClientTransformState} State
+ * @param {AssignmentExpression} node
+ * @param {import('zimmerframe').Context<SvelteNode, State>} context
+ * @returns
+ */
+function get_assignment_value(node, { state, visit }) {
+	if (node.left.type === 'Identifier') {
+		const operator = node.operator;
+		return operator === '='
+			? /** @type {Expression} */ (visit(node.right))
+			: // turn something like x += 1 into x = x + 1
+				b.binary(
+					/** @type {BinaryOperator} */ (operator.slice(0, -1)),
+					build_getter(node.left, state),
+					/** @type {Expression} */ (visit(node.right))
+				);
+	} else if (
+		node.left.type === 'MemberExpression' &&
+		node.left.object.type === 'ThisExpression' &&
+		node.left.property.type === 'PrivateIdentifier' &&
+		state.private_state.has(node.left.property.name)
+	) {
+		const operator = node.operator;
+		return operator === '='
+			? /** @type {Expression} */ (visit(node.right))
+			: // turn something like x += 1 into x = x + 1
+				b.binary(
+					/** @type {BinaryOperator} */ (operator.slice(0, -1)),
+					/** @type {Expression} */ (visit(node.left)),
+					/** @type {Expression} */ (visit(node.right))
+				);
+	} else {
+		return /** @type {Expression} */ (visit(node.right));
+	}
+}

From 41b355e9fd2668d0c5f750d3ae3006d7a1019956 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 15:32:18 -0400
Subject: [PATCH 53/86] remove stuff

---
 .../client/visitors/AssignmentExpression.js   | 54 +++++++------------
 1 file changed, 20 insertions(+), 34 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 5967065b79b8..8b6381c422be 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -19,10 +19,9 @@ export function AssignmentExpression(node, context) {
  * @param {AssignmentExpression} node
  * @param {import('zimmerframe').Context<SvelteNode, State>} context
  * @param {() => any} fallback
- * @param {boolean | null} [prefix] - If the assignment is a transformed update expression, set this. Else `null`
  * @returns {Expression}
  */
-export function build_setter(node, context, fallback, prefix) {
+export function build_setter(node, context, fallback) {
 	const { state, visit } = context;
 
 	const assignee = node.left;
@@ -46,7 +45,7 @@ export function build_setter(node, context, fallback, prefix) {
 			const value = path.expression?.(b.id(tmp_id));
 			const assignment = b.assignment('=', path.node, value);
 			original_assignments.push(assignment);
-			assignments.push(build_setter(assignment, context, () => assignment, prefix));
+			assignments.push(build_setter(assignment, context, () => assignment));
 		}
 
 		if (assignments.every((assignment, i) => assignment === original_assignments[i])) {
@@ -205,39 +204,26 @@ export function build_setter(node, context, fallback, prefix) {
 	}
 
 	if (
-		node.right.type === 'Literal' &&
-		prefix != null &&
-		(node.operator === '+=' || node.operator === '-=')
+		binding.kind !== 'state' &&
+		binding.kind !== 'frozen_state' &&
+		binding.kind !== 'prop' &&
+		binding.kind !== 'bindable_prop' &&
+		binding.kind !== 'each' &&
+		binding.kind !== 'legacy_reactive' &&
+		binding.kind !== 'store_sub' &&
+		binding.kind !== 'derived'
 	) {
-		return maybe_skip_ownership_validation(
-			b.update(
-				node.operator === '+=' ? '++' : '--',
-				/** @type {Expression} */ (visit(node.left)),
-				prefix
-			)
-		);
-	} else {
-		if (
-			binding.kind !== 'state' &&
-			binding.kind !== 'frozen_state' &&
-			binding.kind !== 'prop' &&
-			binding.kind !== 'bindable_prop' &&
-			binding.kind !== 'each' &&
-			binding.kind !== 'legacy_reactive' &&
-			binding.kind !== 'store_sub' &&
-			binding.kind !== 'derived'
-		) {
-			// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
-			return fallback();
-		}
-		return maybe_skip_ownership_validation(
-			b.assignment(
-				node.operator,
-				/** @type {Pattern} */ (visit(node.left)),
-				/** @type {Expression} */ (visit(node.right))
-			)
-		);
+		// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
+		return fallback();
 	}
+
+	return maybe_skip_ownership_validation(
+		b.assignment(
+			node.operator,
+			/** @type {Pattern} */ (visit(node.left)),
+			/** @type {Expression} */ (visit(node.right))
+		)
+	);
 }
 
 /**

From 2a7d864d659b3579f02033a3284670fd4791edb7 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 15:36:12 -0400
Subject: [PATCH 54/86] tweak

---
 .../client/visitors/AssignmentExpression.js   | 34 ++++++++++---------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 8b6381c422be..376df97005d9 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -1,4 +1,4 @@
-/** @import { AssignmentExpression, BinaryOperator, Expression, Pattern } from 'estree' */
+/** @import { AssignmentExpression, BinaryOperator, Expression, Identifier, MemberExpression, Pattern } from 'estree' */
 /** @import { SvelteNode } from '#compiler' */
 /** @import { ClientTransformState, Context } from '../types.js' */
 import * as b from '../../../../utils/builders.js';
@@ -11,19 +11,6 @@ import { build_getter, build_proxy_reassignment, should_proxy_or_freeze } from '
  * @param {Context} context
  */
 export function AssignmentExpression(node, context) {
-	return build_setter(node, context, context.next);
-}
-
-/**
- * @template {ClientTransformState} State
- * @param {AssignmentExpression} node
- * @param {import('zimmerframe').Context<SvelteNode, State>} context
- * @param {() => any} fallback
- * @returns {Expression}
- */
-export function build_setter(node, context, fallback) {
-	const { state, visit } = context;
-
 	const assignee = node.left;
 	if (
 		assignee.type === 'ArrayPattern' ||
@@ -50,10 +37,10 @@ export function build_setter(node, context, fallback) {
 
 		if (assignments.every((assignment, i) => assignment === original_assignments[i])) {
 			// No change to output -> nothing to transform -> we can keep the original assignment
-			return fallback();
+			return;
 		}
 
-		const rhs_expression = /** @type {Expression} */ (visit(node.right));
+		const rhs_expression = /** @type {Expression} */ (context.visit(node.right));
 
 		const iife_is_async =
 			is_expression_async(rhs_expression) ||
@@ -81,6 +68,21 @@ export function build_setter(node, context, fallback) {
 		throw new Error(`Unexpected assignment type ${assignee.type}`);
 	}
 
+	return build_setter(node, context, context.next);
+}
+
+/**
+ * @template {ClientTransformState} State
+ * @param {AssignmentExpression} node
+ * @param {import('zimmerframe').Context<SvelteNode, State>} context
+ * @param {() => any} fallback
+ * @returns {Expression}
+ */
+export function build_setter(node, context, fallback) {
+	const { state, visit } = context;
+
+	const assignee = /** @type {Identifier | MemberExpression} */ (node.left);
+
 	// Handle class private/public state assignment cases
 	if (assignee.type === 'MemberExpression') {
 		if (

From 08c0fddf1fa737cc5ac51c5d3e553c920136ce89 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 19:51:33 -0400
Subject: [PATCH 55/86] tweak

---
 .../client/visitors/AssignmentExpression.js   | 32 ++++++++-----------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 376df97005d9..1f1eab001a87 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -84,17 +84,20 @@ export function build_setter(node, context, fallback) {
 	const assignee = /** @type {Identifier | MemberExpression} */ (node.left);
 
 	// Handle class private/public state assignment cases
-	if (assignee.type === 'MemberExpression') {
-		if (
-			assignee.object.type === 'ThisExpression' &&
-			assignee.property.type === 'PrivateIdentifier'
-		) {
+	if (
+		context.state.analysis.runes &&
+		assignee.type === 'MemberExpression' &&
+		assignee.object.type === 'ThisExpression'
+	) {
+		if (assignee.property.type === 'PrivateIdentifier') {
 			const private_state = context.state.private_state.get(assignee.property.name);
-			const value = get_assignment_value(node, context);
+
 			if (private_state !== undefined) {
+				const value = get_assignment_value(node, context);
+
 				if (state.in_constructor) {
 					// See if we should wrap value in $.proxy
-					if (context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)) {
+					if (should_proxy_or_freeze(value, context.state.scope)) {
 						const assignment = fallback();
 						if (assignment.type === 'AssignmentExpression') {
 							assignment.right =
@@ -108,7 +111,7 @@ export function build_setter(node, context, fallback) {
 					return b.call(
 						'$.set',
 						assignee,
-						context.state.analysis.runes && should_proxy_or_freeze(value, context.state.scope)
+						should_proxy_or_freeze(value, context.state.scope)
 							? private_state.kind === 'frozen_state'
 								? b.call('$.freeze', value)
 								: build_proxy_reassignment(value, private_state.id)
@@ -116,19 +119,12 @@ export function build_setter(node, context, fallback) {
 					);
 				}
 			}
-		} else if (
-			assignee.object.type === 'ThisExpression' &&
-			assignee.property.type === 'Identifier' &&
-			state.in_constructor
-		) {
+		} else if (assignee.property.type === 'Identifier' && state.in_constructor) {
 			const public_state = context.state.public_state.get(assignee.property.name);
 			const value = get_assignment_value(node, context);
+
 			// See if we should wrap value in $.proxy
-			if (
-				context.state.analysis.runes &&
-				public_state !== undefined &&
-				should_proxy_or_freeze(value, context.state.scope)
-			) {
+			if (public_state !== undefined && should_proxy_or_freeze(value, context.state.scope)) {
 				const assignment = fallback();
 				if (assignment.type === 'AssignmentExpression') {
 					assignment.right =

From 71e057ea64ebfb77f59b33bcfc3401730f1649a2 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 21:00:10 -0400
Subject: [PATCH 56/86] fix

---
 .../client/visitors/AssignmentExpression.js   | 45 +++++++++----------
 1 file changed, 22 insertions(+), 23 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 1f1eab001a87..064d35b0c2ee 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -93,30 +93,27 @@ export function build_setter(node, context, fallback) {
 			const private_state = context.state.private_state.get(assignee.property.name);
 
 			if (private_state !== undefined) {
-				const value = get_assignment_value(node, context);
+				let value = get_assignment_value(node, context);
+				let transformed = false;
+
+				if (should_proxy_or_freeze(value, context.state.scope)) {
+					transformed = true;
+					value =
+						private_state.kind === 'frozen_state'
+							? b.call('$.freeze', value)
+							: build_proxy_reassignment(value, private_state.id);
+				}
 
 				if (state.in_constructor) {
-					// See if we should wrap value in $.proxy
-					if (should_proxy_or_freeze(value, context.state.scope)) {
-						const assignment = fallback();
-						if (assignment.type === 'AssignmentExpression') {
-							assignment.right =
-								private_state.kind === 'frozen_state'
-									? b.call('$.freeze', value)
-									: build_proxy_reassignment(value, private_state.id);
-							return assignment;
-						}
+					if (transformed) {
+						return b.assignment(
+							node.operator,
+							/** @type {Pattern} */ (context.visit(node.left)),
+							value
+						);
 					}
 				} else {
-					return b.call(
-						'$.set',
-						assignee,
-						should_proxy_or_freeze(value, context.state.scope)
-							? private_state.kind === 'frozen_state'
-								? b.call('$.freeze', value)
-								: build_proxy_reassignment(value, private_state.id)
-							: value
-					);
+					return b.call('$.set', assignee, value);
 				}
 			}
 		} else if (assignee.property.type === 'Identifier' && state.in_constructor) {
@@ -241,7 +238,9 @@ function get_assignment_value(node, { state, visit }) {
 					build_getter(node.left, state),
 					/** @type {Expression} */ (visit(node.right))
 				);
-	} else if (
+	}
+
+	if (
 		node.left.type === 'MemberExpression' &&
 		node.left.object.type === 'ThisExpression' &&
 		node.left.property.type === 'PrivateIdentifier' &&
@@ -256,7 +255,7 @@ function get_assignment_value(node, { state, visit }) {
 					/** @type {Expression} */ (visit(node.left)),
 					/** @type {Expression} */ (visit(node.right))
 				);
-	} else {
-		return /** @type {Expression} */ (visit(node.right));
 	}
+
+	return /** @type {Expression} */ (visit(node.right));
 }

From 833b749eeabd156ad8da952b3736109bd9caeb28 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 21:12:10 -0400
Subject: [PATCH 57/86] tweak

---
 .../client/visitors/AssignmentExpression.js      | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 064d35b0c2ee..4d180a11ccdf 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -120,16 +120,14 @@ export function build_setter(node, context, fallback) {
 			const public_state = context.state.public_state.get(assignee.property.name);
 			const value = get_assignment_value(node, context);
 
-			// See if we should wrap value in $.proxy
 			if (public_state !== undefined && should_proxy_or_freeze(value, context.state.scope)) {
-				const assignment = fallback();
-				if (assignment.type === 'AssignmentExpression') {
-					assignment.right =
-						public_state.kind === 'frozen_state'
-							? b.call('$.freeze', value)
-							: build_proxy_reassignment(value, public_state.id);
-					return assignment;
-				}
+				return b.assignment(
+					node.operator,
+					/** @type {Pattern} */ (context.visit(node.left)),
+					public_state.kind === 'frozen_state'
+						? b.call('$.freeze', value)
+						: build_proxy_reassignment(value, public_state.id)
+				);
 			}
 		}
 	}

From 95b517fd1ccbce195910881ca33fe8f83f0517ed Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 21:48:01 -0400
Subject: [PATCH 58/86] tidy up

---
 .../client/visitors/AssignmentExpression.js   | 66 ++++++++++---------
 1 file changed, 36 insertions(+), 30 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 4d180a11ccdf..8224ca93f3a4 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -32,7 +32,7 @@ export function AssignmentExpression(node, context) {
 			const value = path.expression?.(b.id(tmp_id));
 			const assignment = b.assignment('=', path.node, value);
 			original_assignments.push(assignment);
-			assignments.push(build_setter(assignment, context, () => assignment));
+			assignments.push(build_assignment(assignment, context, () => assignment));
 		}
 
 		if (assignments.every((assignment, i) => assignment === original_assignments[i])) {
@@ -68,7 +68,7 @@ export function AssignmentExpression(node, context) {
 		throw new Error(`Unexpected assignment type ${assignee.type}`);
 	}
 
-	return build_setter(node, context, context.next);
+	return build_assignment(node, context, context.next);
 }
 
 /**
@@ -78,10 +78,11 @@ export function AssignmentExpression(node, context) {
  * @param {() => any} fallback
  * @returns {Expression}
  */
-export function build_setter(node, context, fallback) {
+export function build_assignment(node, context, fallback) {
 	const { state, visit } = context;
+	const { operator, left, right } = node;
 
-	const assignee = /** @type {Identifier | MemberExpression} */ (node.left);
+	const assignee = /** @type {Identifier | MemberExpression} */ (left);
 
 	// Handle class private/public state assignment cases
 	if (
@@ -106,11 +107,7 @@ export function build_setter(node, context, fallback) {
 
 				if (state.in_constructor) {
 					if (transformed) {
-						return b.assignment(
-							node.operator,
-							/** @type {Pattern} */ (context.visit(node.left)),
-							value
-						);
+						return b.assignment(operator, /** @type {Pattern} */ (context.visit(left)), value);
 					}
 				} else {
 					return b.call('$.set', assignee, value);
@@ -122,8 +119,8 @@ export function build_setter(node, context, fallback) {
 
 			if (public_state !== undefined && should_proxy_or_freeze(value, context.state.scope)) {
 				return b.assignment(
-					node.operator,
-					/** @type {Pattern} */ (context.visit(node.left)),
+					operator,
+					/** @type {Pattern} */ (context.visit(left)),
 					public_state.kind === 'frozen_state'
 						? b.call('$.freeze', value)
 						: build_proxy_reassignment(value, public_state.id)
@@ -132,23 +129,32 @@ export function build_setter(node, context, fallback) {
 		}
 	}
 
-	const left = object(assignee);
+	let object = left;
 
-	const binding = left && state.scope.get(left.name);
+	while (object.type === 'MemberExpression') {
+		// @ts-expect-error
+		object = object.object;
+	}
+
+	if (object.type !== 'Identifier') {
+		return fallback();
+	}
+
+	const binding = state.scope.get(object.name);
 	if (!binding) return fallback();
 
-	const transform = Object.hasOwn(context.state.transform, left.name)
-		? context.state.transform[left.name]
+	const transform = Object.hasOwn(context.state.transform, object.name)
+		? context.state.transform[object.name]
 		: null;
 
 	// reassignment
-	if (left === node.left && transform?.assign) {
-		let value = /** @type {Expression} */ (visit(node.right));
+	if (object === left && transform?.assign) {
+		let value = /** @type {Expression} */ (visit(right));
 
-		if (node.operator !== '=') {
+		if (operator !== '=') {
 			value = b.binary(
-				/** @type {BinaryOperator} */ (node.operator.slice(0, -1)),
-				/** @type {Expression} */ (visit(left)),
+				/** @type {BinaryOperator} */ (operator.slice(0, -1)),
+				/** @type {Expression} */ (visit(object)),
 				value
 			);
 		}
@@ -166,11 +172,11 @@ export function build_setter(node, context, fallback) {
 			if (binding.kind === 'frozen_state') {
 				value = b.call('$.freeze', value);
 			} else {
-				value = build_proxy_reassignment(value, left.name);
+				value = build_proxy_reassignment(value, object.name);
 			}
 		}
 
-		return transform.assign(left, value);
+		return transform.assign(object, value);
 	}
 
 	/**
@@ -178,7 +184,7 @@ export function build_setter(node, context, fallback) {
 	 * @returns
 	 */
 	const maybe_skip_ownership_validation = (serialized) => {
-		if (is_ignored(node, 'ownership_invalid_mutation')) {
+		if (is_ignored(left, 'ownership_invalid_mutation')) {
 			return b.call('$.skip_ownership_validation', b.thunk(serialized));
 		}
 
@@ -188,12 +194,12 @@ export function build_setter(node, context, fallback) {
 	// mutation
 	if (transform?.mutate) {
 		const mutation = b.assignment(
-			node.operator,
-			/** @type {Pattern} */ (context.visit(node.left)),
-			/** @type {Expression} */ (context.visit(node.right))
+			operator,
+			/** @type {Pattern} */ (context.visit(left)),
+			/** @type {Expression} */ (context.visit(right))
 		);
 
-		return maybe_skip_ownership_validation(transform.mutate(left, mutation));
+		return maybe_skip_ownership_validation(transform.mutate(object, mutation));
 	}
 
 	if (
@@ -212,9 +218,9 @@ export function build_setter(node, context, fallback) {
 
 	return maybe_skip_ownership_validation(
 		b.assignment(
-			node.operator,
-			/** @type {Pattern} */ (visit(node.left)),
-			/** @type {Expression} */ (visit(node.right))
+			operator,
+			/** @type {Pattern} */ (visit(left)),
+			/** @type {Expression} */ (visit(right))
 		)
 	);
 }

From a4d57677e1fd226f0718e389e3bc6957f786a09b Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 21:52:39 -0400
Subject: [PATCH 59/86] tidy up

---
 .../client/visitors/AssignmentExpression.js   | 60 +++++--------------
 1 file changed, 15 insertions(+), 45 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 8224ca93f3a4..c76e0b1ec955 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -79,7 +79,6 @@ export function AssignmentExpression(node, context) {
  * @returns {Expression}
  */
 export function build_assignment(node, context, fallback) {
-	const { state, visit } = context;
 	const { operator, left, right } = node;
 
 	const assignee = /** @type {Identifier | MemberExpression} */ (left);
@@ -105,7 +104,7 @@ export function build_assignment(node, context, fallback) {
 							: build_proxy_reassignment(value, private_state.id);
 				}
 
-				if (state.in_constructor) {
+				if (context.state.in_constructor) {
 					if (transformed) {
 						return b.assignment(operator, /** @type {Pattern} */ (context.visit(left)), value);
 					}
@@ -113,7 +112,7 @@ export function build_assignment(node, context, fallback) {
 					return b.call('$.set', assignee, value);
 				}
 			}
-		} else if (assignee.property.type === 'Identifier' && state.in_constructor) {
+		} else if (assignee.property.type === 'Identifier' && context.state.in_constructor) {
 			const public_state = context.state.public_state.get(assignee.property.name);
 			const value = get_assignment_value(node, context);
 
@@ -140,7 +139,7 @@ export function build_assignment(node, context, fallback) {
 		return fallback();
 	}
 
-	const binding = state.scope.get(object.name);
+	const binding = context.state.scope.get(object.name);
 	if (!binding) return fallback();
 
 	const transform = Object.hasOwn(context.state.transform, object.name)
@@ -149,12 +148,12 @@ export function build_assignment(node, context, fallback) {
 
 	// reassignment
 	if (object === left && transform?.assign) {
-		let value = /** @type {Expression} */ (visit(right));
+		let value = /** @type {Expression} */ (context.visit(right));
 
 		if (operator !== '=') {
 			value = b.binary(
 				/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-				/** @type {Expression} */ (visit(object)),
+				/** @type {Expression} */ (context.visit(object)),
 				value
 			);
 		}
@@ -179,50 +178,21 @@ export function build_assignment(node, context, fallback) {
 		return transform.assign(object, value);
 	}
 
-	/**
-	 * @param {any} serialized
-	 * @returns
-	 */
-	const maybe_skip_ownership_validation = (serialized) => {
-		if (is_ignored(left, 'ownership_invalid_mutation')) {
-			return b.call('$.skip_ownership_validation', b.thunk(serialized));
-		}
-
-		return serialized;
-	};
+	/** @type {Expression} */
+	let mutation = b.assignment(
+		operator,
+		/** @type {Pattern} */ (context.visit(left)),
+		/** @type {Expression} */ (context.visit(right))
+	);
 
 	// mutation
 	if (transform?.mutate) {
-		const mutation = b.assignment(
-			operator,
-			/** @type {Pattern} */ (context.visit(left)),
-			/** @type {Expression} */ (context.visit(right))
-		);
-
-		return maybe_skip_ownership_validation(transform.mutate(object, mutation));
+		mutation = transform.mutate(object, mutation);
 	}
 
-	if (
-		binding.kind !== 'state' &&
-		binding.kind !== 'frozen_state' &&
-		binding.kind !== 'prop' &&
-		binding.kind !== 'bindable_prop' &&
-		binding.kind !== 'each' &&
-		binding.kind !== 'legacy_reactive' &&
-		binding.kind !== 'store_sub' &&
-		binding.kind !== 'derived'
-	) {
-		// TODO error if it's a computed (or rest prop)? or does that already happen elsewhere?
-		return fallback();
-	}
-
-	return maybe_skip_ownership_validation(
-		b.assignment(
-			operator,
-			/** @type {Pattern} */ (visit(left)),
-			/** @type {Expression} */ (visit(right))
-		)
-	);
+	return is_ignored(left, 'ownership_invalid_mutation')
+		? b.call('$.skip_ownership_validation', b.thunk(mutation))
+		: mutation;
 }
 
 /**

From 768db25cc51f5d910f9e8b1feb154fdecc98c1ab Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 21:57:07 -0400
Subject: [PATCH 60/86] tidy up

---
 .../client/visitors/AssignmentExpression.js   | 38 +++++++++----------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index c76e0b1ec955..65dd7ac9c397 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -1,4 +1,4 @@
-/** @import { AssignmentExpression, BinaryOperator, Expression, Identifier, MemberExpression, Pattern } from 'estree' */
+/** @import { AssignmentExpression, AssignmentOperator, BinaryOperator, Expression, Identifier, MemberExpression, Pattern } from 'estree' */
 /** @import { SvelteNode } from '#compiler' */
 /** @import { ClientTransformState, Context } from '../types.js' */
 import * as b from '../../../../utils/builders.js';
@@ -93,7 +93,7 @@ export function build_assignment(node, context, fallback) {
 			const private_state = context.state.private_state.get(assignee.property.name);
 
 			if (private_state !== undefined) {
-				let value = get_assignment_value(node, context);
+				let value = get_assignment_value(operator, left, right, context);
 				let transformed = false;
 
 				if (should_proxy_or_freeze(value, context.state.scope)) {
@@ -114,7 +114,7 @@ export function build_assignment(node, context, fallback) {
 			}
 		} else if (assignee.property.type === 'Identifier' && context.state.in_constructor) {
 			const public_state = context.state.public_state.get(assignee.property.name);
-			const value = get_assignment_value(node, context);
+			const value = get_assignment_value(operator, left, right, context);
 
 			if (public_state !== undefined && should_proxy_or_freeze(value, context.state.scope)) {
 				return b.assignment(
@@ -197,39 +197,39 @@ export function build_assignment(node, context, fallback) {
 
 /**
  * @template {ClientTransformState} State
- * @param {AssignmentExpression} node
+ * @param {AssignmentOperator} operator
+ * @param {Pattern} left
+ * @param {Expression} right
  * @param {import('zimmerframe').Context<SvelteNode, State>} context
  * @returns
  */
-function get_assignment_value(node, { state, visit }) {
-	if (node.left.type === 'Identifier') {
-		const operator = node.operator;
+function get_assignment_value(operator, left, right, { state, visit }) {
+	if (left.type === 'Identifier') {
 		return operator === '='
-			? /** @type {Expression} */ (visit(node.right))
+			? /** @type {Expression} */ (visit(right))
 			: // turn something like x += 1 into x = x + 1
 				b.binary(
 					/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-					build_getter(node.left, state),
-					/** @type {Expression} */ (visit(node.right))
+					build_getter(left, state),
+					/** @type {Expression} */ (visit(right))
 				);
 	}
 
 	if (
-		node.left.type === 'MemberExpression' &&
-		node.left.object.type === 'ThisExpression' &&
-		node.left.property.type === 'PrivateIdentifier' &&
-		state.private_state.has(node.left.property.name)
+		left.type === 'MemberExpression' &&
+		left.object.type === 'ThisExpression' &&
+		left.property.type === 'PrivateIdentifier' &&
+		state.private_state.has(left.property.name)
 	) {
-		const operator = node.operator;
 		return operator === '='
-			? /** @type {Expression} */ (visit(node.right))
+			? /** @type {Expression} */ (visit(right))
 			: // turn something like x += 1 into x = x + 1
 				b.binary(
 					/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-					/** @type {Expression} */ (visit(node.left)),
-					/** @type {Expression} */ (visit(node.right))
+					/** @type {Expression} */ (visit(left)),
+					/** @type {Expression} */ (visit(right))
 				);
 	}
 
-	return /** @type {Expression} */ (visit(node.right));
+	return /** @type {Expression} */ (visit(right));
 }

From 94f6e65d3e209aa9ca55aa50f04d37b93344d0bd Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 22:03:21 -0400
Subject: [PATCH 61/86] tweak

---
 .../client/visitors/AssignmentExpression.js          | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 65dd7ac9c397..72bb34fa57dc 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -32,7 +32,7 @@ export function AssignmentExpression(node, context) {
 			const value = path.expression?.(b.id(tmp_id));
 			const assignment = b.assignment('=', path.node, value);
 			original_assignments.push(assignment);
-			assignments.push(build_assignment(assignment, context, () => assignment));
+			assignments.push(build_assignment('=', path.node, value, context, () => assignment));
 		}
 
 		if (assignments.every((assignment, i) => assignment === original_assignments[i])) {
@@ -68,19 +68,19 @@ export function AssignmentExpression(node, context) {
 		throw new Error(`Unexpected assignment type ${assignee.type}`);
 	}
 
-	return build_assignment(node, context, context.next);
+	return build_assignment(node.operator, node.left, node.right, context, context.next);
 }
 
 /**
  * @template {ClientTransformState} State
- * @param {AssignmentExpression} node
+ * @param {AssignmentOperator} operator
+ * @param {Pattern} left
+ * @param {Expression} right
  * @param {import('zimmerframe').Context<SvelteNode, State>} context
  * @param {() => any} fallback
  * @returns {Expression}
  */
-export function build_assignment(node, context, fallback) {
-	const { operator, left, right } = node;
-
+export function build_assignment(operator, left, right, context, fallback) {
 	const assignee = /** @type {Identifier | MemberExpression} */ (left);
 
 	// Handle class private/public state assignment cases

From 21d787bd766e8d71ba47e0261d300b19dd0858d9 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 22:08:00 -0400
Subject: [PATCH 62/86] simplify

---
 .../client/visitors/AssignmentExpression.js   | 43 +++++++++----------
 1 file changed, 20 insertions(+), 23 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 72bb34fa57dc..f71a71e12805 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -17,27 +17,22 @@ export function AssignmentExpression(node, context) {
 		assignee.type === 'ObjectPattern' ||
 		assignee.type === 'RestElement'
 	) {
-		// Turn assignment into an IIFE, so that `$.set` calls etc don't produce invalid code
-		const tmp_id = context.state.scope.generate('tmp');
+		const rhs = b.id('$$value');
 
-		/** @type {AssignmentExpression[]} */
-		const original_assignments = [];
+		let changed = false;
 
-		/** @type {Expression[]} */
-		const assignments = [];
+		const assignments = extract_paths(node.left).map((path) => {
+			const value = path.expression?.(rhs);
 
-		const paths = extract_paths(assignee);
+			let assignment = build_assignment('=', path.node, value, context);
+			if (assignment !== null) changed = true;
 
-		for (const path of paths) {
-			const value = path.expression?.(b.id(tmp_id));
-			const assignment = b.assignment('=', path.node, value);
-			original_assignments.push(assignment);
-			assignments.push(build_assignment('=', path.node, value, context, () => assignment));
-		}
+			return assignment ?? /** @type {Expression} */ (context.next());
+		});
 
-		if (assignments.every((assignment, i) => assignment === original_assignments[i])) {
+		if (!changed) {
 			// No change to output -> nothing to transform -> we can keep the original assignment
-			return;
+			return context.next();
 		}
 
 		const rhs_expression = /** @type {Expression} */ (context.visit(node.right));
@@ -49,11 +44,11 @@ export function AssignmentExpression(node, context) {
 		const iife = b.arrow(
 			[],
 			b.block([
-				b.const(tmp_id, rhs_expression),
+				b.const(rhs, rhs_expression),
 				b.stmt(b.sequence(assignments)),
 				// return because it could be used in a nested expression where the value is needed.
 				// example: { foo: ({ bar } = { bar: 1 })}
-				b.return(b.id(tmp_id))
+				b.return(rhs)
 			])
 		);
 
@@ -68,7 +63,10 @@ export function AssignmentExpression(node, context) {
 		throw new Error(`Unexpected assignment type ${assignee.type}`);
 	}
 
-	return build_assignment(node.operator, node.left, node.right, context, context.next);
+	return (
+		build_assignment(node.operator, node.left, node.right, context) ??
+		/** @type {Expression} */ (context.next())
+	);
 }
 
 /**
@@ -77,10 +75,9 @@ export function AssignmentExpression(node, context) {
  * @param {Pattern} left
  * @param {Expression} right
  * @param {import('zimmerframe').Context<SvelteNode, State>} context
- * @param {() => any} fallback
- * @returns {Expression}
+ * @returns {Expression | null}
  */
-export function build_assignment(operator, left, right, context, fallback) {
+export function build_assignment(operator, left, right, context) {
 	const assignee = /** @type {Identifier | MemberExpression} */ (left);
 
 	// Handle class private/public state assignment cases
@@ -136,11 +133,11 @@ export function build_assignment(operator, left, right, context, fallback) {
 	}
 
 	if (object.type !== 'Identifier') {
-		return fallback();
+		return null;
 	}
 
 	const binding = context.state.scope.get(object.name);
-	if (!binding) return fallback();
+	if (!binding) return null;
 
 	const transform = Object.hasOwn(context.state.transform, object.name)
 		? context.state.transform[object.name]

From 0a6e48c751ef6bf3932213eb136a6464ff14117f Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 22:09:20 -0400
Subject: [PATCH 63/86] tidy up

---
 .../3-transform/client/visitors/AssignmentExpression.js     | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index f71a71e12805..4afa2f6d505d 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -52,11 +52,7 @@ export function AssignmentExpression(node, context) {
 			])
 		);
 
-		if (iife_is_async) {
-			return b.await(b.call(b.async(iife)));
-		} else {
-			return b.call(iife);
-		}
+		return iife_is_async ? b.await(b.call(b.async(iife))) : b.call(iife);
 	}
 
 	if (assignee.type !== 'Identifier' && assignee.type !== 'MemberExpression') {

From cff694a38f8b3295fc248805c986f26ac96d5c4b Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 22:18:49 -0400
Subject: [PATCH 64/86] simplify

---
 .../client/visitors/AssignmentExpression.js   | 54 +++++--------------
 1 file changed, 13 insertions(+), 41 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 4afa2f6d505d..7f0e16789e10 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -107,9 +107,10 @@ export function build_assignment(operator, left, right, context) {
 			}
 		} else if (assignee.property.type === 'Identifier' && context.state.in_constructor) {
 			const public_state = context.state.public_state.get(assignee.property.name);
-			const value = get_assignment_value(operator, left, right, context);
 
-			if (public_state !== undefined && should_proxy_or_freeze(value, context.state.scope)) {
+			if (public_state !== undefined && should_proxy_or_freeze(right, context.state.scope)) {
+				const value = /** @type {Expression} */ (context.visit(right));
+
 				return b.assignment(
 					operator,
 					/** @type {Pattern} */ (context.visit(left)),
@@ -141,15 +142,7 @@ export function build_assignment(operator, left, right, context) {
 
 	// reassignment
 	if (object === left && transform?.assign) {
-		let value = /** @type {Expression} */ (context.visit(right));
-
-		if (operator !== '=') {
-			value = b.binary(
-				/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-				/** @type {Expression} */ (context.visit(object)),
-				value
-			);
-		}
+		let value = get_assignment_value(operator, left, right, context);
 
 		// special case — if an element binding, we know it's a primitive
 		const path = context.path.map((node) => node.type);
@@ -194,35 +187,14 @@ export function build_assignment(operator, left, right, context) {
  * @param {Pattern} left
  * @param {Expression} right
  * @param {import('zimmerframe').Context<SvelteNode, State>} context
- * @returns
  */
-function get_assignment_value(operator, left, right, { state, visit }) {
-	if (left.type === 'Identifier') {
-		return operator === '='
-			? /** @type {Expression} */ (visit(right))
-			: // turn something like x += 1 into x = x + 1
-				b.binary(
-					/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-					build_getter(left, state),
-					/** @type {Expression} */ (visit(right))
-				);
-	}
-
-	if (
-		left.type === 'MemberExpression' &&
-		left.object.type === 'ThisExpression' &&
-		left.property.type === 'PrivateIdentifier' &&
-		state.private_state.has(left.property.name)
-	) {
-		return operator === '='
-			? /** @type {Expression} */ (visit(right))
-			: // turn something like x += 1 into x = x + 1
-				b.binary(
-					/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-					/** @type {Expression} */ (visit(left)),
-					/** @type {Expression} */ (visit(right))
-				);
-	}
-
-	return /** @type {Expression} */ (visit(right));
+function get_assignment_value(operator, left, right, { visit }) {
+	return operator === '='
+		? /** @type {Expression} */ (visit(right))
+		: // turn something like x += 1 into x = x + 1
+			b.binary(
+				/** @type {BinaryOperator} */ (operator.slice(0, -1)),
+				/** @type {Expression} */ (visit(left)),
+				/** @type {Expression} */ (visit(right))
+			);
 }

From ce4166dd2ef3c0bad7a237a10008b98121a43589 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 22:20:43 -0400
Subject: [PATCH 65/86] tidy up

---
 .../client/visitors/AssignmentExpression.js   | 31 +++++++++----------
 1 file changed, 14 insertions(+), 17 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 7f0e16789e10..2064b2990364 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -1,10 +1,10 @@
-/** @import { AssignmentExpression, AssignmentOperator, BinaryOperator, Expression, Identifier, MemberExpression, Pattern } from 'estree' */
+/** @import { AssignmentExpression, AssignmentOperator, BinaryOperator, Expression, Pattern } from 'estree' */
 /** @import { SvelteNode } from '#compiler' */
 /** @import { ClientTransformState, Context } from '../types.js' */
 import * as b from '../../../../utils/builders.js';
-import { extract_paths, is_expression_async, object } from '../../../../utils/ast.js';
+import { extract_paths, is_expression_async } from '../../../../utils/ast.js';
 import { is_ignored } from '../../../../state.js';
-import { build_getter, build_proxy_reassignment, should_proxy_or_freeze } from '../utils.js';
+import { build_proxy_reassignment, should_proxy_or_freeze } from '../utils.js';
 
 /**
  * @param {AssignmentExpression} node
@@ -74,16 +74,14 @@ export function AssignmentExpression(node, context) {
  * @returns {Expression | null}
  */
 export function build_assignment(operator, left, right, context) {
-	const assignee = /** @type {Identifier | MemberExpression} */ (left);
-
 	// Handle class private/public state assignment cases
 	if (
 		context.state.analysis.runes &&
-		assignee.type === 'MemberExpression' &&
-		assignee.object.type === 'ThisExpression'
+		left.type === 'MemberExpression' &&
+		left.object.type === 'ThisExpression'
 	) {
-		if (assignee.property.type === 'PrivateIdentifier') {
-			const private_state = context.state.private_state.get(assignee.property.name);
+		if (left.property.type === 'PrivateIdentifier') {
+			const private_state = context.state.private_state.get(left.property.name);
 
 			if (private_state !== undefined) {
 				let value = get_assignment_value(operator, left, right, context);
@@ -102,11 +100,11 @@ export function build_assignment(operator, left, right, context) {
 						return b.assignment(operator, /** @type {Pattern} */ (context.visit(left)), value);
 					}
 				} else {
-					return b.call('$.set', assignee, value);
+					return b.call('$.set', left, value);
 				}
 			}
-		} else if (assignee.property.type === 'Identifier' && context.state.in_constructor) {
-			const public_state = context.state.public_state.get(assignee.property.name);
+		} else if (left.property.type === 'Identifier' && context.state.in_constructor) {
+			const public_state = context.state.public_state.get(left.property.name);
 
 			if (public_state !== undefined && should_proxy_or_freeze(right, context.state.scope)) {
 				const value = /** @type {Expression} */ (context.visit(right));
@@ -154,11 +152,10 @@ export function build_assignment(operator, left, right, context) {
 			context.state.analysis.runes &&
 			should_proxy_or_freeze(value, context.state.scope)
 		) {
-			if (binding.kind === 'frozen_state') {
-				value = b.call('$.freeze', value);
-			} else {
-				value = build_proxy_reassignment(value, object.name);
-			}
+			value =
+				binding.kind === 'frozen_state'
+					? b.call('$.freeze', value)
+					: build_proxy_reassignment(value, object.name);
 		}
 
 		return transform.assign(object, value);

From 0a0b0396e489d8dc55e48c412191d50be2f2d025 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 22:36:02 -0400
Subject: [PATCH 66/86] improve output

---
 .../client/visitors/AssignmentExpression.js   | 51 ++++++++++---------
 1 file changed, 28 insertions(+), 23 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 2064b2990364..97a013025ec0 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -1,4 +1,4 @@
-/** @import { AssignmentExpression, AssignmentOperator, BinaryOperator, Expression, Pattern } from 'estree' */
+/** @import { AssignmentExpression, AssignmentOperator, BinaryOperator, Expression, Node, Pattern } from 'estree' */
 /** @import { SvelteNode } from '#compiler' */
 /** @import { ClientTransformState, Context } from '../types.js' */
 import * as b from '../../../../utils/builders.js';
@@ -11,13 +11,17 @@ import { build_proxy_reassignment, should_proxy_or_freeze } from '../utils.js';
  * @param {Context} context
  */
 export function AssignmentExpression(node, context) {
-	const assignee = node.left;
+	const parent = /** @type {Node} */ (context.path.at(-1));
+	const is_standalone = parent.type.endsWith('Statement');
+
 	if (
-		assignee.type === 'ArrayPattern' ||
-		assignee.type === 'ObjectPattern' ||
-		assignee.type === 'RestElement'
+		node.left.type === 'ArrayPattern' ||
+		node.left.type === 'ObjectPattern' ||
+		node.left.type === 'RestElement'
 	) {
-		const rhs = b.id('$$value');
+		const value = /** @type {Expression} */ (context.visit(node.right));
+		const should_cache = value.type !== 'Identifier';
+		const rhs = should_cache ? b.id('$$value') : value;
 
 		let changed = false;
 
@@ -35,28 +39,29 @@ export function AssignmentExpression(node, context) {
 			return context.next();
 		}
 
-		const rhs_expression = /** @type {Expression} */ (context.visit(node.right));
+		const sequence = b.sequence(assignments);
+
+		if (!is_standalone) {
+			// this is part of an expression, we need the sequence to end with the value
+			sequence.expressions.push(rhs);
+		}
 
-		const iife_is_async =
-			is_expression_async(rhs_expression) ||
-			assignments.some((assignment) => is_expression_async(assignment));
+		if (should_cache) {
+			// the right hand side is a complex expression, wrap in an IIFE to cache it
+			const iife = b.arrow([rhs], sequence);
 
-		const iife = b.arrow(
-			[],
-			b.block([
-				b.const(rhs, rhs_expression),
-				b.stmt(b.sequence(assignments)),
-				// return because it could be used in a nested expression where the value is needed.
-				// example: { foo: ({ bar } = { bar: 1 })}
-				b.return(rhs)
-			])
-		);
+			const iife_is_async =
+				is_expression_async(value) ||
+				assignments.some((assignment) => is_expression_async(assignment));
+
+			return iife_is_async ? b.await(b.call(b.async(iife), value)) : b.call(iife, value);
+		}
 
-		return iife_is_async ? b.await(b.call(b.async(iife))) : b.call(iife);
+		return sequence;
 	}
 
-	if (assignee.type !== 'Identifier' && assignee.type !== 'MemberExpression') {
-		throw new Error(`Unexpected assignment type ${assignee.type}`);
+	if (node.left.type !== 'Identifier' && node.left.type !== 'MemberExpression') {
+		throw new Error(`Unexpected assignment type ${node.left.type}`);
 	}
 
 	return (

From f1ebccda599dcf35806f461f363ec08e7b82243f Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 23:13:49 -0400
Subject: [PATCH 67/86] delete comments

---
 .../2-analyze/visitors/shared/component.js    | 25 -------------------
 .../client/visitors/shared/component.js       |  6 -----
 .../server/visitors/shared/component.js       | 19 --------------
 3 files changed, 50 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index 27e2ea561d9b..b728c7382034 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -107,29 +107,4 @@ export function visit_component(node, context) {
 			}
 		);
 	}
-
-	// context.visit({ ...node.fragment, nodes: default_slot_nodes }, default_state);
-	// context.visit({ ...node.fragment, nodes: named_slot_nodes }, named_state);
-
-	// context.visit(child, is_slotted_content ? named_state : default_state);
-
-	// if (
-	// 	is_element_node(child) &&
-	// 	child.attributes.some(
-	// 		(a) => a.type === 'Attribute' && a.name === 'slot' && is_text_attribute(a)
-	// 	)
-	// ) {
-	// 	context.visit(child);
-	// } else {
-	// 	context.visit(child, { scope });
-	// }
-
-	// context.visit(node, attribute.type === 'LetDirective' ? default_state : named_state);
-	// }
-
-	// context.next({
-	// 	...context.state,
-	// 	parent_element: null,
-	// 	component_slots: new Set()
-	// });
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index aaf2b024bd74..799fcd765827 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -259,12 +259,6 @@ export function build_component(node, component_name, context, anchor = context.
 							scope: node.metadata.scopes[slot_name],
 							transform: { ...context.state.transform }
 						}
-				// {
-				// 	...context.state,
-				// 	scope:
-				// 		context.state.scopes.get(slot_name === 'default' ? children[slot_name][0] : node) ??
-				// 		context.state.scope
-				// }
 			)
 		);
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
index ce2eb246ee61..941088228a1a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
@@ -159,26 +159,7 @@ export function build_inline_component(node, expression, context) {
 							...context.state,
 							scope: node.metadata.scopes[slot_name]
 						}
-				// {
-				// 	...context.state,
-				// 	scope:
-				// 		context.state.scopes.get(slot_name === 'default' ? children[slot_name][0] : node) ??
-				// 		context.state.scope
-				// }
 			)
-			// context.visit(
-			// 	{
-			// 		...node.fragment,
-			// 		// @ts-expect-error
-			// 		nodes: children[slot_name]
-			// 	},
-			// 	{
-			// 		...context.state,
-			// 		scope:
-			// 			context.state.scopes.get(slot_name === 'default' ? children[slot_name][0] : node) ??
-			// 			context.state.scope
-			// 	}
-			// )
 		);
 
 		if (block.body.length === 0) continue;

From a738c99ecceaa363de5537cfecaa6988ff53e376 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 9 Aug 2024 23:15:00 -0400
Subject: [PATCH 68/86] more

---
 packages/svelte/src/compiler/phases/scope.js | 86 +-------------------
 1 file changed, 1 insertion(+), 85 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index 9a04b8761c28..15ed9d219a2a 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -1,15 +1,13 @@
 /** @import { ClassDeclaration, Expression, FunctionDeclaration, Identifier, ImportDeclaration, MemberExpression, Node, Pattern, VariableDeclarator } from 'estree' */
 /** @import { Context, Visitor } from 'zimmerframe' */
-/** @import { AnimateDirective, Attribute, Binding, Component, DeclarationKind, EachBlock, ElementLike, LetDirective, SvelteComponent, SvelteNode, SvelteSelf, TransitionDirective, UseDirective } from '#compiler' */
+/** @import { AnimateDirective, Binding, Component, DeclarationKind, EachBlock, ElementLike, LetDirective, SvelteComponent, SvelteNode, SvelteSelf, TransitionDirective, UseDirective } from '#compiler' */
 import is_reference from 'is-reference';
 import { walk } from 'zimmerframe';
-import { is_element_node } from './nodes.js';
 import * as b from '../utils/builders.js';
 import * as e from '../errors.js';
 import {
 	extract_identifiers,
 	extract_identifiers_from_destructuring,
-	is_text_attribute,
 	object,
 	unwrap_pattern
 } from '../utils/ast.js';
@@ -292,7 +290,6 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 	 * @type {Visitor<ElementLike, State, SvelteNode>}
 	 */
 	const SvelteFragment = (node, { state, next }) => {
-		// const [scope] = analyze_let_directives(node, state.scope);
 		const scope = state.scope.child();
 		scopes.set(node, scope);
 		next({ scope });
@@ -334,89 +331,8 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 
 			context.visit(child, state);
 		}
-
-		// // let:x is super weird:
-		// // - for the default slot, its scope only applies to children that are not slots themselves
-		// // - for named slots, its scope applies to the component itself, too
-		// const [scope, is_default_slot] = analyze_let_directives(node, state.scope);
-		// if (is_default_slot) {
-		// 	for (const attribute of node.attributes) {
-		// 		visit(attribute);
-		// 	}
-		// } else {
-		// 	scopes.set(node, scope);
-
-		// 	for (const attribute of node.attributes) {
-		// 		visit(attribute, { ...state, scope });
-		// 	}
-		// }
-
-		// for (const child of node.fragment.nodes) {
-		// 	if (
-		// 		is_element_node(child) &&
-		// 		child.attributes.some(
-		// 			(attribute) => attribute.type === 'Attribute' && attribute.name === 'slot'
-		// 		)
-		// 	) {
-		// 		// <div slot="..."> inherits the scope above the component unless the component is a named slot itself, because slots are hella weird
-		// 		scopes.set(child, is_default_slot ? state.scope : scope);
-		// 		visit(child, { scope: is_default_slot ? state.scope : scope });
-		// 	} else {
-		// 		if (child.type === 'ExpressionTag') {
-		// 			// expression tag is a special case — we don't visit it directly, but via process_children,
-		// 			// so we need to set the scope on the expression rather than the tag itself
-		// 			scopes.set(child.expression, scope);
-		// 		} else {
-		// 			scopes.set(child, scope);
-		// 		}
-
-		// 		visit(child, { scope });
-		// 	}
-		// }
 	};
 
-	/**
-	 * @param {ElementLike} node
-	 * @param {Scope} parent
-	 */
-	function analyze_let_directives(node, parent) {
-		const scope = parent.child();
-		let is_default_slot = true;
-
-		for (const attribute of node.attributes) {
-			if (attribute.type === 'LetDirective') {
-				/** @type {Binding[]} */
-				const bindings = [];
-				scope.declarators.set(attribute, bindings);
-
-				// attach the scope to the directive itself, as well as the
-				// contents to which it applies
-				scopes.set(attribute, scope);
-
-				if (attribute.expression) {
-					for (const id of extract_identifiers_from_destructuring(attribute.expression)) {
-						const binding = scope.declare(id, 'derived', 'const');
-						bindings.push(binding);
-					}
-				} else {
-					/** @type {Identifier} */
-					const id = {
-						name: attribute.name,
-						type: 'Identifier',
-						start: attribute.start,
-						end: attribute.end
-					};
-					const binding = scope.declare(id, 'derived', 'const');
-					bindings.push(binding);
-				}
-			} else if (attribute.type === 'Attribute' && attribute.name === 'slot') {
-				is_default_slot = false;
-			}
-		}
-
-		return /** @type {const} */ ([scope, is_default_slot]);
-	}
-
 	/**
 	 * @type {Visitor<AnimateDirective | TransitionDirective | UseDirective, State, SvelteNode>}
 	 */

From 771dabaac1ec7079e1085befba39aef5a52c4fea Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 13:36:05 -0400
Subject: [PATCH 69/86] unused

---
 .../src/compiler/phases/2-analyze/visitors/shared/attribute.js  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/attribute.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/attribute.js
index 4102460cbaa2..8f60a67c62b0 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/attribute.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/attribute.js
@@ -1,4 +1,4 @@
-/** @import { Attribute, ElementLike, SvelteNode } from '#compiler' */
+/** @import { Attribute, ElementLike } from '#compiler' */
 /** @import { Context } from '../../types' */
 import * as e from '../../../../errors.js';
 import { is_text_attribute } from '../../../../utils/ast.js';

From 8f579d5e961dbc82e4e85210360e5d77f80aaa87 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 13:41:30 -0400
Subject: [PATCH 70/86] tidy up

---
 .../2-analyze/visitors/shared/component.js    | 25 +++++++++----------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index b728c7382034..4a2b8b1406c0 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -1,4 +1,4 @@
-/** @import { Component, Fragment, SvelteComponent, SvelteSelf } from '#compiler' */
+/** @import { Comment, Component, Fragment, SvelteComponent, SvelteSelf } from '#compiler' */
 /** @import { Context } from '../../types' */
 import * as e from '../../../../errors.js';
 import { get_attribute_expression, is_expression_attribute } from '../../../../utils/ast.js';
@@ -63,27 +63,25 @@ export function visit_component(node, context) {
 
 	const component_slots = new Set();
 
-	const slot_scope_applies_to_itself = !!determine_slot(node);
-
-	const default_state = slot_scope_applies_to_itself
+	// If the component has a slot attribute — `<Foo slot="whatever" .../>` —
+	// then `let:` directives apply to other attributes, instead of just the
+	// top-level contents of the component. Yes, this is very weird.
+	const default_state = !!determine_slot(node)
 		? context.state
 		: {
 				...context.state,
-				scope: node.metadata.scopes.default,
-				parent_element: null,
-				component_slots
+				scope: node.metadata.scopes.default
 			};
 
 	for (const attribute of node.attributes) {
 		context.visit(attribute, attribute.type === 'LetDirective' ? default_state : context.state);
 	}
 
-	const comments = [];
+	/** @type {Comment[]} */
+	let comments = [];
 
 	/** @type {Record<string, Fragment['nodes']>} */
-	const nodes = {
-		default: []
-	};
+	const nodes = { default: [] };
 
 	for (const child of node.fragment.nodes) {
 		if (child.type === 'Comment') {
@@ -91,9 +89,10 @@ export function visit_component(node, context) {
 			continue;
 		}
 
-		let slot_name = determine_slot(child) ?? 'default';
-
+		const slot_name = determine_slot(child) ?? 'default';
 		(nodes[slot_name] ??= []).push(...comments, child);
+
+		comments = [];
 	}
 
 	for (const slot_name in nodes) {

From 61ad1298d97480d710369a06da2dee0fda1b502a Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 13:42:27 -0400
Subject: [PATCH 71/86] tidy up

---
 .../2-analyze/visitors/shared/component.js    | 26 ++++++++-----------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index 4a2b8b1406c0..19895595cf8d 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -61,17 +61,12 @@ export function visit_component(node, context) {
 		}
 	}
 
-	const component_slots = new Set();
-
 	// If the component has a slot attribute — `<Foo slot="whatever" .../>` —
 	// then `let:` directives apply to other attributes, instead of just the
 	// top-level contents of the component. Yes, this is very weird.
 	const default_state = !!determine_slot(node)
 		? context.state
-		: {
-				...context.state,
-				scope: node.metadata.scopes.default
-			};
+		: { ...context.state, scope: node.metadata.scopes.default };
 
 	for (const attribute of node.attributes) {
 		context.visit(attribute, attribute.type === 'LetDirective' ? default_state : context.state);
@@ -95,15 +90,16 @@ export function visit_component(node, context) {
 		comments = [];
 	}
 
+	const component_slots = new Set();
+
 	for (const slot_name in nodes) {
-		context.visit(
-			{ ...node.fragment, nodes: nodes[slot_name] },
-			{
-				...context.state,
-				scope: node.metadata.scopes[slot_name],
-				parent_element: null,
-				component_slots
-			}
-		);
+		const state = {
+			...context.state,
+			scope: node.metadata.scopes[slot_name],
+			parent_element: null,
+			component_slots
+		};
+
+		context.visit({ ...node.fragment, nodes: nodes[slot_name] }, state);
 	}
 }

From 09d714d6923e1a33a48ad3d2563bbf40fa49beb8 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 13:48:24 -0400
Subject: [PATCH 72/86] fix

---
 .../src/compiler/phases/2-analyze/visitors/shared/component.js  | 2 +-
 .../src/compiler/phases/3-transform/client/transform-client.js  | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index 19895595cf8d..e9d58e5b4747 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -87,7 +87,7 @@ export function visit_component(node, context) {
 		const slot_name = determine_slot(child) ?? 'default';
 		(nodes[slot_name] ??= []).push(...comments, child);
 
-		comments = [];
+		if (slot_name !== 'default') comments = [];
 	}
 
 	const component_slots = new Set();
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 72ac67e0f5fc..3a6a6707996b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -65,7 +65,6 @@ const visitors = {
 		if (scope && scope !== state.scope) {
 			const transform = { ...state.transform };
 
-			// TODO do this in add_state_transformers and visit_function etc?
 			for (const [name, binding] of scope.declarations) {
 				if (binding.kind === 'normal') {
 					delete transform[name];

From bf5fb61b12eda3648f092491970ea03f6e2e3ba9 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 13:55:43 -0400
Subject: [PATCH 73/86] move some stuff

---
 .../3-transform/client/transform-client.js    |  29 +--
 .../phases/3-transform/client/types.d.ts      |   3 +
 .../3-transform/client/visitors/Program.js    | 165 ++++++++++--------
 3 files changed, 98 insertions(+), 99 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index 3a6a6707996b..c4709f565993 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -142,6 +142,7 @@ export function client_component(analysis, options) {
 		is_instance: false,
 		hoisted: [b.import_all('$', 'svelte/internal/client')],
 		node: /** @type {any} */ (null), // populated by the root node
+		legacy_reactive_imports: [],
 		legacy_reactive_statements: new Map(),
 		metadata: {
 			context: {
@@ -167,32 +168,6 @@ export function client_component(analysis, options) {
 		locations: /** @type {any} */ (null)
 	};
 
-	/** @type {ESTree.Statement[]} */
-	const legacy_reactive_imports = [];
-
-	if (!analysis.runes) {
-		state.transform['$$props'] = {
-			read: (node) => ({ ...node, name: '$$sanitized_props' })
-		};
-
-		for (const [name, binding] of state.scope.declarations) {
-			// Very very dirty way of making import statements reactive in legacy mode if needed
-			// TODO move this into the Program visitor
-			if (binding.declaration_kind === 'import' && binding.mutated) {
-				const id = b.id('$$_import_' + name);
-
-				state.transform[name] = {
-					read: (node) => b.call(id),
-					mutate: (node, mutation) => {
-						return b.call(id, mutation);
-					}
-				};
-
-				legacy_reactive_imports.push(b.var(id, b.call('$.reactive_import', b.thunk(b.id(name)))));
-			}
-		}
-	}
-
 	const module = /** @type {ESTree.Program} */ (
 		walk(/** @type {SvelteNode} */ (analysis.module.ast), state, visitors)
 	);
@@ -222,7 +197,7 @@ export function client_component(analysis, options) {
 		)
 	);
 
-	instance.body.unshift(...legacy_reactive_imports);
+	instance.body.unshift(...state.legacy_reactive_imports);
 
 	/** @type {ESTree.Statement[]} */
 	const store_setup = [];
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index b576ddeecaed..ba0c9016d017 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -23,6 +23,9 @@ export interface ClientTransformState extends TransformState {
 	 */
 	readonly in_constructor: boolean;
 
+	/** Imports that should be re-evaluated in legacy mode following a mutation */
+	readonly legacy_reactive_imports: Statement[];
+
 	/** The $: calls, which will be ordered in the end */
 	readonly legacy_reactive_statements: Map<LabeledStatement, Statement>;
 	readonly transform: Record<
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index 07fb459f3eb5..e1bf60454218 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -9,94 +9,115 @@ import { add_state_transformers } from './shared/declarations.js';
  * @param {ComponentContext} context
  */
 export function Program(node, context) {
-	if (context.state.is_instance) {
+	if (!context.state.analysis.runes) {
+		context.state.transform['$$props'] = {
+			read: (node) => ({ ...node, name: '$$sanitized_props' })
+		};
+
 		for (const [name, binding] of context.state.scope.declarations) {
-			if (binding.kind === 'store_sub') {
-				const store = /** @type {Expression} */ (context.visit(b.id(name.slice(1))));
+			if (binding.declaration_kind === 'import' && binding.mutated) {
+				const id = b.id('$$_import_' + name);
 
 				context.state.transform[name] = {
-					read: b.call,
-					assign: (node, value) => {
-						return b.call('$.store_set', store, value);
-					},
+					read: (node) => b.call(id),
 					mutate: (node, mutation) => {
-						// We need to untrack the store read, for consistency with Svelte 4
-						const untracked = b.call('$.untrack', node);
+						return b.call(id, mutation);
+					}
+				};
 
-						/**
-						 *
-						 * @param {Expression} n
-						 * @returns {Expression}
-						 */
-						function replace(n) {
-							if (n.type === 'MemberExpression') {
-								return {
-									...n,
-									object: replace(/** @type {Expression} */ (n.object)),
-									property: n.property
-								};
-							}
+				context.state.legacy_reactive_imports.push(
+					b.var(id, b.call('$.reactive_import', b.thunk(b.id(name))))
+				);
+			}
+		}
+	}
 
-							return untracked;
+	for (const [name, binding] of context.state.scope.declarations) {
+		if (binding.kind === 'store_sub') {
+			const store = /** @type {Expression} */ (context.visit(b.id(name.slice(1))));
+
+			context.state.transform[name] = {
+				read: b.call,
+				assign: (node, value) => {
+					return b.call('$.store_set', store, value);
+				},
+				mutate: (node, mutation) => {
+					// We need to untrack the store read, for consistency with Svelte 4
+					const untracked = b.call('$.untrack', node);
+
+					/**
+					 *
+					 * @param {Expression} n
+					 * @returns {Expression}
+					 */
+					function replace(n) {
+						if (n.type === 'MemberExpression') {
+							return {
+								...n,
+								object: replace(/** @type {Expression} */ (n.object)),
+								property: n.property
+							};
 						}
 
-						return b.call(
-							'$.store_mutate',
-							store,
-							b.assignment(
-								mutation.operator,
-								/** @type {MemberExpression} */ (
-									replace(/** @type {MemberExpression} */ (mutation.left))
-								),
-								mutation.right
+						return untracked;
+					}
+
+					return b.call(
+						'$.store_mutate',
+						store,
+						b.assignment(
+							mutation.operator,
+							/** @type {MemberExpression} */ (
+								replace(/** @type {MemberExpression} */ (mutation.left))
 							),
-							untracked
-						);
+							mutation.right
+						),
+						untracked
+					);
+				},
+				update: (node) => {
+					return b.call(
+						node.prefix ? '$.update_pre_store' : '$.update_store',
+						build_getter(b.id(name.slice(1)), context.state),
+						b.call(node.argument),
+						node.operator === '--' && b.literal(-1)
+					);
+				}
+			};
+		}
+
+		if (binding.kind === 'prop' || binding.kind === 'bindable_prop') {
+			if (is_prop_source(binding, context.state)) {
+				context.state.transform[name] = {
+					read: b.call,
+					assign: (node, value) => {
+						return b.call(node, value);
+					},
+					mutate: (node, value) => {
+						if (binding.kind === 'bindable_prop') {
+							// only necessary for interop with legacy parent bindings
+							return b.call(node, value, b.true);
+						}
+
+						return value;
 					},
 					update: (node) => {
 						return b.call(
-							node.prefix ? '$.update_pre_store' : '$.update_store',
-							build_getter(b.id(name.slice(1)), context.state),
-							b.call(node.argument),
+							node.prefix ? '$.update_pre_prop' : '$.update_prop',
+							node.argument,
 							node.operator === '--' && b.literal(-1)
 						);
 					}
 				};
-			}
-
-			if (binding.kind === 'prop' || binding.kind === 'bindable_prop') {
-				if (is_prop_source(binding, context.state)) {
-					context.state.transform[name] = {
-						read: b.call,
-						assign: (node, value) => {
-							return b.call(node, value);
-						},
-						mutate: (node, value) => {
-							if (binding.kind === 'bindable_prop') {
-								// only necessary for interop with legacy parent bindings
-								return b.call(node, value, b.true);
-							}
-
-							return value;
-						},
-						update: (node) => {
-							return b.call(
-								node.prefix ? '$.update_pre_prop' : '$.update_prop',
-								node.argument,
-								node.operator === '--' && b.literal(-1)
-							);
-						}
-					};
-				} else if (binding.prop_alias) {
-					const key = b.key(binding.prop_alias);
-					context.state.transform[name] = {
-						read: (node) => b.member(b.id('$$props'), key, key.type === 'Literal')
-					};
-				} else {
-					context.state.transform[name] = {
-						read: (node) => b.member(b.id('$$props'), node)
-					};
-				}
+			} else if (binding.prop_alias) {
+				const key = b.key(binding.prop_alias);
+				context.state.transform[name] = {
+					read: (node) => b.member(b.id('$$props'), key, key.type === 'Literal')
+				};
+			} else {
+				context.state.transform[name] = {
+					read: (node) => b.member(b.id('$$props'), node)
+				};
 			}
 		}
 	}

From ee666d559fa504d5258979c826535bc54200278f Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 13:58:23 -0400
Subject: [PATCH 74/86] tweak

---
 .../src/compiler/phases/3-transform/client/visitors/Program.js   | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index e1bf60454218..4cb6046b85e5 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -111,6 +111,7 @@ export function Program(node, context) {
 				};
 			} else if (binding.prop_alias) {
 				const key = b.key(binding.prop_alias);
+
 				context.state.transform[name] = {
 					read: (node) => b.member(b.id('$$props'), key, key.type === 'Literal')
 				};

From e9fda1ea69a52a9f77e0cd3fe115d098138ca0e8 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 14:00:36 -0400
Subject: [PATCH 75/86] tidy up

---
 .../3-transform/client/visitors/AssignmentExpression.js       | 4 +---
 .../3-transform/server/visitors/AssignmentExpression.js       | 4 +---
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 97a013025ec0..9acf61f9cf67 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -11,9 +11,6 @@ import { build_proxy_reassignment, should_proxy_or_freeze } from '../utils.js';
  * @param {Context} context
  */
 export function AssignmentExpression(node, context) {
-	const parent = /** @type {Node} */ (context.path.at(-1));
-	const is_standalone = parent.type.endsWith('Statement');
-
 	if (
 		node.left.type === 'ArrayPattern' ||
 		node.left.type === 'ObjectPattern' ||
@@ -39,6 +36,7 @@ export function AssignmentExpression(node, context) {
 			return context.next();
 		}
 
+		const is_standalone = /** @type {Node} */ (context.path.at(-1)).type.endsWith('Statement');
 		const sequence = b.sequence(assignments);
 
 		if (!is_standalone) {
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
index c349f64b3d27..4910b53d97ea 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
@@ -10,9 +10,6 @@ import { build_getter } from './shared/utils.js';
  * @param {Context} context
  */
 export function AssignmentExpression(node, context) {
-	const parent = /** @type {Node} */ (context.path.at(-1));
-	const is_standalone = parent.type.endsWith('Statement');
-
 	if (
 		node.left.type === 'ArrayPattern' ||
 		node.left.type === 'ObjectPattern' ||
@@ -38,6 +35,7 @@ export function AssignmentExpression(node, context) {
 			return context.next();
 		}
 
+		const is_standalone = /** @type {Node} */ (context.path.at(-1)).type.endsWith('Statement');
 		const sequence = b.sequence(assignments);
 
 		if (!is_standalone) {

From b1eaeaecb70b892163e82902797cf986ac193b50 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 14:09:38 -0400
Subject: [PATCH 76/86] DRY

---
 .../client/visitors/AssignmentExpression.js   | 32 +++++++------------
 .../server/visitors/AssignmentExpression.js   | 15 +++------
 packages/svelte/src/compiler/utils/ast.js     | 12 +++++++
 3 files changed, 27 insertions(+), 32 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 9acf61f9cf67..074b3816a9e6 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -2,7 +2,11 @@
 /** @import { SvelteNode } from '#compiler' */
 /** @import { ClientTransformState, Context } from '../types.js' */
 import * as b from '../../../../utils/builders.js';
-import { extract_paths, is_expression_async } from '../../../../utils/ast.js';
+import {
+	build_assignment_value,
+	extract_paths,
+	is_expression_async
+} from '../../../../utils/ast.js';
 import { is_ignored } from '../../../../state.js';
 import { build_proxy_reassignment, should_proxy_or_freeze } from '../utils.js';
 
@@ -87,7 +91,9 @@ export function build_assignment(operator, left, right, context) {
 			const private_state = context.state.private_state.get(left.property.name);
 
 			if (private_state !== undefined) {
-				let value = get_assignment_value(operator, left, right, context);
+				let value = /** @type {Expression} */ (
+					context.visit(build_assignment_value(operator, left, right))
+				);
 				let transformed = false;
 
 				if (should_proxy_or_freeze(value, context.state.scope)) {
@@ -143,7 +149,9 @@ export function build_assignment(operator, left, right, context) {
 
 	// reassignment
 	if (object === left && transform?.assign) {
-		let value = get_assignment_value(operator, left, right, context);
+		let value = /** @type {Expression} */ (
+			context.visit(build_assignment_value(operator, left, right))
+		);
 
 		// special case — if an element binding, we know it's a primitive
 		const path = context.path.map((node) => node.type);
@@ -180,21 +188,3 @@ export function build_assignment(operator, left, right, context) {
 		? b.call('$.skip_ownership_validation', b.thunk(mutation))
 		: mutation;
 }
-
-/**
- * @template {ClientTransformState} State
- * @param {AssignmentOperator} operator
- * @param {Pattern} left
- * @param {Expression} right
- * @param {import('zimmerframe').Context<SvelteNode, State>} context
- */
-function get_assignment_value(operator, left, right, { visit }) {
-	return operator === '='
-		? /** @type {Expression} */ (visit(right))
-		: // turn something like x += 1 into x = x + 1
-			b.binary(
-				/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-				/** @type {Expression} */ (visit(left)),
-				/** @type {Expression} */ (visit(right))
-			);
-}
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
index 4910b53d97ea..5e0a34eb520c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
@@ -2,7 +2,7 @@
 /** @import { SvelteNode } from '#compiler' */
 /** @import { Context, ServerTransformState } from '../types.js' */
 import * as b from '../../../../utils/builders.js';
-import { extract_paths } from '../../../../utils/ast.js';
+import { build_assignment_value, extract_paths } from '../../../../utils/ast.js';
 import { build_getter } from './shared/utils.js';
 
 /**
@@ -81,16 +81,9 @@ function build_assignment(operator, left, right, context) {
 	}
 
 	if (object === left) {
-		let value = /** @type {Expression} */ (context.visit(right));
-
-		if (operator !== '=') {
-			// turn `x += 1` into `x = x + 1`
-			value = b.binary(
-				/** @type {BinaryOperator} */ (operator.slice(0, -1)),
-				build_getter(left, context.state),
-				value
-			);
-		}
+		let value = /** @type {Expression} */ (
+			context.visit(build_assignment_value(operator, left, right))
+		);
 
 		return b.call('$.store_set', b.id(name), value);
 	}
diff --git a/packages/svelte/src/compiler/utils/ast.js b/packages/svelte/src/compiler/utils/ast.js
index 95b5d2fb2d7e..47bbdb945fb4 100644
--- a/packages/svelte/src/compiler/utils/ast.js
+++ b/packages/svelte/src/compiler/utils/ast.js
@@ -563,3 +563,15 @@ export function build_fallback(expression, fallback) {
 		? b.await(b.call('$.fallback', expression, b.thunk(fallback, true), b.true))
 		: b.call('$.fallback', expression, b.thunk(fallback), b.true);
 }
+
+/**
+ * @param {ESTree.AssignmentOperator} operator
+ * @param {ESTree.Identifier | ESTree.MemberExpression} left
+ * @param {ESTree.Expression} right
+ */
+export function build_assignment_value(operator, left, right) {
+	return operator === '='
+		? right
+		: // turn something like x += 1 into x = x + 1
+			b.binary(/** @type {ESTree.BinaryOperator} */ (operator.slice(0, -1)), left, right);
+}

From e7a390d7ce3366002bb1de5e9c962dd1a8440e76 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 14:15:43 -0400
Subject: [PATCH 77/86] synchronise

---
 .../3-transform/client/visitors/AssignmentExpression.js  | 9 ++++++++-
 .../3-transform/server/visitors/AssignmentExpression.js  | 9 ++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 074b3816a9e6..11db2d1bcb10 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -32,7 +32,14 @@ export function AssignmentExpression(node, context) {
 			let assignment = build_assignment('=', path.node, value, context);
 			if (assignment !== null) changed = true;
 
-			return assignment ?? /** @type {Expression} */ (context.next());
+			return (
+				assignment ??
+				b.assignment(
+					'=',
+					/** @type {Pattern} */ (context.visit(path.node)),
+					/** @type {Expression} */ (context.visit(value))
+				)
+			);
 		});
 
 		if (!changed) {
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
index 5e0a34eb520c..d5a511cdbfd1 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
@@ -27,7 +27,14 @@ export function AssignmentExpression(node, context) {
 			let assignment = build_assignment('=', path.node, value, context);
 			if (assignment !== null) changed = true;
 
-			return assignment ?? b.assignment('=', path.node, value);
+			return (
+				assignment ??
+				b.assignment(
+					'=',
+					/** @type {Pattern} */ (context.visit(path.node)),
+					/** @type {Expression} */ (context.visit(value))
+				)
+			);
 		});
 
 		if (!changed) {

From 7a4354298565c53877010b56c4c321a41978b25e Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 14:26:25 -0400
Subject: [PATCH 78/86] DRY out

---
 .../client/visitors/AssignmentExpression.js   | 78 ++-----------------
 .../server/visitors/AssignmentExpression.js   | 56 +------------
 .../phases/3-transform/shared/assignments.js  | 77 ++++++++++++++++++
 3 files changed, 87 insertions(+), 124 deletions(-)
 create mode 100644 packages/svelte/src/compiler/phases/3-transform/shared/assignments.js

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index 11db2d1bcb10..b94dc34923f7 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -1,90 +1,24 @@
-/** @import { AssignmentExpression, AssignmentOperator, BinaryOperator, Expression, Node, Pattern } from 'estree' */
-/** @import { SvelteNode } from '#compiler' */
-/** @import { ClientTransformState, Context } from '../types.js' */
+/** @import { AssignmentExpression, AssignmentOperator, Expression, Pattern } from 'estree' */
+/** @import { Context } from '../types.js' */
 import * as b from '../../../../utils/builders.js';
-import {
-	build_assignment_value,
-	extract_paths,
-	is_expression_async
-} from '../../../../utils/ast.js';
+import { build_assignment_value } from '../../../../utils/ast.js';
 import { is_ignored } from '../../../../state.js';
 import { build_proxy_reassignment, should_proxy_or_freeze } from '../utils.js';
+import { visit_assignment_expression } from '../../shared/assignments.js';
 
 /**
  * @param {AssignmentExpression} node
  * @param {Context} context
  */
 export function AssignmentExpression(node, context) {
-	if (
-		node.left.type === 'ArrayPattern' ||
-		node.left.type === 'ObjectPattern' ||
-		node.left.type === 'RestElement'
-	) {
-		const value = /** @type {Expression} */ (context.visit(node.right));
-		const should_cache = value.type !== 'Identifier';
-		const rhs = should_cache ? b.id('$$value') : value;
-
-		let changed = false;
-
-		const assignments = extract_paths(node.left).map((path) => {
-			const value = path.expression?.(rhs);
-
-			let assignment = build_assignment('=', path.node, value, context);
-			if (assignment !== null) changed = true;
-
-			return (
-				assignment ??
-				b.assignment(
-					'=',
-					/** @type {Pattern} */ (context.visit(path.node)),
-					/** @type {Expression} */ (context.visit(value))
-				)
-			);
-		});
-
-		if (!changed) {
-			// No change to output -> nothing to transform -> we can keep the original assignment
-			return context.next();
-		}
-
-		const is_standalone = /** @type {Node} */ (context.path.at(-1)).type.endsWith('Statement');
-		const sequence = b.sequence(assignments);
-
-		if (!is_standalone) {
-			// this is part of an expression, we need the sequence to end with the value
-			sequence.expressions.push(rhs);
-		}
-
-		if (should_cache) {
-			// the right hand side is a complex expression, wrap in an IIFE to cache it
-			const iife = b.arrow([rhs], sequence);
-
-			const iife_is_async =
-				is_expression_async(value) ||
-				assignments.some((assignment) => is_expression_async(assignment));
-
-			return iife_is_async ? b.await(b.call(b.async(iife), value)) : b.call(iife, value);
-		}
-
-		return sequence;
-	}
-
-	if (node.left.type !== 'Identifier' && node.left.type !== 'MemberExpression') {
-		throw new Error(`Unexpected assignment type ${node.left.type}`);
-	}
-
-	return (
-		build_assignment(node.operator, node.left, node.right, context) ??
-		/** @type {Expression} */ (context.next())
-	);
+	return visit_assignment_expression(node, context, build_assignment);
 }
 
 /**
- * @template {ClientTransformState} State
  * @param {AssignmentOperator} operator
  * @param {Pattern} left
  * @param {Expression} right
- * @param {import('zimmerframe').Context<SvelteNode, State>} context
+ * @param {Context} context
  * @returns {Expression | null}
  */
 export function build_assignment(operator, left, right, context) {
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
index d5a511cdbfd1..e92d54c3b79b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AssignmentExpression.js
@@ -1,64 +1,16 @@
-/** @import { AssignmentExpression, AssignmentOperator, BinaryOperator, Expression, Node, Pattern } from 'estree' */
+/** @import { AssignmentExpression, AssignmentOperator, Expression, Pattern } from 'estree' */
 /** @import { SvelteNode } from '#compiler' */
 /** @import { Context, ServerTransformState } from '../types.js' */
 import * as b from '../../../../utils/builders.js';
-import { build_assignment_value, extract_paths } from '../../../../utils/ast.js';
-import { build_getter } from './shared/utils.js';
+import { build_assignment_value } from '../../../../utils/ast.js';
+import { visit_assignment_expression } from '../../shared/assignments.js';
 
 /**
  * @param {AssignmentExpression} node
  * @param {Context} context
  */
 export function AssignmentExpression(node, context) {
-	if (
-		node.left.type === 'ArrayPattern' ||
-		node.left.type === 'ObjectPattern' ||
-		node.left.type === 'RestElement'
-	) {
-		const value = /** @type {Expression} */ (context.visit(node.right));
-		const should_cache = value.type !== 'Identifier';
-		const rhs = should_cache ? b.id('$$value') : value;
-
-		let changed = false;
-
-		const assignments = extract_paths(node.left).map((path) => {
-			const value = path.expression?.(rhs);
-
-			let assignment = build_assignment('=', path.node, value, context);
-			if (assignment !== null) changed = true;
-
-			return (
-				assignment ??
-				b.assignment(
-					'=',
-					/** @type {Pattern} */ (context.visit(path.node)),
-					/** @type {Expression} */ (context.visit(value))
-				)
-			);
-		});
-
-		if (!changed) {
-			// No change to output -> nothing to transform -> we can keep the original assignment
-			return context.next();
-		}
-
-		const is_standalone = /** @type {Node} */ (context.path.at(-1)).type.endsWith('Statement');
-		const sequence = b.sequence(assignments);
-
-		if (!is_standalone) {
-			// this is part of an expression, we need the sequence to end with the value
-			sequence.expressions.push(rhs);
-		}
-
-		if (should_cache) {
-			// the right hand side is a complex expression, wrap in an IIFE to cache it
-			return b.call(b.arrow([rhs], sequence), value);
-		}
-
-		return sequence;
-	}
-
-	return build_assignment(node.operator, node.left, node.right, context) || context.next();
+	return visit_assignment_expression(node, context, build_assignment);
 }
 
 /**
diff --git a/packages/svelte/src/compiler/phases/3-transform/shared/assignments.js b/packages/svelte/src/compiler/phases/3-transform/shared/assignments.js
new file mode 100644
index 000000000000..ce7595a06e13
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/3-transform/shared/assignments.js
@@ -0,0 +1,77 @@
+/** @import { AssignmentExpression, AssignmentOperator, Expression, Node, Pattern } from 'estree' */
+/** @import { Context as ClientContext } from '../client/types.js' */
+/** @import { Context as ServerContext } from '../server/types.js' */
+import { extract_paths, is_expression_async } from '../../../utils/ast.js';
+import * as b from '../../../utils/builders.js';
+
+/**
+ * @template {ClientContext | ServerContext} Context
+ * @param {AssignmentExpression} node
+ * @param {Context} context
+ * @param {(operator: AssignmentOperator, left: Pattern, right: Expression, context: Context) => Expression | null} build_assignment
+ * @returns
+ */
+export function visit_assignment_expression(node, context, build_assignment) {
+	if (
+		node.left.type === 'ArrayPattern' ||
+		node.left.type === 'ObjectPattern' ||
+		node.left.type === 'RestElement'
+	) {
+		const value = /** @type {Expression} */ (context.visit(node.right));
+		const should_cache = value.type !== 'Identifier';
+		const rhs = should_cache ? b.id('$$value') : value;
+
+		let changed = false;
+
+		const assignments = extract_paths(node.left).map((path) => {
+			const value = path.expression?.(rhs);
+
+			let assignment = build_assignment('=', path.node, value, context);
+			if (assignment !== null) changed = true;
+
+			return (
+				assignment ??
+				b.assignment(
+					'=',
+					/** @type {Pattern} */ (context.visit(path.node)),
+					/** @type {Expression} */ (context.visit(value))
+				)
+			);
+		});
+
+		if (!changed) {
+			// No change to output -> nothing to transform -> we can keep the original assignment
+			return context.next();
+		}
+
+		const is_standalone = /** @type {Node} */ (context.path.at(-1)).type.endsWith('Statement');
+		const sequence = b.sequence(assignments);
+
+		if (!is_standalone) {
+			// this is part of an expression, we need the sequence to end with the value
+			sequence.expressions.push(rhs);
+		}
+
+		if (should_cache) {
+			// the right hand side is a complex expression, wrap in an IIFE to cache it
+			const iife = b.arrow([rhs], sequence);
+
+			const iife_is_async =
+				is_expression_async(value) ||
+				assignments.some((assignment) => is_expression_async(assignment));
+
+			return iife_is_async ? b.await(b.call(b.async(iife), value)) : b.call(iife, value);
+		}
+
+		return sequence;
+	}
+
+	if (node.left.type !== 'Identifier' && node.left.type !== 'MemberExpression') {
+		throw new Error(`Unexpected assignment type ${node.left.type}`);
+	}
+
+	return (
+		build_assignment(node.operator, node.left, node.right, context) ??
+		/** @type {Expression} */ (context.next())
+	);
+}

From 1a1b099413728e337d31db1e426d52d31750821d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 14:30:15 -0400
Subject: [PATCH 79/86] tidy up

---
 .../svelte/src/compiler/phases/3-transform/client/utils.js   | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index ce9825ad018f..d5e6420d5d2f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -290,10 +290,7 @@ export function with_loc(target, source) {
  */
 export function create_derived_block_argument(node, context) {
 	if (node.type === 'Identifier') {
-		context.state.transform[node.name] = {
-			read: get_value
-		};
-
+		context.state.transform[node.name] = { read: get_value };
 		return { id: node, declarations: null };
 	}
 

From 115e2855427dbbe0137b2957e051eb1ee4002416 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 14:37:49 -0400
Subject: [PATCH 80/86] tidy up

---
 .../client/visitors/AssignmentExpression.js   | 10 ++++------
 .../3-transform/client/visitors/ConstTag.js   |  4 +---
 .../3-transform/client/visitors/EachBlock.js  |  4 +---
 .../3-transform/client/visitors/Program.js    | 20 +++++++------------
 4 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
index b94dc34923f7..afd2d50ba40c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js
@@ -32,10 +32,10 @@ export function build_assignment(operator, left, right, context) {
 			const private_state = context.state.private_state.get(left.property.name);
 
 			if (private_state !== undefined) {
+				let transformed = false;
 				let value = /** @type {Expression} */ (
 					context.visit(build_assignment_value(operator, left, right))
 				);
-				let transformed = false;
 
 				if (should_proxy_or_freeze(value, context.state.scope)) {
 					transformed = true;
@@ -45,12 +45,10 @@ export function build_assignment(operator, left, right, context) {
 							: build_proxy_reassignment(value, private_state.id);
 				}
 
-				if (context.state.in_constructor) {
-					if (transformed) {
-						return b.assignment(operator, /** @type {Pattern} */ (context.visit(left)), value);
-					}
-				} else {
+				if (!context.state.in_constructor) {
 					return b.call('$.set', left, value);
+				} else if (transformed) {
+					return b.assignment(operator, /** @type {Pattern} */ (context.visit(left)), value);
 				}
 			}
 		} else if (left.property.type === 'Identifier' && context.state.in_constructor) {
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
index 1a7b2904d920..bfff38338bb2 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
@@ -25,9 +25,7 @@ export function ConstTag(node, context) {
 			)
 		);
 
-		context.state.transform[declaration.id.name] = {
-			read: get_value
-		};
+		context.state.transform[declaration.id.name] = { read: get_value };
 
 		// we need to eagerly evaluate the expression in order to hit any
 		// 'Cannot access x before initialization' errors
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index 8491850de896..a5b96d64e642 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -222,9 +222,7 @@ export function EachBlock(node, context) {
 				declarations.push(b.stmt(read(b.id(name))));
 			}
 
-			key_state.transform[name] = {
-				read: () => path.node
-			};
+			delete key_state.transform[name];
 		}
 	}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
index 4cb6046b85e5..c222d74d6e16 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js
@@ -5,10 +5,10 @@ import * as b from '../../../../utils/builders.js';
 import { add_state_transformers } from './shared/declarations.js';
 
 /**
- * @param {Program} node
+ * @param {Program} _
  * @param {ComponentContext} context
  */
-export function Program(node, context) {
+export function Program(_, context) {
 	if (!context.state.analysis.runes) {
 		context.state.transform['$$props'] = {
 			read: (node) => ({ ...node, name: '$$sanitized_props' })
@@ -19,10 +19,8 @@ export function Program(node, context) {
 				const id = b.id('$$_import_' + name);
 
 				context.state.transform[name] = {
-					read: (node) => b.call(id),
-					mutate: (node, mutation) => {
-						return b.call(id, mutation);
-					}
+					read: (_) => b.call(id),
+					mutate: (_, mutation) => b.call(id, mutation)
 				};
 
 				context.state.legacy_reactive_imports.push(
@@ -38,9 +36,7 @@ export function Program(node, context) {
 
 			context.state.transform[name] = {
 				read: b.call,
-				assign: (node, value) => {
-					return b.call('$.store_set', store, value);
-				},
+				assign: (_, value) => b.call('$.store_set', store, value),
 				mutate: (node, mutation) => {
 					// We need to untrack the store read, for consistency with Svelte 4
 					const untracked = b.call('$.untrack', node);
@@ -90,9 +86,7 @@ export function Program(node, context) {
 			if (is_prop_source(binding, context.state)) {
 				context.state.transform[name] = {
 					read: b.call,
-					assign: (node, value) => {
-						return b.call(node, value);
-					},
+					assign: (node, value) => b.call(node, value),
 					mutate: (node, value) => {
 						if (binding.kind === 'bindable_prop') {
 							// only necessary for interop with legacy parent bindings
@@ -113,7 +107,7 @@ export function Program(node, context) {
 				const key = b.key(binding.prop_alias);
 
 				context.state.transform[name] = {
-					read: (node) => b.member(b.id('$$props'), key, key.type === 'Literal')
+					read: (_) => b.member(b.id('$$props'), key, key.type === 'Literal')
 				};
 			} else {
 				context.state.transform[name] = {

From 97f3bd7aad527978b197ad6c3999dc676189cfa5 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 14:48:44 -0400
Subject: [PATCH 81/86] tidy up

---
 .../phases/3-transform/client/visitors/EachBlock.js       | 8 ++------
 .../phases/3-transform/client/visitors/SnippetBlock.js    | 4 +---
 .../3-transform/client/visitors/shared/component.js       | 4 +---
 packages/svelte/src/compiler/phases/scope.js              | 1 -
 4 files changed, 4 insertions(+), 13 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index a5b96d64e642..fa19509c066b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -173,7 +173,7 @@ export function EachBlock(node, context) {
 	if (node.context.type === 'Identifier') {
 		child_state.transform[node.context.name] = {
 			read: getter,
-			assign: (node, value) => {
+			assign: (_, value) => {
 				const left = b.member(
 					each_node_meta.array_name ? b.call(each_node_meta.array_name) : collection,
 					index,
@@ -182,10 +182,7 @@ export function EachBlock(node, context) {
 
 				return b.sequence([b.assignment('=', left, value), ...sequence]);
 			},
-			mutate: (node, mutation) => {
-				return b.sequence([mutation, ...sequence]);
-			}
-			// TODO update (`item++`) — this was unaccounted for previously
+			mutate: (_, mutation) => b.sequence([mutation, ...sequence])
 		};
 
 		delete key_state.transform[node.context.name];
@@ -213,7 +210,6 @@ export function EachBlock(node, context) {
 				mutate: (node, mutation) => {
 					return b.sequence([mutation, ...sequence]);
 				}
-				// TODO update (`item++`) — this was unaccounted for previously
 			};
 
 			// we need to eagerly evaluate the expression in order to hit any
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
index 750b1b6a3b0d..b62a58c8d797 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
@@ -36,9 +36,7 @@ export function SnippetBlock(node, context) {
 				right: b.id('$.noop')
 			});
 
-			transform[argument.name] = {
-				read: b.call
-			};
+			transform[argument.name] = { read: b.call };
 
 			continue;
 		}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index 799fcd765827..44f943ddec43 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -50,13 +50,11 @@ export function build_component(node, component_name, context, anchor = context.
 	 */
 	const binding_initializers = [];
 
-	const self_slot = determine_slot(node);
-
 	/**
 	 * If this component has a slot property, it is a named slot within another component. In this case
 	 * the slot scope applies to the component itself, too, and not just its children.
 	 */
-	let slot_scope_applies_to_itself = !!self_slot;
+	let slot_scope_applies_to_itself = !!determine_slot(node);
 
 	/**
 	 * Components may have a children prop and also have child nodes. In this case, we assume
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index 15ed9d219a2a..17957292a5fe 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -306,7 +306,6 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 		const default_state = !!determine_slot(node)
 			? context.state
 			: { scope: node.metadata.scopes.default };
-		// scopes.set(node, scope);
 
 		for (const attribute of node.attributes) {
 			if (attribute.type === 'LetDirective') {

From 8a665b97e887e7a294278dc44fbe157d4874ee7e Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 14:51:04 -0400
Subject: [PATCH 82/86] add test that fails on main

---
 .../samples/each-blocks-update/_config.js     | 27 +++++++++++++++++++
 .../samples/each-blocks-update/main.svelte    |  9 +++++++
 2 files changed, 36 insertions(+)
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/each-blocks-update/_config.js
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/each-blocks-update/main.svelte

diff --git a/packages/svelte/tests/runtime-legacy/samples/each-blocks-update/_config.js b/packages/svelte/tests/runtime-legacy/samples/each-blocks-update/_config.js
new file mode 100644
index 000000000000..a00605a634a5
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/each-blocks-update/_config.js
@@ -0,0 +1,27 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	html: `
+		<button>1</button>
+		<button>2</button>
+		<button>3</button>
+		<p>1, 2, 3</p>
+	`,
+
+	test({ assert, target }) {
+		let buttons = target.querySelectorAll('button');
+
+		flushSync(() => buttons[2].click());
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<button>1</button>
+				<button>2</button>
+				<button>4</button>
+				<p>1, 2, 4</p>
+			`
+		);
+	}
+});
diff --git a/packages/svelte/tests/runtime-legacy/samples/each-blocks-update/main.svelte b/packages/svelte/tests/runtime-legacy/samples/each-blocks-update/main.svelte
new file mode 100644
index 000000000000..0abded02ff93
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/each-blocks-update/main.svelte
@@ -0,0 +1,9 @@
+<script>
+	let arr = [1, 2, 3];
+</script>
+
+{#each arr as n}
+	<button on:click={() => n++}>{n}</button>
+{/each}
+
+<p>{arr.join(', ')}</p>

From b241c6f799362b43ffcb8f4525fa1f114cfb8b5f Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 14:59:54 -0400
Subject: [PATCH 83/86] snapshot test

---
 .../_expected/client/index.svelte.js                 | 12 ++++++++++++
 .../_expected/server/index.svelte.js                 |  9 +++++++++
 .../samples/destructured-assignments/index.svelte.js |  6 ++++++
 3 files changed, 27 insertions(+)
 create mode 100644 packages/svelte/tests/snapshot/samples/destructured-assignments/_expected/client/index.svelte.js
 create mode 100644 packages/svelte/tests/snapshot/samples/destructured-assignments/_expected/server/index.svelte.js
 create mode 100644 packages/svelte/tests/snapshot/samples/destructured-assignments/index.svelte.js

diff --git a/packages/svelte/tests/snapshot/samples/destructured-assignments/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/destructured-assignments/_expected/client/index.svelte.js
new file mode 100644
index 000000000000..9400b5271840
--- /dev/null
+++ b/packages/svelte/tests/snapshot/samples/destructured-assignments/_expected/client/index.svelte.js
@@ -0,0 +1,12 @@
+/* index.svelte.js generated by Svelte VERSION */
+import * as $ from "svelte/internal/client";
+
+let a = $.source(1);
+let b = $.source(2);
+
+export function update(array) {
+	(
+		$.set(a, $.proxy(array[0])),
+		$.set(b, $.proxy(array[1]))
+	);
+}
\ No newline at end of file
diff --git a/packages/svelte/tests/snapshot/samples/destructured-assignments/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/destructured-assignments/_expected/server/index.svelte.js
new file mode 100644
index 000000000000..846ed4845858
--- /dev/null
+++ b/packages/svelte/tests/snapshot/samples/destructured-assignments/_expected/server/index.svelte.js
@@ -0,0 +1,9 @@
+/* index.svelte.js generated by Svelte VERSION */
+import * as $ from "svelte/internal/server";
+
+let a = 1;
+let b = 2;
+
+export function update(array) {
+	[a, b] = array;
+}
\ No newline at end of file
diff --git a/packages/svelte/tests/snapshot/samples/destructured-assignments/index.svelte.js b/packages/svelte/tests/snapshot/samples/destructured-assignments/index.svelte.js
new file mode 100644
index 000000000000..9c0da7558a50
--- /dev/null
+++ b/packages/svelte/tests/snapshot/samples/destructured-assignments/index.svelte.js
@@ -0,0 +1,6 @@
+let a = $state(1);
+let b = $state(2);
+
+export function update(array) {
+	[a, b] = array;
+}

From 46c63adbae979ea39c84d9cd01ee9c88196d338d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 15:00:51 -0400
Subject: [PATCH 84/86] changesets

---
 .changeset/nine-ants-invite.md     | 5 +++++
 .changeset/perfect-hairs-matter.md | 5 +++++
 2 files changed, 10 insertions(+)
 create mode 100644 .changeset/nine-ants-invite.md
 create mode 100644 .changeset/perfect-hairs-matter.md

diff --git a/.changeset/nine-ants-invite.md b/.changeset/nine-ants-invite.md
new file mode 100644
index 000000000000..fdf33c27a9c8
--- /dev/null
+++ b/.changeset/nine-ants-invite.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: invalidate signals following ++/-- inside each block
diff --git a/.changeset/perfect-hairs-matter.md b/.changeset/perfect-hairs-matter.md
new file mode 100644
index 000000000000..8ec02f7507ea
--- /dev/null
+++ b/.changeset/perfect-hairs-matter.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+feat: better code generation for destructuring assignments

From b8b07e0128199c884c42d7f9b461eaac4d87dffc Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 15:03:13 -0400
Subject: [PATCH 85/86] lint

---
 .../phases/3-transform/client/transform-client.js     |  1 -
 .../src/compiler/phases/3-transform/client/types.d.ts | 11 ++++++-----
 packages/svelte/types/index.d.ts                      | 11 ++++++++---
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index c4709f565993..c4af60f24b8d 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -639,7 +639,6 @@ export function client_module(analysis, options) {
 		options,
 		scope: analysis.module.scope,
 		scopes: analysis.module.scopes,
-		legacy_reactive_statements: new Map(),
 		public_state: new Map(),
 		private_state: new Map(),
 		transform: {},
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index ba0c9016d017..cae1a10940ae 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -23,11 +23,6 @@ export interface ClientTransformState extends TransformState {
 	 */
 	readonly in_constructor: boolean;
 
-	/** Imports that should be re-evaluated in legacy mode following a mutation */
-	readonly legacy_reactive_imports: Statement[];
-
-	/** The $: calls, which will be ordered in the end */
-	readonly legacy_reactive_statements: Map<LabeledStatement, Statement>;
 	readonly transform: Record<
 		string,
 		{
@@ -84,6 +79,12 @@ export interface ComponentClientTransformState extends ClientTransformState {
 
 	/** The anchor node for the current context */
 	readonly node: Identifier;
+
+	/** Imports that should be re-evaluated in legacy mode following a mutation */
+	readonly legacy_reactive_imports: Statement[];
+
+	/** The $: calls, which will be ordered in the end */
+	readonly legacy_reactive_statements: Map<LabeledStatement, Statement>;
 }
 
 export interface StateField {
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index 969f89222da3..df012254f64f 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -920,7 +920,6 @@ declare module 'svelte/compiler' {
 		 * - `snippet`: A snippet parameter
 		 * - `store_sub`: A $store value
 		 * - `legacy_reactive`: A `$:` declaration
-		 * - `legacy_reactive_import`: An imported binding that is mutated inside the component
 		 */
 		kind:
 			| 'normal'
@@ -933,8 +932,7 @@ declare module 'svelte/compiler' {
 			| 'each'
 			| 'snippet'
 			| 'store_sub'
-			| 'legacy_reactive'
-			| 'legacy_reactive_import';
+			| 'legacy_reactive';
 		declaration_kind: DeclarationKind;
 		/**
 		 * What the value was initialized with.
@@ -1733,6 +1731,7 @@ declare module 'svelte/compiler' {
 	interface Component extends BaseElement {
 		type: 'Component';
 		metadata: {
+			scopes: Record<string, Scope>;
 			dynamic: boolean;
 		};
 	}
@@ -1769,6 +1768,9 @@ declare module 'svelte/compiler' {
 		type: 'SvelteComponent';
 		name: 'svelte:component';
 		expression: Expression;
+		metadata: {
+			scopes: Record<string, Scope>;
+		};
 	}
 
 	interface SvelteDocument extends BaseElement {
@@ -1814,6 +1816,9 @@ declare module 'svelte/compiler' {
 	interface SvelteSelf extends BaseElement {
 		type: 'SvelteSelf';
 		name: 'svelte:self';
+		metadata: {
+			scopes: Record<string, Scope>;
+		};
 	}
 
 	interface SvelteWindow extends BaseElement {

From 576763a16774e92e403de48743bbf8b169cd3f23 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 10 Aug 2024 15:07:42 -0400
Subject: [PATCH 86/86] ugh

---
 .../src/compiler/phases/2-analyze/visitors/shared/component.js  | 2 +-
 packages/svelte/src/compiler/phases/scope.js                    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index e9d58e5b4747..e6bb3c067edb 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -64,7 +64,7 @@ export function visit_component(node, context) {
 	// If the component has a slot attribute — `<Foo slot="whatever" .../>` —
 	// then `let:` directives apply to other attributes, instead of just the
 	// top-level contents of the component. Yes, this is very weird.
-	const default_state = !!determine_slot(node)
+	const default_state = determine_slot(node)
 		? context.state
 		: { ...context.state, scope: node.metadata.scopes.default };
 
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index 17957292a5fe..633f326080ba 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -303,7 +303,7 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 			default: context.state.scope.child()
 		};
 
-		const default_state = !!determine_slot(node)
+		const default_state = determine_slot(node)
 			? context.state
 			: { scope: node.metadata.scopes.default };