[fix] Handle windows paths and regexp chars in kit.alias (#6034)

Fixes #5962

Author: dummdidumm

.changeset/mighty-students-develop.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Handle windows paths and regexp chars in kit.alias

packages/kit/src/vite/utils.js

@@ -2,6 +2,7 @@ import fs from 'fs';
 import path from 'path';
 import { loadConfigFromFile, loadEnv, normalizePath } from 'vite';
 import { runtime_directory } from '../core/utils.js';
+import { posixify } from '../utils/filesystem.js';
 
 /**
  * @param {import('vite').ResolvedConfig} config
@@ -113,18 +114,22 @@ export function get_aliases(config) {
 	];
 
 	for (let [key, value] of Object.entries(config.alias)) {
+		value = posixify(value);
 		if (value.endsWith('/*')) {
 			value = value.slice(0, -2);
 		}
 		if (key.endsWith('/*')) {
 			// Doing just `{ find: key.slice(0, -2) ,..}` would mean `import .. from "key"` would also be matched, which we don't want
 			alias.push({
-				find: new RegExp(`^${key.slice(0, -2)}\\/(.+)$`),
+				find: new RegExp(`^${escape_for_regexp(key.slice(0, -2))}\\/(.+)$`),
 				replacement: `${path.resolve(value)}/$1`
 			});
 		} else if (key + '/*' in config.alias) {
 			// key and key/* both exist -> the replacement for key needs to happen _only_ on import .. from "key"
-			alias.push({ find: new RegExp(`^${key}$`), replacement: path.resolve(value) });
+			alias.push({
+				find: new RegExp(`^${escape_for_regexp(key)}$`),
+				replacement: path.resolve(value)
+			});
 		} else {
 			alias.push({ find: key, replacement: path.resolve(value) });
 		}
@@ -133,6 +138,13 @@ export function get_aliases(config) {
 	return alias;
 }
 
+/**
+ * @param {string} str
+ */
+function escape_for_regexp(str) {
+	return str.replace(/[.*+?^${}()|[\]\\]/g, (match) => '\\' + match);
+}
+
 /**
  * Given an entry point like [cwd]/src/hooks, returns a filename like [cwd]/src/hooks.js or [cwd]/src/hooks/index.js
  * @param {string} entry

packages/kit/src/vite/utils.spec.js

@@ -207,7 +207,15 @@ test('merge resolve.alias', () => {
 
 test('transform kit.alias to resolve.alias', () => {
 	const config = validate_config({
-		kit: { alias: { simpleKey: 'simple/value', key: 'value', 'key/*': 'value/*' } }
+		kit: {
+			alias: {
+				simpleKey: 'simple/value',
+				key: 'value',
+				'key/*': 'value/*',
+				$regexChar: 'windows\\path',
+				'$regexChar/*': 'windows\\path\\*'
+			}
+		}
 	});
 
 	const transformed = get_aliases(config.kit).map((entry) => {
@@ -227,7 +235,9 @@ test('transform kit.alias to resolve.alias', () => {
 		{ find: '$lib', replacement: 'src/lib' },
 		{ find: 'simpleKey', replacement: 'simple/value' },
 		{ find: /^key$/.toString(), replacement: 'value' },
-		{ find: /^key\/(.+)$/.toString(), replacement: 'value/$1' }
+		{ find: /^key\/(.+)$/.toString(), replacement: 'value/$1' },
+		{ find: /^\$regexChar$/.toString(), replacement: 'windows/path' },
+		{ find: /^\$regexChar\/(.+)$/.toString(), replacement: 'windows/path/$1' }
 	]);
 });