From 7cf806b23b9c7524b5f7a372c4d99b83489c485a Mon Sep 17 00:00:00 2001
From: Phaqui <Phaqui@gmail.com>
Date: Fri, 29 Jan 2021 03:30:53 +0100
Subject: [PATCH 1/3] Fixes #5858: Class binding name cannot be empty

---
 src/compiler/parse/state/tag.ts                        |  7 +++++++
 .../samples/error-empty-classname-binding/error.json   | 10 ++++++++++
 .../samples/error-empty-classname-binding/input.svelte |  1 +
 3 files changed, 18 insertions(+)
 create mode 100644 test/parser/samples/error-empty-classname-binding/error.json
 create mode 100644 test/parser/samples/error-empty-classname-binding/input.svelte

diff --git a/src/compiler/parse/state/tag.ts b/src/compiler/parse/state/tag.ts
index 696a47b649fc..c18de84bd06c 100644
--- a/src/compiler/parse/state/tag.ts
+++ b/src/compiler/parse/state/tag.ts
@@ -387,6 +387,13 @@ function read_attribute(parser: Parser, unique_names: Set<string>) {
 			}, start);
 		}
 
+        if (type === 'Class' && directive_name === '') {
+            parser.error({
+                code: 'invalid-class-directive-value',
+                message: 'Class binding name cannot be empty'
+            }, start + colon_index + 1);
+        }
+
 		if (value[0]) {
 			if ((value as any[]).length > 1 || value[0].type === 'Text') {
 				parser.error({
diff --git a/test/parser/samples/error-empty-classname-binding/error.json b/test/parser/samples/error-empty-classname-binding/error.json
new file mode 100644
index 000000000000..69e4667f7e6d
--- /dev/null
+++ b/test/parser/samples/error-empty-classname-binding/error.json
@@ -0,0 +1,10 @@
+{
+    "code": "invalid-class-directive-value",
+    "message": "Class binding name cannot be empty",
+    "start": {
+        "line": 1,
+        "column": 10,
+        "character": 10
+    },
+    "pos": 10
+}
diff --git a/test/parser/samples/error-empty-classname-binding/input.svelte b/test/parser/samples/error-empty-classname-binding/input.svelte
new file mode 100644
index 000000000000..3a4e5980eea3
--- /dev/null
+++ b/test/parser/samples/error-empty-classname-binding/input.svelte
@@ -0,0 +1 @@
+<h1 class:={true}>Hello</h1>

From 1feb9a0c9d7635e536052b7684d69ad859fe89eb Mon Sep 17 00:00:00 2001
From: Conduitry <git@chor.date>
Date: Fri, 29 Jan 2021 10:24:54 -0500
Subject: [PATCH 2/3] fix indentation

---
 src/compiler/parse/state/tag.ts                  | 12 ++++++------
 .../error-empty-classname-binding/error.json     | 16 ++++++++--------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/compiler/parse/state/tag.ts b/src/compiler/parse/state/tag.ts
index c18de84bd06c..e9c5ac0bb795 100644
--- a/src/compiler/parse/state/tag.ts
+++ b/src/compiler/parse/state/tag.ts
@@ -387,12 +387,12 @@ function read_attribute(parser: Parser, unique_names: Set<string>) {
 			}, start);
 		}
 
-        if (type === 'Class' && directive_name === '') {
-            parser.error({
-                code: 'invalid-class-directive-value',
-                message: 'Class binding name cannot be empty'
-            }, start + colon_index + 1);
-        }
+		if (type === 'Class' && directive_name === '') {
+			parser.error({
+				code: 'invalid-class-directive-value',
+				message: 'Class binding name cannot be empty'
+			}, start + colon_index + 1);
+		}
 
 		if (value[0]) {
 			if ((value as any[]).length > 1 || value[0].type === 'Text') {
diff --git a/test/parser/samples/error-empty-classname-binding/error.json b/test/parser/samples/error-empty-classname-binding/error.json
index 69e4667f7e6d..64e05c112d2e 100644
--- a/test/parser/samples/error-empty-classname-binding/error.json
+++ b/test/parser/samples/error-empty-classname-binding/error.json
@@ -1,10 +1,10 @@
 {
-    "code": "invalid-class-directive-value",
-    "message": "Class binding name cannot be empty",
-    "start": {
-        "line": 1,
-        "column": 10,
-        "character": 10
-    },
-    "pos": 10
+	"code": "invalid-class-directive-value",
+	"message": "Class binding name cannot be empty",
+	"start": {
+		"line": 1,
+		"column": 10,
+		"character": 10
+	},
+	"pos": 10
 }

From 6e6014227ded2582003a377381e5ff8e335aa7e2 Mon Sep 17 00:00:00 2001
From: Conduitry <git@chor.date>
Date: Fri, 29 Jan 2021 10:28:20 -0500
Subject: [PATCH 3/3] adjust error code

---
 src/compiler/parse/state/tag.ts                              | 2 +-
 test/parser/samples/error-empty-classname-binding/error.json | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/compiler/parse/state/tag.ts b/src/compiler/parse/state/tag.ts
index e9c5ac0bb795..aedffffe21a0 100644
--- a/src/compiler/parse/state/tag.ts
+++ b/src/compiler/parse/state/tag.ts
@@ -389,7 +389,7 @@ function read_attribute(parser: Parser, unique_names: Set<string>) {
 
 		if (type === 'Class' && directive_name === '') {
 			parser.error({
-				code: 'invalid-class-directive-value',
+				code: 'invalid-class-directive',
 				message: 'Class binding name cannot be empty'
 			}, start + colon_index + 1);
 		}
diff --git a/test/parser/samples/error-empty-classname-binding/error.json b/test/parser/samples/error-empty-classname-binding/error.json
index 64e05c112d2e..edc09ff8e120 100644
--- a/test/parser/samples/error-empty-classname-binding/error.json
+++ b/test/parser/samples/error-empty-classname-binding/error.json
@@ -1,5 +1,5 @@
 {
-	"code": "invalid-class-directive-value",
+	"code": "invalid-class-directive",
 	"message": "Class binding name cannot be empty",
 	"start": {
 		"line": 1,