Merge branch 'master' into pr/5936

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Svelte changelog
 
+## Unreleased
+
+* Throw a parser error for `class:` directives with an empty class name ([#5858](https://github.com/sveltejs/svelte/issues/5858))
+* Fix type inference for derived stores ([#5935](https://github.com/sveltejs/svelte/pull/5935))
+
 ## 3.32.0
 
 * Allow multiple instances of the same action on an element ([#5516](https://github.com/sveltejs/svelte/issues/5516))

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',
+				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({

src/runtime/store/index.ts

@@ -125,10 +125,12 @@ type StoresValues<T> = T extends Readable<infer U> ? U :
  *
  * @param stores - input stores
  * @param fn - function callback that aggregates the values
+ * @param initial_value - when used asynchronously
  */
 export function derived<S extends Stores, T>(
 	stores: S,
-	fn: (values: StoresValues<S>) => T
+	fn: (values: StoresValues<S>, set: (value: T) => void) => Unsubscriber | void,
+	initial_value?: T
 ): Readable<T>;
 
 /**
@@ -137,12 +139,10 @@ export function derived<S extends Stores, T>(
  *
  * @param stores - input stores
  * @param fn - function callback that aggregates the values
- * @param initial_value - when used asynchronously
  */
 export function derived<S extends Stores, T>(
 	stores: S,
-	fn: (values: StoresValues<S>, set: (value: T) => void) => Unsubscriber | void,
+	fn: (values: StoresValues<S>) => T
-	initial_value?: T
 ): Readable<T>;
 
 export function derived<T>(stores: Stores, fn: Function, initial_value?: T): Readable<T> {

test/parser/samples/error-empty-classname-binding/error.json

@@ -0,0 +1,10 @@
+{
+	"code": "invalid-class-directive",
+	"message": "Class binding name cannot be empty",
+	"start": {
+		"line": 1,
+		"column": 10,
+		"character": 10
+	},
+	"pos": 10
+}

test/parser/samples/error-empty-classname-binding/input.svelte

@@ -0,0 +1 @@
+<h1 class:={true}>Hello</h1>