feat: add Svelte 5 support to no-not-function-handler (#1013)

Author: baseballyama

.changeset/brown-dots-change.md

@@ -0,0 +1,5 @@
+---
+'eslint-plugin-svelte': minor
+---
+
+feat: add Svelte 5 support to `no-not-function-handler`

docs/rules/no-not-function-handler.md

@@ -29,16 +29,16 @@ If you use a non-function value for the event handler, it event handler will not
 </script>
 
 <!-- ✓ GOOD -->
-<button on:click={foo} />
+<button onclick={foo} />
 <button
-  on:click={() => {
+  onclick={() => {
     /*  */
   }}
 />
 
 <!-- ✗ BAD -->
-<button on:click={{ foo }} />
-<button on:click={bar} />
+<button onclick={{ foo }} />
+<button onclick={bar} />
 ```
 
 ## :wrench: Options

packages/eslint-plugin-svelte/src/rules/no-not-function-handler.ts

@@ -2,6 +2,7 @@ import type { AST } from 'svelte-eslint-parser';
 import type { TSESTree } from '@typescript-eslint/types';
 import { createRule } from '../utils/index.js';
 import { findVariable } from '../utils/ast-utils.js';
+import { EVENT_NAMES } from '../utils/events.js';
 
 const PHRASES = {
 	ObjectExpression: 'object',
@@ -95,6 +96,18 @@ export default createRule('no-not-function-handler', {
 					return;
 				}
 				verify(node.expression);
+			},
+			SvelteAttribute(node) {
+				if (node.key.type === 'SvelteName' && EVENT_NAMES.includes(node.key.name)) {
+					const { value } = node;
+					if (Array.isArray(value)) {
+						for (const v of value) {
+							if (v.type === 'SvelteMustacheTag') {
+								verify(v.expression);
+							}
+						}
+					}
+				}
 			}
 		};
 	}