[fix] allow invalidating variables from @const declared function (#7858)

src/compiler/compile/nodes/shared/Expression.ts

@@ -274,41 +274,7 @@ export default class Expression {
 					);
 
 					const declaration = b`const ${id} = ${node}`;
-
-					if (owner.type === 'ConstTag') {
-						let child_scope = scope;
-						walk(node, {
-							enter(node: Node, parent: any) {
-								if (map.has(node)) child_scope = map.get(node);
-								if (node.type === 'Identifier' && is_reference(node, parent)) {
-									if (child_scope.has(node.name)) return;
-									this.replace(block.renderer.reference(node, ctx));
-								}
-							},
-							leave(node: Node) {
-								if (map.has(node)) child_scope = child_scope.parent;
-							}
-						});
-					} else if (dependencies.size === 0 && contextual_dependencies.size === 0) {
-						// we can hoist this out of the component completely
-						component.fully_hoisted.push(declaration);
-
-						this.replace(id as any);
-
-						component.add_var(node, {
-							name: id.name,
-							internal: true,
-							hoistable: true,
-							referenced: true
-						});
-					} else if (contextual_dependencies.size === 0) {
-						// function can be hoisted inside the component init
-						component.partly_hoisted.push(declaration);
-
-						block.renderer.add_to_context(id.name);
-						this.replace(block.renderer.reference(id));
-					} else {
-						// we need a combo block/init recipe
+					const extract_functions = () => {
 						const deps = Array.from(contextual_dependencies);
 						const function_expression = node as FunctionExpression;
 
@@ -318,7 +284,7 @@ export default class Expression {
 							...function_expression.params
 						];
 
-						const context_args = deps.map(name => block.renderer.reference(name));
+						const context_args = deps.map(name => block.renderer.reference(name, ctx));
 
 						component.partly_hoisted.push(declaration);
 
@@ -334,6 +300,50 @@ export default class Expression {
 							: b`function ${id}() {
 								return ${callee}(${context_args});
 							}`;
+						return { deps, func_declaration };
+					};
+
+					if (owner.type === 'ConstTag') {
+						// we need a combo block/init recipe
+						if (contextual_dependencies.size === 0) {
+							let child_scope = scope;
+							walk(node, {
+								enter(node: Node, parent: any) {
+									if (map.has(node)) child_scope = map.get(node);
+									if (node.type === 'Identifier' && is_reference(node, parent)) {
+										if (child_scope.has(node.name)) return;
+										this.replace(block.renderer.reference(node, ctx));
+									}
+								},
+								leave(node: Node) {
+									if (map.has(node)) child_scope = child_scope.parent;
+								}
+							});
+						} else {
+							const { func_declaration } = extract_functions();
+							this.replace(func_declaration[0]);
+						}
+					} else if (dependencies.size === 0 && contextual_dependencies.size === 0) {
+						// we can hoist this out of the component completely
+						component.fully_hoisted.push(declaration);
+
+						this.replace(id as any);
+
+						component.add_var(node, {
+							name: id.name,
+							internal: true,
+							hoistable: true,
+							referenced: true
+						});
+					} else if (contextual_dependencies.size === 0) {
+						// function can be hoisted inside the component init
+						component.partly_hoisted.push(declaration);
+
+						block.renderer.add_to_context(id.name);
+						this.replace(block.renderer.reference(id));
+					} else {
+						// we need a combo block/init recipe
+						const { deps, func_declaration } = extract_functions();
 
 						if (owner.type === 'Attribute' && owner.parent.name === 'slot') {
 							const dep_scopes = new Set<INode>(deps.map(name => template_scope.get_owner(name)));

test/runtime/samples/const-tag-invalidate/_config.js

@@ -0,0 +1,34 @@
+export default {
+	html: `
+		<div>[Y] A <button>Toggle</button></div>
+		<div>[N] B <button>Toggle</button></div>
+		<div>[N] C <button>Toggle</button></div>
+	`,
+	async test({ component, target, assert, window }) {
+		const [btn1, btn2, btn3] = target.querySelectorAll('button');
+		await btn1.dispatchEvent(new window.MouseEvent('click'));
+		await btn2.dispatchEvent(new window.MouseEvent('click'));
+
+		assert.htmlEqual(target.innerHTML, `
+			<div>[N] A <button>Toggle</button></div>
+			<div>[Y] B <button>Toggle</button></div>
+			<div>[N] C <button>Toggle</button></div>
+		`);
+
+		await btn2.dispatchEvent(new window.MouseEvent('click'));
+
+		assert.htmlEqual(target.innerHTML, `
+			<div>[N] A <button>Toggle</button></div>
+			<div>[N] B <button>Toggle</button></div>
+			<div>[N] C <button>Toggle</button></div>
+		`);
+
+		await btn3.dispatchEvent(new window.MouseEvent('click'));
+
+		assert.htmlEqual(target.innerHTML, `
+			<div>[N] A <button>Toggle</button></div>
+			<div>[N] B <button>Toggle</button></div>
+			<div>[Y] C <button>Toggle</button></div>
+		`);
+	}
+};

test/runtime/samples/const-tag-invalidate/main.svelte

@@ -0,0 +1,16 @@
+<script>
+	let items = [
+		{ name: 'A', selected: true },
+		{ name: 'B', selected: false },
+		{ name: 'C', selected: false },
+	]
+</script>
+
+{#each items as item}
+	{@const toggle = () => item.selected = !item.selected}
+	<div>
+		{item.selected ? '[Y]' : '[N]'}
+		{item.name}
+		<button on:click={toggle}>Toggle</button>
+	</div>
+{/each}