Add test case for #2115 and possible fix

src/compile/nodes/Attribute.ts

@@ -86,14 +86,14 @@ export default class Attribute extends Node {
 		return Array.from(dependencies);
 	}
 
-	getValue() {
+	getValue(block) {
 		if (this.isTrue) return true;
 		if (this.chunks.length === 0) return `""`;
 
 		if (this.chunks.length === 1) {
 			return this.chunks[0].type === 'Text'
 				? stringify(this.chunks[0].data)
-				: this.chunks[0].render();
+				: this.chunks[0].render(block);
 		}
 
 		return (this.chunks[0].type === 'Text' ? '' : `"" + `) +

src/compile/render-dom/wrappers/Element/Attribute.ts

@@ -179,7 +179,7 @@ export default class AttributeWrapper {
 				);
 			}
 		} else {
-			const value = this.node.getValue();
+			const value = this.node.getValue(block);
 
 			const statement = (
 				isLegacyInputType

src/compile/render-dom/wrappers/Element/index.ts

@@ -579,7 +579,7 @@ export default class ElementWrapper extends Wrapper {
 
 					updates.push(condition ? `${condition} && ${snippet}` : snippet);
 				} else {
-					const snippet = `{ ${quoteNameIfNecessary(attr.name)}: ${attr.getValue()} }`;
+					const snippet = `{ ${quoteNameIfNecessary(attr.name)}: ${attr.getValue(block)} }`;
 					initialProps.push(snippet);
 
 					updates.push(condition ? `${condition} && ${snippet}` : snippet);

src/compile/render-dom/wrappers/InlineComponent/index.ts

@@ -118,7 +118,7 @@ export default class InlineComponentWrapper extends Wrapper {
 		const attributeObject = usesSpread
 			? stringifyProps(slot_props)
 			: stringifyProps(
-				this.node.attributes.map(attr => `${quoteNameIfNecessary(attr.name)}: ${attr.getValue()}`).concat(slot_props)
+				this.node.attributes.map(attr => `${quoteNameIfNecessary(attr.name)}: ${attr.getValue(block)}`).concat(slot_props)
 			);
 
 		if (this.node.attributes.length || this.node.bindings.length || slot_props.length) {
@@ -190,7 +190,7 @@ export default class InlineComponentWrapper extends Wrapper {
 
 						changes.push(condition ? `${condition} && ${value}` : value);
 					} else {
-						const obj = `{ ${quoteNameIfNecessary(name)}: ${attr.getValue()} }`;
+						const obj = `{ ${quoteNameIfNecessary(name)}: ${attr.getValue(block)} }`;
 						initialProps.push(obj);
 
 						changes.push(condition ? `${condition} && ${obj}` : obj);
@@ -224,7 +224,7 @@ export default class InlineComponentWrapper extends Wrapper {
 							updates.push(deindent`
 								if (${[...attribute.dependencies]
 									.map(dependency => `changed.${dependency}`)
-									.join(' || ')}) ${name_changes}${quotePropIfNecessary(attribute.name)} = ${attribute.getValue()};
+									.join(' || ')}) ${name_changes}${quotePropIfNecessary(attribute.name)} = ${attribute.getValue(block)};
 							`);
 						}
 					});

test/js/samples/attribute-expression/expected.js

@@ -0,0 +1,97 @@
+/* generated by Svelte vX.Y.Z */
+import { SvelteComponent as SvelteComponent_1, createComment, createElement, destroyEach, detachNode, init, insert, noop, safe_not_equal, setAttribute } from "svelte/internal";
+
+function get_each_context(ctx, list, i) {
+	const child_ctx = Object.create(ctx);
+	child_ctx.item = list[i];
+	return child_ctx;
+}
+
+// (1:0) {#each Array(1) as item}
+function create_each_block(ctx) {
+	var boo;
+
+	function func() {
+		return ctx.func(ctx);
+	}
+
+	return {
+		c() {
+			boo = createElement("boo");
+			setAttribute(boo, "cb", func);
+		},
+
+		m(target, anchor) {
+			insert(target, boo, anchor);
+		},
+
+		p(changed, new_ctx) {
+			ctx = new_ctx;
+		},
+
+		d(detach) {
+			if (detach) {
+				detachNode(boo);
+			}
+		}
+	};
+}
+
+function create_fragment(ctx) {
+	var each_anchor;
+
+	var each_value = Array(1);
+
+	var each_blocks = [];
+
+	for (var i = 0; i < each_value.length; i += 1) {
+		each_blocks[i] = create_each_block(get_each_context(ctx, each_value, i));
+	}
+
+	return {
+		c() {
+			for (var i = 0; i < each_blocks.length; i += 1) {
+				each_blocks[i].c();
+			}
+
+			each_anchor = createComment();
+		},
+
+		m(target, anchor) {
+			for (var i = 0; i < each_blocks.length; i += 1) {
+				each_blocks[i].m(target, anchor);
+			}
+
+			insert(target, each_anchor, anchor);
+		},
+
+		p: noop,
+		i: noop,
+		o: noop,
+
+		d(detach) {
+			destroyEach(each_blocks, detach);
+
+			if (detach) {
+				detachNode(each_anchor);
+			}
+		}
+	};
+}
+
+function instance($$self) {
+	function func({ item }) {
+		return item;
+	}
+
+	return { func };
+}
+
+class SvelteComponent extends SvelteComponent_1 {
+	constructor(options) {
+		super();
+		init(this, options, instance, create_fragment, safe_not_equal);
+	}
+}
+
+export default SvelteComponent;

test/js/samples/attribute-expression/input.svelte

@@ -0,0 +1,3 @@
+{#each Array(1) as item}
+	<boo cb="{() => item}" />
+{/each}