fix: ensure inline object literals are correctly serialised (#14325)

* fix: ensure inline object literals are correctly serialised

* Apply suggestions from code review

* address feedback

* address feedback

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>

.changeset/wicked-readers-knock.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: treat property accesses of literals as pure

packages/svelte/src/compiler/phases/2-analyze/visitors/shared/utils.js

@@ -1,4 +1,4 @@
-/** @import { AssignmentExpression, Expression, Identifier, Pattern, PrivateIdentifier, Super, UpdateExpression, VariableDeclarator } from 'estree' */
+/** @import { AssignmentExpression, Expression, Literal, Pattern, PrivateIdentifier, Super, UpdateExpression, VariableDeclarator } from 'estree' */
 /** @import { AST, Binding } from '#compiler' */
 /** @import { AnalysisState, Context } from '../../types' */
 /** @import { Scope } from '../../../scope' */
@@ -176,21 +176,42 @@ export function is_safe_identifier(expression, scope) {
 }
 
 /**
- * @param {Expression | Super} node
+ * @param {Expression | Literal | Super} node
  * @param {Context} context
  * @returns {boolean}
  */
 export function is_pure(node, context) {
+	if (node.type === 'Literal') {
+		return true;
+	}
+	if (node.type === 'CallExpression') {
+		if (!is_pure(node.callee, context)) {
+			return false;
+		}
+		for (let arg of node.arguments) {
+			if (!is_pure(arg.type === 'SpreadElement' ? arg.argument : arg, context)) {
+				return false;
+			}
+		}
+		return true;
+	}
 	if (node.type !== 'Identifier' && node.type !== 'MemberExpression') {
 		return false;
 	}
 
-	const left = object(node);
+	/** @type {Expression | Super | null} */
+	let left = node;
+	while (left.type === 'MemberExpression') {
+		left = left.object;
+	}
+
 	if (!left) return false;
 
 	if (left.type === 'Identifier') {
 		const binding = context.state.scope.get(left.name);
 		if (binding === null) return true; // globals are assumed to be safe
+	} else if (is_pure(left, context)) {
+		return true;
 	}
 
 	// TODO add more cases (safe Svelte imports, etc)

packages/svelte/tests/runtime-legacy/samples/inline-expressions-2/_config.js

@@ -0,0 +1,11 @@
+import { test } from '../../test';
+
+export default test({
+	html: `
+		<p>Without text expression: 7.36</p>
+		<p>With text expression: 7.36</p>
+		<p>With text expression and function call: 7.36</p>
+		<p>With text expression and property access: 4</p>
+		<h1>Hello name!</h1>
+		<p>4</p>`
+});

packages/svelte/tests/runtime-legacy/samples/inline-expressions-2/main.svelte

@@ -0,0 +1,6 @@
+<p>Without text expression: 7.36</p>
+<p>With text expression: {7.36}</p>
+<p>With text expression and function call: {(7.36).toLocaleString()}</p>
+<p>With text expression and property access: {"test".length}</p>
+<h1>Hello {('name').toUpperCase().toLowerCase()}!</h1>
+<p>{"test".length}</p>