fix: handle patterns in destructured literals (#8871)

fixes #8863

---------

Co-authored-by: Ben McCann <[email protected]>

.changeset/lucky-knives-crash.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: handle destructured primitive literals

packages/playground/README.md

@@ -4,4 +4,6 @@ To prevent any changes you make in this directory from being accidentally commit
 
 If you would actually like to make some changes to the files here for everyone then run `git update-index --no-skip-worktree ./**/*.*` before committing.
 
-If you're using VS Code, you can use the "Playground: Full" launch configuration to run the playground and attach the debugger to both the compiler and the browser.
+If you're using VS Code, you can use the "Playground: Full" launch configuration to run the playground and attach the debugger to both the compiler and the browser. This will SSR the component and then also hydrate it on the client side using rollup to bundle any other imports.
+
+You can also just compile the `App.svelte` file by running `node compile.js` if you'd like to check some compiler behaviour in isolation.

packages/playground/compile.js

@@ -0,0 +1,6 @@
+import { readFileSync } from 'node:fs';
+import { compile } from '../svelte/src/compiler/index.js';
+
+const code = readFileSync('src/App.svelte', 'utf8');
+
+console.log(compile(code));

packages/svelte/src/compiler/compile/Component.js

@@ -1292,26 +1292,22 @@ export default class Component {
 					// everything except const values can be changed by e.g. svelte devtools
 					// which means we can't hoist it
 					if (node.kind !== 'const' && this.compile_options.dev) return false;
-					const { name } = /** @type {import('estree').Identifier} */ (d.id);
-					const v = this.var_lookup.get(name);
-					if (v.reassigned) return false;
-					if (v.export_name) return false;
-					if (this.var_lookup.get(name).reassigned) return false;
-					if (
-						this.vars.find(
-							/** @param {any} variable */ (variable) => variable.name === name && variable.module
-						)
-					) {
-						return false;
+					for (const name of extract_names(d.id)) {
+						const v = this.var_lookup.get(name);
+						if (v.reassigned) return false;
+						if (v.export_name) return false;
+
+						if (this.vars.find((variable) => variable.name === name && variable.module)) {
+							return false;
+						}
 					}
 					return true;
 				});
 				if (all_hoistable) {
 					node.declarations.forEach((d) => {
-						const variable = this.var_lookup.get(
-							/** @type {import('estree').Identifier} */ (d.id).name
-						);
-						variable.hoistable = true;
+						for (const name of extract_names(d.id)) {
+							this.var_lookup.get(name).hoistable = true;
+						}
 					});
 					hoistable_nodes.add(node);
 					body.splice(i--, 1);

packages/svelte/test/js/samples/hoisted-const/expected.js

@@ -15,7 +15,7 @@ function create_fragment(ctx) {
 	return {
 		c() {
 			b = element("b");
-			b.textContent = `${get_answer()}`;
+			b.textContent = `${get_answer()} ${length}`;
 		},
 		m(target, anchor) {
 			insert(target, b, anchor);
@@ -32,6 +32,7 @@ function create_fragment(ctx) {
 }
 
 const ANSWER = 42;
+const { length } = 'abc';
 
 function get_answer() {
 	return ANSWER;

packages/svelte/test/js/samples/hoisted-const/input.svelte

@@ -1,6 +1,7 @@
 <script>
 	const ANSWER = 42;
+	const { length } = 'abc';
 	function get_answer() { return ANSWER; }
 </script>
 
-<b>{get_answer()}</b>
+<b>{get_answer()} {length}</b>