From 1bc89b5eb6e745f05fd534b45dc62b2d269f05f2 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Tue, 21 Nov 2023 03:49:36 -0500
Subject: [PATCH] fix: deconflict generated names against globals (#9570)

fixes #9559
---
 .changeset/green-hounds-play.md                   |  5 +++++
 packages/svelte/src/compiler/phases/scope.js      |  4 ++++
 .../samples/globals-deconflicted/_config.js       | 15 +++++++++++++++
 .../samples/globals-deconflicted/main.svelte      |  1 +
 4 files changed, 25 insertions(+)
 create mode 100644 .changeset/green-hounds-play.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/globals-deconflicted/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/globals-deconflicted/main.svelte

diff --git a/.changeset/green-hounds-play.md b/.changeset/green-hounds-play.md
new file mode 100644
index 0000000000..6a2922d0d5
--- /dev/null
+++ b/.changeset/green-hounds-play.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: deconflict generated names against globals
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index 5c18e78f7c..22e5d3eaec 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -184,6 +184,10 @@ export class Scope {
 			declaration.references.push({ node, path });
 		} else if (this.#parent) {
 			this.#parent.reference(node, path);
+		} else {
+			// no declaration was found, and this is the top level scope,
+			// which means this is a global
+			this.root.conflicts.add(node.name);
 		}
 	}
 }
diff --git a/packages/svelte/tests/runtime-runes/samples/globals-deconflicted/_config.js b/packages/svelte/tests/runtime-runes/samples/globals-deconflicted/_config.js
new file mode 100644
index 0000000000..3d1ab275b9
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/globals-deconflicted/_config.js
@@ -0,0 +1,15 @@
+import { test } from '../../test';
+
+export default test({
+	html: `<p>hello</p>`,
+
+	before_test: () => {
+		// @ts-expect-error
+		globalThis.frag = 'hello';
+	},
+
+	after_test: () => {
+		// @ts-expect-error
+		delete globalThis.frag;
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/globals-deconflicted/main.svelte b/packages/svelte/tests/runtime-runes/samples/globals-deconflicted/main.svelte
new file mode 100644
index 0000000000..25a651859c
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/globals-deconflicted/main.svelte
@@ -0,0 +1 @@
+<p>{frag}</p>