From 033061842d463c1db9a0ebed3b27a2ab5b7fddb7 Mon Sep 17 00:00:00 2001
From: Torsten Dittmann <torsten.dittmann@googlemail.com>
Date: Tue, 12 Nov 2024 18:13:05 +0100
Subject: [PATCH] fix: named slots with reserved keywords during migration
 (#14278)

Fixes named slots with a reserved keyword not working anymore after migration. Re-uses the @migration-task logic for invalid identifiers.

Fixes #14277
---
 .changeset/mean-worms-fetch.md                           | 5 +++++
 packages/svelte/src/compiler/migrate/index.js            | 4 ++--
 .../migrate/samples/slot-non-identifier/input.svelte     | 8 +++++++-
 .../migrate/samples/slot-non-identifier/output.svelte    | 9 ++++++++-
 4 files changed, 22 insertions(+), 4 deletions(-)
 create mode 100644 .changeset/mean-worms-fetch.md

diff --git a/.changeset/mean-worms-fetch.md b/.changeset/mean-worms-fetch.md
new file mode 100644
index 0000000000..d573a631de
--- /dev/null
+++ b/.changeset/mean-worms-fetch.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: bail on named slots with that have reserved keywords during migration
diff --git a/packages/svelte/src/compiler/migrate/index.js b/packages/svelte/src/compiler/migrate/index.js
index 4942dd7db2..9db09158a1 100644
--- a/packages/svelte/src/compiler/migrate/index.js
+++ b/packages/svelte/src/compiler/migrate/index.js
@@ -17,7 +17,7 @@ import {
 } from '../utils/ast.js';
 import { migrate_svelte_ignore } from '../utils/extract_svelte_ignore.js';
 import { validate_component_options } from '../validate-options.js';
-import { is_svg, is_void } from '../../utils.js';
+import { is_reserved, is_svg, is_void } from '../../utils.js';
 import { regex_is_valid_identifier } from '../phases/patterns.js';
 
 const regex_style_tags = /(<style[^>]+>)([\S\s]*?)(<\/style>)/g;
@@ -1440,7 +1440,7 @@ function migrate_slot_usage(node, path, state) {
 			if (snippet_name === 'default') {
 				snippet_name = 'children';
 			}
-			if (!regex_is_valid_identifier.test(snippet_name)) {
+			if (!regex_is_valid_identifier.test(snippet_name) || is_reserved(snippet_name)) {
 				has_migration_task = true;
 				state.str.appendLeft(
 					node.start,
diff --git a/packages/svelte/tests/migrate/samples/slot-non-identifier/input.svelte b/packages/svelte/tests/migrate/samples/slot-non-identifier/input.svelte
index a62eff1b74..7cf7dd86bb 100644
--- a/packages/svelte/tests/migrate/samples/slot-non-identifier/input.svelte
+++ b/packages/svelte/tests/migrate/samples/slot-non-identifier/input.svelte
@@ -14,6 +14,12 @@
 	</div>
 </Comp>
 
+<Comp>
+	<div slot="new">
+		reserved keyword
+	</div>
+</Comp>
+
 <Comp>
 	<div slot="stuff">
 		cool
@@ -63,4 +69,4 @@
 	<svelte:fragment let:should_stay slot="cool stuff">
 		cool
 	</svelte:fragment>
-</Comp>
\ No newline at end of file
+</Comp>
diff --git a/packages/svelte/tests/migrate/samples/slot-non-identifier/output.svelte b/packages/svelte/tests/migrate/samples/slot-non-identifier/output.svelte
index 85913264b4..fb262e8c25 100644
--- a/packages/svelte/tests/migrate/samples/slot-non-identifier/output.svelte
+++ b/packages/svelte/tests/migrate/samples/slot-non-identifier/output.svelte
@@ -16,6 +16,13 @@
 	</div>
 </Comp>
 
+<Comp>
+	<!-- @migration-task: migrate this slot by hand, `new` is an invalid identifier -->
+	<div slot="new">
+		reserved keyword
+	</div>
+</Comp>
+
 <Comp>
 	{#snippet stuff()}
 		<div >
@@ -75,4 +82,4 @@
 	<svelte:fragment let:should_stay slot="cool stuff">
 		cool
 	</svelte:fragment>
-</Comp>
\ No newline at end of file
+</Comp>