From 9a5088b705d3084ecbdee4bcc858610380c3ac53 Mon Sep 17 00:00:00 2001
From: Simon Holthausen <simon.holthausen@vercel.com>
Date: Fri, 26 Apr 2024 15:49:23 +0200
Subject: [PATCH] props alias

---
 packages/svelte/src/compiler/migrate/index.js | 24 +++++++++++++++++++
 .../samples/props-export-alias/input.svelte   |  6 +++++
 .../samples/props-export-alias/output.svelte  |  8 +++++++
 3 files changed, 38 insertions(+)
 create mode 100644 packages/svelte/tests/migrate/samples/props-export-alias/input.svelte
 create mode 100644 packages/svelte/tests/migrate/samples/props-export-alias/output.svelte

diff --git a/packages/svelte/src/compiler/migrate/index.js b/packages/svelte/src/compiler/migrate/index.js
index 5de2bebc65..5c94738f7f 100644
--- a/packages/svelte/src/compiler/migrate/index.js
+++ b/packages/svelte/src/compiler/migrate/index.js
@@ -163,6 +163,27 @@ const instance_script = {
 	Identifier(node, { state }) {
 		handle_identifier(node, state);
 	},
+	ExportNamedDeclaration(node, { state, next }) {
+		if (node.declaration) {
+			next();
+			return;
+		}
+
+		let count_removed = 0;
+		for (const specifier of node.specifiers) {
+			const binding = state.scope.get(specifier.local.name);
+			if (binding?.kind === 'bindable_prop') {
+				state.str.remove(
+					/** @type {number} */ (specifier.start),
+					/** @type {number} */ (specifier.end)
+				);
+				count_removed++;
+			}
+		}
+		if (count_removed === node.specifiers.length) {
+			state.str.remove(/** @type {number} */ (node.start), /** @type {number} */ (node.end));
+		}
+	},
 	VariableDeclaration(node, { state, path }) {
 		if (state.scope !== state.analysis.instance.scope) {
 			return;
@@ -192,6 +213,9 @@ const instance_script = {
 
 				if (declarator.id.type !== 'Identifier') {
 					// TODO
+					throw new Error(
+						'Encountered an export declaration pattern that is not supported for automigration.'
+					);
 					// Turn export let into props. It's really really weird because export let { x: foo, z: [bar]} = ..
 					// means that foo and bar are the props (i.e. the leafs are the prop names), not x and z.
 					// const tmp = state.scope.generate('tmp');
diff --git a/packages/svelte/tests/migrate/samples/props-export-alias/input.svelte b/packages/svelte/tests/migrate/samples/props-export-alias/input.svelte
new file mode 100644
index 0000000000..1cb57ef5fd
--- /dev/null
+++ b/packages/svelte/tests/migrate/samples/props-export-alias/input.svelte
@@ -0,0 +1,6 @@
+<script lang="ts">
+	let klass = '';
+	export { klass as class }
+</script>
+
+{klass}
diff --git a/packages/svelte/tests/migrate/samples/props-export-alias/output.svelte b/packages/svelte/tests/migrate/samples/props-export-alias/output.svelte
new file mode 100644
index 0000000000..76d25afb08
--- /dev/null
+++ b/packages/svelte/tests/migrate/samples/props-export-alias/output.svelte
@@ -0,0 +1,8 @@
+<script lang="ts">
+	interface Props { class?: string }
+
+	let { class: klass = '' }: Props = $props();
+	
+</script>
+
+{klass}
\ No newline at end of file