fix: correctly set filename on HMR wrappers (#12543)

* fix: correctly set filename on HMR wrappers

* changeset

Author: Rich-Harris

.changeset/tender-suns-love.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: correctly set filename on HMR wrappers

packages/svelte/src/compiler/phases/3-transform/client/transform-client.js

@@ -439,10 +439,16 @@ export function client_component(source, analysis, options) {
 
 		const hmr = b.block([
 			b.const(b.id('s'), b.call('$.source', b.id(analysis.name))),
-			b.const(b.id('filename'), b.member(b.id(analysis.name), b.id('filename'))),
+			b.const(b.id('$$filename'), b.member(b.id(analysis.name), b.id('$.FILENAME'), true)),
 			b.const(b.id('$$original'), b.id(analysis.name)),
 			b.stmt(b.assignment('=', b.id(analysis.name), b.call('$.hmr', b.id('s')))),
-			b.stmt(b.assignment('=', b.member(b.id(analysis.name), b.id('filename')), b.id('filename'))),
+			b.stmt(
+				b.assignment(
+					'=',
+					b.member(b.id(analysis.name), b.id('$.FILENAME'), true),
+					b.id('$$filename')
+				)
+			),
 			// Assign the original component to the wrapper so we can use it on hot reload patching,
 			// else we would call the HMR function two times
 			b.stmt(

packages/svelte/tests/snapshot/samples/hmr/_expected/client/index.svelte.js

@@ -11,11 +11,11 @@ function Hmr($$anchor) {
 
 if (import.meta.hot) {
 	const s = $.source(Hmr);
-	const filename = Hmr.filename;
+	const $$filename = Hmr[$.FILENAME];
 	const $$original = Hmr;
 
 	Hmr = $.hmr(s);
-	Hmr.filename = filename;
+	Hmr[$.FILENAME] = $$filename;
 	Hmr[$.ORIGINAL] = $$original;
 
 	import.meta.hot.accept((module) => {