feat: move dev-time component properties to private symbols

Author: Rich-Harris

.changeset/fluffy-colts-grin.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+feat: move dev-time component properties to private symbols'

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

@@ -418,7 +418,7 @@ export function client_component(source, analysis, options) {
 
 	if (options.hmr) {
 		const accept_fn_body = [
-			b.stmt(b.call('$.set', b.id('s'), b.member(b.id('module.default'), b.id('original'))))
+			b.stmt(b.call('$.set', b.id('s'), b.member(b.id('module.default'), b.id('$.ORIGINAL'), true)))
 		];
 
 		if (analysis.css.hash) {
@@ -446,7 +446,11 @@ export function client_component(source, analysis, options) {
 			// 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(
-				b.assignment('=', b.member(b.id(analysis.name), b.id('original')), b.id('$$original'))
+				b.assignment(
+					'=',
+					b.member(b.id(analysis.name), b.id('$.ORIGINAL'), true),
+					b.id('$$original')
+				)
 			),
 			b.stmt(b.call('import.meta.hot.accept', b.arrow([b.id('module')], b.block(accept_fn_body))))
 		]);

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

@@ -16,10 +16,10 @@ if (import.meta.hot) {
 
 	Hmr = $.hmr(s);
 	Hmr.filename = filename;
-	Hmr.original = $$original;
+	Hmr[$.ORIGINAL] = $$original;
 
 	import.meta.hot.accept((module) => {
-		$.set(s, module.default.original);
+		$.set(s, module.default[$.ORIGINAL]);
 	});
 }