fix: don't wrap pseudo classes inside :global(...) with another :global(...)

.changeset/hot-ladybugs-clap.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: don't wrap pseudo classes inside `:global(...)` with another `:global(...)` during migration

packages/svelte/src/compiler/migrate/index.js

@@ -40,9 +40,10 @@ class MigrationError extends Error {
  */
 function migrate_css(state) {
 	if (!state.analysis.css.ast?.start) return;
-	let code = state.str
+	const css_contents = state.str
 		.snip(state.analysis.css.ast.start, /** @type {number} */ (state.analysis.css.ast?.end))
 		.toString();
+	let code = css_contents;
 	let starting = 0;
 
 	// since we already blank css we can't work directly on `state.str` so we will create a copy that we can update
@@ -56,23 +57,28 @@ function migrate_css(state) {
 		) {
 			let start = code.indexOf('(') + 1;
 			let is_global = false;
+
 			const global_str = ':global';
 			const next_global = code.indexOf(global_str);
 			const str_between = code.substring(start, next_global);
 			if (!str_between.trim()) {
 				is_global = true;
 				start += global_str.length;
+			} else {
+				const prev_global = css_contents.lastIndexOf(global_str, starting);
+				if (prev_global > -1) {
+					const end =
+						find_closing_parenthesis(css_contents.indexOf('(', prev_global) + 1, css_contents) -
+						starting;
+					if (end > start) {
+						starting += end;
+						code = code.substring(end);
+						continue;
+					}
+				}
 			}
-			let parenthesis = 1;
-			let end = start;
-			let char = code[end];
-			// find the closing parenthesis
-			while (parenthesis !== 0 && char) {
-				if (char === '(') parenthesis++;
-				if (char === ')') parenthesis--;
-				end++;
-				char = code[end];
-			}
+
+			const end = find_closing_parenthesis(start, code);
 			if (start && end) {
 				if (!is_global && !code.startsWith(':not')) {
 					str.prependLeft(starting + start, ':global(');
@@ -89,6 +95,24 @@ function migrate_css(state) {
 	state.str.update(state.analysis.css.ast?.start, state.analysis.css.ast?.end, str.toString());
 }
 
+/**
+ * @param {number} start
+ * @param {string} code
+ */
+function find_closing_parenthesis(start, code) {
+	let parenthesis = 1;
+	let end = start;
+	let char = code[end];
+	// find the closing parenthesis
+	while (parenthesis !== 0 && char) {
+		if (char === '(') parenthesis++;
+		if (char === ')') parenthesis--;
+		end++;
+		char = code[end];
+	}
+	return end;
+}
+
 /**
  * Does a best-effort migration of Svelte code towards using runes, event attributes and render tags.
  * May throw an error if the code is too complex to migrate automatically.

packages/svelte/tests/migrate/samples/is-not-where-has/input.svelte

@@ -47,6 +47,8 @@ what if i'm talking about `:has()` in my blog?
 	div :where(:global(.class:is(span:has(* > *)))){}
 	div :is(:global(.class:is(span:is(:hover)), .x)){}
 
+	:global(button:has(.is-active)){}
+
 	div{
 		p:has(&){
 

packages/svelte/tests/migrate/samples/is-not-where-has/output.svelte

@@ -47,6 +47,8 @@ what if i'm talking about `:has()` in my blog?
 	div :where(:global(.class:is(span:has(* > *)))){}
 	div :is(:global(.class:is(span:is(:hover)), .x)){}
 
+	:global(button:has(.is-active)){}
+
 	div{
 		p:has(:global(&)){