Revert "fix(compiler): support complex selectors in :nth-child()"

mattrbeck · thePunderWoman · commit a44658ba3ef0 · 2025-11-13T15:44:25.000-08:00
This reverts commit 9419ea3.
diff --git a/packages/compiler/src/shadow_css.ts b/packages/compiler/src/shadow_css.ts
@@ -1029,9 +1029,9 @@ class SafeSelector {
 
     // Replaces the expression in `:nth-child(2n + 1)` with a placeholder.
     // WS and "+" would otherwise be interpreted as selector separators.
-    this._content = selector.replace(nthRegex, (_, pseudo, exp) => {
+    this._content = selector.replace(/(:nth-[-\w]+)(\([^)]+\))/g, (_, pseudo, exp) => {
       const replaceBy = `__ph-${this.index}__`;
-      this.placeholders.push(`(${exp})`);
+      this.placeholders.push(exp);
       this.index++;
       return pseudo + replaceBy;
     });
@@ -1076,7 +1076,6 @@ const _level1Parens = String.raw`(?:\(${_noParens}\)|${_noParens})+?`;
 // Matches content with at most TWO levels of nesting, e.g., "a(b(c)d)e"
 const _level2Parens = String.raw`(?:\(${_level1Parens}\)|${_noParens})+?`;
 const _parenSuffix = String.raw`(?:\((${_level2Parens})\))`;
-const nthRegex = new RegExp(String.raw`(:nth-[-\w]+)` + _parenSuffix, 'g');
 const _cssColonHostRe = new RegExp(_polyfillHost + _parenSuffix + '?([^,{]*)', 'gim');
 // note: :host-context patterns are terminated with `{`, as opposed to :host which
 // is both `{` and `,` because :host-context handles top-level commas differently.
diff --git a/packages/compiler/test/shadow_css/host_and_host_context_spec.ts b/packages/compiler/test/shadow_css/host_and_host_context_spec.ts
@@ -71,9 +71,6 @@ describe('ShadowCss, :host and :host-context', () => {
       expect(shim(':host:nth-child(8n+1) {}', 'contenta', 'a-host')).toEqualCss(
         '[a-host]:nth-child(8n+1) {}',
       );
-      expect(shim(':host(:nth-child(3n of :not(p, a))) {}', 'contenta', 'a-host')).toEqualCss(
-        '[a-host]:nth-child(3n of :not(p, a)) {}',
-      );
       expect(shim(':host:nth-of-type(8n+1) {}', 'contenta', 'a-host')).toEqualCss(
         '[a-host]:nth-of-type(8n+1) {}',
       );
diff --git a/packages/compiler/test/shadow_css/shadow_css_spec.ts b/packages/compiler/test/shadow_css/shadow_css_spec.ts
@@ -214,20 +214,6 @@ describe('ShadowCss', () => {
       'table[contenta] [contenta]:where(td, th):hover { color:lime;}',
     );
 
-    // :nth
-    expect(shim(':nth-child(3n of :not(p, a), :is(.foo)) {}', 'contenta', 'hosta')).toEqualCss(
-      '[contenta]:nth-child(3n of :not(p, a), :is(.foo)) {}',
-    );
-    expect(shim('li:nth-last-child(-n + 3) {}', 'contenta', 'a-host')).toEqualCss(
-      'li[contenta]:nth-last-child(-n + 3) {}',
-    );
-    expect(shim('dd:nth-last-of-type(3n) {}', 'contenta', 'a-host')).toEqualCss(
-      'dd[contenta]:nth-last-of-type(3n) {}',
-    );
-    expect(shim('dd:nth-of-type(even) {}', 'contenta', 'a-host')).toEqualCss(
-      'dd[contenta]:nth-of-type(even) {}',
-    );
-
     // complex selectors
     expect(shim(':host:is([foo],[foo-2])>div.example-2 {}', 'contenta', 'a-host')).toEqualCss(
       '[a-host]:is([foo],[foo-2]) > div.example-2[contenta] {}',
