packages/tailwindcss/src/selector-parser.ts (1)

300-324: ⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Skip quoted and escaped ) while scanning non-nesting function arguments.

This fallback scan stops at the first ) even when it appears inside a quoted string or after an escape. Valid selectors like :lang("en)") get split incorrectly and leave the trailing quote/paren to the outer parser.

Proposed fix

-          for (let j = i + 1; j < input.length; j++) {
-            peekChar = input.charCodeAt(j)
-            if (peekChar === OPEN_PAREN) {
-              nesting++
-              continue
-            }
-            if (peekChar === CLOSE_PAREN) {
-              if (nesting === 0) {
-                i = j
-                break
-              }
-              nesting--
-            }
-          }
+          for (let j = i + 1; j < input.length; j++) {
+            peekChar = input.charCodeAt(j)
+
+            if (peekChar === BACKSLASH) {
+              j += 1
+              continue
+            }
+
+            if (peekChar === SINGLE_QUOTE || peekChar === DOUBLE_QUOTE) {
+              let quote = peekChar
+              for (j = j + 1; j < input.length; j++) {
+                peekChar = input.charCodeAt(j)
+                if (peekChar === BACKSLASH) {
+                  j += 1
+                } else if (peekChar === quote) {
+                  break
+                }
+              }
+              continue
+            }
+
+            if (peekChar === OPEN_PAREN) {
+              nesting++
+              continue
+            }
+
+            if (peekChar === CLOSE_PAREN) {
+              if (nesting === 0) {
+                i = j
+                break
+              }
+              nesting--
+            }
+          }

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/tailwindcss/src/selector-parser.ts` around lines 300 - 324, The
fallback scanner that finds the closing `)` for non-nesting functions (the loop
starting at `for (let j = i + 1; j < input.length; j++)` in selector-parser.ts,
guarded by the `node.value !== ':not'`/`:where`/`:has`/`:is` checks) incorrectly
stops on `)` inside quoted strings or when escaped; modify that loop to skip
over quoted segments and escaped characters by tracking quote state and
backslashes: when encountering a quote (`'` or `"`) enter a quoted mode and
advance until the matching unescaped quote, and treat a backslash as escaping
the next character so a `\)` is ignored; only treat `(` and `)` as nesting
tokens or a closing delimiter when not inside a quote and not escaped, and then
set `i = j` when the real closing `)` is found.