Handle vendor-prefixed selector functions in custom variants

[OllieinCanada]

Fixes #20483.

What changed

• parse :-moz-any() and :-webkit-any() arguments as selector lists, matching their standard :is() counterpart
• allow nesting replacement to substitute & inside these legacy selector functions
• cover both vendor-prefixed parser forms and the reported @custom-variant firefox (:-moz-any(&)) compilation path

Why

The selector parser treated unknown function arguments as opaque values. After the nesting changes in #20124, that meant the & inside :-moz-any(&) could not be replaced and the custom variant was emitted as a descendant selector instead.

These two vendor-prefixed functions are legacy aliases for selector-list matching, so handling them alongside :is() keeps the change narrowly scoped.

Validation

• reproduced the regression on current main: .firefox\\:underline :-moz-any(:scope)
• confirmed the new assertions fail when only the parser change is reverted
• vitest run packages/tailwindcss/src/index.test.ts packages/tailwindcss/src/selector-parser.test.ts — 299 tests passed
• Prettier check passed for all changed files
• tailwindcss production build passed, including ESM, CJS, and declaration output

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge, with the parser and downstream nesting behavior aligned and covered by focused tests.

_{Reviews (1) · Last reviewed commit: "Handle vendor-prefixed selector function..."}

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Advanced

Run ID: f48b5db8-dd9e-4cce-8f38-98d3a553ccf5

📥 Commits

Reviewing files that changed from the base of the PR and between 41d9cae and 03c029e.

📒 Files selected for processing (3)

• packages/tailwindcss/src/index.test.ts
• packages/tailwindcss/src/selector-parser.test.ts
• packages/tailwindcss/src/selector-parser.ts

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Walkthrough

The selector parser now parses :-moz-any(...) and :-webkit-any(...) arguments as selector lists. Tests cover the resulting parser nodes and verify that the body-less @custom-variant firefox (:-moz-any(&)); syntax generates the expected firefox:underline CSS.

Priority: ➖ Normal

Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 03c02

The vendor-prefixed custom-variant regression is covered by passing parser and compiler tests, so no actionable merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: support for vendor-prefixed selector functions in custom variants.
Description check	✅ Passed	The description directly explains the parser fix, nesting replacement behavior, affected custom variant syntax, regression cause, and validation results.
Linked Issues check	✅ Passed	The change addresses issue #20483. selector-parser.ts now parses :-moz-any() and :-webkit-any() contents as selector lists. The parser test covers & and .foo. The `@custom-variant firefox (:…
Out of Scope Changes check	✅ Passed	The pull request changes only selector parsing and tests for vendor-prefixed selector functions and the linked custom-variant compilation path. These changes directly support issue #20483 and contain …

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