Move modifier of not-*, has-*, and in-* variant to sub variant (#19100)

This PR fixes an issue where a compound variant with a modifier such as
`not-group-hover/name:flex` would not generate anything because the
`/name` modifier belongs to the `not` variant, and not the compounded
`group-hover` variant.

This PR is a **workaround** (and definitely not perfect) by special
casing the `not`, `has`, and `in` variants such that their modifiers are
moved internally to the sub variant as-if the `/name` existed on
`group-hover`.

We don't do it for other compound variants such as `group` and `peer`
because then `group-peer-focus/name:underline` would result in a
breaking change:

```diff
- .group-peer-focus\\/name\\:flex:is(:where(.group\\/name):is(:where(.peer):focus ~ *) *)
+ .group-peer-focus\/name\:flex:is(:where(.group):is(:where(.peer\/name):focus ~ *) *) 
```

In case the diff is not clear, the name has moved:
<img width="1219" height="78" alt="image"
src="https://github.com/user-attachments/assets/dce7bc95-9d93-452d-a275-b3891a05a1a4"
/>


This is also a limited workaround, because if you need multiple
modifiers it won't work. I would've loved to special case this _inside_
the `not`, `has`, and `in` code that handles these variants, but we
handle the variants in a depth-first way, so by the time you are
handling the `not` variant, the sub variant was already handled...

In a perfect world, you can use something like `not-group/name-hover`
but then it becomes unambiguous because is `name` the name, is
`name-hover`?

## Test plan

Added a new test that wouldn't generate anything before this fix.

Fixes: #15772

Author: RobinMalfait

CHANGELOG.md

@@ -14,8 +14,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fix Safari devtools rendering issue due to `color-mix` fallback ([#19069](https://github.com/tailwindlabs/tailwindcss/pull/19069))
-- Suppress Lightning CSS warnings about `:deep`, `:slotted` and `:global` ([#19094](https://github.com/tailwindlabs/tailwindcss/pull/19094))
+- Suppress Lightning CSS warnings about `:deep`, `:slotted`, and `:global` ([#19094](https://github.com/tailwindlabs/tailwindcss/pull/19094))
 - Fix resolving theme keys when starting with the name of another theme key in JS configs and plugins ([#19097](https://github.com/tailwindlabs/tailwindcss/pull/19097))
+- Allow named groups in combination with `not-*`, `has-*`, and `in-*` ([#19100](https://github.com/tailwindlabs/tailwindcss/pull/19100))
 
 ## [4.1.14] - 2025-10-01
 

packages/tailwindcss/src/candidate.test.ts

@@ -2102,6 +2102,11 @@ const variants = [
   // Handle special `@` variants. These shouldn't be printed as `@-`
   ['@xl:', '@xl:'],
   ['@[123px]:', '@[123px]:'],
+
+  // Compound variants that forward modifiers
+  ['not-group-hover/name:', 'not-group-hover/name:'],
+  ['has-group-peer-hover/name:', 'has-group-peer-hover/name:'],
+  ['in-group-peer-hover/name:', 'in-group-peer-hover/name:'],
 ]
 
 let combinations: [string, string][] = []

packages/tailwindcss/src/candidate.ts

@@ -806,6 +806,13 @@ export function parseVariant(variant: string, designSystem: DesignSystem): Varia
         case 'compound': {
           if (value === null) return null
 
+          // Forward the modifier of the compound variants to its subVariant.
+          // This allows for `not-group-hover/name:flex` to work.
+          if (modifier && (root === 'not' || root === 'has' || root === 'in')) {
+            value = `${value}/${modifier}`
+            modifier = null
+          }
+
           let subVariant = designSystem.parseVariant(value)
           if (subVariant === null) return null
 

packages/tailwindcss/src/variants.test.ts

@@ -2586,6 +2586,24 @@ test('matchVariant sorts deterministically', async () => {
   }
 })
 
+test('move modifier of compound variant to sub-variant if its also a compound variant', async () => {
+  expect(
+    await run([
+      'not-group-focus/name:flex',
+      'has-group-focus/name:flex',
+      'in-group-focus/name:flex',
+
+      // Keep the `name` on the `group`, don't move it to the `peer` because
+      // that would be a breaking change.
+      'group-peer-focus/name:flex',
+    ]),
+  ).toMatchInlineSnapshot(`
+    ".not-group-focus\\/name\\:flex:not(:is(:where(.group\\/name):focus *)), .group-peer-focus\\/name\\:flex:is(:where(.group\\/name):is(:where(.peer):focus ~ *) *), :where(:is(:where(.group\\/name):focus *)) .in-group-focus\\/name\\:flex, .has-group-focus\\/name\\:flex:has(:is(:where(.group\\/name):focus *)) {
+      display: flex;
+    }"
+  `)
+})
+
 test.each([
   // These are style rules
   [['.foo'], Compounds.StyleRules],