Handle variable colors that have variable fallback values (#12049)

* Parse colors even when variable has fallback that is a variable

* Update changelog

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Skip `calc()` normalisation in nested `theme()` calls ([#11705](https://github.com/tailwindlabs/tailwindcss/pull/11705))
 - Fix incorrectly generated CSS when using square brackets inside arbitrary properties ([#11709](https://github.com/tailwindlabs/tailwindcss/pull/11709))
 - Make `content` optional for presets in TypeScript types ([#11730](https://github.com/tailwindlabs/tailwindcss/pull/11730))
+- Handle variable colors that have variable fallback values ([#12049](https://github.com/tailwindlabs/tailwindcss/pull/12049))
 
 ### Added
 

src/util/color.js

@@ -5,7 +5,7 @@ let SHORT_HEX = /^#([a-f\d])([a-f\d])([a-f\d])([a-f\d])?$/i
 let VALUE = /(?:\d+|\d*\.\d+)%?/
 let SEP = /(?:\s*,\s*|\s+)/
 let ALPHA_SEP = /\s*[,/]\s*/
-let CUSTOM_PROPERTY = /var\(--(?:[^ )]*?)\)/
+let CUSTOM_PROPERTY = /var\(--(?:[^ )]*?)(?:,(?:[^ )]*?|var\(--[^ )]*?\)))?\)/
 
 let RGB = new RegExp(
   `^(rgba?)\\(\\s*(${VALUE.source}|${CUSTOM_PROPERTY.source})(?:${SEP.source}(${VALUE.source}|${CUSTOM_PROPERTY.source}))?(?:${SEP.source}(${VALUE.source}|${CUSTOM_PROPERTY.source}))?(?:${ALPHA_SEP.source}(${VALUE.source}|${CUSTOM_PROPERTY.source}))?\\s*\\)$`

tests/opacity.test.js

@@ -1045,3 +1045,21 @@ it('can replace the potential alpha value in rgba/hsla syntax', async () => {
     }
   `)
 })
+
+it('variables with variable fallback values can use opacity modifier', async () => {
+  let config = {
+    content: [
+      {
+        raw: html`<div class="bg-[rgb(var(--some-var,var(--some-other-var)))]/50"></div>`,
+      },
+    ],
+  }
+
+  let result = await run(`@tailwind utilities;`, config)
+
+  expect(result.css).toMatchFormattedCss(css`
+    .bg-\[rgb\(var\(--some-var\,var\(--some-other-var\)\)\)\]\/50 {
+      background-color: rgb(var(--some-var, var(--some-other-var)) / 0.5);
+    }
+  `)
+})