Avoid over-extracting utilities from candidates with decimal values (#13959)

* Avoid over-extracting utilities from candidates with decimal values

Prevent candidates like `px-1.5` from generating both the `px-1.5` class and the `px-1` class.

* Update CHANGELOG.md

---------

Co-authored-by: Adam Wathan <4323180+adamwathan@users.noreply.github.com>

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Disable automatic `var()` injection for anchor properties ([#13826](https://github.com/tailwindlabs/tailwindcss/pull/13826))
 - Use no value instead of `blur(0px)` for `backdrop-blur-none` and `blur-none` utilities ([#13830](https://github.com/tailwindlabs/tailwindcss/pull/13830))
 - Add `.mts` and `.cts` config file detection ([#13940](https://github.com/tailwindlabs/tailwindcss/pull/13940))
+- Don't generate utilities like `px-1` unnecessarily when using utilities like `px-1.5` ([#13959](https://github.com/tailwindlabs/tailwindcss/pull/13959))
 
 ## [3.4.4] - 2024-06-05
 

src/lib/defaultExtractor.js

@@ -1,4 +1,5 @@
 import * as regex from './regex'
+import { splitAtTopLevelOnly } from '../util/splitAtTopLevelOnly'
 
 export function defaultExtractor(context) {
   let patterns = Array.from(buildRegExps(context))
@@ -16,6 +17,30 @@ export function defaultExtractor(context) {
       }
     }
 
+    // Extract any subclasses from languages like Slim and Pug, eg:
+    // div.flex.px-5.underline
+    for (let result of results.slice()) {
+      let segments = splitAtTopLevelOnly(result, '.')
+
+      for (let idx = 0; idx < segments.length; idx++) {
+        let segment = segments[idx]
+        if (idx >= segments.length - 1) {
+          results.push(segment)
+          continue
+        }
+
+        // If the next segment is a number, discard both, for example seeing
+        // `px-1` and `5` means the real candidate was `px-1.5` which is already
+        // captured.
+        let next = parseInt(segments[idx + 1])
+        if (isNaN(next)) {
+          results.push(segment)
+        } else {
+          idx++
+        }
+      }
+    }
+
     return results
   }
 }
@@ -127,9 +152,6 @@ function* buildRegExps(context) {
       utility,
     ])
   }
-
-  // 5. Inner matches
-  yield /[^<>"'`\s.(){}[\]#=%$]*[^<>"'`\s.(){}[\]#=%:$]/g
 }
 
 // We want to capture any "special" characters

tests/default-extractor.test.js

@@ -476,6 +476,19 @@ test('classes in slim templates', async () => {
   expect(extractions).toContain('text-gray-500')
 })
 
+test("classes with fractional numeric values don't also generate the whole number utility", async () => {
+  const extractions = defaultExtractor(`
+    <div class="px-1.5 py-2.75">Hello world!</div>
+  `)
+
+  expect(extractions).toContain('px-1.5')
+  expect(extractions).toContain('py-2.75')
+  expect(extractions).not.toContain('px-1')
+  expect(extractions).not.toContain('5')
+  expect(extractions).not.toContain('py-2')
+  expect(extractions).not.toContain('75')
+})
+
 test('multi-word + arbitrary values + quotes', async () => {
   const extractions = defaultExtractor(`
     grid-cols-['repeat(2)']