Merge branch 'main' into fix/issue-19422

Author: RobinMalfait

CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Allow multiple `@utility` definitions with the same name but different value types ([#19777](https://github.com/tailwindlabs/tailwindcss/pull/19777))
 - Export missing `PluginWithConfig` type from `tailwindcss/plugin` to fix errors when inferring plugin config types ([#19707](https://github.com/tailwindlabs/tailwindcss/pull/19707))
 - Allow `@apply` to be used with CSS mixins ([#19427](https://github.com/tailwindlabs/tailwindcss/pull/19427))
+- Ensure `start` and `end` legacy utilities without values do not generate CSS ([#20003](https://github.com/tailwindlabs/tailwindcss/pull/20003))
 
 ## [4.2.4] - 2026-04-21
 

integrations/postcss/core-as-postcss-plugin.test.ts

@@ -50,7 +50,7 @@ describe.each(Object.keys(variantConfig))('%s', (variant) => {
     async ({ exec, expect }) => {
       await expect(
         exec('pnpm postcss src/index.css --output dist/out.css', undefined, { ignoreStdErr: true }),
-      ).rejects.toThrowError(
+      ).rejects.toThrow(
         `It looks like you're trying to use \`tailwindcss\` directly as a PostCSS plugin. The PostCSS plugin has moved to a separate package, so to continue using Tailwind CSS with PostCSS you'll need to install \`@tailwindcss/postcss\` and update your PostCSS configuration.`,
       )
     },

integrations/utils.ts

@@ -1,10 +1,11 @@
 import dedent from 'dedent'
 import fastGlob from 'fast-glob'
-import { exec, spawn } from 'node:child_process'
+import { exec, execFile, spawn, type ChildProcess } from 'node:child_process'
 import fs from 'node:fs/promises'
+import { createServer } from 'node:net'
 import { platform, tmpdir } from 'node:os'
 import path from 'node:path'
-import { stripVTControlCharacters } from 'node:util'
+import { promisify, stripVTControlCharacters } from 'node:util'
 import { RawSourceMap, SourceMapConsumer } from 'source-map-js'
 import { test as defaultTest, type ExpectStatic } from 'vitest'
 import { createLineTable } from '../packages/tailwindcss/src/source-maps/line-table'
@@ -64,12 +65,15 @@ interface TestFlags {
   only?: boolean
   skip?: boolean
   debug?: boolean
+  concurrent?: boolean
 }
 
 type SpawnActor = { predicate: (message: string) => boolean; resolve: () => void }
 
 export const IS_WINDOWS = platform() === 'win32'
 
+const execFileAsync = promisify(execFile)
+
 const TEST_TIMEOUT = IS_WINDOWS ? 120000 : 60000
 const ASSERTION_TIMEOUT = IS_WINDOWS ? 10000 : 5000
 
@@ -82,7 +86,7 @@ export function test(
   name: string,
   config: TestConfig,
   testCallback: TestCallback,
-  { only = false, skip = false, debug = false }: TestFlags = {},
+  { only = false, skip = false, debug = false, concurrent = false }: TestFlags = {},
 ) {
   return defaultTest(
     name,
@@ -91,7 +95,7 @@ export function test(
       retry: process.env.CI ? 2 : 0,
       only: only || (!process.env.CI && debug),
       skip,
-      concurrent: true,
+      concurrent,
     },
     async (options) => {
       let rootDir = debug ? path.join(REPO_ROOT, '.debug') : TMP_ROOT
@@ -170,6 +174,7 @@ export function test(
           if (debug) console.log(`>& ${command}`)
           let child = spawn(command, {
             cwd,
+            detached: !IS_WINDOWS,
             shell: true,
             ...childProcessOptions,
             env: {
@@ -178,19 +183,22 @@ export function test(
             },
           })
 
-          function dispose() {
-            if (!child.kill()) {
-              child.kill('SIGKILL')
-            }
+          let disposed = false
+
+          async function dispose() {
+            if (disposed) return disposePromise
+            disposed = true
+
+            await killProcessTree(child)
 
-            let timer = setTimeout(
-              () =>
-                rejectDisposal?.(new Error(`spawned process (${command}) did not exit in time`)),
-              ASSERTION_TIMEOUT,
+            let timer = setTimeout(() => {
+              forceKillProcessTree(child)
+              rejectDisposal?.(new Error(`spawned process (${command}) did not exit in time`))
+            }, ASSERTION_TIMEOUT)
+            disposePromise.then(
+              () => clearTimeout(timer),
+              () => clearTimeout(timer),
             )
-            disposePromise.finally(() => {
-              clearTimeout(timer)
-            })
             return disposePromise
           }
           disposables.push(dispose)
@@ -428,11 +436,18 @@ export function test(
       let disposables: (() => Promise<void>)[] = []
 
       async function dispose() {
-        await Promise.all(disposables.map((dispose) => dispose()))
+        let results = await Promise.allSettled(disposables.map((dispose) => dispose()))
 
         if (!debug) {
           await gracefullyRemove(root)
         }
+
+        let errors = results.flatMap((result) =>
+          result.status === 'rejected' ? [result.reason] : [],
+        )
+        if (errors.length > 0) {
+          throw new AggregateError(errors, 'Failed to clean up spawned processes')
+        }
       }
 
       options.onTestFinished(dispose)
@@ -461,6 +476,9 @@ test.only = (name: string, config: TestConfig, testCallback: TestCallback) => {
 test.skip = (name: string, config: TestConfig, testCallback: TestCallback) => {
   return test(name, config, testCallback, { skip: true })
 }
+test.concurrent = (name: string, config: TestConfig, testCallback: TestCallback) => {
+  return test(name, config, testCallback, { concurrent: true })
+}
 test.debug = (name: string, config: TestConfig, testCallback: TestCallback) => {
   return test(name, config, testCallback, { debug: true })
 }
@@ -607,6 +625,65 @@ export async function fetchStyles(base: string, path = '/'): Promise<string> {
   }, '')
 }
 
+export async function getRandomPort() {
+  return new Promise<number>((resolve, reject) => {
+    let server = createServer()
+    server.unref()
+    server.on('error', reject)
+    server.listen(0, '127.0.0.1', () => {
+      let address = server.address()
+      server.close(() => {
+        if (address && typeof address === 'object') {
+          resolve(address.port)
+        } else {
+          reject(new Error('Unable to allocate random port'))
+        }
+      })
+    })
+  })
+}
+
+async function killProcessTree(child: ChildProcess) {
+  if (child.exitCode !== null || child.signalCode !== null || child.pid === undefined) {
+    return
+  }
+
+  if (IS_WINDOWS) {
+    await execFileAsync('taskkill', ['/pid', String(child.pid), '/T', '/F'], {
+      timeout: ASSERTION_TIMEOUT,
+      windowsHide: true,
+    }).catch(() => {})
+    return
+  }
+
+  try {
+    process.kill(-child.pid, 'SIGTERM')
+  } catch (error: any) {
+    if (error?.code !== 'ESRCH') {
+      child.kill()
+    }
+  }
+}
+
+function forceKillProcessTree(child: ChildProcess) {
+  if (child.exitCode !== null || child.signalCode !== null || child.pid === undefined) {
+    return
+  }
+
+  if (IS_WINDOWS) {
+    execFile('taskkill', ['/pid', String(child.pid), '/T', '/F'], { windowsHide: true }, () => {})
+    return
+  }
+
+  try {
+    process.kill(-child.pid, 'SIGKILL')
+  } catch (error: any) {
+    if (error?.code !== 'ESRCH') {
+      child.kill('SIGKILL')
+    }
+  }
+}
+
 async function gracefullyRemove(dir: string) {
   // Skip removing the directory in CI because it can stall on Windows
   if (!process.env.CI) {

integrations/vite/index.test.ts

@@ -836,7 +836,7 @@ describe.each(['postcss', 'lightningcss'])('%s', (transformer) => {
     async ({ root, fs, exec, expect }) => {
       await expect(() =>
         exec('pnpm vite build', { cwd: path.join(root, 'project-a') }, { ignoreStdErr: true }),
-      ).rejects.toThrowError('The `source(../i-do-not-exist)` does not exist')
+      ).rejects.toThrow('The `source(../i-do-not-exist)` does not exist')
 
       let files = await fs.glob('project-a/dist/**/*.css')
       expect(files).toHaveLength(0)

integrations/vite/nuxt.test.ts

@@ -1,4 +1,14 @@
-import { candidate, css, fetchStyles, html, json, retryAssertion, test, ts } from '../utils'
+import {
+  candidate,
+  css,
+  fetchStyles,
+  getRandomPort,
+  html,
+  json,
+  retryAssertion,
+  test,
+  ts,
+} from '../utils'
 
 const SETUP = {
   fs: {
@@ -84,7 +94,8 @@ test('build', SETUP, async ({ spawn, exec, expect }) => {
   await exec('pnpm nuxt build')
   // The Nuxt preview server does not automatically assign a free port if 3000
   // is taken, so we use a random port instead.
-  let process = await spawn(`pnpm nuxt preview --port 8724`, {
+  let port = await getRandomPort()
+  let process = await spawn(`pnpm nuxt preview --port ${port}`, {
     env: {
       TEST: 'false',
       NODE_ENV: 'development',

packages/@tailwindcss-cli/package.json

@@ -32,7 +32,7 @@
     "@parcel/watcher": "^2.5.1",
     "@tailwindcss/node": "workspace:*",
     "@tailwindcss/oxide": "workspace:*",
-    "enhanced-resolve": "^5.20.1",
+    "enhanced-resolve": "^5.21.0",
     "mri": "^1.2.0",
     "picocolors": "^1.1.1",
     "tailwindcss": "workspace:*"

packages/@tailwindcss-node/package.json

@@ -38,7 +38,7 @@
   },
   "dependencies": {
     "@jridgewell/remapping": "^2.3.5",
-    "enhanced-resolve": "^5.20.1",
+    "enhanced-resolve": "^5.21.0",
     "jiti": "^2.6.1",
     "lightningcss": "catalog:",
     "magic-string": "^0.30.21",

packages/@tailwindcss-postcss/src/index.test.ts

@@ -120,7 +120,7 @@ describe('processing without specifying a base path', () => {
   afterEach(() => unlink(filepath))
 
   test('the current working directory is used by default', async () => {
-    const spy = vi.spyOn(process, 'cwd')
+    using spy = vi.spyOn(process, 'cwd')
     spy.mockReturnValue(dir)
 
     let processor = postcss([tailwindcss({ optimize: { minify: false } })])
@@ -389,7 +389,7 @@ describe('concurrent builds', () => {
   afterEach(() => rm(dir, { recursive: true, force: true }))
 
   test('does experience a race-condition when calling the plugin two times for the same change', async () => {
-    const spy = vi.spyOn(process, 'cwd')
+    using spy = vi.spyOn(process, 'cwd')
     spy.mockReturnValue(dir)
 
     let from = path.join(dir, 'index.css')

packages/@tailwindcss-standalone/package.json

@@ -30,7 +30,7 @@
     "@tailwindcss/forms": "^0.5.11",
     "@tailwindcss/typography": "^0.5.19",
     "detect-libc": "1.0.3",
-    "enhanced-resolve": "^5.20.1",
+    "enhanced-resolve": "^5.21.0",
     "tailwindcss": "workspace:*"
   },
   "__notes": "These binary packages must be included so Bun can build the CLI for all supported platforms. We also rely on Lightning CSS and Parcel being patched so Bun can statically analyze the executables.",

packages/@tailwindcss-upgrade/package.json

@@ -30,7 +30,7 @@
     "@tailwindcss/node": "workspace:*",
     "@tailwindcss/oxide": "workspace:*",
     "dedent": "1.7.2",
-    "enhanced-resolve": "^5.20.1",
+    "enhanced-resolve": "^5.21.0",
     "globby": "^16.2.0",
     "jiti": "^2.6.1",
     "mri": "^1.2.0",