fix: tailwind css sourcemap warning

packages/playground/tailwind-sourcemap/__tests__/build.spec.ts

@@ -0,0 +1,13 @@
+import { isBuild } from 'testUtils'
+
+if (isBuild) {
+  test('should not output sourcemap warning (#4939)', () => {
+    serverLogs.forEach((log) => {
+      expect(log).not.toMatch('Sourcemap is likely to be incorrect')
+    })
+  })
+} else {
+  test('this file only includes test for build', () => {
+    expect(true).toBe(true)
+  })
+}

packages/playground/tailwind-sourcemap/__tests__/serve.spec.ts

@@ -0,0 +1,13 @@
+import { isBuild } from 'testUtils'
+
+if (!isBuild) {
+  test('should not output missing source file warning', () => {
+    serverLogs.forEach((log) => {
+      expect(log).not.toMatch(/Sourcemap for .+ points to missing source files/)
+    })
+  })
+} else {
+  test('this file only includes test for serve', () => {
+    expect(true).toBe(true)
+  })
+}

packages/playground/tailwind-sourcemap/index.html

@@ -0,0 +1,9 @@
+<div class="wrapper">
+  <h1>Tailwind Sourcemap</h1>
+
+  <p class="text-red-400">foo</p>
+</div>
+
+<script type="module">
+  import './tailwind.css'
+</script>

packages/playground/tailwind-sourcemap/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "test-tailwind-sourcemap",
+  "private": true,
+  "version": "0.0.0",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "debug": "node --inspect-brk ../../vite/bin/vite",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "tailwindcss": "^3.0.23"
+  }
+}

packages/playground/tailwind-sourcemap/postcss.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  plugins: {
+    tailwindcss: { config: __dirname + '/tailwind.config.js' }
+  }
+}

packages/playground/tailwind-sourcemap/tailwind.config.js

@@ -0,0 +1,7 @@
+module.exports = {
+  content: ['./index.html'],
+  theme: {
+    extend: {}
+  },
+  plugins: []
+}

packages/playground/tailwind-sourcemap/tailwind.css

@@ -0,0 +1,3 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;

packages/playground/tailwind-sourcemap/vite.config.js

@@ -0,0 +1,11 @@
+/**
+ * @type {import('vite').UserConfig}
+ */
+module.exports = {
+  css: {
+    devSourcemap: true
+  },
+  build: {
+    sourcemap: true
+  }
+}

packages/vite/src/node/plugins/css.ts

@@ -783,7 +783,9 @@ async function compileCSS(
       map: {
         inline: false,
         annotation: false,
-        sourcesContent: false
+        // postcss may return virtual files
+        // we cannot obtain content of them, so this needs to be enabled
+        sourcesContent: true
         // when "prev: preprocessorMap", the result map may include duplicate filename in `postcssResult.map.sources`
         // prev: preprocessorMap,
       }
@@ -862,19 +864,33 @@ export function formatPostcssSourceMap(
   file: string
 ): ExistingRawSourceMap {
   const inputFileDir = path.dirname(file)
-  const sources = rawMap.sources
+
+  const sources: string[] = []
+  const sourcesContent: string[] = []
+  for (const [i, source] of rawMap.sources.entries()) {
     // remove <no source> from sources, to prevent source map to be combined incorrectly
-    .filter((source) => source !== '<no source>')
-    .map((source) => {
-      const cleanSource = cleanUrl(decodeURIComponent(source))
-      return normalizePath(path.resolve(inputFileDir, cleanSource))
-    })
+    if (source === '<no source>') continue
+
+    const cleanSource = cleanUrl(decodeURIComponent(source))
+
+    // postcss returns virtual files
+    if (/^<.+>$/.test(cleanSource)) {
+      sources.push(`\0${cleanSource}`)
+    } else {
+      sources.push(normalizePath(path.resolve(inputFileDir, cleanSource)))
+    }
+
+    if (rawMap.sourcesContent) {
+      sourcesContent.push(rawMap.sourcesContent[i])
+    }
+  }
 
   return {
     file,
     mappings: rawMap.mappings,
     names: rawMap.names,
     sources,
+    sourcesContent,
     version: rawMap.version
   }
 }