Only reset the require cache for build dependencies

integrations/postcss/config.test.ts

@@ -156,6 +156,14 @@ test(
       'color: blue',
     ])
 
+    // While working on this test we noticed that it was failing in about 1-2%
+    // of the runs. We tracked this down to being a proper `delete
+    // require.cache` call for the `my-color.js` file but for some reason
+    // reading it will result in the previous contents.
+    //
+    // To work around this, we give postcss some time to stabilize.
+    await new Promise((resolve) => setTimeout(resolve, 500))
+
     await fs.write('my-color.js', js`module.exports = 'red'`)
 
     await fs.expectFileToContain('dist/out.css', [

packages/@tailwindcss-cli/src/commands/build/index.ts

@@ -226,8 +226,8 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
                   `,
               args['--input'] ?? base,
             )
+            clearRequireCache(fullRebuildPaths)
             fullRebuildPaths = cssImportPaths
-            clearRequireCache()
 
             // Create a new compiler, given the new `input`
             compiler = await compile(input)

packages/@tailwindcss-node/src/require-cache.cts

@@ -1,5 +1,5 @@
-export function clearRequireCache() {
-  for (const key in require.cache) {
+export function clearRequireCache(files: string[]) {
+  for (const key of files) {
     delete require.cache[key]
   }
 }

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

@@ -84,7 +84,7 @@ function tailwindcss(opts: PluginOptions = {}): AcceptedPlugin {
           let inputBasePath = path.dirname(path.resolve(inputFile))
 
           function createCompiler() {
-            clearRequireCache()
+            clearRequireCache(context.fullRebuildPaths)
             context.fullRebuildPaths = []
             return compile(root.toString(), {
               loadPlugin: async (pluginPath) => {

packages/@tailwindcss-vite/src/index.ts

@@ -17,6 +17,7 @@ export default function tailwindcss(): Plugin[] {
   let scanner: Scanner | null = null
   let changedContent: { content: string; extension: string }[] = []
   let candidates = new Set<string>()
+  let fullRebuildPaths: string[] = []
 
   // In serve mode this is treated as a set — the content doesn't matter.
   // In build mode, we store file contents to use them in renderChunk.
@@ -84,7 +85,8 @@ export default function tailwindcss(): Plugin[] {
 
   async function generateCss(css: string, inputPath: string, addWatchFile: (file: string) => void) {
     let inputBasePath = path.dirname(path.resolve(inputPath))
-    clearRequireCache()
+    clearRequireCache(fullRebuildPaths)
+    fullRebuildPaths = []
     let { build, globs } = await compile(css, {
       loadPlugin: async (pluginPath) => {
         if (pluginPath[0] !== '.') {
@@ -93,8 +95,10 @@ export default function tailwindcss(): Plugin[] {
 
         let resolvedPath = path.resolve(inputBasePath, pluginPath)
         addWatchFile(resolvedPath)
+        fullRebuildPaths.push(resolvedPath)
         for (let file of getModuleDependencies(resolvedPath)) {
           addWatchFile(file)
+          fullRebuildPaths.push(file)
         }
         return import(pathToFileURL(resolvedPath).href + '?id=' + Date.now()).then(
           (m) => m.default ?? m,
@@ -108,8 +112,10 @@ export default function tailwindcss(): Plugin[] {
 
         let resolvedPath = path.resolve(inputBasePath, configPath)
         addWatchFile(resolvedPath)
+        fullRebuildPaths.push(resolvedPath)
         for (let file of getModuleDependencies(resolvedPath)) {
           addWatchFile(file)
+          fullRebuildPaths.push(file)
         }
         return import(pathToFileURL(resolvedPath).href + '?id=' + Date.now()).then(
           (m) => m.default ?? m,