fix(optimizer): scan deep imports with custom extensions

packages/vite/src/node/optimizer/scan.ts

@@ -611,14 +611,14 @@ function rolldownScanPlugin(
           // If we can optimize this html type, skip it so it's handled by the
           // bare import resolve, and recorded as optimization dep.
           if (
-            isInNodeModules(resolved) &&
-            isOptimizable(resolved, optimizeDepsOptions)
-          )
-            return
-          if (shouldExternalizeDep(resolved, id)) {
-            return externalUnlessEntry({ path: id })
+            !isInNodeModules(resolved) ||
+            !isOptimizable(resolved, optimizeDepsOptions)
+          ) {
+            if (shouldExternalizeDep(resolved, id)) {
+              return externalUnlessEntry({ path: id })
+            }
+            return resolved
           }
-          return resolved
         }
 
         // bare imports: record and externalize ----------------------------------

playground/optimize-deps/__tests__/optimize-deps.spec.ts

@@ -424,6 +424,18 @@ test('dependency with external sub-dependencies', async () => {
     .toBe('foo bar')
 })
 
+test.runIf(isServe)(
+  'discovers deep imports with custom html-like extensions during dep scan',
+  async () => {
+    await expect
+      .poll(() => page.textContent('.svelte-deep-import'))
+      .toBe('[success]')
+    expect(serverLogs.join('\n')).not.toContain(
+      "Could not resolve './relative.svelte' in virtual-module:",
+    )
+  },
+)
+
 test('virtual module with .vue extension does not error during scan', async () => {
   await expect.poll(() => page.textContent('.virtual-module-vue')).toBe('ok')
 })

playground/optimize-deps/dep-not-js/deep-import.svelte

@@ -0,0 +1,5 @@
+<script>
+import value from './relative.svelte'
+
+export default value
+</script>

playground/optimize-deps/dep-not-js/relative.svelte

@@ -0,0 +1,3 @@
+<script>
+export default '[success]'
+</script>

playground/optimize-deps/index.html

@@ -76,6 +76,10 @@ <h2>Import from dependency with process.env.NODE_ENV</h2>
 <h2>Import from dependency with .notjs files</h2>
 <div class="not-js"></div>
 
+<h2>Deep import from dependency with .svelte files</h2>
+<div class="svelte-deep-import"></div>
+<script type="module" src="./svelte-deep-import.js"></script>
+
 <h2>
   Import from dependency which uses relative path which needs to be resolved by
   main field

playground/optimize-deps/svelte-deep-import.js

@@ -0,0 +1,3 @@
+import value from '@vitejs/test-dep-not-js/deep-import.svelte'
+
+document.querySelector('.svelte-deep-import').textContent = value

playground/optimize-deps/vite.config.js

@@ -61,6 +61,7 @@ export default defineConfig({
   plugins: [
     testVue(),
     notjs(),
+    svelteDeepImport(),
     virtualModulePlugin(),
     injectImportIntoOptimizedDep(),
     {
@@ -103,6 +104,44 @@ export default defineComponent({
   }
 }
 
+function svelteDeepImport() {
+  const transformSvelte = (code) =>
+    code.match(/<script>([\s\S]*)<\/script>/)?.[1]
+
+  return {
+    name: 'svelte-deep-import',
+    config() {
+      return {
+        optimizeDeps: {
+          extensions: ['.svelte'],
+          rolldownOptions: {
+            plugins: [
+              {
+                name: 'svelte-deep-import-optimizer',
+                transform: {
+                  filter: { id: /\.svelte$/ },
+                  handler(code) {
+                    const transformed = transformSvelte(code)
+                    if (transformed) {
+                      return { code: transformed, moduleType: 'js' }
+                    }
+                  },
+                },
+              },
+            ],
+          },
+        },
+      }
+    },
+    transform(code, id) {
+      if (id.endsWith('.svelte')) {
+        const transformed = transformSvelte(code)
+        if (transformed) return { code: transformed }
+      }
+    },
+  }
+}
+
 // Handles .notjs file, basically remove wrapping <notjs> and </notjs> tags
 function notjs() {
   return {