[turbopack] Stop exposing globals from Turbopack runtime (vercel#81727)

Author: eps1lon

packages/next/src/server/app-render/entry-base.ts

@@ -58,6 +58,20 @@ if (process.env.NODE_ENV === 'development') {
   SegmentViewStateNode = mod.SegmentViewStateNode
 }
 
+// For hot-reloader
+declare global {
+  var __next__clear_chunk_cache__: (() => void) | null | undefined
+  var __turbopack_clear_chunk_cache__: () => void | null | undefined
+}
+// hot-reloader modules are not bundled so we need to inject `__next__clear_chunk_cache__`
+// into globalThis from this file which is bundled.
+if (process.env.TURBOPACK) {
+  globalThis.__next__clear_chunk_cache__ = __turbopack_clear_chunk_cache__
+} else {
+  // Webpack does not have chunks on the server
+  globalThis.__next__clear_chunk_cache__ = null
+}
+
 // patchFetch makes use of APIs such as `React.unstable_postpone` which are only available
 // in the experimental channel of React, so export it from here so that it comes from the bundled runtime
 export function patchFetch() {

packages/next/src/server/dev/hot-reloader-turbopack.ts

@@ -109,6 +109,8 @@ const isTestMode = !!(
 
 const sessionId = Math.floor(Number.MAX_SAFE_INTEGER * Math.random())
 
+declare const __next__clear_chunk_cache__: (() => void) | null | undefined
+
 /**
  * Replaces turbopack:///[project] with the specified project in the `source` field.
  */
@@ -342,10 +344,11 @@ export async function createHotReloaderTurbopack(
 
     resetFetch()
 
-    // Edge uses the browser runtime which already disposes chunks individually.
-    // TODO: process.env.NEXT_RUNTIME is 'nodejs' even though Node.js runtime is not used.
-    if ('__turbopack_clear_chunk_cache__' in globalThis) {
-      ;(globalThis as any).__turbopack_clear_chunk_cache__()
+    // Not available in:
+    // - Pages Router (no server-side HMR)
+    // - Edge Runtime (uses browser runtime which already disposes chunks individually)
+    if (typeof __next__clear_chunk_cache__ === 'function') {
+      __next__clear_chunk_cache__()
     }
 
     const serverPaths = writtenEndpoint.serverPaths.map(({ path: p }) =>

turbopack/crates/turbopack-ecmascript-runtime/js/src/browser/runtime/base/dev-base.ts

@@ -212,6 +212,7 @@ function instantiateModule(moduleId: ModuleId, source: SourceInfo): Module {
           n: exportNamespace.bind(null, module, devModuleCache),
           m: module,
           c: devModuleCache,
+          C: null,
           M: moduleFactories,
           l: loadChunk.bind(null, sourceInfo),
           L: loadChunkByUrl.bind(null, sourceInfo),

turbopack/crates/turbopack-ecmascript-runtime/js/src/nodejs/runtime.ts

@@ -302,6 +302,7 @@ function instantiateModule(id: ModuleId, source: SourceInfo): Module {
         type: SourceType.Parent,
         parentId: id,
       }),
+      C: clearChunkCache,
       w: loadWebAssembly,
       u: loadWebAssemblyModule,
       P: resolveAbsolutePath,
@@ -381,9 +382,6 @@ function isJs(chunkUrlOrPath: ChunkUrl | ChunkPath): boolean {
   return regexJsUrl.test(chunkUrlOrPath)
 }
 
-// For hot-reloader
-;(globalThis as any).__turbopack_clear_chunk_cache__ = clearChunkCache
-
 module.exports = {
   getOrInstantiateRuntimeModule,
   loadChunk,

turbopack/crates/turbopack-ecmascript/src/runtime_functions.rs

@@ -56,6 +56,8 @@ pub const TURBOPACK_LOAD: &TurbopackRuntimeFunctionShortcut =
     &TurbopackRuntimeFunctionShortcut::new("__turbopack_context__.l", "l");
 pub const TURBOPACK_LOAD_BY_URL: &TurbopackRuntimeFunctionShortcut =
     &TurbopackRuntimeFunctionShortcut::new("__turbopack_context__.L", "L");
+pub const TURBOPACK_CLEAR_CHUNK_CACHE: &TurbopackRuntimeFunctionShortcut =
+    &TurbopackRuntimeFunctionShortcut::new("__turbopack_context__.C", "C");
 pub const TURBOPACK_DYNAMIC: &TurbopackRuntimeFunctionShortcut =
     &TurbopackRuntimeFunctionShortcut::new("__turbopack_context__.j", "j");
 pub const TURBOPACK_RESOLVE_ABSOLUTE_PATH: &TurbopackRuntimeFunctionShortcut =
@@ -81,7 +83,7 @@ pub const TURBOPACK_REQUIRE_REAL: &TurbopackRuntimeFunctionShortcut =
 
 /// Adding an entry to this list will automatically ensure that `__turbopack_XXX__` can be called
 /// from user code (by inserting a replacement into free_var_references)
-pub const TURBOPACK_RUNTIME_FUNCTION_SHORTCUTS: [(&str, &TurbopackRuntimeFunctionShortcut); 21] = [
+pub const TURBOPACK_RUNTIME_FUNCTION_SHORTCUTS: [(&str, &TurbopackRuntimeFunctionShortcut); 22] = [
     ("__turbopack_require__", TURBOPACK_REQUIRE),
     ("__turbopack_module_context__", TURBOPACK_MODULE_CONTEXT),
     ("__turbopack_import__", TURBOPACK_IMPORT),
@@ -109,4 +111,8 @@ pub const TURBOPACK_RUNTIME_FUNCTION_SHORTCUTS: [(&str, &TurbopackRuntimeFunctio
     ("__turbopack_refresh__", TURBOPACK_REFRESH),
     ("__turbopack_require_stub__", TURBOPACK_REQUIRE_STUB),
     ("__turbopack_require_real__", TURBOPACK_REQUIRE_REAL),
+    (
+        "__turbopack_clear_chunk_cache__",
+        TURBOPACK_CLEAR_CHUNK_CACHE,
+    ),
 ];