fix: returning exports from runtime for libraries (#2415)

Author: underfin

.changeset/brown-countries-attack.md

@@ -0,0 +1,5 @@
+---
+"@rspack/core": patch
+---
+
+fix: returning exports from runtime for libraries

crates/rspack_core/src/runtime_globals.rs

@@ -147,3 +147,8 @@ pub const GET_FULL_HASH: &str = "__webpack_require__.h";
  * the global object
  */
 pub const GLOBAL: &str = "__webpack_require__.g";
+
+/**
+ * runtime need to return the exports of the last entry module
+ */
+pub const RETURN_EXPORTS_FROM_RUNTIME: &str = "return-exports-from-runtime";

crates/rspack_plugin_javascript/src/plugin.rs

@@ -160,6 +160,9 @@ impl JsPlugin {
   pub async fn render_main(&self, args: &rspack_core::RenderManifestArgs<'_>) -> Result<BoxSource> {
     let compilation = args.compilation;
     let chunk = args.chunk();
+    let runtime_requirements = compilation
+      .chunk_graph
+      .get_tree_runtime_requirements(&args.chunk_ukey);
     let mut sources = ConcatSource::default();
     sources.add(RawSource::from("var __webpack_modules__ = "));
     sources.add(render_chunk_modules(compilation, &args.chunk_ukey)?);
@@ -169,6 +172,9 @@ impl JsPlugin {
     if chunk.has_entry_module(&compilation.chunk_graph) {
       // TODO: how do we handle multiple entry modules?
       sources.add(generate_chunk_entry_code(compilation, &args.chunk_ukey));
+      if runtime_requirements.contains(runtime_globals::RETURN_EXPORTS_FROM_RUNTIME) {
+        sources.add(RawSource::from("return __webpack_exports__;\n"));
+      }
       if let Some(source) =
         compilation
           .plugin_driver

crates/rspack_plugin_library/src/amd_library_plugin.rs

@@ -1,6 +1,7 @@
 use rspack_core::{
   rspack_sources::{ConcatSource, RawSource, SourceExt},
-  ExternalModule, Filename, LibraryName, LibraryOptions, Plugin, PluginContext,
+  runtime_globals, AdditionalChunkRuntimeRequirementsArgs, ExternalModule, Filename, LibraryName,
+  LibraryOptions, Plugin, PluginAdditionalChunkRuntimeRequirementsOutput, PluginContext,
   PluginRenderHookOutput, RenderArgs, SourceType,
 };
 use rspack_error::Result;
@@ -39,6 +40,17 @@ impl Plugin for AmdLibraryPlugin {
     "AmdLibraryPlugin"
   }
 
+  fn additional_chunk_runtime_requirements(
+    &self,
+    _ctx: PluginContext,
+    args: &mut AdditionalChunkRuntimeRequirementsArgs,
+  ) -> PluginAdditionalChunkRuntimeRequirementsOutput {
+    args
+      .runtime_requirements
+      .insert(runtime_globals::RETURN_EXPORTS_FROM_RUNTIME);
+    Ok(())
+  }
+
   fn render(&self, _ctx: PluginContext, args: &RenderArgs) -> PluginRenderHookOutput {
     let compilation = &args.compilation;
     let chunk = args.chunk();

crates/rspack_plugin_library/src/umd_library_plugin.rs

@@ -1,6 +1,7 @@
 use rspack_core::{
   rspack_sources::{ConcatSource, RawSource, SourceExt},
-  Chunk, ExternalModule, Filename, LibraryAuxiliaryComment, Plugin, PluginContext,
+  runtime_globals, AdditionalChunkRuntimeRequirementsArgs, Chunk, ExternalModule, Filename,
+  LibraryAuxiliaryComment, Plugin, PluginAdditionalChunkRuntimeRequirementsOutput, PluginContext,
   PluginRenderHookOutput, RenderArgs, SourceType,
 };
 
@@ -24,6 +25,17 @@ impl Plugin for UmdLibraryPlugin {
     "UmdLibraryPlugin"
   }
 
+  fn additional_chunk_runtime_requirements(
+    &self,
+    _ctx: PluginContext,
+    args: &mut AdditionalChunkRuntimeRequirementsArgs,
+  ) -> PluginAdditionalChunkRuntimeRequirementsOutput {
+    args
+      .runtime_requirements
+      .insert(runtime_globals::RETURN_EXPORTS_FROM_RUNTIME);
+    Ok(())
+  }
+
   fn render(&self, _ctx: PluginContext, args: &RenderArgs) -> PluginRenderHookOutput {
     let compilation = &args.compilation;
     let chunk = args.chunk();

crates/rspack_plugin_runtime/src/array_push_callback_chunk_format.rs

@@ -103,6 +103,13 @@ impl Plugin for ArrayPushCallbackChunkFormatPlugin {
         }
         if has_entry {
           source.add(generate_chunk_entry_code(args.compilation, args.chunk_ukey));
+          let runtime_requirements = args
+            .compilation
+            .chunk_graph
+            .get_tree_runtime_requirements(args.chunk_ukey);
+          if runtime_requirements.contains(runtime_globals::RETURN_EXPORTS_FROM_RUNTIME) {
+            source.add(RawSource::from("return __webpack_exports__;\n"));
+          }
           if let Some(s) =
             args
               .compilation

packages/rspack/tests/configCases/library/umd/index.js

@@ -1 +1,6 @@
-it("should run", function () {});
+it("should run", function () {
+	var fs = require("fs");
+	var source = fs.readFileSync(__filename, "utf-8");
+
+	expect(source.includes("return __webpack_exports__")).toBe(true);
+});