fix: lazy compilation with only loader module (#11443)

Author: SyMind

crates/rspack_plugin_lazy_compilation/src/module.rs

@@ -43,7 +43,8 @@ pub(crate) struct LazyCompilationProxyModule {
 
   source_map_kind: SourceMapKind,
   create_data: ModuleFactoryCreateData,
-  pub resource: String,
+  resource: String,
+  virtual_trigger_path: String,
 
   pub active: bool,
   pub data: String,
@@ -70,6 +71,7 @@ impl LazyCompilationProxyModule {
     lib_ident: Option<String>,
     create_data: ModuleFactoryCreateData,
     resource: String,
+    virtual_trigger_path: String,
     cacheable: bool,
     active: bool,
     data: String,
@@ -90,6 +92,7 @@ impl LazyCompilationProxyModule {
       create_data,
       readable_identifier,
       lib_ident,
+      virtual_trigger_path,
       resource,
       identifier,
       source_map_kind: SourceMapKind::empty(),
@@ -173,7 +176,7 @@ impl Module for LazyCompilationProxyModule {
     } else {
       let mut files = FxHashSet::default();
       files.extend(self.create_data.file_dependencies.clone());
-      files.insert(Path::new(&self.resource).into());
+      files.insert(Path::new(&self.virtual_trigger_path).into());
       self.build_info.file_dependencies = files;
     }
 

crates/rspack_plugin_lazy_compilation/src/plugin.rs

@@ -1,8 +1,10 @@
 use std::{
   fmt::Debug,
+  hash::Hash,
   sync::{Arc, LazyLock},
 };
 
+use rspack_collections::Identifier;
 use rspack_core::{
   BoxModule, Compilation, CompilationId, CompilationParams, CompilerCompilation, CompilerId,
   DependencyType, EntryDependency, LibIdentOptions, Module, ModuleFactory, ModuleFactoryCreateData,
@@ -186,18 +188,18 @@ async fn normal_module_factory_module(
   let lib_ident = module.lib_ident(LibIdentOptions {
     context: module_factory_create_data.options.context.as_str(),
   });
+  let virtual_trigger_path = create_virtual_trigger_path(&module_identifier);
+
   let info = backend
-    .module(
-      module_identifier,
-      create_data.resource_resolve_data.resource.clone(),
-    )
+    .module(module_identifier, virtual_trigger_path.to_string())
     .await?;
 
   *module = Box::new(LazyCompilationProxyModule::new(
     module_identifier,
     lib_ident.map(|ident| ident.into_owned()),
     module_factory_create_data.clone(),
-    create_data.resource_resolve_data.resource.clone(),
+    create_data.resource_resolve_data.resource.to_string(),
+    virtual_trigger_path,
     self.cacheable,
     info.active,
     info.data,
@@ -221,3 +223,13 @@ impl<T: Backend + 'static, F: LazyCompilationTestCheck + 'static> Plugin
     Ok(())
   }
 }
+
+// Generates a virtual file path to trigger module graph updates for lazy compilation.
+//
+// This creates a synthetic file path that can be used as a "changed file" parameter
+// to trigger module graph updates, specifically for modules without associated physical
+// files (e.g., loader-only imports like `import("./loader!")`).
+fn create_virtual_trigger_path(module_identifier: &Identifier) -> String {
+  let hash = module_identifier.precomputed_hash();
+  format!("/rspack_lazy_compilation/{:x}", hash)
+}

tests/e2e/cases/lazy-compilation/loader-only-module/index.test.ts

@@ -0,0 +1,13 @@
+import { expect, test } from "@/fixtures";
+
+test("lazy compilation handles loader-only entries without resource paths", async ({ page }) => {
+    // Wait for the lazy-compiled content to load
+    const actionButton = page.getByRole("button", { name: "Click me" });
+    await expect(actionButton).toBeVisible({ timeout: 1000 });
+
+    // Test that the lazy module functions correctly
+    await actionButton.click();
+
+    // Verify successful execution
+    await expect(page).toHaveURL(/success$/);
+});

tests/e2e/cases/lazy-compilation/loader-only-module/loader.js

@@ -0,0 +1,8 @@
+module.exports = function () {
+    return `const button = document.createElement("button");
+button.textContent = "Click me";
+button.onclick = () => {
+	history.pushState(null, "", "success");
+};
+document.body.appendChild(button);`
+}

tests/e2e/cases/lazy-compilation/loader-only-module/rspack.config.js

@@ -0,0 +1,18 @@
+const { rspack } = require("@rspack/core");
+
+/** @type { import('@rspack/core').RspackOptions } */
+module.exports = {
+    context: __dirname,
+    entry: {
+        main: "./loader!"
+    },
+    stats: "none",
+    mode: "development",
+    plugins: [new rspack.HtmlRspackPlugin(), new rspack.CssExtractRspackPlugin()],
+    experiments: {
+        lazyCompilation: true
+    },
+    devServer: {
+        hot: true
+    }
+};