fix: add extension when relative import already have an extension

e2e/cases/bundle-false/index.test.ts

@@ -44,10 +44,21 @@ test('auto add extension for relative import', async () => {
   const fixturePath = join(__dirname, 'relative-import');
   const { contents } = await buildAndGetResults(fixturePath);
 
-  expect(Object.values(contents.esm)[1]).toContain(
+  for (const importer of [
     'import * as __WEBPACK_EXTERNAL_MODULE__bar_js__ from "./bar.js";',
-  );
-  expect(Object.values(contents.cjs)[1]).toContain(
+    'import * as __WEBPACK_EXTERNAL_MODULE__baz_js__ from "./baz.js";',
+    'import * as __WEBPACK_EXTERNAL_MODULE__foo_js__ from "./foo.js";',
+    'import * as __WEBPACK_EXTERNAL_MODULE__qux_js__ from "./qux.js";',
+  ]) {
+    expect(Object.values(contents.esm)[3]).toContain(importer);
+  }
+
+  for (const requirer of [
     'var external_bar_cjs_namespaceObject = require("./bar.cjs");',
-  );
+    'var external_baz_cjs_namespaceObject = require("./baz.cjs");',
+    'var external_foo_cjs_namespaceObject = require("./foo.cjs");',
+    'var external_qux_cjs_namespaceObject = require("./qux.cjs");',
+  ]) {
+    expect(Object.values(contents.cjs)[3]).toContain(requirer);
+  }
 });

e2e/cases/bundle-false/relative-import/src/baz.js.ts

@@ -0,0 +1 @@
+export const baz = 'baz';

e2e/cases/bundle-false/relative-import/src/foo.js

@@ -0,0 +1 @@
+export const foo = 'foo';

e2e/cases/bundle-false/relative-import/src/index.ts

@@ -1,3 +1,8 @@
 import { bar } from './bar';
+import { baz } from './baz.js';
+// @ts-ignore
+import { foo } from './foo.js';
+// @ts-ignore
+import { qux } from './qux.cjs';
 
-export const foo = 'foo' + bar;
+export const text = foo + bar + baz + qux;

e2e/cases/bundle-false/relative-import/src/qux.cjs

@@ -0,0 +1,3 @@
+module.exports = {
+  qux: 'qux',
+};

packages/core/src/config.ts

@@ -1,5 +1,5 @@
 import fs from 'node:fs';
-import path, { dirname, isAbsolute, join } from 'node:path';
+import path, { dirname, extname, isAbsolute, join } from 'node:path';
 import {
   type RsbuildConfig,
   type RsbuildInstance,
@@ -475,13 +475,18 @@ const composeBundleConfig = (
           // Prevent from externalizing entry modules here.
           if (data.contextInfo.issuer) {
             // Node.js ECMAScript module loader does no extension searching.
-            // So we add a file extension here when data.request is a relative path
-            return callback(
-              null,
-              data.request[0] === '.'
-                ? `${data.request}${jsExtension}`
-                : data.request,
-            );
+            // Add a file extension according to autoExtension config
+            // when data.request is a relative path and do not have an extension.
+            // If data.request already have an extension, we replace it with new extension
+            // This may result in a change in semantics,
+            // user should use copy to keep origin file or use another separate entry to deal this
+            let request = data.request;
+            if (request[0] === '.') {
+              request = extname(request)
+                ? request.replace(/\.[^.]+$/, jsExtension)
+                : `${request}${jsExtension}`;
+            }
+            return callback(null, request);
           }
           callback();
         },