fix: use referenced project's compiler option to get resolution mode (#2676)

jasonlyu123 · web-flow · commit af884176a0a4 · 2025-03-06T12:41:13.000+01:00
#2673 Fixing the actual problem that makes the OP want this option. The problem is that the referenced project is a common js project which allows extensionless import. But when we used the wrong compiler option to check for the resolution mode. TypeScript thus used the ESM strategy to resolve the import.
diff --git a/packages/language-server/src/plugins/typescript/module-loader.ts b/packages/language-server/src/plugins/typescript/module-loader.ts
@@ -241,7 +241,14 @@ export function createSvelteModuleLoader(
         redirectedReference: ts.ResolvedProjectReference | undefined,
         option: ts.CompilerOptions
     ): ts.ResolvedModuleWithFailedLookupLocations {
-        const mode = impliedNodeFormatResolver.resolve(name, index, containingSourceFile, option);
+        const mode = impliedNodeFormatResolver.resolve(
+            name,
+            index,
+            containingSourceFile,
+            // use the same compiler options as resolveModuleName
+            // otherwise it might not find the module because of inconsistent module resolution strategy
+            redirectedReference?.commandLine.options ?? option
+        );
         const resolvedModuleWithFailedLookup = tsModule.resolveModuleName(
             name,
             containingFile,
diff --git a/packages/language-server/test/plugins/typescript/service.test.ts b/packages/language-server/test/plugins/typescript/service.test.ts
@@ -599,6 +599,54 @@ describe('service', () => {
         assert.deepStrictEqual(getSemanticDiagnosticsMessages(ls, importing), []);
     });
 
+    it('resolve module with source project reference redirect having different module resolution', async () => {
+        const dirPath = getRandomVirtualDirPath(testDir);
+        const { virtualSystem, lsDocumentContext, rootUris } = setup();
+
+        const package1 = path.join(dirPath, 'package1');
+
+        virtualSystem.writeFile(
+            path.join(package1, 'tsconfig.json'),
+            JSON.stringify({
+                references: [{ path: '../package2' }],
+                files: ['index.ts'],
+                compilerOptions: {
+                    moduleResolution: 'Bundler',
+                    module: 'ESNext',
+                    paths: {
+                        package2: ['../package2']
+                    }
+                }
+            })
+        );
+
+        const package2 = path.join(dirPath, 'package2');
+        virtualSystem.writeFile(
+            path.join(package2, 'tsconfig.json'),
+            JSON.stringify({
+                compilerOptions: {
+                    composite: true,
+                    strict: true,
+                    moduleResolution: 'NodeNext'
+                },
+                files: ['index.ts']
+            })
+        );
+
+        const importing = path.join(package1, 'index.ts');
+        virtualSystem.writeFile(importing, 'import { hi } from "package2"; hi((a) => `${a}`);');
+
+        const reExport = path.join(package2, 'index.ts');
+        virtualSystem.writeFile(reExport, 'export * from "./foo"');
+
+        const exportFile = path.join(package2, 'foo.ts');
+        virtualSystem.writeFile(exportFile, 'export function hi(cb: (num: number) => string) {}');
+
+        const ls = await getService(importing, rootUris, lsDocumentContext);
+
+        assert.deepStrictEqual(getSemanticDiagnosticsMessages(ls, importing), []);
+    });
+
     it('skip directory watching if directory is root', async () => {
         const dirPath = getRandomVirtualDirPath(path.join(testDir, 'Test'));
         const { virtualSystem, lsDocumentContext } = setup();
