moduleSpecifiers: specifier from "rootDirs" should be treated as relative (#25369)

Author: Andy

src/compiler/moduleSpecifiers.ts

@@ -18,7 +18,6 @@ namespace ts.moduleSpecifiers {
         const info = getInfo(compilerOptions, importingSourceFile, importingSourceFileName, host);
         const modulePaths = getAllModulePaths(files, toFileName, info.getCanonicalFileName, host);
         return firstDefined(modulePaths, moduleFileName => getGlobalModuleSpecifier(moduleFileName, info, host, compilerOptions)) ||
-            getGlobalModuleSpecifier(toFileName, info, host, compilerOptions) ||
             first(getLocalModuleSpecifiers(toFileName, info, compilerOptions, preferences));
     }
 
@@ -67,19 +66,19 @@ namespace ts.moduleSpecifiers {
         compilerOptions: CompilerOptions,
     ) {
         return tryGetModuleNameFromTypeRoots(compilerOptions, host, getCanonicalFileName, moduleFileName, addJsExtension)
-            || tryGetModuleNameAsNodeModule(compilerOptions, moduleFileName, host, getCanonicalFileName, sourceDirectory)
-            || compilerOptions.rootDirs && tryGetModuleNameFromRootDirs(compilerOptions.rootDirs, moduleFileName, sourceDirectory, getCanonicalFileName);
+            || tryGetModuleNameAsNodeModule(compilerOptions, moduleFileName, host, getCanonicalFileName, sourceDirectory);
     }
 
     function getLocalModuleSpecifiers(
         moduleFileName: string,
         { moduleResolutionKind, addJsExtension, getCanonicalFileName, sourceDirectory }: Info,
         compilerOptions: CompilerOptions,
         preferences: ModuleSpecifierPreferences,
-    ) {
-        const { baseUrl, paths } = compilerOptions;
+    ): ReadonlyArray<string> {
+        const { baseUrl, paths, rootDirs } = compilerOptions;
 
-        const relativePath = removeExtensionAndIndexPostFix(ensurePathIsNonModuleName(getRelativePathFromDirectory(sourceDirectory, moduleFileName, getCanonicalFileName)), moduleResolutionKind, addJsExtension);
+        const relativePath = rootDirs && tryGetModuleNameFromRootDirs(rootDirs, moduleFileName, sourceDirectory, getCanonicalFileName) ||
+            removeExtensionAndIndexPostFix(ensurePathIsNonModuleName(getRelativePathFromDirectory(sourceDirectory, moduleFileName, getCanonicalFileName)), moduleResolutionKind, addJsExtension);
         if (!baseUrl || preferences.importModuleSpecifierPreference === "relative") {
             return [relativePath];
         }

tests/cases/fourslash/importNameCodeFix_rootDirs.ts

@@ -0,0 +1,23 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: /a.ts
+////export const a = 0;
+
+// @Filename: /b.ts
+////a;
+
+// @Filename: /tsconfig.json
+////{
+////    "compilerOptions": {
+////        "baseUrl": ".",
+////        "rootDirs": ["."]
+////    }
+////}
+
+const nonRelative = 'import { a } from "a";\n\na;';
+const relative = nonRelative.replace('"a"', '"./a"');
+
+goTo.file("/b.ts");
+verify.importFixAtPosition([nonRelative, relative]);
+verify.importFixAtPosition([nonRelative], undefined, { importModuleSpecifierPreference: "non-relative" });
+verify.importFixAtPosition([relative], undefined, { importModuleSpecifierPreference: "relative" });