Fix auto import completion inserting wrong module specifier (microsoft#41955)

* Don’t look for reëxports when import source was an ambient module

* Add additional assertion for clarity

Author: andrewbranch

src/harness/fourslashImpl.ts

@@ -2798,7 +2798,12 @@ namespace FourSlash {
 
             const details = this.getCompletionEntryDetails(options.name, options.source, options.preferences);
             if (!details) {
-                return this.raiseError(`No completions were found for the given name, source, and preferences.`);
+                const completions = this.getCompletionListAtCaret(options.preferences)?.entries;
+                const matchingName = completions?.filter(e => e.name === options.name);
+                const detailMessage = matchingName?.length
+                    ? `\n  Found ${matchingName.length} with name '${options.name}' from source(s) ${matchingName.map(e => `'${e.source}'`).join(", ")}.`
+                    : "";
+                return this.raiseError(`No completions were found for the given name, source, and preferences.` + detailMessage);
             }
             const codeActions = details.codeActions;
             if (codeActions?.length !== 1) {

src/services/codefixes/importFixes.ts

@@ -210,7 +210,9 @@ namespace ts.codefix {
         preferences: UserPreferences,
     ): { readonly moduleSpecifier: string, readonly codeAction: CodeAction } {
         const compilerOptions = program.getCompilerOptions();
-        const exportInfos = getAllReExportingModules(sourceFile, exportedSymbol, moduleSymbol, symbolName, host, program, /*useAutoImportProvider*/ true);
+        const exportInfos = pathIsBareSpecifier(stripQuotes(moduleSymbol.name))
+            ? [getSymbolExportInfoForSymbol(exportedSymbol, moduleSymbol, sourceFile, program, host)]
+            : getAllReExportingModules(sourceFile, exportedSymbol, moduleSymbol, symbolName, host, program, /*useAutoImportProvider*/ true);
         const useRequire = shouldUseRequire(sourceFile, program);
         const preferTypeOnlyImport = compilerOptions.importsNotUsedAsValues === ImportsNotUsedAsValues.Error && !isSourceFileJS(sourceFile) && isValidTypeOnlyAliasUseSite(getTokenAtPosition(sourceFile, position));
         const moduleSpecifier = first(getNewImportInfos(program, sourceFile, position, preferTypeOnlyImport, useRequire, exportInfos, host, preferences)).moduleSpecifier;
@@ -228,6 +230,27 @@ namespace ts.codefix {
         return { description, changes, commands };
     }
 
+    function getSymbolExportInfoForSymbol(symbol: Symbol, moduleSymbol: Symbol, importingFile: SourceFile, program: Program, host: LanguageServiceHost): SymbolExportInfo {
+        const compilerOptions = program.getCompilerOptions();
+        const mainProgramInfo = getInfoWithChecker(program.getTypeChecker());
+        if (mainProgramInfo) {
+            return mainProgramInfo;
+        }
+        const autoImportProvider = host.getPackageJsonAutoImportProvider?.()?.getTypeChecker();
+        return Debug.checkDefined(autoImportProvider && getInfoWithChecker(autoImportProvider), `Could not find symbol in specified module for code actions`);
+
+        function getInfoWithChecker(checker: TypeChecker): SymbolExportInfo | undefined {
+            const defaultInfo = getDefaultLikeExportInfo(importingFile, moduleSymbol, checker, compilerOptions);
+            if (defaultInfo && skipAlias(defaultInfo.symbol, checker) === symbol) {
+                return { moduleSymbol, importKind: defaultInfo.kind, exportedSymbolIsTypeOnly: isTypeOnlySymbol(symbol, checker) };
+            }
+            const named = checker.tryGetMemberInModuleExportsAndProperties(symbol.name, moduleSymbol);
+            if (named && skipAlias(named, checker) === symbol) {
+                return { moduleSymbol, importKind: ImportKind.Named, exportedSymbolIsTypeOnly: isTypeOnlySymbol(symbol, checker) };
+            }
+        }
+    }
+
     function getAllReExportingModules(importingFile: SourceFile, exportedSymbol: Symbol, exportingModuleSymbol: Symbol, symbolName: string, host: LanguageServiceHost, program: Program, useAutoImportProvider: boolean): readonly SymbolExportInfo[] {
         const result: SymbolExportInfo[] = [];
         const compilerOptions = program.getCompilerOptions();

tests/cases/fourslash/completionsImport_ambient.ts

@@ -0,0 +1,57 @@
+/// <reference path="fourslash.ts" />
+
+// @module: commonjs
+
+// @Filename: a.d.ts
+//// declare namespace foo { class Bar {} }
+//// declare module 'path1' {
+////   import Bar = foo.Bar;
+////   export default Bar;
+//// }
+//// declare module 'path2longer' {
+////   import Bar = foo.Bar;
+////   export {Bar};
+//// }
+////
+
+// @Filename: b.ts
+//// Ba/**/
+
+verify.completions({
+  marker: "",
+  exact: [
+    completion.globalThisEntry,
+    ...completion.globalsVars,
+    {
+      name: "foo",
+      sortText: completion.SortText.GlobalsOrKeywords
+    },
+    completion.undefinedVarEntry,
+    {
+      name: "Bar",
+      source: "path1",
+      hasAction: true,
+      sortText: completion.SortText.AutoImportSuggestions
+    },
+    {
+      name: "Bar",
+      source: "path2longer",
+      hasAction: true,
+      sortText: completion.SortText.AutoImportSuggestions
+    },
+    ...completion.statementKeywordsWithTypes
+  ],
+  preferences: {
+    includeCompletionsForModuleExports: true
+  }
+});
+
+verify.applyCodeActionFromCompletion("", {
+  name: "Bar",
+  source: "path2longer",
+  description: `Import 'Bar' from module "path2longer"`,
+  newFileContent: `import { Bar } from "path2longer";\n\nBa`,
+  preferences: {
+    includeCompletionsForModuleExports: true
+  }
+});