CodeFix and Diagnostic for Unnecessary Named Import

src/compiler/checker.ts

@@ -48121,6 +48121,16 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         checkAliasSymbol(node);
         if (node.kind === SyntaxKind.ImportSpecifier) {
             checkModuleExportName(node.propertyName);
+
+            // Check for duplicate import names
+            const importSpecifier = node;
+            const namecheck = getTextOfIdentifierOrLiteral(importSpecifier.name);
+            const propertyNamecheck = importSpecifier.propertyName ? getTextOfIdentifierOrLiteral(importSpecifier.propertyName) : "";
+
+            if (namecheck === propertyNamecheck) {
+                errorOrSuggestion(/*isError*/ false, importSpecifier, Diagnostics.Redundant_named_import_0, namecheck);
+            }
+
             if (
                 moduleExportNameIsDefault(node.propertyName || node.name) &&
                 getESModuleInterop(compilerOptions) &&

src/compiler/diagnosticMessages.json

@@ -5337,6 +5337,11 @@
         "category": "Error",
         "code": 6189
     },
+    "Redundant named import '{0}'.": {
+        "category": "Suggestion",
+        "code": 6190,
+        "reportsUnnecessary": true
+    },
     "Whether to keep outdated console output in watch mode instead of clearing the screen.": {
         "category": "Message",
         "code": 6191
@@ -8267,6 +8272,14 @@
         "category": "Message",
         "code": 95197
     },
+    "Simplify redundant import '{0}'": {
+        "category": "Message",
+        "code": 95198
+    },
+    "Simplify all redundant imports": {
+        "category": "Message",
+        "code": 95199
+    },
 
     "No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer.": {
         "category": "Error",

src/services/_namespaces/ts.codefix.ts

@@ -74,3 +74,4 @@ export * from "../codefixes/splitTypeOnlyImport.js";
 export * from "../codefixes/convertConstToLet.js";
 export * from "../codefixes/fixExpectedComma.js";
 export * from "../codefixes/fixAddVoidToPromise.js";
+export * from "../codefixes/removeUnnecessaryNamedImport.js";

src/services/codefixes/removeUnnecessaryNamedImport.ts

@@ -0,0 +1,53 @@
+import {
+    codeFixAll,
+    createCodeFixAction,
+    registerCodeFix,
+} from "../_namespaces/ts.codefix.js";
+import {
+    Diagnostics,
+    factory,
+    getTokenAtPosition,
+    isImportSpecifier,
+    SourceFile,
+    textChanges,
+    TextSpan,
+    tryCast,
+} from "../_namespaces/ts.js";
+
+const fixId = "removeUnnecessaryNamedImport";
+const errorCodes = [
+    Diagnostics.Redundant_named_import_0.code,
+];
+
+registerCodeFix({
+    errorCodes,
+    getCodeActions: function getCodeActionsToRemoveUnnecessaryNamedImport(context) {
+        const changes = textChanges.ChangeTracker.with(context, t => makeChange(t, context.sourceFile, context.span));
+        const token = getTokenAtPosition(context.sourceFile, context.span.start);
+        const importSpecifier = tryCast(token.parent, isImportSpecifier);
+
+        if (!importSpecifier) {
+            return;
+        }
+
+        if (changes.length > 0) {
+            return [createCodeFixAction(fixId, changes, [Diagnostics.Simplify_redundant_import_0, importSpecifier.name.text], fixId, Diagnostics.Simplify_all_redundant_imports)];
+        }
+    },
+    fixIds: [fixId],
+    getAllCodeActions: context => {
+        return codeFixAll(context, errorCodes, (changes, diag) => makeChange(changes, diag.file, diag));
+    },
+});
+
+function makeChange(changeTracker: textChanges.ChangeTracker, sourceFile: SourceFile, span: TextSpan) {
+    const token = getTokenAtPosition(sourceFile, span.start);
+    const importSpecifier = tryCast(token.parent, isImportSpecifier);
+    if (!importSpecifier) {
+        return;
+    }
+
+    if (importSpecifier.propertyName && importSpecifier.propertyName.text === importSpecifier.name.text) {
+        changeTracker.replaceNode(sourceFile, importSpecifier, factory.updateImportSpecifier(importSpecifier, importSpecifier.isTypeOnly, /*propertyName*/ undefined, importSpecifier.name));
+    }
+}

tests/cases/fourslash/codeFixRemoveUnnecessaryNamedImports.ts

@@ -0,0 +1,31 @@
+/// <reference path="fourslash.ts" />
+
+// @filename: /a.ts
+////export const foo = () => console.log('Hello world!');
+////export const bar = () => console.log('Hello world!');
+
+// @filename: /b.ts
+////import { foo as foo, bar as bar } from "./a";
+////foo();
+////bar();
+
+goTo.file("/b.ts");
+
+verify.codeFix({
+    description: 'Simplify redundant import \'foo\'',
+    index: 0,
+    newFileContent:
+`import { foo, bar as bar } from "./a";
+foo();
+bar();`
+});
+
+verify.codeFixAll({
+    fixAllDescription: ts.Diagnostics.Simplify_all_redundant_imports.message,
+    fixId: "removeUnnecessaryNamedImport",
+    newFileContent:
+`import { foo, bar } from "./a";
+foo();
+bar();`
+});
+

tests/cases/fourslash/redundantImportDiagnostic.ts

@@ -0,0 +1,21 @@
+/// <reference path="fourslash.ts" />
+
+// @filename: /a.ts
+//// export const bar = () => console.log('Hello world!');
+
+// @filename: /b.ts
+//// import { bar as bar } from "./a";
+//// bar();
+
+
+goTo.file("/b.ts");
+
+
+verify.getSuggestionDiagnostics([
+    {
+        message: "Redundant named import 'bar'.",
+        code: ts.Diagnostics.Redundant_named_import_0.code,
+        range: {pos: 9, end: 19, fileName:"/b.ts"},
+        reportsUnnecessary: true,
+    }
+]);