From bb33cc87ab6bf5d6c1f97b0303f217178babadc8 Mon Sep 17 00:00:00 2001
From: Danyal Ahmed <58849388+danyalahmed1995@users.noreply.github.com>
Date: Mon, 11 May 2026 02:32:30 +0500
Subject: [PATCH 1/2] Fix implement-interface codefix for invalid interface
 types

---
 .../fixClassIncorrectlyImplementsInterface.ts   | 17 +++++++++++++++--
 ...plementInterfaceTypeParamInstantiateError.ts |  3 +--
 ...ixClassImplementInterfaceUndeclaredSymbol.ts |  3 +--
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
index 49298f9058053..8aefd834ce3fe 100644
--- a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
+++ b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
@@ -5,7 +5,6 @@ import {
     createMissingMemberNodes,
     getNoopSymbolTrackerWithResolver,
     registerCodeFix,
-    TypeConstructionContext,
 } from "../_namespaces/ts.codefix.js";
 import {
     addToSeen,
@@ -13,6 +12,7 @@ import {
     ClassElement,
     ClassLikeDeclaration,
     CodeFixAction,
+    CodeFixContextBase,
     createSymbolTable,
     Debug,
     Diagnostics,
@@ -30,6 +30,7 @@ import {
     isConstructorDeclaration,
     mapDefined,
     ModifierFlags,
+    Node,
     SourceFile,
     Symbol,
     SymbolTable,
@@ -76,7 +77,7 @@ function symbolPointsToNonPrivateMember(symbol: Symbol) {
 }
 
 function addMissingDeclarations(
-    context: TypeConstructionContext,
+    context: CodeFixContextBase,
     implementedTypeNode: ExpressionWithTypeArguments,
     sourceFile: SourceFile,
     classDeclaration: ClassLikeDeclaration,
@@ -90,6 +91,12 @@ function addMissingDeclarations(
     const implementedType = checker.getTypeAtLocation(implementedTypeNode) as InterfaceType;
     const implementedTypeSymbols = checker.getPropertiesOfType(implementedType);
     const nonPrivateAndNotExistedInHeritageClauseMembers = implementedTypeSymbols.filter(and(symbolPointsToNonPrivateMember, symbol => !maybeHeritageClauseSymbol.has(symbol.escapedName)));
+    if (
+        hasBlockingSemanticError(context, implementedTypeNode) ||
+        nonPrivateAndNotExistedInHeritageClauseMembers.some(symbol => symbol.getDeclarations()?.some(declaration => hasBlockingSemanticError(context, declaration)))
+    ) {
+        return;
+    }
 
     const classType = checker.getTypeAtLocation(classDeclaration);
     const constructor = find(classDeclaration.members, m => isConstructorDeclaration(m));
@@ -123,6 +130,12 @@ function addMissingDeclarations(
     }
 }
 
+function hasBlockingSemanticError(context: CodeFixContextBase, node: Node): boolean {
+    return context.program
+        .getSemanticDiagnostics(node.getSourceFile(), context.cancellationToken, [node])
+        .some(diagnostic => !errorCodes.includes(diagnostic.code));
+}
+
 function getHeritageClauseSymbolTable(classDeclaration: ClassLikeDeclaration, checker: TypeChecker): SymbolTable {
     const heritageClauseNode = getEffectiveBaseTypeNode(classDeclaration);
     if (!heritageClauseNode) return createSymbolTable();
diff --git a/tests/cases/fourslash/codeFixClassImplementInterfaceTypeParamInstantiateError.ts b/tests/cases/fourslash/codeFixClassImplementInterfaceTypeParamInstantiateError.ts
index dc816ae86551b..cdc05c06abf3b 100644
--- a/tests/cases/fourslash/codeFixClassImplementInterfaceTypeParamInstantiateError.ts
+++ b/tests/cases/fourslash/codeFixClassImplementInterfaceTypeParamInstantiateError.ts
@@ -8,5 +8,4 @@
 
 // TODO: (arozga) Don't know how to instantiate in codeFix
 // if instantiation is invalid.
-// Should be verify.codeFixAvailable([]);
-verify.codeFixAvailable([{ description: "Implement interface 'I<number>'" }]);
+verify.codeFixAvailable([]);
diff --git a/tests/cases/fourslash/codeFixClassImplementInterfaceUndeclaredSymbol.ts b/tests/cases/fourslash/codeFixClassImplementInterfaceUndeclaredSymbol.ts
index c5bb11e1b40b6..94c5f7c70fe57 100644
--- a/tests/cases/fourslash/codeFixClassImplementInterfaceUndeclaredSymbol.ts
+++ b/tests/cases/fourslash/codeFixClassImplementInterfaceUndeclaredSymbol.ts
@@ -15,5 +15,4 @@
 // Since we can't guess the programmer's intent here, we do nothing.
 
 // TODO: (aozgaa) Acknowledge other errors on class/implemented interface/extended abstract class.
-// Should be verify.codeFixAvailable([]);
-verify.codeFixAvailable([{ description: "Implement interface 'I'" }]);
+verify.codeFixAvailable([]);

From 456f7d951b1f6a869b818b35d24a3c44b818a566 Mon Sep 17 00:00:00 2001
From: Danyal Ahmed <58849388+danyalahmed1995@users.noreply.github.com>
Date: Mon, 11 May 2026 02:44:12 +0500
Subject: [PATCH 2/2] Avoid repeated diagnostics in implement-interface fix

---
 .../fixClassIncorrectlyImplementsInterface.ts | 24 ++++++++++++++-----
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
index 8aefd834ce3fe..535a03526367c 100644
--- a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
+++ b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
@@ -15,6 +15,7 @@ import {
     CodeFixContextBase,
     createSymbolTable,
     Debug,
+    Diagnostic,
     Diagnostics,
     ExpressionWithTypeArguments,
     find,
@@ -91,9 +92,10 @@ function addMissingDeclarations(
     const implementedType = checker.getTypeAtLocation(implementedTypeNode) as InterfaceType;
     const implementedTypeSymbols = checker.getPropertiesOfType(implementedType);
     const nonPrivateAndNotExistedInHeritageClauseMembers = implementedTypeSymbols.filter(and(symbolPointsToNonPrivateMember, symbol => !maybeHeritageClauseSymbol.has(symbol.escapedName)));
+    const semanticDiagnostics = new Map<SourceFile, readonly Diagnostic[]>();
     if (
-        hasBlockingSemanticError(context, implementedTypeNode) ||
-        nonPrivateAndNotExistedInHeritageClauseMembers.some(symbol => symbol.getDeclarations()?.some(declaration => hasBlockingSemanticError(context, declaration)))
+        hasBlockingSemanticError(context, semanticDiagnostics, implementedTypeNode) ||
+        nonPrivateAndNotExistedInHeritageClauseMembers.some(symbol => symbol.getDeclarations()?.some(declaration => hasBlockingSemanticError(context, semanticDiagnostics, declaration)))
     ) {
         return;
     }
@@ -130,10 +132,20 @@ function addMissingDeclarations(
     }
 }
 
-function hasBlockingSemanticError(context: CodeFixContextBase, node: Node): boolean {
-    return context.program
-        .getSemanticDiagnostics(node.getSourceFile(), context.cancellationToken, [node])
-        .some(diagnostic => !errorCodes.includes(diagnostic.code));
+function hasBlockingSemanticError(context: CodeFixContextBase, semanticDiagnostics: Map<SourceFile, readonly Diagnostic[]>, node: Node): boolean {
+    const sourceFile = node.getSourceFile();
+    let diagnostics = semanticDiagnostics.get(sourceFile);
+    if (!diagnostics) {
+        diagnostics = context.program.getSemanticDiagnostics(sourceFile, context.cancellationToken);
+        semanticDiagnostics.set(sourceFile, diagnostics);
+    }
+    return diagnostics.some(diagnostic =>
+        diagnostic.start !== undefined &&
+        diagnostic.length !== undefined &&
+        !errorCodes.includes(diagnostic.code) &&
+        diagnostic.start >= node.pos &&
+        diagnostic.start + diagnostic.length <= node.end
+    );
 }
 
 function getHeritageClauseSymbolTable(classDeclaration: ClassLikeDeclaration, checker: TypeChecker): SymbolTable {