add lookup for extends class when implement interface

src/services/codefixes/helpers.ts

@@ -7,14 +7,25 @@ namespace ts.codefix {
      * @returns Empty string iff there are no member insertions.
      */
     export function createMissingMemberNodes(classDeclaration: ClassLikeDeclaration, possiblyMissingSymbols: ReadonlyArray<Symbol>, checker: TypeChecker, preferences: UserPreferences, out: (node: ClassElement) => void): void {
+        const heritageClauseSymbolTable = getHeritageClauseSymbolTable(classDeclaration, checker);
+
         const classMembers = classDeclaration.symbol.members!;
         for (const symbol of possiblyMissingSymbols) {
-            if (!classMembers.has(symbol.escapedName)) {
+            if (!classMembers.has(symbol.escapedName) && !(heritageClauseSymbolTable && heritageClauseSymbolTable.has(symbol.escapedName))) {
                 addNewNodeForMemberSymbol(symbol, classDeclaration, checker, preferences, out);
             }
         }
     }
 
+    function getHeritageClauseSymbolTable (classDeclaration: ClassLikeDeclaration, checker: TypeChecker): SymbolTable | undefined {
+        const heritageClauseNode = getClassExtendsHeritageClauseElement(classDeclaration);
+        if (!heritageClauseNode) return undefined;
+        const heritageClauseType = checker.getTypeAtLocation(heritageClauseNode) as InterfaceType;
+        const heritageClauseTypeSymbols = checker.getPropertiesOfType(heritageClauseType);
+        const nonPrivateMembers = heritageClauseTypeSymbols.filter(symbol => !(getModifierFlags(symbol.valueDeclaration) & ModifierFlags.Private));
+        return createSymbolTable(nonPrivateMembers);
+    }
+
     /**
      * @returns Empty string iff there we can't figure out a representation for `symbol` in `enclosingDeclaration`.
      */

tests/cases/fourslash/codeFixClassImplementInterfaceHeritageClauseAlreadyHaveMember.ts

@@ -0,0 +1,39 @@
+/// <reference path='fourslash.ts' />
+
+//// class Base {
+////     foo: number;
+//// }
+//// 
+//// class D extends Base {
+////     bar: number;
+//// }
+//// 
+//// interface I {
+////     foo: number;
+////     bar: number;
+////     baz: number;
+//// }
+////
+//// class C extends D implements I { }
+
+verify.codeFix({
+    description: "Implement interface 'I'",
+    newFileContent:
+`class Base {
+    foo: number;
+}
+
+class D extends Base {
+    bar: number;
+}
+
+interface I {
+    foo: number;
+    bar: number;
+    baz: number;
+}
+
+class C extends D implements I {
+    baz: number;
+}`,
+});