Add args to diagnostic message

src/compiler/core.ts

@@ -1078,7 +1078,7 @@ namespace ts {
         }
     }
 
-    function formatStringFromArgs(text: string, args: { [index: number]: string; }, baseIndex?: number): string {
+    export function formatStringFromArgs(text: string, args: { [index: number]: string; }, baseIndex?: number): string {
         baseIndex = baseIndex || 0;
 
         return text.replace(/{(\d+)}/g, (_match, index?) => args[+index + baseIndex]);

src/compiler/diagnosticMessages.json

@@ -3171,11 +3171,11 @@
         "category": "Message",
         "code": 90002
     },
-    "Change 'extends' to 'implements'": {
+    "Change 'extends' to 'implements'.": {
         "category": "Message",
         "code": 90003
     },
-    "Remove unused identifiers": {
+    "Remove unused identifiers.": {
         "category": "Message",
         "code": 90004
     },
@@ -3183,11 +3183,11 @@
         "category": "Message",
         "code": 90005
     },
-    "Implement interface on class": {
+    "Implement interface '{0}'.": {
         "category": "Message",
         "code": 90006
     },
-    "Implement inherited abstract class": {
+    "Implement inherited abstract class.": {
         "category": "Message",
         "code": 90007
     },

src/services/codefixes/fixClassDoesntImplementInheritedAbstractMember.ts

@@ -20,7 +20,7 @@ namespace ts.codefix {
 
                 const insertion = getMissingMembersInsertion(classDecl, abstractAndNonPrivateExtendsSymbols, checker, context.newLineCharacter);
 
-                if (insertion.length > 0) {
+                if (insertion) {
                     return [{
                         description: getLocaleSpecificMessage(Diagnostics.Implement_inherited_abstract_class),
                         changes: [{

src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts

@@ -27,7 +27,10 @@ namespace ts.codefix {
                 const nonPrivateMembers = implementedTypeSymbols.filter(symbolRefersToNonPrivateMember);
 
                 const insertion = getMissingMembersInsertion(classDecl, nonPrivateMembers, checker, context.newLineCharacter);
-                pushAction(result, insertion, getLocaleSpecificMessage(Diagnostics.Implement_interface_on_class));
+                const message = formatStringFromArgs(getLocaleSpecificMessage(Diagnostics.Implement_interface_0), [implementedTypeNode.getText()]);
+                if (insertion) {
+                    pushAction(result, insertion, message);
+                }
             }
 
             return result;
@@ -39,19 +42,17 @@ namespace ts.codefix {
             }
 
             function pushAction(result: CodeAction[], insertion: string, description: string): void {
-                if (insertion && insertion.length) {
-                    const newAction: CodeAction = {
-                        description: description,
-                        changes: [{
-                            fileName: sourceFile.fileName,
-                            textChanges: [{
-                                span: { start: startPos, length: 0 },
-                                newText: insertion
-                            }]
+                const newAction: CodeAction = {
+                    description: description,
+                    changes: [{
+                        fileName: sourceFile.fileName,
+                        textChanges: [{
+                            span: { start: startPos, length: 0 },
+                            newText: insertion
                         }]
-                    };
-                    result.push(newAction);
-                }
+                    }]
+                };
+                result.push(newAction);
             }
         }
     });

src/services/utilities.ts

@@ -1363,6 +1363,7 @@ namespace ts {
      * Finds members of the resolved type that are missing in the class pointed to by class decl
      * and generates source code for the missing members.
      * @param possiblyMissingSymbols The collection of symbols to filter and then get insertions for.
+     * @returns undefined iff there is no insertion available.
      */
     export function getMissingMembersInsertion(classDeclaration: ClassLikeDeclaration, possiblyMissingSymbols: Symbol[], checker: TypeChecker, newlineChar: string): string {
         const classMembers = classDeclaration.symbol.members;
@@ -1373,7 +1374,7 @@ namespace ts {
         for (const symbol of missingMembers) {
             insertion = insertion.concat(getInsertionForMemberSymbol(symbol, classDeclaration, checker, newlineChar));
         }
-        return insertion;
+        return insertion.length > 0 ? insertion : undefined;
     }
 
     function getInsertionForMemberSymbol(symbol: Symbol, enclosingDeclaration: ClassLikeDeclaration, checker: TypeChecker, newlineChar: string): string {