Improve decorator on overload error message (fixes microsoft#6064)

pimterry · pimterry · commit 411e90df44c6 · 2015-12-17T11:56:02.000+01:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -15544,7 +15544,12 @@ namespace ts {
                 return false;
             }
             if (!nodeCanBeDecorated(node)) {
-                return grammarErrorOnFirstToken(node, Diagnostics.Decorators_are_not_valid_here);
+                if (node.kind === SyntaxKind.MethodDeclaration && !ts.nodeIsPresent((<MethodDeclaration>node).body)) {
+                    return grammarErrorOnFirstToken(node, Diagnostics.A_decorator_can_only_decorate_a_method_implementation_not_an_overload);
+                }
+                else {
+                    return grammarErrorOnFirstToken(node, Diagnostics.Decorators_are_not_valid_here);
+                }
             }
             else if (node.kind === SyntaxKind.GetAccessor || node.kind === SyntaxKind.SetAccessor) {
                 const accessors = getAllAccessorDeclarations((<ClassDeclaration>node.parent).members, <AccessorDeclaration>node);
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
@@ -795,6 +795,10 @@
         "category": "Error",
         "code": 1248
     },
+    "A decorator can only decorate a method implementation, not an overload.": {
+        "category": "Error",
+        "code": 1249
+    }, 
     "'with' statements are not allowed in an async function block.": {
         "category": "Error",
         "code": 1300
diff --git a/tests/baselines/reference/decoratorOnClassMethodOverload1.errors.txt b/tests/baselines/reference/decoratorOnClassMethodOverload1.errors.txt
@@ -0,0 +1,13 @@
+tests/cases/conformance/decorators/class/method/decoratorOnClassMethodOverload1.ts(4,5): error TS1249: A decorator can only decorate a method implementation, not an overload.
+
+
+==== tests/cases/conformance/decorators/class/method/decoratorOnClassMethodOverload1.ts (1 errors) ====
+    declare function dec<T>(target: any, propertyKey: string, descriptor: TypedPropertyDescriptor<T>): TypedPropertyDescriptor<T>;
+    
+    class C {
+        @dec
+        ~
+!!! error TS1249: A decorator can only decorate a method implementation, not an overload.
+        method()
+        method() { }
+    }
diff --git a/tests/baselines/reference/decoratorOnClassMethodOverload1.js b/tests/baselines/reference/decoratorOnClassMethodOverload1.js
@@ -0,0 +1,16 @@
+//// [decoratorOnClassMethodOverload1.ts]
+declare function dec<T>(target: any, propertyKey: string, descriptor: TypedPropertyDescriptor<T>): TypedPropertyDescriptor<T>;
+
+class C {
+    @dec
+    method()
+    method() { }
+}
+
+//// [decoratorOnClassMethodOverload1.js]
+var C = (function () {
+    function C() {
+    }
+    C.prototype.method = function () { };
+    return C;
+}());
diff --git a/tests/cases/conformance/decorators/class/method/decoratorOnClassMethodOverload1.ts b/tests/cases/conformance/decorators/class/method/decoratorOnClassMethodOverload1.ts
@@ -0,0 +1,9 @@
+// @target: ES5
+// @experimentaldecorators: true
+declare function dec<T>(target: any, propertyKey: string, descriptor: TypedPropertyDescriptor<T>): TypedPropertyDescriptor<T>;
+
+class C {
+    @dec
+    method()
+    method() { }
+}

Original file line number	Diff line number	Diff line change
`@@ -15544,7 +15544,12 @@ namespace ts {`
`15544`	`15544`	`return false;`
`15545`	`15545`	`}`
`15546`	`15546`	`if (!nodeCanBeDecorated(node)) {`
`15547`		`- return grammarErrorOnFirstToken(node, Diagnostics.Decorators_are_not_valid_here);`
	`15547`	`+ if (node.kind === SyntaxKind.MethodDeclaration && !ts.nodeIsPresent((<MethodDeclaration>node).body)) {`
	`15548`	`+ return grammarErrorOnFirstToken(node, Diagnostics.A_decorator_can_only_decorate_a_method_implementation_not_an_overload);`
	`15549`	`+ }`
	`15550`	`+ else {`
	`15551`	`+ return grammarErrorOnFirstToken(node, Diagnostics.Decorators_are_not_valid_here);`
	`15552`	`+ }`
`15548`	`15553`	`}`
`15549`	`15554`	`else if (node.kind === SyntaxKind.GetAccessor \|\| node.kind === SyntaxKind.SetAccessor) {`
`15550`	`15555`	`const accessors = getAllAccessorDeclarations((<ClassDeclaration>node.parent).members, <AccessorDeclaration>node);`