abstract accessors can't have implementations

Author: Arthur Ozga

src/compiler/checker.ts

@@ -21239,6 +21239,9 @@ namespace ts {
             else if (accessor.body === undefined && !(getModifierFlags(accessor) & ModifierFlags.Abstract)) {
                 return grammarErrorAtPos(getSourceFileOfNode(accessor), accessor.end - 1, ";".length, Diagnostics._0_expected, "{");
             }
+            else if (accessor.body && getModifierFlags(accessor) & ModifierFlags.Abstract) {
+                return grammarErrorOnNode(accessor, Diagnostics.An_abstract_accessor_cannot_have_an_implementation);
+            }
             else if (accessor.typeParameters) {
                 return grammarErrorOnNode(accessor.name, Diagnostics.An_accessor_cannot_have_type_parameters);
             }

src/compiler/diagnosticMessages.json

@@ -851,6 +851,10 @@
         "category": "Error",
         "code": 1317
     },
+    "An abstract accessor cannot have an implementation.": {
+        "category": "Error",
+        "code": 1318
+    },
     "Duplicate identifier '{0}'.": {
         "category": "Error",
         "code": 2300

tests/baselines/reference/classAbstractAccessor.errors.txt

@@ -0,0 +1,22 @@
+tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractAccessor.ts(2,17): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
+tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractAccessor.ts(3,17): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
+tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractAccessor.ts(4,17): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
+tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractAccessor.ts(5,17): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
+
+
+==== tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractAccessor.ts (4 errors) ====
+    abstract class A {
+       abstract get a();
+                    ~
+!!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
+       abstract get aa() { return 1; } // error
+                    ~~
+!!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
+       abstract set b(x: string);
+                    ~
+!!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
+       abstract set bb(x: string) {} // error
+                    ~~
+!!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
+    }
+    

tests/baselines/reference/classAbstractAccessor.js

@@ -0,0 +1,27 @@
+//// [classAbstractAccessor.ts]
+abstract class A {
+   abstract get a();
+   abstract get aa() { return 1; } // error
+   abstract set b(x: string);
+   abstract set bb(x: string) {} // error
+}
+
+
+//// [classAbstractAccessor.js]
+var A = (function () {
+    function A() {
+    }
+    Object.defineProperty(A.prototype, "aa", {
+        get: function () { return 1; } // error
+        ,
+        enumerable: true,
+        configurable: true
+    });
+    Object.defineProperty(A.prototype, "bb", {
+        set: function (x) { } // error
+        ,
+        enumerable: true,
+        configurable: true
+    });
+    return A;
+}());

tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractAccessor.ts

@@ -0,0 +1,6 @@
+abstract class A {
+   abstract get a();
+   abstract get aa() { return 1; } // error
+   abstract set b(x: string);
+   abstract set bb(x: string) {} // error
+}