Fixing #442: Impossible to define static 'length' function on class

src/compiler/checker.ts

@@ -14771,6 +14771,49 @@ namespace ts {
             }
         }
 
+        // Static members may conflict with non-configurable non-writable built-in Function object properties 
+        // see https://github.com/microsoft/typescript/issues/442.
+        function checkClassForStaticPropertyNameConflicts(node: ClassLikeDeclaration) {
+            const message = Diagnostics.Static_property_0_conflicts_with_built_in_property_Function_0_of_constructor_function_1;
+            const className = getSymbolOfNode(node).name;
+            for (const member of node.members) {
+                const isStatic = forEach(member.modifiers, (m: Modifier) => m.kind  === SyntaxKind.StaticKeyword);
+                const isMethod = member.kind === SyntaxKind.MethodDeclaration;
+                const memberNameNode = member.name;
+                if (isStatic && memberNameNode) {
+                    const memberName = getPropertyNameForPropertyNameNode(memberNameNode);
+                    if (languageVersion <= ScriptTarget.ES5) {  // ES3, ES5
+                        // see also http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.3
+                        // see also http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.5
+                        if (memberName === "prototype" ||
+                            memberName === "name" ||
+                            memberName === "length" ||
+                            memberName === "caller" ||
+                            memberName === "arguments"
+                        ) {
+                            error(memberNameNode, message, memberName, className);
+                        }
+                    }
+                    else { // ES6+
+                        // see also http://www.ecma-international.org/ecma-262/6.0/#sec-properties-of-the-function-constructor
+                        // see also http://www.ecma-international.org/ecma-262/6.0/#sec-function-instances
+                        if (memberName === "prototype") {
+                            error(memberNameNode, message, memberName, className);
+                        }
+                        else if ((
+                            memberName === "name" ||
+                            memberName === "length" ||
+                            memberName === "caller" ||
+                            memberName === "arguments") &&
+                            isMethod === false
+                        ) {
+                            error(memberNameNode, message, memberName, className);
+                        }
+                    }
+                }
+            }
+        }
+
         function checkObjectTypeForDuplicateDeclarations(node: TypeLiteralNode | InterfaceDeclaration) {
             const names = createMap<boolean>();
             for (const member of node.members) {
@@ -17259,6 +17302,7 @@ namespace ts {
             const staticType = <ObjectType>getTypeOfSymbol(symbol);
             checkTypeParameterListsIdentical(node, symbol);
             checkClassForDuplicateDeclarations(node);
+            checkClassForStaticPropertyNameConflicts(node);
 
             const baseTypeNode = getClassExtendsHeritageClauseElement(node);
             if (baseTypeNode) {

src/compiler/diagnosticMessages.json

@@ -1983,7 +1983,10 @@
         "category": "Error",
         "code": 2697
     },
-
+    "Static property '{0}' conflicts with built-in property 'Function.{0}' of constructor function '{1}'.": {
+        "category": "Error",
+        "code": 2699
+    },
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
         "code": 4000
@@ -2268,7 +2271,6 @@
         "category": "Message",
         "code": 4090
     },
-
     "The current host does not support the '{0}' option.": {
         "category": "Error",
         "code": 5001

tests/baselines/reference/propertyNamedPrototype.errors.txt

@@ -0,0 +1,10 @@
+tests/cases/conformance/classes/propertyMemberDeclarations/propertyNamedPrototype.ts(3,12): error TS2699: Static property 'prototype' conflicts with built-in property 'Function.prototype' of constructor function 'C'.
+
+
+==== tests/cases/conformance/classes/propertyMemberDeclarations/propertyNamedPrototype.ts (1 errors) ====
+    class C {
+        prototype: number; // ok
+        static prototype: C; // error
+               ~~~~~~~~~
+!!! error TS2699: Static property 'prototype' conflicts with built-in property 'Function.prototype' of constructor function 'C'.
+    }

tests/baselines/reference/staticMemberOfClassAndPublicMemberOfAnotherClassAssignment.errors.txt

@@ -1,43 +1,43 @@
 tests/cases/compiler/staticMemberOfClassAndPublicMemberOfAnotherClassAssignment.ts(12,1): error TS2322: Type 'C' is not assignable to type 'A'.
-  Property 'name' is missing in type 'C'.
+  Property 'prop' is missing in type 'C'.
 tests/cases/compiler/staticMemberOfClassAndPublicMemberOfAnotherClassAssignment.ts(13,1): error TS2322: Type 'typeof B' is not assignable to type 'A'.
-  Property 'name' is missing in type 'typeof B'.
+  Property 'prop' is missing in type 'typeof B'.
 tests/cases/compiler/staticMemberOfClassAndPublicMemberOfAnotherClassAssignment.ts(16,5): error TS2322: Type 'C' is not assignable to type 'B'.
-  Property 'name' is missing in type 'C'.
+  Property 'prop' is missing in type 'C'.
 tests/cases/compiler/staticMemberOfClassAndPublicMemberOfAnotherClassAssignment.ts(17,1): error TS2322: Type 'typeof B' is not assignable to type 'B'.
-  Property 'name' is missing in type 'typeof B'.
+  Property 'prop' is missing in type 'typeof B'.
 
 
 ==== tests/cases/compiler/staticMemberOfClassAndPublicMemberOfAnotherClassAssignment.ts (4 errors) ====
     interface A {
-        name();
+        prop();
     }
     class B {
-        public name() { }
+        public prop() { }
     }
     class C {
-        public static name() { }
+        public static prop() { }
     }
 
     var a: A = new B();
-    a = new C(); // error name is missing
+    a = new C(); // error prop is missing
     ~
 !!! error TS2322: Type 'C' is not assignable to type 'A'.
-!!! error TS2322:   Property 'name' is missing in type 'C'.
-    a = B; // error name is missing
+!!! error TS2322:   Property 'prop' is missing in type 'C'.
+    a = B; // error prop is missing
     ~
 !!! error TS2322: Type 'typeof B' is not assignable to type 'A'.
-!!! error TS2322:   Property 'name' is missing in type 'typeof B'.
+!!! error TS2322:   Property 'prop' is missing in type 'typeof B'.
     a = C;
 
-    var b: B = new C(); // error name is missing
+    var b: B = new C(); // error prop is missing
         ~
 !!! error TS2322: Type 'C' is not assignable to type 'B'.
-!!! error TS2322:   Property 'name' is missing in type 'C'.
-    b = B; // error name is missing
+!!! error TS2322:   Property 'prop' is missing in type 'C'.
+    b = B; // error prop is missing
     ~
 !!! error TS2322: Type 'typeof B' is not assignable to type 'B'.
-!!! error TS2322:   Property 'name' is missing in type 'typeof B'.
+!!! error TS2322:   Property 'prop' is missing in type 'typeof B'.
     b = C;
     b = a;
 

tests/baselines/reference/staticMemberOfClassAndPublicMemberOfAnotherClassAssignment.js

@@ -1,21 +1,21 @@
 //// [staticMemberOfClassAndPublicMemberOfAnotherClassAssignment.ts]
 interface A {
-    name();
+    prop();
 }
 class B {
-    public name() { }
+    public prop() { }
 }
 class C {
-    public static name() { }
+    public static prop() { }
 }
 
 var a: A = new B();
-a = new C(); // error name is missing
-a = B; // error name is missing
+a = new C(); // error prop is missing
+a = B; // error prop is missing
 a = C;
 
-var b: B = new C(); // error name is missing
-b = B; // error name is missing
+var b: B = new C(); // error prop is missing
+b = B; // error prop is missing
 b = C;
 b = a;
 
@@ -29,21 +29,21 @@ c = a;
 var B = (function () {
     function B() {
     }
-    B.prototype.name = function () { };
+    B.prototype.prop = function () { };
     return B;
 }());
 var C = (function () {
     function C() {
     }
-    C.name = function () { };
+    C.prop = function () { };
     return C;
 }());
 var a = new B();
-a = new C(); // error name is missing
-a = B; // error name is missing
+a = new C(); // error prop is missing
+a = B; // error prop is missing
 a = C;
-var b = new C(); // error name is missing
-b = B; // error name is missing
+var b = new C(); // error prop is missing
+b = B; // error prop is missing
 b = C;
 b = a;
 var c = new B();

tests/baselines/reference/staticPropertyNameConflictsEs5.errors.txt

@@ -0,0 +1,92 @@
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(4,12): error TS2699: Static property 'name' conflicts with built-in property 'Function.name' of constructor function 'StaticName'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(9,12): error TS2699: Static property 'name' conflicts with built-in property 'Function.name' of constructor function 'StaticNameFn'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(15,12): error TS2699: Static property 'length' conflicts with built-in property 'Function.length' of constructor function 'StaticLength'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(20,12): error TS2699: Static property 'length' conflicts with built-in property 'Function.length' of constructor function 'StaticLengthFn'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(26,12): error TS2699: Static property 'prototype' conflicts with built-in property 'Function.prototype' of constructor function 'StaticPrototype'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(31,12): error TS2300: Duplicate identifier 'prototype'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(31,12): error TS2699: Static property 'prototype' conflicts with built-in property 'Function.prototype' of constructor function 'StaticPrototypeFn'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(37,12): error TS2699: Static property 'caller' conflicts with built-in property 'Function.caller' of constructor function 'StaticCaller'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(42,12): error TS2699: Static property 'caller' conflicts with built-in property 'Function.caller' of constructor function 'StaticCallerFn'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(48,12): error TS2699: Static property 'arguments' conflicts with built-in property 'Function.arguments' of constructor function 'StaticArguments'.
+tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts(53,12): error TS2699: Static property 'arguments' conflicts with built-in property 'Function.arguments' of constructor function 'StaticArgumentsFn'.
+
+
+==== tests/cases/conformance/classes/propertyMemberDeclarations/staticPropertyNameConflictsEs5.ts (11 errors) ====
+
+    // static name
+    class StaticName {
+        static name: number; // error
+               ~~~~
+!!! error TS2699: Static property 'name' conflicts with built-in property 'Function.name' of constructor function 'StaticName'.
+        name: string; // ok
+    }
+
+    class StaticNameFn {
+        static name() {} // error
+               ~~~~
+!!! error TS2699: Static property 'name' conflicts with built-in property 'Function.name' of constructor function 'StaticNameFn'.
+        name() {} // ok
+    }
+
+
+    class StaticLength {
+        static length: number; // error
+               ~~~~~~
+!!! error TS2699: Static property 'length' conflicts with built-in property 'Function.length' of constructor function 'StaticLength'.
+        length: string; // ok
+    }
+
+    class StaticLengthFn {
+        static length() {} // error
+               ~~~~~~
+!!! error TS2699: Static property 'length' conflicts with built-in property 'Function.length' of constructor function 'StaticLengthFn'.
+        length() {} // ok
+    }
+
+
+    class StaticPrototype {
+        static prototype: number; // error
+               ~~~~~~~~~
+!!! error TS2699: Static property 'prototype' conflicts with built-in property 'Function.prototype' of constructor function 'StaticPrototype'.
+        prototype: string; // ok
+    }
+
+    class StaticPrototypeFn {
+        static prototype() {} // error
+               ~~~~~~~~~
+!!! error TS2300: Duplicate identifier 'prototype'.
+               ~~~~~~~~~
+!!! error TS2699: Static property 'prototype' conflicts with built-in property 'Function.prototype' of constructor function 'StaticPrototypeFn'.
+        prototype() {} // ok
+    }
+
+
+    class StaticCaller {
+        static caller: number; // error
+               ~~~~~~
+!!! error TS2699: Static property 'caller' conflicts with built-in property 'Function.caller' of constructor function 'StaticCaller'.
+        caller: string; // ok
+    }
+
+    class StaticCallerFn {
+        static caller() {} // error
+               ~~~~~~
+!!! error TS2699: Static property 'caller' conflicts with built-in property 'Function.caller' of constructor function 'StaticCallerFn'.
+        caller() {} // ok
+    }
+
+
+    class StaticArguments {
+        static arguments: number; // error
+               ~~~~~~~~~
+!!! error TS2699: Static property 'arguments' conflicts with built-in property 'Function.arguments' of constructor function 'StaticArguments'.
+        arguments: string; // ok
+    }
+
+    class StaticArgumentsFn {
+        static arguments() {} // error
+               ~~~~~~~~~
+!!! error TS2699: Static property 'arguments' conflicts with built-in property 'Function.arguments' of constructor function 'StaticArgumentsFn'.
+        arguments() {} // ok
+    }
+