Wrap classes with decorators or static properties in an IIFE, even for ES2015+

src/compiler/transformers/ts.ts

@@ -23,11 +23,10 @@ namespace ts {
         IsNamedExternalExport = 1 << 4,
         IsDefaultExternalExport = 1 << 5,
         IsDerivedClass = 1 << 6,
-        UseImmediatelyInvokedFunctionExpression = 1 << 7,
 
         HasAnyDecorators = HasConstructorDecorators | HasMemberDecorators,
         NeedsName = HasStaticInitializedProperties | HasMemberDecorators,
-        MayNeedImmediatelyInvokedFunctionExpression = HasAnyDecorators | HasStaticInitializedProperties,
+        UseImmediatelyInvokedFunctionExpression = HasAnyDecorators | HasStaticInitializedProperties,
         IsExported = IsExportOfNamespace | IsDefaultExternalExport | IsNamedExternalExport,
     }
 
@@ -590,7 +589,6 @@ namespace ts {
             if (isExportOfNamespace(node)) facts |= ClassFacts.IsExportOfNamespace;
             else if (isDefaultExternalModuleExport(node)) facts |= ClassFacts.IsDefaultExternalExport;
             else if (isNamedExternalModuleExport(node)) facts |= ClassFacts.IsNamedExternalExport;
-            if (languageVersion <= ScriptTarget.ES5 && (facts & ClassFacts.MayNeedImmediatelyInvokedFunctionExpression)) facts |= ClassFacts.UseImmediatelyInvokedFunctionExpression;
             return facts;
         }
 
@@ -661,6 +659,12 @@ namespace ts {
                 const iife = createImmediatelyInvokedArrowFunction(statements);
                 setEmitFlags(iife, EmitFlags.TypeScriptClassWrapper);
 
+                // Class comment is already added by the ES2015 transform when targeting ES5 or below.
+                // Only add if targetting ES2015+ to prevent duplicates
+                if (languageVersion > ScriptTarget.ES5) {
+                    addSyntheticLeadingComment(iife, SyntaxKind.MultiLineCommentTrivia, "* @class ");
+                }
+
                 const varStatement = createVariableStatement(
                     /*modifiers*/ undefined,
                     createVariableDeclarationList([
@@ -669,7 +673,7 @@ namespace ts {
                             /*type*/ undefined,
                             iife
                         )
-                    ])
+                    ], languageVersion > ScriptTarget.ES5 ? NodeFlags.Let : undefined)
                 );
 
                 setOriginalNode(varStatement, node);

tests/baselines/reference/awaitAndYieldInProperty.js

@@ -19,27 +19,31 @@ async function* test(x: Promise<string>) {
 
 //// [awaitAndYieldInProperty.js]
 async function* test(x) {
-    var _a, _b, _c, _d, _e, _f, _g, _h, _j;
-    class C {
-        constructor() {
-            this[_a] = await x;
-            this[_c] = yield 2;
-        }
-    }
-    _a = await x, _b = await x, _c = yield 1, _d = yield 3;
-    C[_b] = await x;
-    C[_d] = yield 4;
-    return _j = class {
+    var _a, _b, _c, _d, _e;
+    let C = /** @class */ (() => {
+        var _e, _f, _g, _h;
+        class C {
             constructor() {
                 this[_e] = await x;
                 this[_g] = yield 2;
             }
+        }
+        _e = await x, _f = await x, _g = yield 1, _h = yield 3;
+        C[_f] = await x;
+        C[_h] = yield 4;
+        return C;
+    })();
+    return _e = class {
+            constructor() {
+                this[_a] = await x;
+                this[_c] = yield 2;
+            }
         },
-        _e = await x,
-        _f = await x,
-        _g = yield 1,
-        _h = yield 3,
-        _j[_f] = await x,
-        _j[_h] = yield 4,
-        _j;
+        _a = await x,
+        _b = await x,
+        _c = yield 1,
+        _d = yield 3,
+        _e[_b] = await x,
+        _e[_d] = yield 4,
+        _e;
 }

tests/baselines/reference/classDeclarationCheckUsedBeforeDefinitionInItself.js

@@ -4,6 +4,9 @@ class C3 {
 }
 
 //// [classDeclarationCheckUsedBeforeDefinitionInItself.js]
-class C3 {
-}
-C3.intance = new C3(); // ok
+let C3 = /** @class */ (() => {
+    class C3 {
+    }
+    C3.intance = new C3(); // ok
+    return C3;
+})();

tests/baselines/reference/computedPropertyNames12_ES6.js

@@ -17,16 +17,19 @@ class C {
 }
 
 //// [computedPropertyNames12_ES6.js]
-var _a, _b, _c;
 var s;
 var n;
 var a;
-class C {
-    constructor() {
-        this[_a] = n;
-        this[_b] = 2;
-        this[`hello bye`] = 0;
+let C = /** @class */ (() => {
+    var _a, _b, _c;
+    class C {
+        constructor() {
+            this[_a] = n;
+            this[_b] = 2;
+            this[`hello bye`] = 0;
+        }
     }
-}
-_a = n, s + s, _b = s + n, +s, _c = `hello ${a} bye`;
-C[_c] = 0;
+    _a = n, s + s, _b = s + n, +s, _c = `hello ${a} bye`;
+    C[_c] = 0;
+    return C;
+})();

tests/baselines/reference/computedPropertyNamesWithStaticProperty.js

@@ -11,13 +11,16 @@ class C {
 }
 
 //// [computedPropertyNamesWithStaticProperty.js]
-class C {
-    get [C.staticProp]() {
-        return "hello";
+let C = /** @class */ (() => {
+    class C {
+        get [C.staticProp]() {
+            return "hello";
+        }
+        set [C.staticProp](x) {
+            var y = x;
+        }
+        [C.staticProp]() { }
     }
-    set [C.staticProp](x) {
-        var y = x;
-    }
-    [C.staticProp]() { }
-}
-C.staticProp = 10;
+    C.staticProp = 10;
+    return C;
+})();

tests/baselines/reference/decoratedClassExportsCommonJS1.js

@@ -14,12 +14,15 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
     else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
     return c > 3 && r && Object.defineProperty(target, key, r), r;
 };
-var Testing123_1;
 Object.defineProperty(exports, "__esModule", { value: true });
-let Testing123 = Testing123_1 = class Testing123 {
-};
-Testing123.prop1 = Testing123_1.prop0;
-Testing123 = Testing123_1 = __decorate([
-    Something({ v: () => Testing123_1 })
-], Testing123);
+let Testing123 = /** @class */ (() => {
+    var Testing123_1;
+    let Testing123 = Testing123_1 = class Testing123 {
+    };
+    Testing123.prop1 = Testing123_1.prop0;
+    Testing123 = Testing123_1 = __decorate([
+        Something({ v: () => Testing123_1 })
+    ], Testing123);
+    return Testing123;
+})();
 exports.Testing123 = Testing123;

tests/baselines/reference/decoratedClassExportsCommonJS2.js

@@ -12,11 +12,14 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
     else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
     return c > 3 && r && Object.defineProperty(target, key, r), r;
 };
-var Testing123_1;
 Object.defineProperty(exports, "__esModule", { value: true });
-let Testing123 = Testing123_1 = class Testing123 {
-};
-Testing123 = Testing123_1 = __decorate([
-    Something({ v: () => Testing123_1 })
-], Testing123);
+let Testing123 = /** @class */ (() => {
+    var Testing123_1;
+    let Testing123 = Testing123_1 = class Testing123 {
+    };
+    Testing123 = Testing123_1 = __decorate([
+        Something({ v: () => Testing123_1 })
+    ], Testing123);
+    return Testing123;
+})();
 exports.Testing123 = Testing123;

tests/baselines/reference/decoratedClassExportsSystem1.js

@@ -16,17 +16,21 @@ System.register([], function (exports_1, context_1) {
         else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
         return c > 3 && r && Object.defineProperty(target, key, r), r;
     };
-    var Testing123_1, Testing123;
+    var Testing123;
     var __moduleName = context_1 && context_1.id;
     return {
         setters: [],
         execute: function () {
-            Testing123 = Testing123_1 = class Testing123 {
-            };
-            Testing123.prop1 = Testing123_1.prop0;
-            Testing123 = Testing123_1 = __decorate([
-                Something({ v: () => Testing123_1 })
-            ], Testing123);
+            Testing123 = /** @class */ (() => {
+                var Testing123_1;
+                let Testing123 = Testing123_1 = class Testing123 {
+                };
+                Testing123.prop1 = Testing123_1.prop0;
+                Testing123 = Testing123_1 = __decorate([
+                    Something({ v: () => Testing123_1 })
+                ], Testing123);
+                return Testing123;
+            })();
             exports_1("Testing123", Testing123);
         }
     };

tests/baselines/reference/decoratedClassExportsSystem2.js

@@ -13,16 +13,20 @@ System.register([], function (exports_1, context_1) {
         else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
         return c > 3 && r && Object.defineProperty(target, key, r), r;
     };
-    var Testing123_1, Testing123;
+    var Testing123;
     var __moduleName = context_1 && context_1.id;
     return {
         setters: [],
         execute: function () {
-            Testing123 = Testing123_1 = class Testing123 {
-            };
-            Testing123 = Testing123_1 = __decorate([
-                Something({ v: () => Testing123_1 })
-            ], Testing123);
+            Testing123 = /** @class */ (() => {
+                var Testing123_1;
+                let Testing123 = Testing123_1 = class Testing123 {
+                };
+                Testing123 = Testing123_1 = __decorate([
+                    Something({ v: () => Testing123_1 })
+                ], Testing123);
+                return Testing123;
+            })();
             exports_1("Testing123", Testing123);
         }
     };

tests/baselines/reference/decoratedClassFromExternalModule.js

@@ -17,10 +17,13 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
     return c > 3 && r && Object.defineProperty(target, key, r), r;
 };
 function decorate(target) { }
-let Decorated = class Decorated {
-};
-Decorated = __decorate([
-    decorate
-], Decorated);
+let Decorated = /** @class */ (() => {
+    let Decorated = class Decorated {
+    };
+    Decorated = __decorate([
+        decorate
+    ], Decorated);
+    return Decorated;
+})();
 export default Decorated;
 //// [undecorated.js]

tests/baselines/reference/decoratedDefaultExportsGetExportedAmd.js

@@ -24,11 +24,14 @@ define(["require", "exports"], function (require, exports) {
     "use strict";
     Object.defineProperty(exports, "__esModule", { value: true });
     var decorator;
-    let Foo = class Foo {
-    };
-    Foo = __decorate([
-        decorator
-    ], Foo);
+    let Foo = /** @class */ (() => {
+        let Foo = class Foo {
+        };
+        Foo = __decorate([
+            decorator
+        ], Foo);
+        return Foo;
+    })();
     exports.default = Foo;
 });
 //// [b.js]
@@ -42,10 +45,13 @@ define(["require", "exports"], function (require, exports) {
     "use strict";
     Object.defineProperty(exports, "__esModule", { value: true });
     var decorator;
-    let default_1 = class {
-    };
-    default_1 = __decorate([
-        decorator
-    ], default_1);
+    let default_1 = /** @class */ (() => {
+        let default_1 = class {
+        };
+        default_1 = __decorate([
+            decorator
+        ], default_1);
+        return default_1;
+    })();
     exports.default = default_1;
 });

tests/baselines/reference/decoratedDefaultExportsGetExportedCommonjs.js

@@ -23,11 +23,14 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
 };
 Object.defineProperty(exports, "__esModule", { value: true });
 var decorator;
-let Foo = class Foo {
-};
-Foo = __decorate([
-    decorator
-], Foo);
+let Foo = /** @class */ (() => {
+    let Foo = class Foo {
+    };
+    Foo = __decorate([
+        decorator
+    ], Foo);
+    return Foo;
+})();
 exports.default = Foo;
 //// [b.js]
 "use strict";
@@ -39,9 +42,12 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
 };
 Object.defineProperty(exports, "__esModule", { value: true });
 var decorator;
-let default_1 = class {
-};
-default_1 = __decorate([
-    decorator
-], default_1);
+let default_1 = /** @class */ (() => {
+    let default_1 = class {
+    };
+    default_1 = __decorate([
+        decorator
+    ], default_1);
+    return default_1;
+})();
 exports.default = default_1;

tests/baselines/reference/decoratedDefaultExportsGetExportedSystem.js

@@ -26,11 +26,14 @@ System.register([], function (exports_1, context_1) {
     return {
         setters: [],
         execute: function () {
-            Foo = class Foo {
-            };
-            Foo = __decorate([
-                decorator
-            ], Foo);
+            Foo = /** @class */ (() => {
+                let Foo = class Foo {
+                };
+                Foo = __decorate([
+                    decorator
+                ], Foo);
+                return Foo;
+            })();
             exports_1("default", Foo);
         }
     };
@@ -49,11 +52,14 @@ System.register([], function (exports_1, context_1) {
     return {
         setters: [],
         execute: function () {
-            default_1 = class {
-            };
-            default_1 = __decorate([
-                decorator
-            ], default_1);
+            default_1 = /** @class */ (() => {
+                let default_1 = class {
+                };
+                default_1 = __decorate([
+                    decorator
+                ], default_1);
+                return default_1;
+            })();
             exports_1("default", default_1);
         }
     };