Export anonymous functions in 2 steps, declare as variable and then assign to exports. (#39820)

* Preserve the variable name when exporting an arrow or anonymous function
 This allows the browser or node to properly name the (arrow) function

* Updated tests to reflect previous change

* Remove duplicated comment

* Transforms variable.initializer using moduleExpressionElementVisitor

* PR feedback: rbuckton
 - Use isArrowFunction and isFunctionExpression

* PR feedback: rbuckton
- Consider ClassExpresion, they can also be named based on the
  variable.

Author: josejulio

src/compiler/transformers/module/module.ts

@@ -1195,6 +1195,7 @@ namespace ts {
 
             if (hasSyntacticModifier(node, ModifierFlags.Export)) {
                 let modifiers: NodeArray<Modifier> | undefined;
+                let removeCommentsOnExpressions = false;
 
                 // If we're exporting these variables, then these just become assignments to 'exports.x'.
                 for (const variable of node.declarationList.declarations) {
@@ -1206,7 +1207,31 @@ namespace ts {
                         variables = append(variables, variable);
                     }
                     else if (variable.initializer) {
-                        expressions = append(expressions, transformInitializedVariable(variable as InitializedVariableDeclaration));
+                        if (!isBindingPattern(variable.name) && (isArrowFunction(variable.initializer) || isFunctionExpression(variable.initializer) || isClassExpression(variable.initializer))) {
+                            const expression = factory.createAssignment(
+                                setTextRange(
+                                    factory.createPropertyAccessExpression(
+                                        factory.createIdentifier("exports"),
+                                        variable.name
+                                    ),
+                                    /*location*/ variable.name
+                                ),
+                                factory.createIdentifier(getTextOfIdentifierOrLiteral(variable.name))
+                            );
+                            const updatedVariable = factory.createVariableDeclaration(
+                                variable.name,
+                                variable.exclamationToken,
+                                variable.type,
+                                visitNode(variable.initializer, moduleExpressionElementVisitor)
+                            );
+
+                            variables = append(variables, updatedVariable);
+                            expressions = append(expressions, expression);
+                            removeCommentsOnExpressions = true;
+                        }
+                        else {
+                            expressions = append(expressions, transformInitializedVariable(variable as InitializedVariableDeclaration));
+                        }
                     }
                 }
 
@@ -1215,7 +1240,11 @@ namespace ts {
                 }
 
                 if (expressions) {
-                    statements = append(statements, setOriginalNode(setTextRange(factory.createExpressionStatement(factory.inlineExpressions(expressions)), node), node));
+                    const statement = setOriginalNode(setTextRange(factory.createExpressionStatement(factory.inlineExpressions(expressions)), node), node);
+                    if (removeCommentsOnExpressions) {
+                        removeAllComments(statement);
+                    }
+                    statements = append(statements, statement);
                 }
             }
             else {

tests/baselines/reference/aliasUsedAsNameValue.js

@@ -36,7 +36,8 @@ exports.a = void 0;
 ///<reference path='aliasUsedAsNameValue_1.ts' />
 var mod = require("./aliasUsedAsNameValue_0");
 var b = require("./aliasUsedAsNameValue_1");
-exports.a = function () {
+var a = function () {
     //var x = mod.id; // TODO needed hack that mod is loaded
     b.b(mod);
 };
+exports.a = a;

tests/baselines/reference/declarationEmitAliasExportStar.js

@@ -30,7 +30,8 @@ __exportStar(require("./thingB"), exports);
 "use strict";
 exports.__esModule = true;
 exports.thing2 = void 0;
-exports.thing2 = function (param) { return null; };
+var thing2 = function (param) { return null; };
+exports.thing2 = thing2;
 
 
 //// [thingB.d.ts]

tests/baselines/reference/declarationEmitBundleWithAmbientReferences.js

@@ -29,9 +29,10 @@ define("conditional_directive_field", ["require", "exports"], function (require,
     "use strict";
     exports.__esModule = true;
     exports.build = void 0;
-    exports.build = function () {
+    var build = function () {
         return null;
     };
+    exports.build = build;
 });
 
 

tests/baselines/reference/declarationEmitComputedNameCausesImportToBePainted.js

@@ -28,10 +28,11 @@ var context_1 = require("./context");
 exports.context = (_a = {},
     _a[context_1.Key] = 'bar',
     _a);
-exports.withContext = function (_a) {
+var withContext = function (_a) {
     var _b = context_1.Key, value = _a[_b];
     return value;
 };
+exports.withContext = withContext;
 
 
 //// [context.d.ts]

tests/baselines/reference/declarationEmitExpandoWithGenericConstraint.js

@@ -18,8 +18,10 @@ Point.zero = (): Point => Point(0, 0);
 "use strict";
 exports.__esModule = true;
 exports.Rect = exports.Point = void 0;
-exports.Point = function (x, y) { return ({ x: x, y: y }); };
-exports.Rect = function (a, b) { return ({ a: a, b: b }); };
+var Point = function (x, y) { return ({ x: x, y: y }); };
+exports.Point = Point;
+var Rect = function (a, b) { return ({ a: a, b: b }); };
+exports.Rect = Rect;
 exports.Point.zero = function () { return exports.Point(0, 0); };
 
 

tests/baselines/reference/declarationEmitExportAliasVisibiilityMarking.js

@@ -25,7 +25,8 @@ exports["default"] = (function (suit, rank) { return ({ suit: suit, rank: rank }
 "use strict";
 exports.__esModule = true;
 exports.lazyCard = void 0;
-exports.lazyCard = function () { return Promise.resolve().then(function () { return require('./Card'); }).then(function (a) { return a["default"]; }); };
+var lazyCard = function () { return Promise.resolve().then(function () { return require('./Card'); }).then(function (a) { return a["default"]; }); };
+exports.lazyCard = lazyCard;
 
 
 //// [Types.d.ts]

tests/baselines/reference/declarationEmitOptionalMethod.js

@@ -11,7 +11,8 @@ export const Foo = (opts: {
 "use strict";
 exports.__esModule = true;
 exports.Foo = void 0;
-exports.Foo = function (opts) { return ({}); };
+var Foo = function (opts) { return ({}); };
+exports.Foo = Foo;
 
 
 //// [declarationEmitOptionalMethod.d.ts]

tests/baselines/reference/declarationEmitRetainsJsdocyComments.js

@@ -52,7 +52,7 @@ exports.someMethod = exports.Foo = exports.foo = void 0;
  * comment1
  * @param p
  */
-exports.foo = function (p) {
+var foo = function (p) {
     return {
         /**
          * comment2
@@ -66,6 +66,7 @@ exports.foo = function (p) {
         bar2: function (s) { }
     };
 };
+exports.foo = foo;
 var Foo = /** @class */ (function () {
     function Foo() {
     }

tests/baselines/reference/declarationEmitTypeAliasWithTypeParameters1.js

@@ -7,7 +7,8 @@ export const y = (x: Foo<string>) => 1
 "use strict";
 exports.__esModule = true;
 exports.y = void 0;
-exports.y = function (x) { return 1; };
+var y = function (x) { return 1; };
+exports.y = y;
 
 
 //// [declarationEmitTypeAliasWithTypeParameters1.d.ts]

tests/baselines/reference/declarationEmitTypeAliasWithTypeParameters2.js

@@ -8,7 +8,8 @@ export const y = (x: Baa<number>) => 1
 "use strict";
 exports.__esModule = true;
 exports.y = void 0;
-exports.y = function (x) { return 1; };
+var y = function (x) { return 1; };
+exports.y = y;
 
 
 //// [declarationEmitTypeAliasWithTypeParameters2.d.ts]

tests/baselines/reference/declarationEmitWithInvalidPackageJsonTypings.js

@@ -33,10 +33,11 @@ function useRef(current) {
     return { current: current };
 }
 exports.useRef = useRef;
-exports.useCsvParser = function () {
+var useCsvParser = function () {
     var parserRef = useRef(null);
     return parserRef;
 };
+exports.useCsvParser = useCsvParser;
 
 
 //// [index.d.ts]

tests/baselines/reference/declarationsForFileShadowingGlobalNoError.js

@@ -39,7 +39,7 @@ var __extends = (this && this.__extends) || (function () {
 })();
 exports.__esModule = true;
 exports.mixin = void 0;
-exports.mixin = function (Base) {
+var mixin = function (Base) {
     return /** @class */ (function (_super) {
         __extends(class_1, _super);
         function class_1() {
@@ -49,6 +49,7 @@ exports.mixin = function (Base) {
         return class_1;
     }(Base));
 };
+exports.mixin = mixin;
 
 
 //// [dom.d.ts]

tests/baselines/reference/declarationsWithRecursiveInternalTypesProduceUniqueTypeParams.js

@@ -57,7 +57,7 @@ var __assign = (this && this.__assign) || function () {
 };
 exports.__esModule = true;
 exports.testRecFun = exports.updateIfChanged = void 0;
-exports.updateIfChanged = function (t) {
+var updateIfChanged = function (t) {
     var reduce = function (u, update) {
         var set = function (newU) { return Object.is(u, newU) ? t : update(newU); };
         return Object.assign(function (key) {
@@ -69,15 +69,17 @@ exports.updateIfChanged = function (t) {
     };
     return reduce(t, function (t) { return t; });
 };
+exports.updateIfChanged = updateIfChanged;
 // example from https://github.com/microsoft/TypeScript/issues/31605
-exports.testRecFun = function (parent) {
+var testRecFun = function (parent) {
     return {
         result: parent,
         deeper: function (child) {
             return exports.testRecFun(__assign(__assign({}, parent), child));
         }
     };
 };
+exports.testRecFun = testRecFun;
 var p1 = exports.testRecFun({ one: '1' });
 void p1.result.one;
 var p2 = p1.deeper({ two: '2' });

tests/baselines/reference/errorsWithInvokablesInUnions01.js

@@ -23,7 +23,8 @@ export let ctor: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<n
 "use strict";
 exports.__esModule = true;
 exports.ctor = exports.blah = void 0;
-exports.blah = function (x) { };
+var blah = function (x) { };
+exports.blah = blah;
 exports.ctor = /** @class */ (function () {
     function class_1() {
     }

tests/baselines/reference/esModuleInteropImportTSLibHasImport.js

@@ -20,7 +20,8 @@ sayHello(username());
 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
 exports.username = void 0;
-exports.username = () => 'username';
+const username = () => 'username';
+exports.username = username;
 //// [index.js]
 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });

tests/baselines/reference/genericIndexedAccessMethodIntersectionCanBeAccessed.js

@@ -24,9 +24,10 @@ export const createService = <T>(
 "use strict";
 exports.__esModule = true;
 exports.createService = void 0;
-exports.createService = function (ServiceCtr) {
+var createService = function (ServiceCtr) {
     Object.keys(ServiceCtr).forEach(function (key) {
         var method = (ServiceCtr)[key];
         var __$daemonMode = method.__$daemonMode, __$action = method.__$action, id = method.id;
     });
 };
+exports.createService = createService;

tests/baselines/reference/importCallExpressionAsyncES3AMD.js

@@ -139,7 +139,7 @@ define(["require", "exports"], function (require, exports) {
         return cl2;
     }());
     exports.cl2 = cl2;
-    exports.l = function () { return __awaiter(void 0, void 0, void 0, function () {
+    var l = function () { return __awaiter(void 0, void 0, void 0, function () {
         var req;
         return __generator(this, function (_a) {
             switch (_a.label) {
@@ -151,4 +151,5 @@ define(["require", "exports"], function (require, exports) {
             }
         });
     }); };
+    exports.l = l;
 });

tests/baselines/reference/importCallExpressionAsyncES3CJS.js

@@ -138,7 +138,7 @@ var cl2 = /** @class */ (function () {
     return cl2;
 }());
 exports.cl2 = cl2;
-exports.l = function () { return __awaiter(void 0, void 0, void 0, function () {
+var l = function () { return __awaiter(void 0, void 0, void 0, function () {
     var req;
     return __generator(this, function (_a) {
         switch (_a.label) {
@@ -150,3 +150,4 @@ exports.l = function () { return __awaiter(void 0, void 0, void 0, function () {
         }
     });
 }); };
+exports.l = l;

tests/baselines/reference/importCallExpressionAsyncES3UMD.js

@@ -148,7 +148,7 @@ var __generator = (this && this.__generator) || function (thisArg, body) {
         return cl2;
     }());
     exports.cl2 = cl2;
-    exports.l = function () { return __awaiter(void 0, void 0, void 0, function () {
+    var l = function () { return __awaiter(void 0, void 0, void 0, function () {
         var req;
         return __generator(this, function (_a) {
             switch (_a.label) {
@@ -160,4 +160,5 @@ var __generator = (this && this.__generator) || function (thisArg, body) {
             }
         });
     }); };
+    exports.l = l;
 });

tests/baselines/reference/importCallExpressionAsyncES5AMD.js

@@ -139,7 +139,7 @@ define(["require", "exports"], function (require, exports) {
         return cl2;
     }());
     exports.cl2 = cl2;
-    exports.l = function () { return __awaiter(void 0, void 0, void 0, function () {
+    var l = function () { return __awaiter(void 0, void 0, void 0, function () {
         var req;
         return __generator(this, function (_a) {
             switch (_a.label) {
@@ -151,4 +151,5 @@ define(["require", "exports"], function (require, exports) {
             }
         });
     }); };
+    exports.l = l;
 });

tests/baselines/reference/importCallExpressionAsyncES5CJS.js

@@ -138,7 +138,7 @@ var cl2 = /** @class */ (function () {
     return cl2;
 }());
 exports.cl2 = cl2;
-exports.l = function () { return __awaiter(void 0, void 0, void 0, function () {
+var l = function () { return __awaiter(void 0, void 0, void 0, function () {
     var req;
     return __generator(this, function (_a) {
         switch (_a.label) {
@@ -150,3 +150,4 @@ exports.l = function () { return __awaiter(void 0, void 0, void 0, function () {
         }
     });
 }); };
+exports.l = l;

tests/baselines/reference/importCallExpressionAsyncES5UMD.js

@@ -148,7 +148,7 @@ var __generator = (this && this.__generator) || function (thisArg, body) {
         return cl2;
     }());
     exports.cl2 = cl2;
-    exports.l = function () { return __awaiter(void 0, void 0, void 0, function () {
+    var l = function () { return __awaiter(void 0, void 0, void 0, function () {
         var req;
         return __generator(this, function (_a) {
             switch (_a.label) {
@@ -160,4 +160,5 @@ var __generator = (this && this.__generator) || function (thisArg, body) {
             }
         });
     }); };
+    exports.l = l;
 });

tests/baselines/reference/importCallExpressionAsyncES6AMD.js

@@ -71,7 +71,8 @@ define(["require", "exports"], function (require, exports) {
         }
     }
     exports.cl2 = cl2;
-    exports.l = () => __awaiter(void 0, void 0, void 0, function* () {
+    const l = () => __awaiter(void 0, void 0, void 0, function* () {
         const req = yield new Promise((resolve_5, reject_5) => { require(['./test'], resolve_5, reject_5); }); // FIVE
     });
+    exports.l = l;
 });

tests/baselines/reference/importCallExpressionAsyncES6CJS.js

@@ -70,6 +70,7 @@ class cl2 {
     }
 }
 exports.cl2 = cl2;
-exports.l = () => __awaiter(void 0, void 0, void 0, function* () {
+const l = () => __awaiter(void 0, void 0, void 0, function* () {
     const req = yield Promise.resolve().then(() => require('./test')); // FIVE
 });
+exports.l = l;

tests/baselines/reference/importCallExpressionAsyncES6UMD.js

@@ -80,7 +80,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         }
     }
     exports.cl2 = cl2;
-    exports.l = () => __awaiter(void 0, void 0, void 0, function* () {
+    const l = () => __awaiter(void 0, void 0, void 0, function* () {
         const req = yield __syncRequire ? Promise.resolve().then(() => require('./test')) : new Promise((resolve_5, reject_5) => { require(['./test'], resolve_5, reject_5); }); // FIVE
     });
+    exports.l = l;
 });

tests/baselines/reference/inlineJsxFactoryDeclarationsLocalTypes.js

@@ -94,13 +94,14 @@ exports.__esModule = true;
 exports.tree = exports.MyClass = exports.MySFC = void 0;
 /** @jsx predom */
 var renderer2_1 = require("./renderer2");
-exports.MySFC = function (props) { return renderer2_1.predom("p", null,
+var MySFC = function (props) { return renderer2_1.predom("p", null,
     props.x,
     " + ",
     props.y,
     " = ",
     props.x + props.y,
     _this.props.children); };
+exports.MySFC = MySFC;
 var MyClass = /** @class */ (function () {
     function MyClass(props) {
         this.props = props;