Indirect calls for imported functions

src/compiler/emitter.ts

@@ -2473,7 +2473,17 @@ namespace ts {
         }
 
         function emitCallExpression(node: CallExpression) {
+            const indirectCall = getEmitFlags(node) & EmitFlags.IndirectCall;
+            if (indirectCall) {
+                writePunctuation("(");
+                writeLiteral("0");
+                writePunctuation(",");
+                writeSpace();
+            }
             emitExpression(node.expression, parenthesizer.parenthesizeLeftSideOfAccess);
+            if (indirectCall) {
+                writePunctuation(")");
+            }
             emit(node.questionDotToken);
             emitTypeArguments(node, node.typeArguments);
             emitExpressionList(node, node.arguments, ListFormat.CallExpressionArguments, parenthesizer.parenthesizeExpressionForDisallowedComma);
@@ -2488,7 +2498,17 @@ namespace ts {
         }
 
         function emitTaggedTemplateExpression(node: TaggedTemplateExpression) {
+            const indirectCall = getEmitFlags(node) & EmitFlags.IndirectCall;
+            if (indirectCall) {
+                writePunctuation("(");
+                writeLiteral("0");
+                writePunctuation(",");
+                writeSpace();
+            }
             emitExpression(node.tag, parenthesizer.parenthesizeLeftSideOfAccess);
+            if (indirectCall) {
+                writePunctuation(")");
+            }
             emitTypeArguments(node, node.typeArguments);
             writeSpace();
             emitExpression(node.template);

src/compiler/transformers/module/module.ts

@@ -33,6 +33,8 @@ namespace ts {
         const previousOnEmitNode = context.onEmitNode;
         context.onSubstituteNode = onSubstituteNode;
         context.onEmitNode = onEmitNode;
+        context.enableSubstitution(SyntaxKind.CallExpression); // Substitute calls to imported/exported symbols to avoid incorrect `this`.
+        context.enableSubstitution(SyntaxKind.TaggedTemplateExpression); // Substitute calls to imported/exported symbols to avoid incorrect `this`.
         context.enableSubstitution(SyntaxKind.Identifier); // Substitutes expression identifiers with imported/exported symbols.
         context.enableSubstitution(SyntaxKind.BinaryExpression); // Substitutes assignments to exported symbols.
         context.enableSubstitution(SyntaxKind.PrefixUnaryExpression); // Substitutes updates to exported symbols.
@@ -1741,6 +1743,10 @@ namespace ts {
             switch (node.kind) {
                 case SyntaxKind.Identifier:
                     return substituteExpressionIdentifier(node as Identifier);
+                case SyntaxKind.CallExpression:
+                    return substituteCallExpression(node as CallExpression);
+                case SyntaxKind.TaggedTemplateExpression:
+                    return substituteTaggedTemplateExpression(node as TaggedTemplateExpression);
                 case SyntaxKind.BinaryExpression:
                     return substituteBinaryExpression(node as BinaryExpression);
                 case SyntaxKind.PostfixUnaryExpression:
@@ -1751,6 +1757,43 @@ namespace ts {
             return node;
         }
 
+        function substituteCallExpression(node: CallExpression) {
+            if (isIdentifier(node.expression)) {
+                const expression = substituteExpressionIdentifier(node.expression);
+                noSubstitution[getNodeId(expression)] = true;
+                if (!isIdentifier(expression)) {
+                    return addEmitFlags(
+                        factory.updateCallExpression(node,
+                            expression,
+                            /*typeArguments*/ undefined,
+                            node.arguments
+                        ),
+                        EmitFlags.IndirectCall
+                    );
+
+                }
+            }
+            return node;
+        }
+
+        function substituteTaggedTemplateExpression(node: TaggedTemplateExpression) {
+            if (isIdentifier(node.tag)) {
+                const tag = substituteExpressionIdentifier(node.tag);
+                noSubstitution[getNodeId(tag)] = true;
+                if (!isIdentifier(tag)) {
+                    return addEmitFlags(
+                        factory.updateTaggedTemplateExpression(node,
+                            tag,
+                            /*typeArguments*/ undefined,
+                            node.template
+                        ),
+                        EmitFlags.IndirectCall
+                    );
+                }
+            }
+            return node;
+        }
+
         /**
          * Substitution for an Identifier expression that may contain an imported or exported
          * symbol.

src/compiler/types.ts

@@ -6728,6 +6728,7 @@ namespace ts {
         /*@internal*/ NeverApplyImportHelper = 1 << 26, // Indicates the node should never be wrapped with an import star helper (because, for example, it imports tslib itself)
         /*@internal*/ IgnoreSourceNewlines = 1 << 27,   // Overrides `printerOptions.preserveSourceNewlines` to print this node (and all descendants) with default whitespace.
         /*@internal*/ Immutable = 1 << 28,      // Indicates a node is a singleton intended to be reused in multiple locations. Any attempt to make further changes to the node will result in an error.
+        /*@internal*/ IndirectCall = 1 << 29,   // Emit CallExpression as an indirect call: `(0, f)()`
     }
 
     export interface EmitHelperBase {

src/testRunner/tsconfig.json

@@ -93,6 +93,7 @@
         "unittests/evaluation/asyncGenerator.ts",
         "unittests/evaluation/awaiter.ts",
         "unittests/evaluation/destructuring.ts",
+        "unittests/evaluation/externalModules.ts",
         "unittests/evaluation/forAwaitOf.ts",
         "unittests/evaluation/forOf.ts",
         "unittests/evaluation/optionalCall.ts",

src/testRunner/unittests/evaluation/externalModules.ts

@@ -0,0 +1,84 @@
+describe("unittests:: evaluation:: externalModules", () => {
+    // https://github.com/microsoft/TypeScript/issues/35420
+    it("Correct 'this' in function exported from external module", async () => {
+        const result = evaluator.evaluateTypeScript({
+            files: {
+                "/.src/output.ts": `
+                    export const output: any[] = [];
+                `,
+                "/.src/other.ts": `
+                    import { output } from "./output";
+                    export function f(this: any, expected) {
+                        output.push(this === expected);
+                    }
+
+                    // 0
+                    f(undefined);
+                `,
+                "/.src/main.ts": `
+                    export { output } from "./output";
+                    import { output } from "./output";
+                    import { f } from "./other";
+                    import * as other from "./other";
+
+                    // 1
+                    f(undefined);
+
+                    // 2
+                    const obj = {};
+                    f.call(obj, obj);
+
+                    // 3
+                    other.f(other);
+                `
+            },
+            rootFiles: ["/.src/main.ts"],
+            main: "/.src/main.ts"
+        });
+        assert.equal(result.output[0], true); // `f(undefined)` inside module. Existing behavior is correct.
+        assert.equal(result.output[1], true); // `f(undefined)` from import. New behavior to match first case.
+        assert.equal(result.output[2], true); // `f.call(obj, obj)`. Behavior of `.call` (or `.apply`, etc.) should not be affected.
+        assert.equal(result.output[3], true); // `other.f(other)`. `this` is still namespace because it is left of `.`.
+    });
+
+    it("Correct 'this' in function expression exported from external module", async () => {
+        const result = evaluator.evaluateTypeScript({
+            files: {
+                "/.src/output.ts": `
+                    export const output: any[] = [];
+                `,
+                "/.src/other.ts": `
+                    import { output } from "./output";
+                    export const f = function(this: any, expected) {
+                        output.push(this === expected);
+                    }
+
+                    // 0
+                    f(undefined);
+                `,
+                "/.src/main.ts": `
+                    export { output } from "./output";
+                    import { output } from "./output";
+                    import { f } from "./other";
+                    import * as other from "./other";
+
+                    // 1
+                    f(undefined);
+
+                    // 2
+                    const obj = {};
+                    f.call(obj, obj);
+
+                    // 3
+                    other.f(other);
+                `
+            },
+            rootFiles: ["/.src/main.ts"],
+            main: "/.src/main.ts"
+        });
+        assert.equal(result.output[0], true); // `f(undefined)` inside module. Existing behavior is incorrect.
+        assert.equal(result.output[1], true); // `f(undefined)` from import. New behavior to match first case.
+        assert.equal(result.output[2], true); // `f.call(obj, obj)`. Behavior of `.call` (or `.apply`, etc.) should not be affected.
+        assert.equal(result.output[3], true); // `other.f(other)`. `this` is still namespace because it is left of `.`.
+    });
+});

src/testRunner/unittests/tsserver/projectReferenceCompileOnSave.ts

@@ -55,8 +55,8 @@ exports.fn3 = fn3;`;
                 content: `"use strict";
 exports.__esModule = true;${appendJsText === changeJs ? "\nexports.fn3 = void 0;" : ""}
 var fns_1 = require("../decls/fns");
-fns_1.fn1();
-fns_1.fn2();
+(0, fns_1.fn1)();
+(0, fns_1.fn2)();
 ${appendJs}`
             }];
         }

tests/baselines/reference/allowJscheckJsTypeParameterNoCrash.js

@@ -30,7 +30,7 @@ exports.__esModule = true;
 exports.a = void 0;
 var func_1 = require("./func");
 // hover on vextend
-exports.a = func_1.vextend({
+exports.a = (0, func_1.vextend)({
     watch: {
         data1: function (val) {
             this.data2 = 1;

tests/baselines/reference/allowSyntheticDefaultImportsCanPaintCrossModuleDeclaration.js

@@ -23,7 +23,7 @@ exports.__esModule = true;
 exports.__esModule = true;
 exports.A = void 0;
 var file1_1 = require("./file1");
-exports.A = file1_1.styled();
+exports.A = (0, file1_1.styled)();
 
 
 //// [color.d.ts]

tests/baselines/reference/ambientDeclarationsPatterns.js

@@ -37,9 +37,9 @@ foo(fileText);
 exports.__esModule = true;
 ///<reference path="declarations.d.ts" />
 var foobarbaz_1 = require("foobarbaz");
-foobarbaz_1.foo(foobarbaz_1.baz);
+(0, foobarbaz_1.foo)(foobarbaz_1.baz);
 var foosball_1 = require("foosball");
-foobarbaz_1.foo(foosball_1.foos);
+(0, foobarbaz_1.foo)(foosball_1.foos);
 // Works with relative file name
 var file_text_1 = require("./file!text");
-foobarbaz_1.foo(file_text_1["default"]);
+(0, foobarbaz_1.foo)(file_text_1["default"]);

tests/baselines/reference/ambientShorthand.js

@@ -20,4 +20,4 @@ exports.__esModule = true;
 var jquery_1 = require("jquery");
 var baz = require("fs");
 var boom = require("jquery");
-jquery_1["default"](jquery_1.bar, baz, boom);
+(0, jquery_1["default"])(jquery_1.bar, baz, boom);

tests/baselines/reference/ambientShorthand_reExport.js

@@ -49,4 +49,4 @@ exports.__esModule = true;
 var reExportX_1 = require("./reExportX");
 var $ = require("./reExportAll");
 // '$' is not callable, it is an object.
-reExportX_1.x($);
+(0, reExportX_1.x)($);

tests/baselines/reference/amdDeclarationEmitNoExtraDeclare.js

@@ -72,7 +72,7 @@ define("Class", ["require", "exports", "Configurable"], function (require, expor
             return _super !== null && _super.apply(this, arguments) || this;
         }
         return ActualClass;
-    }(Configurable_1.Configurable(HiddenClass)));
+    }((0, Configurable_1.Configurable)(HiddenClass)));
     exports.ActualClass = ActualClass;
 });
 

tests/baselines/reference/anonClassDeclarationEmitIsAnon.js

@@ -96,7 +96,7 @@ var __extends = (this && this.__extends) || (function () {
 exports.__esModule = true;
 exports.TimestampedUser = exports.User = void 0;
 var wrapClass_1 = require("./wrapClass");
-exports["default"] = wrapClass_1.wrapClass(0);
+exports["default"] = (0, wrapClass_1.wrapClass)(0);
 // Simple class
 var User = /** @class */ (function () {
     function User() {
@@ -112,7 +112,7 @@ var TimestampedUser = /** @class */ (function (_super) {
         return _super.call(this) || this;
     }
     return TimestampedUser;
-}(wrapClass_1.Timestamped(User)));
+}((0, wrapClass_1.Timestamped)(User)));
 exports.TimestampedUser = TimestampedUser;
 
 

tests/baselines/reference/callbackTagVariadicType.js

@@ -22,7 +22,7 @@ exports.x = void 0;
 /** @type {Foo} */
 var x = function () { return 1; };
 exports.x = x;
-var res = exports.x('a', 'b');
+var res = (0, exports.x)('a', 'b');
 
 
 //// [callbackTagVariadicType.d.ts]

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsx,module=commonjs).js

@@ -25,7 +25,7 @@ var Component = /** @class */ (function () {
     function Component() {
     }
     Component.prototype.render = function () {
-        return _a.jsx("div", { children: null /* preserved */ }, void 0);
+        return (0, _a.jsx)("div", { children: null /* preserved */ }, void 0);
     };
     return Component;
 }());

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsxdev,module=commonjs).js

@@ -26,7 +26,7 @@ var Component = /** @class */ (function () {
     function Component() {
     }
     Component.prototype.render = function () {
-        return _a.jsxDEV("div", { children: null /* preserved */ }, void 0, false, { fileName: _jsxFileName, lineNumber: 5, columnNumber: 15 }, this);
+        return (0, _a.jsxDEV)("div", { children: null /* preserved */ }, void 0, false, { fileName: _jsxFileName, lineNumber: 5, columnNumber: 15 }, this);
     };
     return Component;
 }());

tests/baselines/reference/commonjsSafeImport.js

@@ -19,7 +19,7 @@ exports.Foo = Foo;
 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
 var _10_lib_1 = require("./10_lib");
-_10_lib_1.Foo();
+(0, _10_lib_1.Foo)();
 
 
 //// [10_lib.d.ts]

tests/baselines/reference/declarationEmitCommonJsModuleReferencedType.js

@@ -30,5 +30,5 @@ exports.__esModule = true;
 exports.y = exports.x = void 0;
 var foo_1 = require("foo");
 var root_1 = require("root");
-exports.x = foo_1.foo();
-exports.y = root_1.bar();
+exports.x = (0, foo_1.foo)();
+exports.y = (0, root_1.bar)();

tests/baselines/reference/declarationEmitExpandoPropertyPrivateName.js

@@ -23,7 +23,7 @@ exports.q = void 0;
 var a_1 = require("./a");
 function q() { }
 exports.q = q;
-q.val = a_1.f();
+q.val = (0, a_1.f)();
 
 
 //// [a.d.ts]

tests/baselines/reference/declarationEmitExpandoWithGenericConstraint.js

@@ -22,7 +22,7 @@ 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); };
+exports.Point.zero = function () { return (0, exports.Point)(0, 0); };
 
 
 //// [declarationEmitExpandoWithGenericConstraint.d.ts]

tests/baselines/reference/declarationEmitExportAssignedNamespaceNoTripleSlashTypesReference.js

@@ -53,7 +53,7 @@ var get_comp_1 = require("./get-comp");
 // this shouldn't need any triple-slash references - it should have a direct import to `react` and that's it
 // This issue (#35343) _only_ reproduces in the test harness when the file in question is in a subfolder
 exports.obj = {
-    comp: get_comp_1.getComp()
+    comp: (0, get_comp_1.getComp)()
 };
 //// [some-other-file.js]
 "use strict";

tests/baselines/reference/declarationEmitExportDeclaration.js

@@ -26,7 +26,7 @@ Object.defineProperty(exports, "__esModule", { value: true });
 exports.bar = void 0;
 var utils_1 = require("./utils");
 Object.defineProperty(exports, "bar", { enumerable: true, get: function () { return utils_1.bar; } });
-utils_1.foo();
+(0, utils_1.foo)();
 var obj;
 
 

tests/baselines/reference/declarationEmitForGlobalishSpecifierSymlink.js

@@ -39,7 +39,7 @@ export const a: import("typescript-fsa").A;
 exports.__esModule = true;
 exports.a = void 0;
 var typescript_fsa_1 = require("typescript-fsa");
-exports.a = typescript_fsa_1.getA();
+exports.a = (0, typescript_fsa_1.getA)();
 
 
 //// [index.d.ts]

tests/baselines/reference/declarationEmitForGlobalishSpecifierSymlink2.js

@@ -27,7 +27,7 @@ export const a: import("typescript-fsa").A;
 exports.__esModule = true;
 exports.a = void 0;
 var typescript_fsa_1 = require("typescript-fsa");
-exports.a = typescript_fsa_1.getA();
+exports.a = (0, typescript_fsa_1.getA)();
 
 
 //// [index.d.ts]

tests/baselines/reference/declarationEmitForModuleImportingModuleAugmentationRetainsImport.js

@@ -31,7 +31,7 @@ var ParentThing = /** @class */ (function () {
     return ParentThing;
 }());
 exports.ParentThing = ParentThing;
-child1_1.child1(ParentThing.prototype);
+(0, child1_1.child1)(ParentThing.prototype);
 //// [child1.js]
 "use strict";
 exports.__esModule = true;

tests/baselines/reference/declarationEmitForTypesWhichNeedImportTypes.js

@@ -25,7 +25,7 @@ exports.createNamed = createNamed;
 exports.__esModule = true;
 exports.Value = void 0;
 var b_1 = require("./b");
-exports.Value = b_1.createNamed();
+exports.Value = (0, b_1.createNamed)();
 
 
 //// [b.d.ts]