Duplicate exports.* = assignments in CommonJS output in some cases

[lauraharker]

🔎 Search Terms

commonjs, exports, function

🕗 Version & Regression Information

• This changed in Handle exported functions in ExportDeclarations for CJS/AMD/UMD emit #58489.

⏯ Playground Link

Thanks for merging I'm still seeing an odd behavior I think is related: here's the minimal repro I could find - bug workbench link

💻 Code

// @showEmittedFile: main.ts
// @module: commonjs

// @filename: main.ts
import { Foo } from "./file-with-export"
export function createFoo(): Foo {
    return {};
}
export {createFoo as createFooV2};

// @filename: file-with-export.ts
export interface Foo {}

🙁 Actual behavior

main.js has two exports for createFoo and createFooV2:

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.createFoo = createFoo;
exports.createFooV2 = createFoo;
exports.createFoo = createFoo;
exports.createFooV2 = createFoo;
function createFoo() {
    return {};
}

🙂 Expected behavior

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.createFoo = createFoo;
exports.createFooV2 = createFoo;
function createFoo() {
    return {};
}

Additional information about the issue

I believe this is a result of the fix for #58473. (I still appreciate having these duplicate exports rather than the compiler dropping the exports entirely 😃 )

In the debugger, I see that this exportedFunctions (

TypeScript/src/compiler/transformers/utilities.ts

Line 108 in 506f3e2

exportedFunctions: Set<FunctionDeclaration>; // all of the top-level exported function declarations

) set contains two separate createFoo nodes.

If I remove the export {createFoo as createFooV2} from the repro, or remove the declared return type : Foo, I get the expected behavior.

This was uncovered by testing the latest TS version in Google (#58685)