EqualMa / rollup-typescript-duplicate-repro

rollup-typescript-duplicate-repro

When tsconfig.json > compilerOptions > module options is set to es6 or esnext, and entry point src/b.ts imports another entry point src/a.ts, the output of src/b.ts will container duplicated codes of src/a.ts.

Note that when tsconfig.json > compilerOptions > module is set to commonjs, this error will not occur.

Input:

// entry point a.ts
export function hello() {
  return "hello";
}

// entry point b.ts
import { hello } from "./a";

export function sayHello() {
  console.log(hello());
}

Expected output: (run npx rollup -c rollup.config.cjs.js to output to dist1)

// a.js
Object.defineProperty(exports, "__esModule", { value: true });
exports.hello = void 0;
function hello() {
  return "hello";
}
exports.hello = hello;

// b.js
Object.defineProperty(exports, "__esModule", { value: true });
exports.sayHello = void 0;
const a_1 = require("./a");
function sayHello() {
  console.log(a_1.hello());
}
exports.sayHello = sayHello;

Actual ouput: (run npx rollup -c to output to dist)

// a.js
Object.defineProperty(exports, '__esModule', { value: true });

function hello() {
    return "hello";
}

exports.hello = hello;


// b.js
Object.defineProperty(exports, '__esModule', { value: true });

function hello() {
    return "hello";
}

function sayHello() {
    console.log(hello());
}

exports.sayHello = sayHello;