Directly exported functions wrapping the dynamic import causes issues when run in "parallel" #51696
Description
Bug Report
When wrapping the dynamic import, exporting the function directly and building for CommonJS, the built artifact will contain a var _a outside of the function's scope which will cause issues when importing in "parallel", for example with Promise.all.
🔎 Search Terms
dynamic import, import, hoist, outside scope, var _a
🕗 Version & Regression Information
- This is a regression starting from version
4.9.0-dev.20221019introduced with fix: avoid downleveled dynamic import closing over specifier expression #49663
⏯ Playground and reproduction link
💻 Code
// importFn.ts
export async function importFn(path: string) {
return import(path);
}The transpiled code will have problems with parallelism, running the following:
// assuming neither module exists
Promise.all(["idontexist-1", "idontexist-2"].map(importFn));will raise an error: "Cannot find module 'idontexist-2'" while importing idontexist-1.
🙁 Actual behavior
// importFn.js
"use strict";
var _a; // 👈 outside func scope
Object.defineProperty(exports, "__esModule", { value: true });
exports.importFn = void 0;
async function importFn(path) {
return _a = path, Promise.resolve().then(() => require(_a));
}
exports.importFn = importFn;🙂 Expected behavior
// importFn.js
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.importFn = void 0;
async function importFn(path) {
var _a; // 👈 inside func scope
return _a = path, Promise.resolve().then(() => require(_a));
}
exports.importFn = importFn;