Functions wrapped in __importDefault with allowSyntheticDefaultImports emit incorrect function calls

Jordan Harband (@ljharb)

The following code:

import allSettled from "promise.allsettled";

const resolved = Promise.resolve(42);
const rejected = Promise.reject(-1);

allSettled([resolved, rejected]).then(results => {
  console.log(results);
});

Is transpiled into the following JS with esModuleInterop & allowSyntheticDefaultImports:

"use strict";
var __importDefault =
  (this && this.__importDefault) ||
  function(mod) {
    return mod && mod.__esModule ? mod : { default: mod };
  };
Object.defineProperty(exports, "__esModule", { value: true });
const promise_allsettled_1 = __importDefault(require("promise.allsettled"));
const resolved = Promise.resolve(42);
const rejected = Promise.reject(-1);
promise_allsettled_1.default([resolved, rejected]).then(results => {
  console.log(results);
});

Full tsconfig.json:

{
  "compilerOptions": {
    "target": "es2018",
    "module": "commonjs",
    "strict": true,
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
  },
  "include": [
    "src"
  ]
}

(CodeSandbox.)

Executing this code leads to:

TypeError: #<Object> is not a constructor
    at Object.resolve (<anonymous>)
    at Object.PromiseResolve (/sandbox/node_modules/es-abstract/es2018.js:160:10)
    at /sandbox/node_modules/promise.allsettled/implementation.js:26:24
    at Function.from (<anonymous>)
    at Object.allSettled (/sandbox/node_modules/promise.allsettled/implementation.js:19:22)
    at Object.allSettled [as default] (/sandbox/node_modules/promise.allsettled/index.js:16:9)
    at Object.<anonymous> (/sandbox/src/demo.ts:6:11)
    at Module._compile (internal/modules/cjs/loader.js:776:30)
    at Module.m._compile (/sandbox/node_modules/ts-node/src/index.ts:536:23)
    at Module._extensions..js (internal/modules/cjs/loader.js:787:10)

That is because the promise.allsettled package handles this according to the spec, see es-shims/Promise.allSettled#5. The author of that library is Jordan Harband (@ljharb) who will have deeper understanding of the specifics than I do. (Also, thanks for nudging me to report this issue!)

The problem is most likely the emitted function call, which looks like this:

promise_allsettled_1.default([resolved, rejected]).then(results => {
  console.log(results);
});

In comparison, Babel + TS emits this (which works):

(0, _promise.default)([resolved, rejected]).then(function (results) {
  console.log(results);
});

Babel playground.

TypeScript Version: 3.7.2

Search Terms: esModuleInterop, allowSyntheticDefaultImports, emit, transpile, downlevel compile, ES Modules, default, wrapper, Node.js, module.

A simpler repro case would be importing module.exports = function () { 'use strict'; return !!this; } (with esModuleInterop and synthetic imports enabled, of course) - a correct downleveling would make invoking this function with no implied receiver return false; TS’s output currently seems to make it return true.

Jordan Harband (@ljharb)

AFAICT the same bug exists for named imports.

// foo.ts
export function foo() { return !!this; }

// bar.ts
import { foo } from './foo.js';
foo();

// transpiled bar.js
var foo_js_1 = require('./foo.js');
foo_js_1.foo(); // this line should be `(0, foo_js_1.foo)()`

Jordan Harband (@ljharb) please correct me if I'm wrong.

Yes, that’s the same bug, thanks.

fix receiver of imported and exported functions

Fix is up at #35877

fix receiver of imported and exported functions

fix receiver on calls of imported and exported functions (#35877)

Ron Buckton (@rbuckton)

Ron Buckton (@rbuckton) Sorry to disturb you, but your PR seems to wrap all imported symbols with (0, ...), but I think it's not necessary and may be skipped when the target is a "const arrow function".

Avoid marking any indirect function call as useless code.

Navigation Menu

Repository navigation

Functions wrapped in `__importDefault` with allowSyntheticDefaultImports emit incorrect function calls #35420

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Functions wrapped in __importDefault with allowSyntheticDefaultImports emit incorrect function calls #35420

Description

Activity

ljharb commented on Nov 29, 2019

ajafff commented on Dec 27, 2019

ljharb commented on Dec 27, 2019

ajafff commented on Dec 27, 2019

gdh1995 commented on Jul 4, 2021

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions

Functions wrapped in `__importDefault` with allowSyntheticDefaultImports emit incorrect function calls #35420