emit file lost import module in .js with package use export = with build by new typescript@next

[bluelovers]

TypeScript Version: 3.7.x-dev.201xxxxx

Search Terms:

Code

Version 4.0.0-dev.20200615

bug-web-46035.zip

download the zip and run yarn build will see

note: remember run yarn for install deps before test

import gitRoot from 'git-root2';

let git_root = gitRoot(process.cwd())

console.dir(git_root)

Expected behavior:

https://www.typescriptlang.org/v2/en/play?module=1#code/JYWwDg9gTgLgBAc2DAShC8BmUIjgciRgFocMAmfAbgCgaAbAU3iIH0z4BeRZNDACjA4AxowDOYgHTCA7gBN+ASkV1hEAHZiITSXOBR+bDoqA

var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const git_root2_1 = __importDefault(require("git-root2"));
let git_root = git_root2_1.default(process.cwd());
console.dir(git_root);

Actual behavior:

Object.defineProperty(exports, "__esModule", { value: true });
let git_root = gitRoot(process.cwd());
console.dir(git_root);
//# sourceMappingURL=index.js.map

Playground Link:

Related Issues:

[RyanCavanaugh]

This is the output I get (in index.js, which is what I'm guessing you're referring to)

"use strict";
/**
 * Created by user on 2020/6/19.
 */
exports.__esModule = true;
var git_root2_1 = require("git-root2");
var git_root = git_root2_1["default"](process.cwd());
console.dir(git_root);

[bluelovers]

@RyanCavanaugh are u install deps before run ?

i forgot say
need to install deps

[bluelovers]

looks like this happen with package use export = with build by new typescript@next

[rbuckton]

Interestingly, when running the following:

yarn
yarn build

I get the following error:

index.ts:7:16 - error TS2552: Cannot find name 'gitRoot'. Did you mean 'git_root'?

7 let git_root = gitRoot(process.cwd())
                 ~~~~~~~

  index.ts:7:5
    7 let git_root = gitRoot(process.cwd())
          ~~~~~~~~
    'git_root' is declared here.


Found 1 error.

However, if I change the source file to this:

import { default as gitRoot } from "git-root2";
...

We both check and emit correctly (i.e., including __importDefault).

For some reason we aren't treating the default import as a valid identifier reference.

[rbuckton]

The underlying issue is that we fail to fully resolve the alias from the export = gitRoot due to the fact that gitRoot is defined as a namespace with a default export in git-root2/core. The following is a fairly simple repro of the issue:

// @esModuleInterop: true
// @filename: main.ts
import gitRoot from "git-root2";
gitRoot(""); // error: Cannot find name 'gitRoot'

// @filename: external.d.ts
declare module "git-root2/core" {
    export function gitRoot(cwd?: string): string;
    export namespace gitRoot {
        var _a: typeof gitRoot;
        export { _a as default };
    }
    export default gitRoot;
}

declare module "git-root2" {
    import { gitRoot } from "git-root2/core";
    export = gitRoot;
}

When we try to resolve import gitRoot from "git-root2", we resolve it to the export= symbol. The export= symbol is an alias to gitRoot in import { gitRoot } from "git-root2/core", which is an alias to gitRoot in core. When we resolve the symbol, we resolve an alias symbol once, which results in another alias symbol, because we never properly resolve the alias in the call to resolveExportByName from getTargetOfImportClause.