`module `...` was resolved to '...', but '--allowJs' is not set` error for explicit node_module import

[justinfagnani]

TypeScript Version: 2.3.2

Code

Project layout:

|__node_modules/
|  |__foo/
|     |__foo.js
|__src/
   |__index.ts

tsonfig.json:

{
  "compilerOptions": {
    "allowJs": true,
    "module": "es2015",
    "moduleResolution": "node",
    "outDir": "lib",
    "rootDir": "src",
    "target": "esnext"
  },
  "include": [
    "src/**/*.ts",
    "src/**/*.tsx"   
  ], "exclude": [
    "node_modules/**/*",
    "third_party/**/*"
  ]
}

index.ts:

import * from '../node_modules/foo/foo.js';

Expected behavior:

Compilation works

Actual behavior:

error TS6059: File '/Users/justin/Documents/Projects/test/node_modules/foo/foo.js' is not under 'rootDir' '/Users/justin/Documents/Projects/test/src'. 'rootDir' is expected to contain all source files.
error

My lib/ directory, which should contain just the compiled contents of src/ contains src/ and node_modules/ subdirectories.

If I remove allowJs, then tsc complains that I'm importing JS and need to add the option.

[mhegazy]

there are a few issues going on here. first --allowJs combined with the import makes the compiler think the node_module is part of your sources, and it will compile it for you, so your output will have node_modules\foo\foo.js, do not think this is what you had in mind.

If I remove allowJs, then tsc complains that I'm importing JS and need to add the option.

I believe this is the real bug here that needs to be fixed. if the file is found on disk, you should not get this error message.

[mhegazy]

With allowJs on, we are running into a similar issue like the one described in #15755