Typescript: Can not find local declaration file for scoped packages

[mlippert]

I am using the noImplicitAny switch, but I'm not sure whether that matters other than not showing that the declaration file is not found as quickly. However I should be able to use the noImplicitAny switch by creating the required declaration file locally.

My testing seems to show that a local declaration file for a non-scoped package is found, but that one for a scoped package (@\/name) is not.

The test sample I've attached uses the @feathersjs/express scoped package to demonstrate the issue.

Note that the feathersjs__express.d.ts file below does contain the declare module 'feathersjs__express'; as specified in the error message.

Also note that the contents of feathersjs__express.d.ts are basically identical to the contents of feathers-mongoose.d.ts which is correctly found (and when remove produces a similar TS7016 error.

TypeScript Version: 2.9.0-dev.20180506

Search Terms:
TS7016: Could not find a declaration file for module

Code

├── package.json
├── src
│   ├── feathersjs__express.d.ts
│   ├── feathers-mongoose.d.ts
│   └── index.ts
├── tsconfig.json

index.ts

import { express } from '@feathersjs/express';
import { service } from 'feathers-mongoose';

feathers-mongoose.d.ts

declare module 'feathers-mongoose'
{
    function init(options: string): any;

    namespace init
    {
        export let service: (options: string) => any;
    }

    export = init;
}

feathersjs__express.d.ts

declare module 'feathersjs__express'
{
    function feathersExpress(feathersApp: string): any;

    namespace feathersExpress
    {
        export let express: (feathersApp: string) => any;
    }

    export = feathersExpress;
}

Zip file containing the sources (as in the tree above)
ts_bug_src.zip

Expected behavior:
No errors

Actual behavior:

src/index.ts:1:25 - error TS7016: Could not find a declaration file for module '@feathersjs/express'. '/home/mjl/Projects/riff/test/node_modules/@feathersjs/express/lib/index.js' implicitly has an 'any' type.
  Try `npm install @types/feathersjs__express` if it exists or add a new declaration (.d.ts) file containing `declare module 'feathersjs__express';`

1 import { express } from '@feathersjs/express';
                          ~~~~~~~~~~~~~~~~~~~~~

Playground Link:

Related Issues:

• #13348 noimplicitany and module without typings
• #15031 Error when importing untyped JS modules
• #133 dialog and noImplicitAny
• #14379 bug: TS7016 Could not find a declaration file for module

[mhegazy]

the file name is irrelevant. in both files you are using declare module "..." { .. } form which is a global declaration..

in the file feathersjs__express, you are saying to the compiler "I know a module exists, whose name is "feathersjs__express" and this is its type".

the problem is you are not naming the module correctly, i.e. your module should look like:

declare module '@feathersjs/express' {
    function init(options: string): any;

    namespace init {
        export let service: (options: string) => any;
    }

    export = init;
}

[mlippert]

@mhegazy I believe that the file name is irrelevant, but then the error message is wrong, because I am naming the module exactly as specified by the error message (see above: add a new declaration (.d.ts) file containing 'declare module 'feathersjs__express';').

And that did work (I thought I had tried using the name early on w/o success, but I probably had other issues at that time).

Thanks, so I think this bug probably needs to be renamed to specify that the error message needs to be corrected.

[mhegazy]

A PR to update the error message would be appreciated.

[mnpenner]

I just encountered this issue. Took me quite awhile to figure it out. Here's the Stackoverflow question I ended up creating because of it, and solution.

[mattmccutchen]

This should be an easy PR. I'm working on it.