Typescript compilation error: Argument of type 'Express' is not assignable [..]

Version info

node v10.16.0

firebase-functions: ^3.3.0

firebase-tools: 7.8.1

express ^4.17.1

Test case

import * as functions from 'firebase-functions';
import * as express from 'express';

const app = express();
export const api = functions.https.onRequest(app);

Steps to reproduce

Add the test case in an Typescript enable environment

Expected behavior

The onRequest handler should not throw Typescript compilation errors

Actual behavior

Typescript compilation error:

error TS2345: Argument of type 'Express' is not assignable to parameter of type '(req: Request, resp: Response) => void'.
  Types of parameters 'req' and 'req' are incompatible.

Were you able to successfully deploy your functions?

Yes, when I ignore typescript by casting it as <any> it deploys and runs as expected:

export const api = functions.https.onRequest(<any>app);

This is only a typing issue.

[jpinilloslr]

Same issue with firebase-functions 3.6.0.

[kossnocorp]

I’ve upgraded to firebase-functions from 3.3.0 to 3.6.0 and now also have this issue. I managed to fix it with any, but it’s not ideal.