Definitelytyped: @types/express-serve-static-core error TS2430: Interface 'Request' incorrectly extends interface 'IncomingMessage'.

[sureshgururajan]

• [x] Package: @types/express-serve-static-core
• [x] I tried using the latest stable version of tsc (2.3.4)
• [x] I have a question that is inappropriate for StackOverflow.
  

  - [x] Authors: @borisyankov (Boris Yankov), Michał Lytek, @kacepe (Kacper Polak)

Issue

When I execute the command tsc, I get the following error:

node_modules/@types/express-serve-static-core/index.d.ts(177,11): error TS2430: Interface 'Request' incorrectly extends interface 'IncomingMessage'.
  Types of property 'headers' are incompatible.
    Type '{ [key: string]: string | undefined; }' is not assignable to type '{ [key: string]: string | string[]; }'.
      Index signatures are incompatible.
        Type 'string | undefined' is not assignable to type 'string | string[]'.
          Type 'undefined' is not assignable to type 'string | string[]'.

The last time there were no such issues was 20 days ago, when the command tsc ran successfully.

Here is a snippet of my package.json file:

{
"devDependencies": {
    "@types/body-parser": "^1.16.3",
    "@types/chai": "^3.5.2",
    "@types/express": "^4.0.36",
    "@types/mocha": "^2.2.41",
    "chai": "^3.5.0",
    "concurrently": "^3.4.0",
    "mocha": "^3.4.1",
    "nodemon": "^1.11.0",
    "tslint": "^5.2.0",
    "typescript": "^2.3.2"
  },
"dependencies": {
    "@types/body-parser": "^1.16.3",
    "@types/node": "^7.0.31",
    "body-parser": "^1.17.2",
    "express": "^4.15.3"
  }
}

[sompylasar]

Happened somewhere between these versions:

Fails

├── @types/[email protected]
├── @types/[email protected]
├── @types/[email protected]
├── @types/[email protected]
├─┬ @types/[email protected]
│ ├── @types/[email protected]
│ └─┬ @types/[email protected]
│   └── @types/[email protected]
├── @types/[email protected]
├── @types/[email protected]
├── @types/[email protected]
├── @types/[email protected]
├─┬ @types/[email protected]
│ └── @types/[email protected]
├── @types/[email protected]

Works

├── @types/[email protected] 
├── @types/[email protected] 
├── @types/[email protected] 
├── @types/[email protected] 
├─┬ @types/[email protected] 
│ ├── @types/[email protected] 
│ └─┬ @types/[email protected] 
│   └── @types/[email protected] 
├── @types/[email protected] 
├── @types/[email protected] 
├── @types/[email protected] 
├── @types/[email protected] 
├─┬ @types/[email protected] 
│ └── @types/[email protected] 
└── @types/[email protected] 

Likely @types/[email protected] -> @types/[email protected]

[sompylasar]

https://github.com/DefinitelyTyped/DefinitelyTyped/commit/c9e01b3e760ee7e2f93a7c9052d432f6713347c8#diff-7d84e08967cded0b99ed4328aab0a1a8R811

https://github.com/DefinitelyTyped/DefinitelyTyped/pull/16705

[sureshgururajan]

Awesome! Works now! Thank you so much for the fix!

Cheers,
Suresh Gururajan

[sompylasar]

Could anyone please link to the fixing commit? @sureshgururajan

[sompylasar]

Found it:
https://github.com/DefinitelyTyped/DefinitelyTyped/pull/17229
https://github.com/DefinitelyTyped/DefinitelyTyped/commit/b9afd83a914c851736565a5f858cff24a486b69a

[sureshgururajan]

@sompylasar - Thank you for referencing it.