Wrong declaration of GatsbyLink with typescript 2.4.2

[DominikGuzei]

Hey there, im trying to use Gatsby with typescript 2.4.2 but it throws an error telling me that the signature of the GatsbyLink export is wrong:

export default class GatsbyLink extends React.Component<GatsbyLinkProps, void> { }

I could fix it by changing it to

export default class GatsbyLink extends React.Component<GatsbyLinkProps> { }

Im just running the starter code for index.tsx:

import * as React from 'react';
import Link from 'gatsby-link';

const IndexPage = () => (
  <div>
    <h1>Hi people</h1>
    <p>Welcome to your new Gatsby site.</p>
    <p>Now go build something great.</p>
    <Link to="/page-2/">Go to page 2</Link>
  </div>
);

export default IndexPage;

The error message:

Error:(9, 5) TS2605:JSX element type 'GatsbyLink' is not a constructor function for JSX elements.
  Types of property 'setState' are incompatible.
    Type '{ <K extends never>(f: (prevState: void, props: GatsbyLinkProps) => Pick<void, K>, callback?: (()...' is not assignable to type '{ <K extends never>(f: (prevState: {}, props: any) => Pick<{}, K>, callback?: (() => any) | undef...'.
      Types of parameters 'f' and 'f' are incompatible.
        Types of parameters 'prevState' and 'prevState' are incompatible.
          Type 'void' is not assignable to type '{}'.

my tsconfig:

{
  "compilerOptions": {
    "outDir": "./dist/",
    "sourceMap": true,
    "noImplicitAny": true,
    "strict": true,
    "strictNullChecks": true,
    "module": "commonjs",
    "target": "esnext",
    "jsx": "react",
    "lib": ["dom", "es2015", "es2017"]
  },
  "include": [
    "./src/**/*"
  ]
}

See last comment on this issue to see how i found the fix.

[KyleAMathews]

@timsuchanek and @fabien0102 comments?

[timsuchanek]

I think the problem is that Typescript got stricter about the generics, in this case the void. With removing the void, it's then using the default {}. (https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/react/index.d.ts#L238)
Do you want to create a PR for that @DominikGuzei ?

[DominikGuzei]

@timsuchanek yeah sure, will set it up!

[DominikGuzei]

@timsuchanek the fix is ready for review: #1628

[KyleAMathews]

Fixed in #1628