InferGetStaticPropsType does not infer props when GetStaticProps is used

[selbekk]

What version of Next.js are you using?

11.0.1

What version of Node.js are you using?

16.9.1

What browser are you using?

Chrome

What operating system are you using?

macOS

How are you deploying your application?

Vercel

Describe the Bug

Props are not being inferred correctly by InferGetStaticPropsType in the following case:

export const getStaticProps: GetStaticProps = (context) => {
  return {
    props: { hello: 'world' }
  }
}

export default function Example({ hello }: InferGetStaticPropsType<typeof getStaticProps>) {
  // here, `hello` is "any"
}

If I remove the GetStaticProps definition on the first line, things work as expected. I assume that's because I could specify the props type as a type argument to GetStaticProps<{ hello: string }>, but I don't want that.

Is this even possible to fix?

Expected Behavior

Would love for this to just propagate the props as expected.

To Reproduce

Create a new Next.js project with TypeScript, and create a new pages file (index.tsx) for example. Paste the following code:

export const getStaticProps: GetStaticProps = (context) => {
  return {
    props: { hello: 'world' }
  }
}

export default function Example({ hello }: InferGetStaticPropsType<typeof getStaticProps>) {
  // here, `hello` is "any"
}

[ephraimduncan]

Don't forget you can obtain argument type in getStaticProps with GetStaticPropsContext.

import { InferGetStaticPropsType, GetStaticPropsContext} from 'next'

export const getStaticProps = (context: GetStaticPropsContext) => {
  return {
    props: { hello: 'world' }
  }
}

export default function Example({ hello }: InferGetStaticPropsType<typeof getStaticProps>) {
}

export default Blog

[selbekk]

That's true – and what I ended up doing as a workaround – but I prefer using the function type, so I don't have to specify both the arguments and the return values separately

[timneutkens]

Going to close this as a duplicate of #15913 to track it in one place.

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.