graphql<T>(...) should infer T automatically

[tippfelher]

Typing the return value of graphql<T>(...) is quite annoying, because one has to pass the query type T manually. For example:

const result= await graphql<Queries.MyQuery>(`
  query My {
    ..
  }
`);

T however, can be inferred from the context.

See this playground to try out type inference and auto-completion.

Comments contain the general idea on how to this can be achieved.

// 1) generate this automatically:
//   - keys are the original queries passed to `graphql()`
//   - values are the graphql types currently generated in `gatsby-types.d.ts`
type QueryTypes = {
    "\n    query AQuery {\n        allMdx {\n            totalCount\n        }\n    }\n": { readonly allMdx: { readonly totalCount: number } },
};

// 2) improve type inferrence for the graphql function (just a sketch)
type WrapMeBabyOneMoreTime<T> = { errors: unknown, data: T };
function graphql<K, U = K extends keyof QueryTypes ? QueryTypes[K] : unknown>(query: K extends keyof QueryTypes ? K : never) {
    return ('something' as unknown) as WrapMeBabyOneMoreTime<U>;
}

// 3) profit
const typedGraphqlA = graphql(`
    query AQuery {
        allMdx {
            totalCount
        }
    }
`);

// autocomplete working
typedGraphqlA.

const typedGraphqlB = graphql('b'); // intended bc there is no type for query 'b'

// autocomplete not working (also intended)
typedGraphqlB.data.