Typing arguments for resolvers in TypeScript with strictFunctionTypes

[jupl]

I have been updating dependencies for a project and came up with an issue with TypeScript. Unfortunately the code below now results in TypeScript errors, specifically highlighting Mutation:

import {IResolvers} from 'graphql-tools'

interface Post {
  id: number
  title: string
  description: string
}

type AddPostArgs = Pick<Post, 'title' | 'description'>

export interface Resolvers extends IResolvers {
  Mutation: {
    addPost(root: {}, args: AddPostArgs): Post
  }
  Query: {
    posts(): Post[]
  }
}

I get a type error under Mutation:

Property 'Mutation' of type '{ addPost(root: {}, args: AddPostArgs): Post; }' is not assignable to string index type '(() => any) | GraphQLScalarType | IEnumResolver | IResolverObject<any, any>'.

If I remove the second args argument from addPost or cast it to something like {}, any, or {[x: string]: any} then it does not complain, but then I lose my typings with my implementation. Apparently it does not like it when I use AddPostArgs for args now? There was no issue with it before. Even if I change AddPostArgs to an interface or inline the type ({title: string, description: string}) it still does not work.

EDIT: Upon further examination, it does seem it's an issue with args:

Type '{ [argument: string]: any; }' is not assignable to type 'Pick<Post, "title" | "description">'.
  Property 'title' is missing in type '{ [argument: string]: any; }'.

EDIT 2: May have something to do with TypeScript's strictFunctionTypes, which is enabled when I have strict: true for tsconfig.json.

[dsebastien]

I concur, it is indeed related to strict mode..
It would be great to be able to simplify the function parameters :)

[stubailo]

Hi! We're going to keep track of TypeScript improvements in #704