打字稿中所有对象文字类型的子类型？

Question

assume strictFunctionTypes is turned on, so that function params are checked contraviariantly

interface Func<T> {
  (p: T): unknown
}
declare let b: Func<{p1: string}>
declare let c: Func<{p2: number}>
declare let d: Func<{p3: number, x: boolean, x1: number}>
// e, f, g... like before
let a: Func<U> // to make b, c, d, e, f... etc all assignable to a, what should U be
a = b
a = c
a = d

a should be assignable to all possable cases with form Func<{x: 1, y: string}> , there are infinity possible number of valid values, I currently can only find any as a valid value for U . And curious about the existence of a more constrained one.

Answer 1

U需要是一个包含所有其他类型的类型，所以是所有类型的交集：

let a: Func<{p1: string, p2: number, p3: number, x: boolean, x1: number}>