Get generic interface extension

Question

Consider the following interfaces:

interface A {
   name: string;
   value: number;
   sub: {
       query: number[]
   },
   old: number;
}

interface B {
   name: string;
   value: string;
   sub: {
       query: string[]
   },
   new: boolean;
}

I looking for a generic solution to get the interface/type:

interface C extends B, A {
}

Where C would be like the interface D:

interface D {
   name: string;
   value: string;
   sub: {
       query: string[]
   },
   old: number;
   new: boolean;
}

So I could have a function:

function merge<T, U>(t: T, u: U): interface C extends T, U {
  // Merge objects
  // ...
  return obj;
}

It doesn't have to be an interface. A type would do it also (I think).

The type A & B does not work because then I have an intersection (e.g. the value would be of type number & string).

Answer 1

I think I got it:

type MergeRightBiased<TLeft, TRight> =
  TLeft extends any[] ? TRight :
    TRight extends any[] ? TRight :
      TLeft extends object ?
        TRight extends object ? {
          // All properties of Left and Right, recursive
          [P in keyof TLeft & keyof TRight]: MergeRightBiased<TLeft[P], TRight[P]>
        } & {
          // All properties of Left not in Right
          [P in Exclude<keyof TLeft, keyof TRight>]: TLeft[P];
        } & {
          // All properties of Right not in Left
          [P in Exclude<keyof TRight, keyof TLeft>]: TRight[P]
        }
          // Prefer Right
          : TRight
        : TRight;

Thank you @Oblosys for your help!