The TypeScript compiler complains with "This overload signature is not compatible with its implementation signature." for any of the following overloads:

export class FullId {
  // other stuff

  static parse(toParse: string): FullId;
  static parse(toParse: string, withIdType: 'U' | 'S' | 'O' | 'T'): FullId;
  static parse(
    toParse: string,
    withIdType: 'U' | 'S' | 'O' | 'T' | undefined,
    withEntityType: string | undefined
  ): FullId;

  static parse(
    toParse: string,
    withIdType: 'U' | 'S' | 'O' | 'T' | undefined,
    withEntityType: string | undefined
  ): FullId {
    // my implementation
   }
}

It’s basically a method which can be called with one, two, or three arguments.
I don’t really understand what the problem is: I’ve created overloads distinct from the implementation, and in the implementation any but the first argument is optional. Removing the static modifier doesn’t change anything as far as I can tell.

>Solution :

Make the arguments optional using the question mark syntax

export class FullId {
  static parse(toParse: string): FullId;
  static parse(toParse: string, withIdType: 'U' | 'S' | 'O' | 'T'): FullId;
  static parse(
    toParse: string,
    withIdType: 'U' | 'S' | 'O' | 'T' | undefined,
    withEntityType: string | undefined
  ): FullId;

  static parse(
    toParse: string,
    withIdType?: 'U' | 'S' | 'O' | 'T',
    withEntityType?: string
  ): FullId {
    // ...
  }
}

For some reason TS doesn’t treat optional argument and argument accepting undefined in the same way here