A mixin class must have a constructor with a single rest parameter of type 'any[]'.

TypeScript Version: 3.8.2

Search Terms: “A mixin class must have a constructor with a single rest parameter of type ‘any[]’.”

Code

export type Constructor<T = {}> = new (...a: any[]) => T;

export function DataMixin<TBase extends Constructor<{}>>(
  superclass: TBase
) {
  return class DataClass<TData> extends superclass {
    data: TData = null;
  };
}

export function QueryMixin<TBase extends Constructor<{}>>(
  superclass: TBase
) {
  return class QueryClass<TData> extends DataMixin<TBase>(superclass)<TData> {
    query(): TData {
      return this.data;
    }
  };
}

Expected behavior:

I’d expect this to compile without error

Actual behavior:

error TS2545: A mixin class must have a constructor with a single rest parameter of type 'any[]'.

Playground Link: Playground Link

Related Issues: https://github.com/Microsoft/TypeScript/issues/16390

[canonic-epicure]

Any hope for at least fixing the case, when mixin has no constructor? That is definitely a valid case.

[Wyctus]

What is the status of this?