Cannot override method in subclass when superclass instance type is a mapped type

TypeScript Version: 3.1.1

Search Terms:
defines instance member property

Code

class A {
    foo(): void {};
    bar: number;
}

class B extends (A as { new(): Pick<A, Exclude<keyof A, "foo">> & Pick<A, "foo"> }) {
    // (1)
    foo(): void {
        super.foo();
    }
    baz: number;
}

Expected behavior:
Compiles successfully

Actual behavior:

Error at (1): [ts] Class 'Pick<A, "bar"> & Pick<A, "foo">' defines instance member property 'foo', but extended class 'B' defines it as instance member function.

Playground Link: http://www.typescriptlang.org/play/index.html#src=class%20A%20%7B%0D%0A%20%20%20%20foo()%3A%20void%20%7B%7D%3B%0D%0A%20%20%20%20bar%3A%20number%3B%0D%0A%7D%0D%0A%0D%0Aclass%20B%20extends%20(A%20as%20%7B%20new()%3A%20Pick%3CA%2C%20Exclude%3Ckeyof%20A%2C%20%22foo%22%3E%3E%20%26%20Pick%3CA%2C%20%22foo%22%3E%20%7D)%20%7B%0D%0A%20%20%20%20foo()%3A%20void%20%7B%0D%0A%20%20%20%20%20%20%20%20super.foo()%3B%0D%0A%20%20%20%20%7D%0D%0A%20%20%20%20baz%3A%20number%3B%0D%0A%7D

A more realistic example of this is when using https://github.com/bterlson/strict-event-emitter-types along with subclassing a superclass with overridable methods:

import StrictEventEmitter from "strict-event-emitter-types";
import * as inspector from "inspector";

interface SessionEvents {
  "Runtime.executionContextCreated": (message: inspector.InspectorNotification<Runtime.ExecutionContextCreatedEventDataType>) => void
}
type StrictSession = StrictEventEmitter<inspector.Session, SessionEvents>;
class CustomSession extends (inspector.Session as { new (): StrictSession }) {
  connect() { // error here
    super.connect();
  }
}

Commencez par l’exemple de code TypeScript et le lien Playground pour reproduire le diagnostic impliquant Pick, Exclude et la redéfinition de la sous-classe. Suivez la manière dont le compilateur compare le membre de la superclasse mappée avec B.foo, puis ajoutez une couverture pour l’exemple et confirmez que la redéfinition valide est compilée sans erreur.