Mixin abstract class: union of abstract propeties is not abstract.

TypeScript Version: 3.9.2

Search Terms: mixin abstract union

Expected behavior:
Union of abstract propeties is abstract property.

Actual behavior:
Union of abstract propeties is not abstract.

Related Issues:

Code

type Constructor = new (...args: any[]) => {};

class BaseClass {}

function AB<TBase extends Constructor>(Base: TBase) {
  abstract class AB extends Base {
    abstract a: number
    abstract b: number
  };
  return AB
}
function AC<TBase extends Constructor>(Base: TBase) {
  abstract class AC extends Base {
    abstract a: number
    abstract c: number
  };
  return AC
}

// should throw "Non-abstract class 'ShouldHavePropA' does not implement inherited abstract member 'a' from class ..."
class ShouldHavePropA extends AB(AC(BaseClass)) { 
    b = 1;
    c = 2;
}

"use strict";
class BaseClass {
}
function AB(Base) {
    class AB extends Base {
    }
    ;
    return AB;
}
function AC(Base) {
    class AC extends Base {
    }
    ;
    return AC;
}
class ShouldHavePropA extends AB(AC(BaseClass)) {
    constructor() {
        super(...arguments);
        this.b = 1;
        this.c = 2;
    }
}

{
  "compilerOptions": {
    "noImplicitAny": true,
    "strictNullChecks": true,
    "strictFunctionTypes": true,
    "strictPropertyInitialization": true,
    "strictBindCallApply": true,
    "noImplicitThis": true,
    "noImplicitReturns": true,
    "alwaysStrict": true,
    "esModuleInterop": true,
    "declaration": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "moduleResolution": 2,
    "target": "ES2017",
    "jsx": "React",
    "module": "ESNext"
  }
}

Playground Link: Provided

Commencez par le lien vers le Playground TypeScript 3.9.2 et réduisez l’exemple de mixin fourni à un test ciblé du compilateur. Suivez la manière dont les propriétés abstraites sont collectées à travers l’union des mixins AB et AC. Le travail est terminé lorsque l’exemple indique que ShouldHavePropA n’implémente pas le membre abstrait hérité a, avec un test de régression couvrant ce comportement.