generic type interface with template literal string wrong generate implemented function

[siosio34]

TS Template added by @mjbvz

TypeScript Version: 4.3.0-dev.20210228

Search Terms

• implement interface
• quick fix

---

• VS Code Version: 1.53.2
• OS Version: Darwin x64 19.6.0
• typescript version: 4.1.5

Steps to Reproduce:

i make generic type interface with template literal string, and i use implements this type in class. but vscode quick auto make interface feature wrong work. please look below screenshot.

i expect when i use implements interface and auto make interface function, setName(arg: string), setAddress(arg: number) maked . but in present name: (arg: string) and address: (arg:number) maked. so make type error in vscode...

but when i make this function myself, not make type error in vscode...

why generate implement function code wrong work with template literal string?

Does this issue occur when all extensions are disabled?: Yes

[mjbvz]

Please share the text of the code along with screenshots

[siosio34]

@mjbvz here my full code! thank you

type NonFunctionPropertyNames<T> = {
  [K in keyof T]: T[K] extends Function ? never : K;
}[keyof T];

type NonFunctionProperties<T> = Pick<T, NonFunctionPropertyNames<T>>;

type IBuilder<T> = {
  [k in keyof NonFunctionProperties<T> as `set${Capitalize<string & k>}`]: (
    arg: T[k]
  ) => IBuilder<T>;
};

interface NoParamConstructor<T> {
  new (): T;
}

class BuilderCommon<T> {
  public object: T;

  constructor(ctor: NoParamConstructor<T>) {
    this.object = new ctor();
  }

  build(): T {
    return this.object;
  }
}

class House {
  name: string;
  address: number;

  constructor() {
    this.name = "";
    this.address = -1;
  }

  setName(arg: string) {
    this.name = arg;
    return this;
  }

  setAddress(arg: number) {
    this.address = arg;
    return this;
  }

  getNameAndAddress() {
    return `${this.name}_${this.address}`;
  }

  getAddressPlusString(arg: string) {
    return arg + this.address;
  }
}

class HouseBuilder extends BuilderCommon<House> implements IBuilder<House> {
  constructor() {
    super(House);
  }

  setName(arg: string) {
    this.object.name = arg;
    return this;
  }

  setAddress(arg: number) {
    this.object.address = arg;
    return this;
  }
}

new HouseBuilder().setName("#21").setAddress(123).build();

``

[siosio34]

@RyanCavanaugh hmm... if you time is okay, can you tell me what fix file for fix this bug?

[Matrixbirds]

I have same problem, you can reproduce here.

[a-tarasyuk]

The latest version of TS doesn't suggest Implement interface QF for this case. I think there are two ways: mark this issue as fixed or try to make definitions from Symbol without declarations (current case omit QF because symbol doesn't declarations)

https://github.com/microsoft/TypeScript/blob/719ab0b47721c7dfe72708d8771f6778f2de58c3/src/services/codefixes/helpers.ts#L62-L64

@RyanCavanaugh @DanielRosenwasser @andrewbranch What do you think?

[andrewbranch]

It would be nice for this to work still. We should be able to generate an implementation just from the type structure, no syntax needed. (I was actually surprised to learn recently that the implement interface fix does rely so heavily on the syntax of the declaring interface.)

[a-tarasyuk]

@andrewbranch Oke, thanks