ts-ignore is stripped from method in declaration output, causing downstream errors

[trusktr]

Bug Report

🔎 Search Terms

ts-ignore stripped from declaration output

🕗 Version & Regression Information

Tried on 4.2.3

⏯ Playground Link

Playground link with relevant code

💻 Code

class Base {
    foo(n: number) {}
}

new Base().foo(123) // ok

class Foo extends Base {
    // @ts-ignore overrides the signature
    foo(n: string) {}
}

new Foo().foo("123") // ok

Declaration output:

declare class Base {
    foo(n: number): void;
}
declare class Foo extends Base {
    foo(n: string): void; // ERROR here because ts-ignore comment is missing.
}

🙁 Actual behavior

A consumer of a library with this declaration output reports errors.

🙂 Expected behavior

The @ts-ignore comment should still be there, so that the types of the consumed library work the same as the library author wrote (without type errors on the Foo subclass).

[MartinJohns]

Related: #37144

[MartinJohns]

Duplicate of #38628. Used search terms: ts-ignore in:title

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.

[tjjfvi]

A (possibly non-ideal) fix for this specific instance is

class Foo extends Base {
    /** @ts-ignore overrides the signature */
    foo(n: string) {}
}

// Emitted .d.ts
declare class Foo extends Base {
    /** @ts-ignore overrides the signature */
    foo(n: string): void;
}