Declaration for object with method named "new" incorrectly emitted with construct signature

[jcalz]

Bug Report

🔎 Search Terms

declaration emit; method named "new"; construct signature

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about declaration emit, construct signatures
  (note: some of this actually changed between TS3.7 and TS3.8, but the behavior in TS3.7 still has the main problem)

⏯ Playground Link

Playground link with relevant code

💻 Code

export const a = {
  new(x: number) { return x + 1 }
}
export const b = {
  "new"(x: number) { return x + 1 }
}
export const c = {
  ["new"](x: number) { return x + 1 }
}

🙁 Actual behavior

The .d.ts file emitted is:

export declare const a: {
    new(x: number): number;
};
export declare const b: {
    new(x: number): number;
};
export declare const c: {
    new(x: number): number;
};

a construct signature that the actual object doesn't have. (For TS 3.7 and below, b and c are emitted as-is with quotes/brackets so there's no problem there. But a is still wrong.) If you consume this declaration weird things happen.

🙂 Expected behavior

Probably for this case new should be emitted as either "new" or ["new"] or something for all three cases:

export declare const a: {
    "new"(x: number): number;
};

Cross-linking to relevant Stack Overflow question