Missing Boolean.toString definition and loose valueOf definition

⚙ Compilation target

ES2017

⚙ Library

lib.es5.d.ts

Missing / Incorrect Definition

interface Boolean {
    toString<T extends boolean>(this: T): `${T}`
    toString(this: Boolean): `${boolean}`
    valueOf<T extends boolean>(this: T): T
    valueOf(this: Boolean): boolean
}

TS Playground

Related issues #30225, #38347

Sample Code

const bool = true as boolean;


let a: `${boolean}` = true.toString();
let b: `${boolean}` = false.toString();
let c: `${boolean}` = bool.toString();
let d: `${boolean}` = new Boolean().toString();
let e: `${boolean}` = Boolean().toString();

let f: true = true.valueOf();
let g: false = false.valueOf();

Documentation Link

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean/toString
https://tc39.es/ecma262/multipage/fundamental-objects.html#sec-boolean.prototype.tostring
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean/valueOf
https://tc39.es/ecma262/multipage/fundamental-objects.html#sec-boolean.prototype.valueof

Start in lib.es5.d.ts and compare the Boolean declarations with the issue's proposed signatures and the linked ECMAScript references. Verify the sample assignments for toString and valueOf compile with the intended literal types; done means the missing and overly broad definitions are corrected.