Uncalled function checks don't work with negation

Bug Report

🔎 Search Terms

uncalled function checks, negation

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

Playground link with relevant code

💻 Code

declare function isFoo(): boolean;
declare const isUndefinedFoo: (() => boolean) | undefined;

if (isFoo) {
    // uncalled function checks already work well here
}

if (!isFoo) {
    // uncalled function checks should cover this case too
}

if (!isUndefinedFoo) {
    // this case should not be covered
}

🙁 Actual behavior

Uncalled function checks do not work with the ! operator.

🙂 Expected behavior

Unless a function may be undefined it would be very helpful to check whether it is called when it is used with the ! operator.

I created this issue to separate a part of the implementation of #42835 resulting from issue #35584. This specific issue was inspired by https://github.com/microsoft/TypeScript/issues/35584#issuecomment-769401594.

Reproduce el comportamiento en el TypeScript Playground enlazado, comparando las comprobaciones positivas y negadas para isFoo e isUndefinedFoo. Lee la implementación de uncalled-function-check asociada a #42835 y la discusión en #35584; se considera terminado cuando la negación informe de funciones no llamadas definitivamente definidas sin informar incorrectamente de funciones posiblemente indefinidas.