Error for explicit return type with no return statements is misleading

[DanielRosenwasser]

function foo(): string {
}

Currently in nightly, you'll get the error

error TS2847: A function whose declared type is neither 'undefined', 'void', nor 'any' must return a value.

But this error message is inaccurate, as you can now annotate with unknown.

[fatcerberus]

In fact can't you now annotate with any type which is inhabited by undefined?

[DanielRosenwasser]

Pretty much, which means that if you wrote

function foo(): string | undefined {
    // oops, forgot to fill this in
}

that'll be okay in TypeScript 5.1. You'll need to enable --noImplicitReturns to catch something like that.