Range bound in Vec::drain may overflow and fail to drain the vector

[Shnatsel]

I tried this code:

fn main() {
    let mut v = vec![1,2,3];
    v.drain(..=usize::MAX);
}

According to the documentation this should panic, since usize::MAX is greater than the length of the vector. Instead, no panic happens and no elements are removed from the vector.

Upon investigation it appears that the increment of the upper range bound silently overflows and the range is interpreted as 0..0.

I believe using .saturating_add(1) instead of +1 should make this panic, which is what I'd expect to happen.

Meta

rustc --version --verbose:

Playground stable (1.45)

Found through fuzzing via https://github.com/jakubadamw/rutenspitz

[Shnatsel]

I'd appreciate if someone from the libs team could confirm what the expected behavior is in this case.

[tmiasko]

#72237 is an existing bug report about overflows in API accepting ranges.

[Shnatsel]

Ah thanks, I'll close this in favor of the existing bug.