clamp on std integer types should probably have a better error message and ideally track caller

[Morgane55440]

when running this code

fn main() {
    println!("{}", 0u8.clamp(7,3))
}

i get the following output

thread 'main' panicked at /playground/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/cmp.rs:1078:9:
assertion failed: min <= max

this is very unhelpful in any non-trivial codebase that uses this method.
this is a pretty niche error but it can happen.

something like

thread 'main' panicked at src/main.rs:3:20:
invalid clamp range : there are no numbers smaller than 7 and greater than 3

would be ideal, but any improvement would be good.

[hanna-kruppe]

The float methods already include min and max in the panic message. Integers don’t have an inherent clamp method, they get it from Ord, and that method can’t print min/max because it doesn’t have a Self: Debug bound (adding one would be backwards incompatible). I’m not sure if adding inherent methods to integer types just for a better panic message is worth it (I’m not even sure if it’s completely backwards compatible).

[Morgane55440]

sorry for not checking floats.

wouldn't it be possible to add a manual clamp implementation to the ord_impl macro that is used in core with said error message ?

and even if it is not possible to display the values, there probably be a slightly better error message than
assertion failed : min <= max

[hanna-kruppe]

Oh right, I guess the Ord impls for integers could just override Ord::clamp, sorry for the noise.