Add signed num::NonZeroI* types
Multiple people have asked for them in https://github.com/rust-lang/rust/issues/49137. Given that the unsigned ones already exist, they are very easy to add and not an additional maintenance burden.
The diagnostic for this error prints `the following implementations
were found` followed by the first N relevant impls, sorted.
This commit makes the sort happen before slicing,
so that the set of impls being printed is deterministic
when the input is not.
Multiple people have asked for them, in
https://github.com/rust-lang/rust/issues/49137.
Given that the unsigned ones already exist,
they are very easy to add and not an additional maintenance burden.
Improve type mismatch error messages
Closes#56115.
Replace "integral variable" with "integer" and replace "floating-point variable" with "floating-point number" to make the message less confusing.
TODO the book and clippy needs to be changed accordingly later.
r? @varkor
