`char::is_ascii` is already a stable `const fn`, so there is no reason
for `u8::is_ascii` to be unstable.

This bug was fixed by rust-lang#67501.

Closes rust-lang#69312

A `Duration` is created from a second and nanoseconds variable. The
documentation says: "This constructor will panic if the carry from the
nanoseconds overflows the seconds counter". This was, however, not tested
in the tests. I doubt the behavior will ever regress, but it is usually a
good idea to test all documented behavior.

Bless tests

…=sfackler

Make `u8::is_ascii` a stable `const fn`

`char::is_ascii` was already stabilized as `const fn` in rust-lang#55278, so there is no reason for `u8::is_ascii` to go through an unstable period.

cc @rust-lang/libs

Add test for rust-lang#69312

This bug was fixed by rust-lang#67501.

Closes rust-lang#69312

…nations, r=Dylan-DPC

Clean up E0323, E0324, E0325 and E0326 explanations

r? @Dylan-DPC

Wrong error message for move_ref_pattern

The current error message states that move occurs *because of `Copy`*:
```Rust
"move occurs because `{}` has type `{}` which does implement the `Copy` trait."
```
I found this randomly when surfing through the sources. This means, I don't have any context and might be completely wrong.

r? @Centril

…=Dylan-DPC

MIR is not an experiment anymore

At least I hope is not 😝

r? @oli-obk

…test, r=Centril

Test `Duration::new` panics on overflow

A `Duration` is created from a second and nanoseconds variable. The
documentation says: "This constructor will panic if the carry from the
nanoseconds overflows the seconds counter". This was, however, not tested
in the tests. I doubt the behavior will ever regress, but it is usually a
good idea to test all documented behavior.

move const_eval.rs into the module folder

This groups the file together with the other `const_eval` files in editors, diff views, etc.

r? @oli-obk