Update a bunch of library types for MCP807

[scottmcm]

This greatly reduces the number of places that actually use the rustc_layout_scalar_valid_range_* attributes down to just 3:

library/core\src\ptr\non_null.rs
68:#[rustc_layout_scalar_valid_range_start(1)]

library/core\src\num\niche_types.rs
19:        #[rustc_layout_scalar_valid_range_start($low)]
20:        #[rustc_layout_scalar_valid_range_end($high)]

Everything else -- PAL Nanoseconds, alloc's Cap, niched FDs, etc -- all just wrap those niche_types types.

r? ghost

[juntyr]

I didn't see this attribute in the new code for the non zero integers

[scottmcm]

Good catch! Thank you.

[scottmcm]

Oh, actually, I think it's fine. The inner ones don't need it because they're not exactly the guaranteed ones, rather the NonZero wrapper struct has it:

rust/library/core/src/num/nonzero.rs

Lines 122 to 126 in 62bf38f

	#[stable(feature = "generic_nonzero", since = "1.79.0")]
	#[repr(transparent)]
	#[rustc_nonnull_optimization_guaranteed]
	#[rustc_diagnostic_item = "NonZero"]
	pub struct NonZero<T: ZeroablePrimitive>(T::NonZeroInner);

[scottmcm]

Yay, finally got through CI 🎉

Hmm, since PAL changes, how about
r? @ChrisDenton

@rustbot ready

[ChrisDenton]

This looks great! And thanks to juntyr for reviewing too.

[ChrisDenton]

It's a shame there isn't a way to say "this is pub only for alloc/std". But I guess having it be unstable is good enough.

[scottmcm]

Yeah, there's a bunch of issue = "none" stuff so that alloc and core can both use it :/

[ChrisDenton]

It's kinda weird to write "same precondition" here as it isn't entirely clear what "same" is referring to. In any case, I think a bit of repetition here would be fine. Especially if things get moved around in the future.

[scottmcm]

Agreed, especially now that it's used cross-crates. (An earlier version of this it was pub(super) and I didn't care as much.) Put proper /// docs and SAFETY on it.

[ChrisDenton]

Thanks!

@bors r+

[bors]

📌 Commit ebd6d3f has been approved by ChrisDenton

It is now in the queue for this repository.