Update a bunch of library types for MCP807 #135236

scottmcm · 2025-01-08T08:09:04Z

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 · 2025-01-09T06:20:53Z

library/core/src/num/nonzero.rs

-                #[derive(Clone, Copy)]
-                #[repr(transparent)]
-                #[rustc_layout_scalar_valid_range_start(1)]
-                #[rustc_nonnull_optimization_guaranteed]


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

Good catch! Thank you.

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);

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.

scottmcm · 2025-01-10T19:36:47Z

Yay, finally got through CI 🎉

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

@rustbot ready

library/alloc/src/raw_vec.rs

ChrisDenton

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

ChrisDenton · 2025-01-10T22:43:48Z

library/core/src/num/mod.rs

+/// 100% perma-unstable
+#[doc(hidden)]
+pub mod niche_types;


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.

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

ChrisDenton · 2025-01-10T22:43:51Z

library/core/src/num/niche_types.rs

+        impl $name {
+            #[inline]
+            pub const unsafe fn new_unchecked(val: $int) -> Self {
+                // SAFETY: same precondition


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.

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 · 2025-01-11T05:13:25Z

Thanks!

@bors r+

bors · 2025-01-11T05:13:28Z

📌 Commit ebd6d3f has been approved by ChrisDenton

It is now in the queue for this repository.

Rollup of 6 pull requests Successful merges: - rust-lang#134074 (bootstrap: `std::io::ErrorKind::CrossesDevices` is finally stable) - rust-lang#135236 (Update a bunch of library types for MCP807) - rust-lang#135301 (re-add a warning for old master branch, but with much simpler logic) - rust-lang#135324 (Initial fs module for uefi) - rust-lang#135326 (support target specific `optimized-compiler-builtins`) - rust-lang#135347 (Use `NonNull::without_provenance` within the standard library) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#135236 - scottmcm:more-mcp807-library-updates, r=ChrisDenton Update a bunch of library types for MCP807 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

scottmcm mentioned this pull request Jan 8, 2025

Tracking issue for banning field projecting into [rustc_layout_scalar_valid_range_*] types (MCP807) #133652

Open

5 tasks