Documentation for aarch64 claims that anything from arm_shared is unstable

[pthariensflame]

In the current nightly documentation for core::arch::aarch64 and for its contained items, the definitions from arm_shared that are reexported by aarch64 are shown as unstable, despite being able to inspect the source and thus prove otherwise. Everything defined within aarch64 directly seems to be displayed properly; it's only the things shared with arm that are misbehaving here.

Screenshots for proof

Main module page, affected parts

Individual item pages, affected parts

Main module page, unaffected parts

Individual item pages, unaffected parts

[Amanieu]

The issue here is that we have only stabilized these intrinsics on aarch64, but not on arm. This is done using an attribute like:

#[cfg_attr(target_arch = "aarch64", stable(feature = "neon_intrinsics", since = "1.59.0"))]

However the Rust docs are built on x86_64, which means that the cfg does not trigger and the function is marked as unstable.

I'm not sure what we should do here:

• Ignore the problem until it solves itself when the arm intrinsics are also stabilized?
• Change the cfg to not(target_arch = "arm") so it appears as stable in the docs? But then the docs are still misleading on arm.

[pthariensflame]

Does rustdoc not have a way to write, say, #[doc(stable)], under a cfg_attr if needed?

[pthariensflame]

Alternatively, could rustdoc for core::arch be built on all stabilized platforms and then recomposed with the rest of core?

[Amanieu]

At this point it's probably easier to just move ahead with the stabilization of arm intrinisics.

[Amanieu]

Partially fixed by #1345.

[Jamesbarford]

With this PR – #1755 – all intrinsics are now generated from YAML.

Subsequent to this, We can make a modification to the generator to differentiate between arm32 and aarch64 from the input YAML, and place the generated intrinsics accordingly:

• all aarch64 in /core_arch/src/aarch64/neon/generated.rs
• arm32 in /core_arch/src/arm_shared/neon/generated.rs

This should resolve the documentation issue without requiring any additional YAML input files or new generated.rs files.

Overall, this seems like a simpler solution than stabilising the intrinsics and should effectively fix the issue.

[Jamesbarford]

The issue appears to be resolved. The arm intrinsics and types now display the correct tags and include stability information, and the aarvh64 variants no longer carry the experimental tag.

Please see the screenshots below. In each image, arm is shown on the left and aarch64 on the right.

Screenshots

• arm; https://doc.rust-lang.org/core/arch/arm/fn.vabd_u8.html
• aarch64; https://doc.rust-lang.org/core/arch/aarch64/fn.vabd_u8.html
  

Perhaps we can close this ticket?