Reexported intrinsics show up in rustdoc intra-doc links instead of their proper paths

[theemathas]

The following functions appear to be intrinsics that are re-exported at a different path (see also: #113387):

• intrinsics::transmute -> mem::transmute
• intrinsics::copy -> ptr::copy
• intrinsics::copy_nonoverlapping -> ptr::copy_nonoverlapping
• intrinsics::write_bytes -> ptr::write_bytes

Searching for these only finds the functions in std::intrinsics. (And for specifically transmute, it also shows core::mem::transmute for some reason.) The search result should ideally show the functions in std::mem/ptr. See below screenshots obtained by searching for transmute and searching for copy_nonoverlapping

[kpreid]

Possibly related: intra-doc links to std::mem::transmute or core::mem::transmute also end up linking to the intrinsic page.

[RalfJung]

Ouch, yes we should not push more people towards these accidentally-stable names. rustdoc should treat #[rustc_allowed_through_unstable_modules] functions in a pub module like pub fn in a private module.

Cc @rust-lang/rustdoc

[workingjubilee]

I wonder if we should just move the intrinsic defs to their reexport site and then reexport them from core::intrinsics.

[RalfJung]

If #135003 lands, we will start emitting a deprecation lint for std::intrinsics::transmute -- would be better if we didn't at the same time have rustdoc recommend exactly that deprecated path.

[theemathas]

Intra-doc links still link to the wrong place. For example, the link at https://doc.rust-lang.org/nightly/std/rc/struct.Rc.html#method.from_raw points to the transmute intrinsic.