Links in an exported proc-macro seem to always be broken without `cargo doc` warning about it?

[AaronKutch]

Take for example from https://docs.rs/awint/0.18.0/awint/index.html:

/// A concatenations of components macro, additionally using the source value to
/// construct an [InlAwi](awint_macro_internals::awint_core::InlAwi). See the
/// [crate documentation](crate) for more.
#[proc_macro]
pub fn inlawi(input: TokenStream) -> TokenStream {

The line [InlAwi](awint_macro_internals::awint_core::InlAwi) simply routes through a dependency of the proc-macro crate that is also plainly available to the awint crate it is reexported in. However, it is just broken. The line [crate documentation](crate) refers to the macro crate this macro is in, so that clicking on it goes to to proc-macros lib docs.

Apparently the [InlAwi](awint_macro_internals::awint_core::InlAwi) one has always been broken with "The requested resource does not exist", and the [crate documentation](crate) kind worked until sometime in the past few months without me noticing or cargo doc warning about it. I have published a workaround but it would be nice to fix this.

[bjorn3]

We intentionally skip processing links in proc macros to their dependencies to avoid an ICE: #133105