rustdoc generates cross-crate links to pages which don't exist because of #[doc(hidden)]

[eefriedman]

For example, https://doc.rust-lang.org/nightly/std/fmt/struct.Formatter.html#method.align links to https://doc.rust-lang.org/nightly/core/fmt/rt/v1/enum.Alignment.html, which doesn't exist because std::fmt::rt is marked #[doc(hidden)] .

[eefriedman]

Related: https://doc.rust-lang.org/nightly/std/fmt/trait.Debug.html links to https://doc.rust-lang.org/nightly/core/num/flt2dec/bignum/struct.Big32x40.html, which doesn't exist because it isn't a public type.

[mitaa]

These instances have been fixed, but the underlying problem is IIRC still present. (#31948, 8aa268e)