Auto merge of #104600 - Dylan-DPC:rollup-glw1e8b, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - #104001 (Improve generating Custom entry function)
 - #104411 (nll: correctly deal with bivariance)
 - #104528 (Properly link `{Once,Lazy}{Cell,Lock}` in docs)
 - #104553 (Improve accuracy of asinh and acosh)
 - #104554 (Use `ErrorGuaranteed::unchecked_claim_error_was_emitted` less)
 - #104566 (couple of clippy::perf fixes)
 - #104575 (deduplicate tests)
 - #104580 (diagnostics: only show one suggestion for method -> assoc fn)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

2 files changed, 12 insertions, 2 deletions

diff --git a/library/core/src/cell/lazy.rs b/library/core/src/cell/lazy.rs
index 7844be5f783..b355d94ce49 100644
--- a/library/core/src/cell/lazy.rs
+++ b/library/core/src/cell/lazy.rs
@@ -4,6 +4,10 @@ use crate::ops::Deref;
 
 /// A value which is initialized on the first access.
 ///
+/// For a thread-safe version of this struct, see [`std::sync::LazyLock`].
+///
+/// [`std::sync::LazyLock`]: ../../std/sync/struct.LazyLock.html
+///
 /// # Examples
 ///
 /// ```
diff --git a/library/core/src/cell/once.rs b/library/core/src/cell/once.rs
index 3c39394dd8c..8c01643c7ac 100644
--- a/library/core/src/cell/once.rs
+++ b/library/core/src/cell/once.rs
@@ -4,8 +4,14 @@ use crate::mem;
 
 /// A cell which can be written to only once.
 ///
-/// Unlike `RefCell`, a `OnceCell` only provides shared `&T` references to its value.
-/// Unlike `Cell`, a `OnceCell` doesn't require copying or replacing the value to access it.
+/// Unlike [`RefCell`], a `OnceCell` only provides shared `&T` references to its value.
+/// Unlike [`Cell`], a `OnceCell` doesn't require copying or replacing the value to access it.
+///
+/// For a thread-safe version of this struct, see [`std::sync::OnceLock`].
+///
+/// [`RefCell`]: crate::cell::RefCell
+/// [`Cell`]: crate::cell::Cell
+/// [`std::sync::OnceLock`]: ../../std/sync/struct.OnceLock.html
 ///
 /// # Examples
 ///