From 271143af72a35df4b1f7bacfee92c65ebeb3bdd2 Mon Sep 17 00:00:00 2001
From: lcnr <rust@lcnr.de>
Date: Fri, 17 Nov 2023 11:03:40 +0000
Subject: [PATCH] only free lifetimes may get erased

(cherry picked from commit 3b0e1d23b7fff6b57a634f529ee19d0d173a95f7)
---
 library/core/src/mem/mod.rs | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs
index 34534ba3b438..eef2145288c3 100644
--- a/library/core/src/mem/mod.rs
+++ b/library/core/src/mem/mod.rs
@@ -1132,10 +1132,12 @@ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
 ///
 /// [Reference]: ../../reference/items/enumerations.html#custom-discriminant-values-for-fieldless-enumerations
 ///
-/// The value of a [`Discriminant<T>`] is independent of any *lifetimes* in `T`. As such, reading
-/// or writing a `Discriminant<Foo<'a>>` as a `Discriminant<Foo<'b>>` (whether via [`transmute`] or
-/// otherwise) is always sound. Note that this is **not** true for other kinds of generic
-/// parameters; `Discriminant<Foo<A>>` and `Discriminant<Foo<B>>` might be incompatible.
+/// The value of a [`Discriminant<T>`] is independent of any *free lifetimes* in `T`. As such,
+/// reading or writing a `Discriminant<Foo<'a>>` as a `Discriminant<Foo<'b>>` (whether via
+/// [`transmute`] or otherwise) is always sound. Note that this is **not** true for other kinds
+/// of generic parameters and for higher-ranked lifetimes; `Discriminant<Foo<A>>` and
+/// `Discriminant<Foo<B>>` as well as `Discriminant<Bar<dyn for<'a> Trait<'a>>>` and
+/// `Discriminant<Bar<dyn Trait<'static>>>` may be incompatible.
 ///
 /// # Examples
 ///