[libc++] Disentangle std::pointer_safety
This patch gets rid of technical debt around std::pointer_safety which,
I claim, is entirely unnecessary. I don't think anybody has used
std::pointer_safety in actual code because we do not implement the
underlying garbage collection support. In fact, P2186 even proposes
removing these facilities entirely from a future C++ version. As such,
I think it's entirely fine to get rid of complex workarounds whose goals
were to avoid breaking the ABI back in 2017.
I'm putting this up both to get reviews and to discuss this proposal for
a breaking change. I think we should be comfortable with making these
tiny breaks if we are confident they won't hurt anyone, which I'm fairly
confident is the case here.
Differential Revision: https://reviews.llvm.org/D100410
NOKEYCHECK=True
GitOrigin-RevId: 49e7be2e5ba1759ae9d4ce9843ce2467cf7823a5
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index 1bcb26d..0cc8c00 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -55,3 +55,13 @@
Also, the extension allowing a tuple to be constructed from an array has been
removed. See https://godbolt.org/z/5esqbW.
+
+- The ``std::pointer_safety`` utility and related functions are not available
+ in C++03 anymore. Furthermore, in other standard modes, it has changed from
+ a struct to a scoped enumeration, which is an ABI break. Finally, the
+ ``std::get_pointer_safety`` function was previously in the dylib, but it
+ is now defined as inline in the headers.
+
+ While this is technically both an API and an ABI break, we do not expect
+ ``std::pointer_safety`` to have been used at all in real code, since we
+ never implemented the underlying support for garbage collection.