[libc++] Make it an error to define _LIBCPP_DEBUG
We have been transitioning off of that macro since LLVM 15.
Differential Revision: https://reviews.llvm.org/D137975
NOKEYCHECK=True
GitOrigin-RevId: 13ea1343231fa4ae12fe9fba4c789728465783d7
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index abcebeb..584eed4 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -97,6 +97,9 @@
Please migrate to ``<memory_resource>`` instead. Per libc++'s TS deprecation policy,
``<experimental/memory_resource>`` will be removed in LLVM 18.
+- The ``_LIBCPP_DEBUG`` macro is not honored anymore, and it is an error to try to use it. Please migrate to
+ ``_LIBCPP_ENABLE_DEBUG_MODE`` instead.
+
Upcoming Deprecations and Removals
----------------------------------