Make libc++'s versioning namespace customizable
Summary:
This patch makes the versioning namespace libc++ uses customizable by the user using `-DLIBCXX_ABI_NAMESPACE=__foo`.
This allows users to build custom versions of libc++ which can be linked into binaries with other libc++ versions without causing symbol conflicts or ODR issues.
Reviewers: mclow.lists, ldionne
Reviewed By: ldionne
Subscribers: kristina, smeenai, mgorny, phosek, libcxx-commits
Differential Revision: https://reviews.llvm.org/D53879
llvm-svn: 345657
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: fe13c13cc236aebe042b58f1e7fa9f6712e037b9
diff --git a/docs/BuildingLibcxx.rst b/docs/BuildingLibcxx.rst
index daf9229..66cfb7b 100644
--- a/docs/BuildingLibcxx.rst
+++ b/docs/BuildingLibcxx.rst
@@ -360,6 +360,18 @@
Build the "unstable" ABI version of libc++. Includes all ABI changing features
on top of the current stable version.
+.. option:: LIBCXX_ABI_NAMESPACE:STRING
+
+ **Default**: ``__n`` where ``n`` is the current ABI version.
+
+ This option defines the name of the inline ABI versioning namespace. It can be used for building
+ custom versions of libc++ with unique symbol names in order to prevent conflicts or ODR issues
+ with other libc++ versions.
+
+ .. warning::
+ When providing a custom namespace, it's the users responsibility to ensure the name won't cause
+ conflicts with other names defined by libc++, both now and in the future.
+
.. option:: LIBCXX_ABI_DEFINES:STRING
**Default**: ``""``