[libc++] Make sure we can build libc++ with -fvisibility=hidden

Summary:
When building with -fvisibility=hidden, some symbols do not get exported from
libc++.dylib. This means that some entities are not explicitly given default
visibility in the source code, and that we rely on the fact -fvisibility=default
is the default. This commit explicitly gives default visibility to those
symbols to avoid being dependent on the command line flags used.

The commit also remove symbols from the dylib -- those symbols do not
actually need to be exported from the dylib and this should not be an
ABI break.

Finally, in the future, we may want to mark the whole std:: namespace as
having hidden visibility (to switch from opt-out to opt-in), in which
case the changes done in this commit will be required.

Reviewers: EricWF

Subscribers: mgorny, christof, dexonsmith, libcxx-commits

Differential Revision: https://reviews.llvm.org/D52662

llvm-svn: 345260

1 files changed, 1 insertions, 1 deletions

diff --git a/libcxx/include/__debug b/libcxx/include/__debug
index d01bacdf7ed..a8788f68f8f 100644
--- a/libcxx/include/__debug
+++ b/libcxx/include/__debug
@@ -74,7 +74,7 @@ typedef void(*__libcpp_debug_function_type)(__libcpp_debug_info const&);
 
 /// __libcpp_debug_function - The handler function called when a _LIBCPP_ASSERT
 ///    fails.
-extern _LIBCPP_EXTERN_VIS __libcpp_debug_function_type __libcpp_debug_function;
+extern _LIBCPP_EXPORTED_FROM_ABI __libcpp_debug_function_type __libcpp_debug_function;
 
 /// __libcpp_abort_debug_function - A debug handler that aborts when called.
 _LIBCPP_NORETURN _LIBCPP_FUNC_VIS