[libc++] Introduce _LIBCPP_EXTERN_VIS to fix __libcpp_debug_function link errors
Summary: On Windows tests that use `_LIBCPP_ASSERT` fail to link because the assertion handler function isn't correctly exported from the libc++ dylib. This patch fixes the dll import/export issues by introducing a new visibility macro `_LIBCPP_EXTERN_VIS` for use on external variables.
Reviewers: compnerd, smeenai, EricWF
Reviewed By: EricWF
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D28728
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@292158 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__config b/include/__config
index 118e3bd..d7ecdcf 100644
--- a/include/__config
+++ b/include/__config
@@ -583,6 +583,7 @@
#define _LIBCPP_TYPE_VIS _LIBCPP_DLL_VIS
#define _LIBCPP_FUNC_VIS _LIBCPP_DLL_VIS
+#define _LIBCPP_EXTERN_VIS _LIBCPP_DLL_VIS
#define _LIBCPP_EXCEPTION_ABI _LIBCPP_DLL_VIS
#define _LIBCPP_HIDDEN
#define _LIBCPP_TEMPLATE_VIS
@@ -636,6 +637,10 @@
# define _LIBCPP_FUNC_VIS_ONLY _LIBCPP_FUNC_VIS
#endif
+#ifndef _LIBCPP_EXTERN_VIS
+# define _LIBCPP_EXTERN_VIS
+#endif
+
#ifndef _LIBCPP_OVERRIDABLE_FUNC_VIS
# define _LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_FUNC_VIS
#endif
diff --git a/include/__debug b/include/__debug
index d95e339..d01bacd 100644
--- a/include/__debug
+++ b/include/__debug
@@ -74,7 +74,7 @@
/// __libcpp_debug_function - The handler function called when a _LIBCPP_ASSERT
/// fails.
-extern __libcpp_debug_function_type __libcpp_debug_function;
+extern _LIBCPP_EXTERN_VIS __libcpp_debug_function_type __libcpp_debug_function;
/// __libcpp_abort_debug_function - A debug handler that aborts when called.
_LIBCPP_NORETURN _LIBCPP_FUNC_VIS