[libcxx] r292158 - [libc++] Introduce _LIBCPP_EXTERN_VIS to fix __libcpp_debug_function link errors

[Eric Fiselier via cfe-commits]

Author: ericwf
Date: Mon Jan 16 15:01:00 2017
New Revision: 292158

URL: http://llvm.org/viewvc/llvm-project?rev=292158&view=rev
Log:
[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

Modified:
    libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst
    libcxx/trunk/include/__config
    libcxx/trunk/include/__debug

Modified: libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst?rev=292158&r1=292157&r2=292158&view=diff
==============================================================================
--- libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst (original)
+++ libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst Mon Jan 16 15:01:00 2017
@@ -22,6 +22,12 @@ Visibility Macros
   Mark a symbol as being exported by the libc++ library. This attribute must
   be applied to the declaration of all functions exported by the libc++ dylib.
 
+**_LIBCPP_EXTERN_VIS**
+  Mark a symbol as being exported by the libc++ library. This attribute may
+  only be applied to objects defined in the libc++ library. On Windows this
+  macro applies `dllimport`/`dllexport` to the symbol. On all other platforms
+  this macro has no effect.
+
 **_LIBCPP_OVERRIDABLE_FUNC_VIS**
   Mark a symbol as being exported by the libc++ library, but allow it to be
   overridden locally. On non-Windows, this is equivalent to `_LIBCPP_FUNC_VIS`.

Modified: libcxx/trunk/include/__config
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__config?rev=292158&r1=292157&r2=292158&view=diff
==============================================================================
--- libcxx/trunk/include/__config (original)
+++ libcxx/trunk/include/__config Mon Jan 16 15:01:00 2017
@@ -583,6 +583,7 @@ namespace std {
 
 #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 @@ namespace std {
 # 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

Modified: libcxx/trunk/include/__debug
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__debug?rev=292158&r1=292157&r2=292158&view=diff
==============================================================================
--- libcxx/trunk/include/__debug (original)
+++ libcxx/trunk/include/__debug Mon Jan 16 15:01:00 2017
@@ -74,7 +74,7 @@ typedef void(*__libcpp_debug_function_ty
 
 /// __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