Author: smeenai Date: Wed Sep 28 17:28:51 2016 New Revision: 282644 URL: http://llvm.org/viewvc/llvm-project?rev=282644&view=rev Log: [libc++] Clarify _LIBCPP_NEW_DELETE_VIS for Windows
Replace a stale reference to cxx_EXPORTS with _LIBCPP_BUILDING_LIBRARY, and clarify why the operator new and delete family of functions are marked dllexport when building but *not* dllimport when including the header externally. The new code is identical to the intent of the old code (and would be functionally equivalent were cxx_EXPORTS still defined when building libc++). The overall behavior is not ideal, since Microsoft's operator new and delete functions will get called instead of libc++'s, but I think consistently calling msvcrt's functions is better than either calling msvcrt's or libc++'s functions depending on header inclusion. Differential Revision: https://reviews.llvm.org/D25042 Modified: libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst libcxx/trunk/include/new Modified: libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst?rev=282644&r1=282643&r2=282644&view=diff ============================================================================== --- libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst (original) +++ libcxx/trunk/docs/DesignDocs/VisibilityMacros.rst Wed Sep 28 17:28:51 2016 @@ -108,6 +108,19 @@ Visibility Macros versioning namespace. This allows throwing and catching some exception types between libc++ and libstdc++. +**_LIBCPP_NEW_DELETE_VIS** + Mark a symbol as being exported by the libc++ library. This macro must be + applied to all `operator new` and `operator delete` overloads. + + **Windows Behavior**: When using the Microsoft CRT, all the `operator new` and + `operator delete` overloads are defined statically in `msvcrt.lib`. Marking + them as `dllimport` in the libc++ `<new>` header is therefore undesirable: if + we were to mark them as `dllimport` and then link against libc++, source files + which included `<new>` would end up linking against libc++'s `operator new` + and `operator delete`, while source files which did not include `<new>` would + end up linking against msvcrt's `operator new` and `operator delete`, which + would be a confusing and potentially error-prone inconsistency. + Links ===== Modified: libcxx/trunk/include/new URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/new?rev=282644&r1=282643&r2=282644&view=diff ============================================================================== --- libcxx/trunk/include/new (original) +++ libcxx/trunk/include/new Wed Sep 28 17:28:51 2016 @@ -125,8 +125,8 @@ _LIBCPP_FUNC_VIS new_handler get_new_han } // std -#if defined(_WIN32) && !defined(cxx_EXPORTS) -# define _LIBCPP_NEW_DELETE_VIS _LIBCPP_FUNC_VIS_ONLY +#if defined(_LIBCPP_MSVCRT) && !defined(_LIBCPP_BUILDING_LIBRARY) +# define _LIBCPP_NEW_DELETE_VIS #else # define _LIBCPP_NEW_DELETE_VIS _LIBCPP_FUNC_VIS #endif _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
