[PATCH] D84023: Make MSVC generate appropriate __cplusplus macro definition

[Tatyana Krasnukha via Phabricator via llvm-commits]

tatyana-krasnukha created this revision.
tatyana-krasnukha added a reviewer: zturner.
Herald added subscribers: llvm-commits, mgorny.
Herald added a project: LLVM.

When the option "/Zc:__cplusplus" is not specified explicitly, macro's value is "199711L", and gtest cannot determine c++11 support correctly.

https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D84023

Files:
  llvm/cmake/modules/AddLLVM.cmake
  llvm/cmake/modules/HandleLLVMOptions.cmake
  llvm/utils/unittest/CMakeLists.txt


Index: llvm/utils/unittest/CMakeLists.txt
===================================================================
--- llvm/utils/unittest/CMakeLists.txt
+++ llvm/utils/unittest/CMakeLists.txt
@@ -19,11 +19,6 @@
   googlemock
   )
 
-# LLVM requires C++11 but gtest doesn't correctly detect the availability
-# of C++11 on MSVC, so we force it on.
-add_definitions(-DGTEST_LANG_CXX11=1)
-add_definitions(-DGTEST_HAS_TR1_TUPLE=0)
-
 if(WIN32)
   add_definitions(-DGTEST_OS_WINDOWS=1)
 endif()
Index: llvm/cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- llvm/cmake/modules/HandleLLVMOptions.cmake
+++ llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -415,6 +415,12 @@
   endif (LLVM_ENABLE_WERROR)
 
   append("/Zc:inline" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+  
+  # Some projects use the __cplusplus preprocessor macro to check support for
+  # a particular version of the C++ standard. When this option is not specified
+  # explicitly, macro's value is "199711L" that implies C++98 Standard.
+  # https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+  append("/Zc:__cplusplus" CMAKE_CXX_FLAGS)
 
   # Allow users to request PDBs in release mode. CMake offeres the
   # RelWithDebInfo configuration, but it uses different optimization settings
Index: llvm/cmake/modules/AddLLVM.cmake
===================================================================
--- llvm/cmake/modules/AddLLVM.cmake
+++ llvm/cmake/modules/AddLLVM.cmake
@@ -1397,13 +1397,6 @@
     set(EXCLUDE_FROM_ALL ON)
   endif()
 
-  # Our current version of gtest does not properly recognize C++11 support
-  # with MSVC, so it falls back to tr1 / experimental classes.  Since LLVM
-  # itself requires C++11, we can safely force it on unconditionally so that
-  # we don't have to fight with the buggy gtest check.
-  add_definitions(-DGTEST_LANG_CXX11=1)
-  add_definitions(-DGTEST_HAS_TR1_TUPLE=0)
-
   include_directories(${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest/include)
   include_directories(${LLVM_MAIN_SRC_DIR}/utils/unittest/googlemock/include)
   if (NOT LLVM_ENABLE_THREADS)


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