[C++11] Switch the CMake option from LLVM_ENABLE_CXX11 (default on) to

LLVM_ENABLE_CXX1Y (default *off*). =D C++98 is dead. Long live C++11.

I don't exactly recommend using C++1y just yet though...

llvm-svn: 202567

Author: chandlerc

llvm/CMakeLists.txt

@@ -198,7 +198,7 @@ else( MSVC )
   option(LLVM_ENABLE_WARNINGS "Enable compiler warnings." ON)
 endif()
 
-option(LLVM_ENABLE_CXX11 "Compile with C++11 enabled." ON)
+option(LLVM_ENABLE_CXX1Y "Compile with C++1y enabled." OFF)
 option(LLVM_ENABLE_LIBCXX "Use libc++ if available." OFF)
 option(LLVM_ENABLE_PEDANTIC "Compile with pedantic enabled." ON)
 option(LLVM_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -287,10 +287,17 @@ elseif( LLVM_COMPILER_IS_GCC_COMPATIBLE )
   if (LLVM_ENABLE_WERROR)
     add_llvm_definitions( -Werror )
   endif (LLVM_ENABLE_WERROR)
-  if (LLVM_ENABLE_CXX11)
+  if (LLVM_ENABLE_CXX1Y)
+    check_cxx_compiler_flag("-std=c++1y" CXX_SUPPORTS_CXX1Y)
+    append_if(CXX_SUPPORTS_CXX1Y "-std=c++1y" CMAKE_CXX_FLAGS)
+  else()
     check_cxx_compiler_flag("-std=c++11" CXX_SUPPORTS_CXX11)
-    append_if(CXX_SUPPORTS_CXX11 "-std=c++11" CMAKE_CXX_FLAGS)
-  endif (LLVM_ENABLE_CXX11)
+    if (CXX_SUPPORTS_CXX11)
+      append("-std=c++11" CMAKE_CXX_FLAGS)
+    else()
+      message(FATAL_ERROR "LLVM requires C++11 support but the '-std=c++11' flag isn't supported.")
+    endif()
+  endif()
 endif( MSVC )
 
 macro(append_common_sanitizer_flags)