+if(NOT LLVM_FORCE_USE_OLD_TOOLCHAIN)
+ if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+ if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.7)
+ message(FATAL_ERROR "Host GCC version must be at least 4.7!")
+ endif()
+ elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+ if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.1)
+ message(FATAL_ERROR "Host Clang version must be at least 3.1!")
+ endif()
+
+ # Also test that we aren't using too old of a version of libstdc++ with the
+ # Clang compiler. This is tricky as there is no real way to check the
+ # version of libstdc++ directly. Instead we test for a known bug in
+ # libstdc++4.6 that is fixed in libstdc++4.7.
+ if(NOT LLVM_ENABLE_LIBCXX)
+ set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+ set(OLD_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
+ set(CMAKE_REQUIRED_FLAGS "-std=c++0x")
+ if (ANDROID)
+ set(CMAKE_REQUIRED_LIBRARIES "atomic")
+ endif()
+ check_cxx_source_compiles("
+#include <atomic>
+std::atomic<float> x(0.0f);
+int main() { return (float)x; }"
+ LLVM_NO_OLD_LIBSTDCXX)
+ if(NOT LLVM_NO_OLD_LIBSTDCXX)
+ message(FATAL_ERROR "Host Clang must be able to find libstdc++4.7 or newer!")
+ endif()
+ set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
+ set(CMAKE_REQUIRED_LIBRARIES ${OLD_CMAKE_REQUIRED_LIBRARIES})
+ endif()
+ elseif(CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
+ if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 17.0)
+ message(FATAL_ERROR "Host Visual Studio must be at least 2012 (MSVC 17.0)")
+ endif()
+ endif()