Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/lib64/cmake/llvm/CheckCompilerVersion.cmake b/linux-x64/clang/lib64/cmake/llvm/CheckCompilerVersion.cmake
new file mode 100644
index 0000000..adf500a
--- /dev/null
+++ b/linux-x64/clang/lib64/cmake/llvm/CheckCompilerVersion.cmake
@@ -0,0 +1,52 @@
+# Check if the host compiler is new enough. LLVM requires at least GCC 4.8,
+# MSVC 2015 (Update 3), or Clang 3.1.
+
+include(CheckCXXSourceCompiles)
+
+if(NOT DEFINED LLVM_COMPILER_CHECKED)
+ set(LLVM_COMPILER_CHECKED ON)
+
+ if(NOT LLVM_FORCE_USE_OLD_TOOLCHAIN)
+ if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+ if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.8)
+ message(FATAL_ERROR "Host GCC version must be at least 4.8!")
+ 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()
+
+ if (CMAKE_CXX_SIMULATE_ID MATCHES "MSVC")
+ if (CMAKE_CXX_SIMULATE_VERSION VERSION_LESS 19.0)
+ message(FATAL_ERROR "Host Clang must have at least -fms-compatibility-version=19.0")
+ endif()
+ set(CLANG_CL 1)
+ elseif(NOT LLVM_ENABLE_LIBCXX)
+ # Otherwise, 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.
+ set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+ set(OLD_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
+ set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++0x")
+ 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++4.8 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 19.0)
+ message(FATAL_ERROR "Host Visual Studio must be at least 2015")
+ elseif(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19.00.24213.1)
+ message(WARNING "Host Visual Studio should at least be 2015 Update 3 (MSVC 19.00.24213.1)"
+ " due to miscompiles from earlier versions")
+ endif()
+ endif()
+ endif()
+endif()