1 files changed, 52 insertions, 0 deletions
diff --git a/cmake/modules/CheckCompilerVersion.cmake b/cmake/modules/CheckCompilerVersion.cmake
new file mode 100644
index 0000000000000..08900a4599e9a
--- /dev/null
+++ b/cmake/modules/CheckCompilerVersion.cmake
@@ -0,0 +1,52 @@
+# Check if the host compiler is new enough. LLVM requires at least GCC 4.7,
+# MSVC 2013, 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 4.7)
+        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()
+
+      if (CMAKE_CXX_SIMULATE_ID MATCHES "MSVC")
+        if (CMAKE_CXX_SIMULATE_VERSION VERSION_LESS 18.0)
+          message(FATAL_ERROR "Host Clang must have at least -fms-compatibility-version=18.0")
+        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 "-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++4.7 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 18.0)
+        message(FATAL_ERROR "Host Visual Studio must be at least 2013")
+      elseif(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 18.0.31101)
+        message(WARNING "Host Visual Studio should at least be 2013 Update 4 (MSVC 18.0.31101)"
+          "  due to miscompiles from earlier versions")
+      endif()
+    endif()
+  endif()
+endif()