Since some time clang itself figures out the default for ms-compatibi…

…lity-version and uses it. Trying to figure it out during build is redundant and also will not work when the environment variable VSINSTALLDIR is not defined (which is not defined if you don't install whole Visual Studio but use Visual C++ Build Tools package).

Tested by bootstrapping clang with clang-cl.

Differential Revision: http://reviews.llvm.org/D20672

llvm-svn: 270860

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -352,19 +352,6 @@ if( MSVC )
   # "Enforce type conversion rules".
   append("/Zc:rvalueCast" CMAKE_CXX_FLAGS)
 
-  if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-    # Find and run MSVC (not clang-cl) and get its version. This will tell
-    # clang-cl what version of MSVC to pretend to be so that the STL works.
-    execute_process(COMMAND "$ENV{VSINSTALLDIR}/VC/bin/cl.exe"
-      OUTPUT_QUIET
-      ERROR_VARIABLE MSVC_COMPAT_VERSION
-      )
-    string(REGEX REPLACE "^.*Compiler Version ([0-9.]+) for .*$" "\\1"
-      MSVC_COMPAT_VERSION "${MSVC_COMPAT_VERSION}")
-    append("-fms-compatibility-version=${MSVC_COMPAT_VERSION}"
-      CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
-  endif()
-
   if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
     # clang-cl and cl by default produce non-deterministic binaries because
     # link.exe /incremental requires a timestamp in the .obj file.  clang-cl