ENH: New function for determining Visual Studio service pack

Modules/CMakeDetermineVSServicePack.cmake

@@ -0,0 +1,81 @@
+# - Includes a public function for assisting users in trying to determine the
+# Visual Studio service pack in use.
+#
+# Sets the passed in variable to one of the following values or an empty
+# string if unknown.
+#    vc80
+#    vc80sp1
+#    vc90
+#    vc90sp1
+#
+# Usage:
+# ===========================
+#
+#    if(MSVC)
+#       include(CMakeDetermineVSServicePack)
+#       DetermineVSServicePack( my_service_pack )
+#
+#       if( my_service_pack )
+#           message(STATUS "Detected: ${my_service_pack}")
+#       endif()
+#    endif()
+#
+# ===========================
+                
+# [INTERNAL]
+# Please do not call this function directly
+function(_DetermineVSServicePackFromCompiler _OUT_VAR _cl_version)
+   if    (${_cl_version} VERSION_EQUAL "14.00.50727.42")
+       set(_version "vc80")
+   elseif(${_cl_version} VERSION_EQUAL "14.00.50727.762")
+       set(_version "vc80sp1")
+   elseif(${_cl_version} VERSION_EQUAL "15.00.21022.08")
+       set(_version "vc90")
+   elseif(${_cl_version} VERSION_EQUAL "15.00.30729.01")
+       set(_version "vc90sp1")
+   else()
+       set(_version "")
+   endif()
+   set(${_OUT_VAR} ${_version} PARENT_SCOPE)
+endfunction()
+
+#
+# A function to call to determine the Visual Studio service pack
+# in use.  See documentation above.
+function(DetermineVSServicePack _pack)
+    if(NOT DETERMINED_VS_SERVICE_PACK OR NOT ${_pack})
+        file(WRITE "${CMAKE_BINARY_DIR}/return0.cc"
+            "int main() { return 0; }\n")
+
+        try_compile(DETERMINED_VS_SERVICE_PACK
+            "${CMAKE_BINARY_DIR}"
+            "${CMAKE_BINARY_DIR}/return0.cc"
+            OUTPUT_VARIABLE _output
+            COPY_FILE "${CMAKE_BINARY_DIR}/return0.cc")
+        
+        file(REMOVE "${CMAKE_BINARY_DIR}/return0.cc")
+                
+        if(DETERMINED_VS_SERVICE_PACK AND _output)
+            string(REGEX MATCH "Compiler Version [0-9]+.[0-9]+.[0-9]+.[0-9]+"
+                _cl_version "${_output}")
+            if(_cl_version)
+                string(REGEX MATCHALL "[0-9]+"
+                    _cl_version_list "${_cl_version}")
+                list(GET _cl_version_list 0 _major)
+                list(GET _cl_version_list 1 _minor)
+                list(GET _cl_version_list 2 _patch)
+                list(GET _cl_version_list 3 _tweak)
+
+                set(_cl_version_string ${_major}.${_minor}.${_patch}.${_tweak})
+                
+                # Call helper function to determine VS version
+                _DetermineVSServicePackFromCompiler(_sp "${_cl_version_string}")
+                if(_sp)
+                    set(${_pack} ${_sp} CACHE INTERNAL
+                        "The Visual Studio Release with Service Pack")
+                endif()
+            endif()
+        endif()
+    endif()
+endfunction()
+