Made this macro work for switch strings that have what look like regular

expressions in them to cmake.

dlib/add_global_compiler_switch.cmake

 
 
+cmake_minimum_required(VERSION 2.8.4)
+
 # Make macros that can add compiler switches to the entire project.  Not just
 # to the current cmake folder being built.  
 macro ( add_global_compiler_switch switch_name )
-   if (NOT CMAKE_CXX_FLAGS MATCHES "${switch_name}")
+   # If removing the switch would change the flags then it's already present
+   # and we don't need to do anything.
+   string(REPLACE "${switch_name}" "" tempstr "${CMAKE_CXX_FLAGS}")
+   if ("${CMAKE_CXX_FLAGS}" STREQUAL "${tempstr}" )
       set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${switch_name}" 
          CACHE STRING "Flags used by the compiler during all C++ builds." 
          FORCE)
@@ -11,9 +16,9 @@ macro ( add_global_compiler_switch switch_name )
 endmacro()
 
 macro ( remove_global_compiler_switch switch_name )
-   if (CMAKE_CXX_FLAGS MATCHES " ${switch_name}")
-      string (REGEX REPLACE " ${switch_name}" "" temp_var ${CMAKE_CXX_FLAGS}) 
-      set (CMAKE_CXX_FLAGS "${temp_var}" 
+   string(REPLACE "${switch_name}" "" tempstr "${CMAKE_CXX_FLAGS}")
+   if (NOT "${CMAKE_CXX_FLAGS}" STREQUAL "${tempstr}" )
+      set (CMAKE_CXX_FLAGS "${tempstr}" 
          CACHE STRING "Flags used by the compiler during all C++ builds." 
          FORCE)
    endif ()