Keep the CMake version less than 2.8.12 happy.

CMake/Modules/GenerateExportHeader.cmake

@@ -314,7 +314,8 @@ macro(_DO_GENERATE_EXPORT_HEADER TARGET_LIBRARY)
   if(_GEH_EXPORT_MACRO_NAME)
     set(EXPORT_MACRO_NAME ${_GEH_PREFIX_NAME}${_GEH_EXPORT_MACRO_NAME})
   endif()
-  string(MAKE_C_IDENTIFIER ${EXPORT_MACRO_NAME} EXPORT_MACRO_NAME)
+  # Urho3D: CMake version less than 2.8.12 does not have this sub-command yet, so comment it out until the cmake minimum required is 2.8.12
+  #string(MAKE_C_IDENTIFIER ${EXPORT_MACRO_NAME} EXPORT_MACRO_NAME)
   if(_GEH_EXPORT_FILE_NAME)
     if(IS_ABSOLUTE ${_GEH_EXPORT_FILE_NAME})
       set(EXPORT_FILE_NAME ${_GEH_EXPORT_FILE_NAME})
@@ -325,15 +326,15 @@ macro(_DO_GENERATE_EXPORT_HEADER TARGET_LIBRARY)
   if(_GEH_DEPRECATED_MACRO_NAME)
     set(DEPRECATED_MACRO_NAME ${_GEH_PREFIX_NAME}${_GEH_DEPRECATED_MACRO_NAME})
   endif()
-  string(MAKE_C_IDENTIFIER ${DEPRECATED_MACRO_NAME} DEPRECATED_MACRO_NAME)
+  #string(MAKE_C_IDENTIFIER ${DEPRECATED_MACRO_NAME} DEPRECATED_MACRO_NAME)
   if(_GEH_NO_EXPORT_MACRO_NAME)
     set(NO_EXPORT_MACRO_NAME ${_GEH_PREFIX_NAME}${_GEH_NO_EXPORT_MACRO_NAME})
   endif()
-  string(MAKE_C_IDENTIFIER ${NO_EXPORT_MACRO_NAME} NO_EXPORT_MACRO_NAME)
+  #string(MAKE_C_IDENTIFIER ${NO_EXPORT_MACRO_NAME} NO_EXPORT_MACRO_NAME)
   if(_GEH_STATIC_DEFINE)
     set(STATIC_DEFINE ${_GEH_PREFIX_NAME}${_GEH_STATIC_DEFINE})
   endif()
-  string(MAKE_C_IDENTIFIER ${STATIC_DEFINE} STATIC_DEFINE)
+  #string(MAKE_C_IDENTIFIER ${STATIC_DEFINE} STATIC_DEFINE)
 
   if(_GEH_DEFINE_NO_DEPRECATED)
     set(DEFINE_NO_DEPRECATED TRUE)
@@ -343,7 +344,7 @@ macro(_DO_GENERATE_EXPORT_HEADER TARGET_LIBRARY)
     set(NO_DEPRECATED_MACRO_NAME
       ${_GEH_PREFIX_NAME}${_GEH_NO_DEPRECATED_MACRO_NAME})
   endif()
-  string(MAKE_C_IDENTIFIER ${NO_DEPRECATED_MACRO_NAME} NO_DEPRECATED_MACRO_NAME)
+  #string(MAKE_C_IDENTIFIER ${NO_DEPRECATED_MACRO_NAME} NO_DEPRECATED_MACRO_NAME)
 
   set(INCLUDE_GUARD_NAME "${EXPORT_MACRO_NAME}_H")
 
@@ -352,7 +353,7 @@ macro(_DO_GENERATE_EXPORT_HEADER TARGET_LIBRARY)
   if(NOT EXPORT_IMPORT_CONDITION)
     set(EXPORT_IMPORT_CONDITION ${TARGET_LIBRARY}_EXPORTS)
   endif()
-  string(MAKE_C_IDENTIFIER ${EXPORT_IMPORT_CONDITION} EXPORT_IMPORT_CONDITION)
+  #string(MAKE_C_IDENTIFIER ${EXPORT_IMPORT_CONDITION} EXPORT_IMPORT_CONDITION)
 
   configure_file("${_GENERATE_EXPORT_HEADER_MODULE_DIR}/exportheader.cmake.in"
     "${EXPORT_FILE_NAME}" @ONLY)

CMake/Modules/Urho3D-CMake-common.cmake

@@ -487,7 +487,10 @@ macro (enable_pch)
                 get_directory_property (INCLUDE_DIRECTORIES INCLUDE_DIRECTORIES)
                 get_target_property (TYPE ${TARGET_NAME} TYPE)
                 if (TYPE MATCHES SHARED)
-                    string (MAKE_C_IDENTIFIER ${TARGET_NAME}_EXPORTS EXPORT_IMPORT_CONDITION)
+                    set (EXPORT_IMPORT_CONDITION ${TARGET_NAME}_EXPORTS)
+                    if (NOT CMAKE_VERSION VERSION_LESS 2.8.12)
+                        string (MAKE_C_IDENTIFIER ${EXPORT_IMPORT_CONDITION} EXPORT_IMPORT_CONDITION)
+                    endif ()
                     list (APPEND COMPILE_DEFINITIONS ${EXPORT_IMPORT_CONDITION})
                     set (PIC -fPIC)
                 endif ()