added FORCE option

Source/cmSetCommand.cxx

@@ -39,6 +39,7 @@ bool cmSetCommand::InitialPass(std::vector<std::string> const& args)
   const char* variable = args[0].c_str(); // VAR is always first
   std::string value;  // optional
   bool cache = false; // optional
+  bool force = false; // optional
   cmCacheManager::CacheEntryType type = cmCacheManager::STRING; // required if cache
   const char* docstring = 0; // required if cache
   std::string::size_type cacheStart = 0;
@@ -60,19 +61,24 @@ bool cmSetCommand::InitialPass(std::vector<std::string> const& args)
       }
     }
   
-    
+  // look for FORCE argument
+  if (args.size() > 4 && args[args.size()-1] == "FORCE")
+    {
+    force = true;
+    }
+  
   if(args.size() == 2)
     {
-      // SET (VAR value )
-      value= args[1];
+    // SET (VAR value )
+    value= args[1];
     }
-  else if(args.size() == 4)
+  else if(args.size() == 4 + (force ? 1 : 0))
     {
     // SET (VAR CACHE TYPE "doc String")
     cache = true;
     cacheStart = 1;
     }
-  else if(args.size() == 5)
+  else if(args.size() == 5 + (force ? 1 : 0))
     {
     //  SET (VAR value CACHE TYPE "doc string")
     cache = true;
@@ -116,7 +122,7 @@ bool cmSetCommand::InitialPass(std::vector<std::string> const& args)
     // is already in the cache and the type is not internal
     // then leave now without setting any definitions in the cache
     // or the makefile
-    if(cache && type != cmCacheManager::INTERNAL)
+    if(cache && type != cmCacheManager::INTERNAL && !force)
       {
       return true;
       }

Source/cmSetCommand.h

@@ -67,14 +67,15 @@ public:
   virtual const char* GetFullDocumentation()
     {
     return
-      "SET(VAR [VALUE] [CACHE TYPE DOCSTRING])\n"
+      "SET(VAR [VALUE] [CACHE TYPE DOCSTRING [FORCE]])\n"
       "Within CMAKE sets VAR to the value VALUE. VALUE is expanded before VAR "
       "is set to it. If CACHE is present, then the VAR is put in the cache."
       " TYPE and DOCSTRING are required.  TYPE may be BOOL, PATH, FILEPATH, STRING, INTERNAL, "
       "or STATIC.  If TYPE is INTERNAL, then the "
       " VALUE is Always written into the cache, replacing any values "
       "existing in the cache.  If it is not a CACHE VAR, then this always "
-      "writes into the current makefile.\n"
+      "writes into the current makefile. The FORCE option will overwrite"
+      "the CACHE value removing any changes from the USER.\n"
       "An optional syntax is SET(VAR VALUE1 ... VALUEN).\n"
       "In this case VAR is set to a ; separated list of values.";
     }