ENH: Added backwards compatability.

Source/cmSourceGroupCommand.cxx

@@ -24,7 +24,7 @@ bool cmSourceGroupCommand::InitialPass(std::vector<std::string> const& args)
     this->SetError("called with incorrect number of arguments");
     return false;
     }  
-
+  
   // Get the source group with the given name.
   cmSourceGroup* sg = m_Makefile->GetSourceGroup(args[0].c_str());
   if(!sg)
@@ -33,6 +33,26 @@ bool cmSourceGroupCommand::InitialPass(std::vector<std::string> const& args)
     sg = m_Makefile->GetSourceGroup(args[0].c_str());
     }
   
+  // If only two arguments are given, the pre-1.8 version of the
+  // command is being invoked.
+  if(args.size() == 2 && args[1] != "FILES")
+    {
+    const char* versionValue =
+      m_Makefile->GetDefinition("CMAKE_BACKWARDS_COMPATIBILITY");
+    if(atof(versionValue) > 1.6)
+      {
+      this->SetError("no longer accepts a two-argument form.  Use the "
+                     "REGULAR_EXPRESSION argument form instead, or set "
+                     "CMAKE_BACKWARDS_COMPATIBILITY to 1.6 or less.\n");
+      return false;
+      }
+    else
+      {
+      sg->SetGroupRegex(args[1].c_str());
+      return true;
+      }
+    }
+  
   // Process arguments.
   bool doingFiles = false;
   for(unsigned int i=1; i < args.size(); ++i)