better IF ELSE handling

Source/cmElseCommand.cxx

@@ -19,28 +19,6 @@
 
 bool cmElseCommand::InitialPass(std::vector<std::string> const& args)
 {
-  bool isValid;
-  bool isTrue = cmIfCommand::IsTrue(args,isValid,m_Makefile);
-  
-  if (!isValid)
-    {
-    this->SetError("An ELSE command had incorrect arguments");
-    return false;
-    }
-  
-  // first remove any function blockers for the IF
-  m_Makefile->RemoveFunctionBlocker("ELSE",args);
-
-  // if is true create a blocker for the else
-  cmIfFunctionBlocker *f = new cmIfFunctionBlocker();
-  f->m_IsBlocking = isTrue;
-  for(std::vector<std::string>::const_iterator j = args.begin();
-      j != args.end(); ++j)
-    {   
-    f->m_Args.push_back(*j);
-    }
-  m_Makefile->AddFunctionBlocker(f);
-  
-  return true;
+  this->SetError("An ELSE command was found outside of a proper IF ENDIF structure. Or its arguments did not match the opening IF command.");
+  return false;
 }
-

Source/cmIfCommand.cxx

@@ -25,6 +25,13 @@ IsFunctionBlocked(const char *name, const std::vector<std::string> &args,
     {
     if (args == m_Args)
       {
+      // if it was an else statement then we should change state
+      // and block this Else Command
+      if (!strcmp(name,"ELSE"))
+        {
+        m_IsBlocking = !m_IsBlocking;
+        return true;
+        }
       return false;
       }
     else if(args.empty())

Source/cmMakefile.cxx

@@ -1242,7 +1242,6 @@ bool cmMakefile::IsFunctionBlocked(const char *name,
     }
 
   // loop over all function blockers to see if any block this command
-  std::list<cmFunctionBlocker *>::iterator pos;
   std::vector<std::string> expandedArguments;
   for(std::vector<std::string>::const_iterator i = args.begin();
       i != args.end(); ++i)
@@ -1255,8 +1254,10 @@ bool cmMakefile::IsFunctionBlocked(const char *name,
       expandedArguments.push_back(tmps);
       }
     }
-  for (pos = m_FunctionBlockers.begin(); 
-       pos != m_FunctionBlockers.end(); ++pos)
+  // evaluate in reverse, this is critical for balanced IF statements etc
+  std::list<cmFunctionBlocker *>::reverse_iterator pos;
+  for (pos = m_FunctionBlockers.rbegin(); 
+       pos != m_FunctionBlockers.rend(); ++pos)
     {
     if ((*pos)->NeedExpandedVariables()) 
       {