cmState: Add Type for policy scope.

Source/cmMakefile.cxx

@@ -189,6 +189,9 @@ cmMakefile::cmMakefile(cmLocalGenerator* localGenerator)
   this->cmAtVarRegex.compile("(@[A-Za-z_0-9/.+-]+@)");
   this->cmNamedCurly.compile("^[A-Za-z0-9/_.+-]+{");
 
+  this->StateSnapshot = this->StateSnapshot.GetState()
+      ->CreatePolicyScopeSnapshot(this->StateSnapshot);
+
   // Protect the directory-level policies.
   this->PushPolicyBarrier();
 
@@ -1705,6 +1708,8 @@ public:
         this->Makefile->StateSnapshot.GetDirectory().GetCurrentSource();
     currentStart += "/CMakeLists.txt";
     this->Makefile->StateSnapshot.SetListFile(currentStart);
+    this->Makefile->StateSnapshot = this->Makefile->StateSnapshot.GetState()
+        ->CreatePolicyScopeSnapshot(this->Makefile->StateSnapshot);
     this->Makefile->PushPolicyBarrier();
     this->Makefile->PushFunctionBlockerBarrier();
 
@@ -1722,6 +1727,8 @@ public:
   {
     this->Makefile->PopFunctionBlockerBarrier(this->ReportError);
     this->Makefile->PopPolicyBarrier(this->ReportError);
+    this->Makefile->StateSnapshot = this->Makefile->StateSnapshot.GetState()
+        ->Pop(this->Makefile->StateSnapshot);
 #if defined(CMAKE_BUILD_WITH_CMAKE)
     this->GG->GetFileLockPool().PopFileScope();
 #endif
@@ -4841,6 +4848,8 @@ cmMakefile::PolicyPushPop::PolicyPushPop(cmMakefile* m, bool weak,
                                          cmPolicies::PolicyMap const& pm):
   Makefile(m), ReportError(true)
 {
+  this->Makefile->StateSnapshot = this->Makefile->StateSnapshot.GetState()
+      ->CreatePolicyScopeSnapshot(this->Makefile->StateSnapshot);
   this->Makefile->PushPolicyBarrier();
   this->Makefile->PushPolicy(weak, pm);
 }
@@ -4850,6 +4859,8 @@ cmMakefile::PolicyPushPop::~PolicyPushPop()
 {
   this->Makefile->PopPolicy();
   this->Makefile->PopPolicyBarrier(this->ReportError);
+  this->Makefile->StateSnapshot = this->Makefile->StateSnapshot.GetState()
+      ->Pop(this->Makefile->StateSnapshot);
 }
 
 //----------------------------------------------------------------------------

Source/cmState.cxx

@@ -809,6 +809,15 @@ cmState::CreateInlineListFileSnapshot(cmState::Snapshot originSnapshot,
   return cmState::Snapshot(this, pos);
 }
 
+cmState::Snapshot
+cmState::CreatePolicyScopeSnapshot(cmState::Snapshot originSnapshot)
+{
+  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
+                                               *originSnapshot.Position);
+  pos->SnapshotType = PolicyScopeType;
+  return cmState::Snapshot(this, pos);
+}
+
 cmState::Snapshot cmState::Pop(cmState::Snapshot originSnapshot)
 {
   PositionType pos = originSnapshot.Position;
@@ -959,13 +968,22 @@ cmState::Snapshot cmState::Snapshot::GetCallStackParent() const
   assert(this->Position != this->State->SnapshotData.Root());
 
   Snapshot snapshot;
-  if (this->Position->SnapshotType == cmState::BuildsystemDirectoryType)
+  PositionType parentPos = this->Position;
+  while(parentPos->SnapshotType == cmState::PolicyScopeType)
+    {
+    ++parentPos;
+    }
+  if (parentPos->SnapshotType == cmState::BuildsystemDirectoryType)
     {
     return snapshot;
     }
 
-  PositionType parentPos = this->Position;
   ++parentPos;
+  while(parentPos->SnapshotType == cmState::PolicyScopeType)
+    {
+    ++parentPos;
+    }
+
   if (parentPos == this->State->SnapshotData.Root())
     {
     return snapshot;

Source/cmState.h

@@ -37,7 +37,8 @@ public:
     FunctionCallType,
     MacroCallType,
     CallStackType,
-    InlineListFileType
+    InlineListFileType,
+    PolicyScopeType
   };
 
   class Directory;
@@ -148,6 +149,7 @@ public:
                                         const std::string& entryPointCommand,
                                         long entryPointLine,
                                         std::string const& fileName);
+  Snapshot CreatePolicyScopeSnapshot(Snapshot originSnapshot);
   Snapshot Pop(Snapshot originSnapshot);
 
   enum CacheEntryType{ BOOL=0, PATH, FILEPATH, STRING, INTERNAL,STATIC,