Merge topic 'cmState-policies'

757a1f54 cmState: Move PolicyState from cmMakefile.
52dbe654 cmState: Record the end position of each directory.
65a5e0c6 cmLinkedTree: Add Clear API.
34835433 cmState: Add Type for policy scope.
af0de01c cmState: Remove call stack parent tracking.
6ae8b30b cmMakefile: Move policy barriers inside cmState scopes.
a5fc17b5 cmMakefile: Re-order policy entries and barriers.
0a01e6c6 cmState: Add Snapshot Type accessor.
f0005bb4 Tests: Verify generate-time policy scope behavior.

5 files changed, 208 insertions, 127 deletions

diff --git a/Source/cmLinkedTree.h b/Source/cmLinkedTree.h
index df00b30..3bcb940 100644
--- a/Source/cmLinkedTree.h
+++ b/Source/cmLinkedTree.h
@@ -155,6 +155,12 @@ public:
     return iterator(this, 1);
   }
 
+  void Clear()
+  {
+    this->UpPositions.clear();
+    this->Data.clear();
+  }
+
 private:
   T& GetReference(PositionType pos)
   {
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 165e271..60a11e1 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -190,12 +190,12 @@ 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);
+
   // Enter a policy level for this directory.
   this->PushPolicy();
 
-  // Protect the directory-level policies.
-  this->PushPolicyBarrier();
-
   // push empty loop block
   this->PushLoopBlockBarrier();
 
@@ -240,11 +240,6 @@ cmMakefile::~cmMakefile()
   this->EvaluationFiles.clear();
 
   this->FunctionBlockers.clear();
-  if (this->PolicyStack.size() != 1)
-  {
-    cmSystemTools::Error("Internal CMake Error, Policy Stack has not been"
-      " popped properly");
-  }
 }
 
 //----------------------------------------------------------------------------
@@ -472,6 +467,14 @@ cmMakefile::IncludeScope::IncludeScope(cmMakefile* mf,
   Makefile(mf), NoPolicyScope(noPolicyScope),
   CheckCMP0011(false), ReportError(true)
 {
+  this->Makefile->PushFunctionBlockerBarrier();
+
+  this->Makefile->StateSnapshot =
+      this->Makefile->GetState()->CreateCallStackSnapshot(
+        this->Makefile->StateSnapshot,
+        this->Makefile->ContextStack.back()->Name,
+        this->Makefile->ContextStack.back()->Line,
+        filenametoread);
   if(!this->NoPolicyScope)
     {
     // Check CMP0011 to determine the policy scope type.
@@ -500,37 +503,19 @@ cmMakefile::IncludeScope::IncludeScope(cmMakefile* mf,
         break;
       }
     }
-
-  // The included file cannot pop our policy scope.
-  this->Makefile->PushPolicyBarrier();
-  this->Makefile->PushFunctionBlockerBarrier();
-
-  this->Makefile->StateSnapshot =
-      this->Makefile->GetState()->CreateCallStackSnapshot(
-        this->Makefile->StateSnapshot,
-        this->Makefile->ContextStack.back()->Name,
-        this->Makefile->ContextStack.back()->Line,
-        filenametoread);
 }
 
 //----------------------------------------------------------------------------
 cmMakefile::IncludeScope::~IncludeScope()
 {
-  this->Makefile->StateSnapshot =
-      this->Makefile->GetState()->Pop(this->Makefile->StateSnapshot);
-  assert(this->Makefile->StateSnapshot.IsValid());
-
-  this->Makefile->PopFunctionBlockerBarrier(this->ReportError);
-  // Enforce matching policy scopes inside the included file.
-  this->Makefile->PopPolicyBarrier(this->ReportError);
-
   if(!this->NoPolicyScope)
     {
     // If we need to enforce policy CMP0011 then the top entry is the
     // one we pushed above.  If the entry is empty, then the included
     // script did not set any policies that might affect the includer so
     // we do not need to enforce the policy.
-    if(this->CheckCMP0011 && this->Makefile->PolicyStack.back().IsEmpty())
+    if(this->CheckCMP0011
+       && !this->Makefile->StateSnapshot.HasDefinedPolicyCMP0011())
       {
       this->CheckCMP0011 = false;
       }
@@ -545,6 +530,9 @@ cmMakefile::IncludeScope::~IncludeScope()
       this->EnforceCMP0011();
       }
     }
+  this->Makefile->PopPolicyBarrier(this->ReportError);
+
+  this->Makefile->PopFunctionBlockerBarrier(this->ReportError);
 }
 
 //----------------------------------------------------------------------------
@@ -639,8 +627,6 @@ public:
   ListFileScope(cmMakefile* mf, std::string const& filenametoread)
     : Makefile(mf), ReportError(true)
   {
-    this->Makefile->PushPolicyBarrier();
-
     long line = 0;
     std::string name;
     if (!this->Makefile->ContextStack.empty())
@@ -652,17 +638,14 @@ public:
         this->Makefile->GetState()->CreateInlineListFileSnapshot(
           this->Makefile->StateSnapshot, name, line, filenametoread);
     assert(this->Makefile->StateSnapshot.IsValid());
+
     this->Makefile->PushFunctionBlockerBarrier();
   }
 
   ~ListFileScope()
   {
-    this->Makefile->StateSnapshot =
-        this->Makefile->GetState()->Pop(this->Makefile->StateSnapshot);
-    assert(this->Makefile->StateSnapshot.IsValid());
-
-    this->Makefile->PopFunctionBlockerBarrier(this->ReportError);
     this->Makefile->PopPolicyBarrier(this->ReportError);
+    this->Makefile->PopFunctionBlockerBarrier(this->ReportError);
   }
 
   void Quiet() { this->ReportError = false; }
@@ -1662,16 +1645,13 @@ void cmMakefile::PushFunctionScope(std::string const& fileName,
   this->PushFunctionBlockerBarrier();
 
   this->PushPolicy(true, pm);
-  this->PushPolicyBarrier();
 }
 
 void cmMakefile::PopFunctionScope(bool reportError)
 {
-  this->PopPolicyBarrier(reportError);
   this->PopPolicy();
 
-  this->StateSnapshot = this->GetState()->Pop(this->StateSnapshot);
-  assert(this->StateSnapshot.IsValid());
+  this->PopPolicyBarrier(reportError);
 
   this->PopFunctionBlockerBarrier(reportError);
 
@@ -1699,16 +1679,12 @@ void cmMakefile::PushMacroScope(std::string const& fileName,
   this->PushFunctionBlockerBarrier();
 
   this->PushPolicy(true, pm);
-  this->PushPolicyBarrier();
 }
 
 void cmMakefile::PopMacroScope(bool reportError)
 {
-  this->PopPolicyBarrier(reportError);
   this->PopPolicy();
-
-  this->StateSnapshot = this->GetState()->Pop(this->StateSnapshot);
-  assert(this->StateSnapshot.IsValid());
+  this->PopPolicyBarrier(reportError);
 
   this->PopFunctionBlockerBarrier(reportError);
 }
@@ -1728,7 +1704,8 @@ public:
         this->Makefile->StateSnapshot.GetDirectory().GetCurrentSource();
     currentStart += "/CMakeLists.txt";
     this->Makefile->StateSnapshot.SetListFile(currentStart);
-    this->Makefile->PushPolicyBarrier();
+    this->Makefile->StateSnapshot = this->Makefile->StateSnapshot.GetState()
+        ->CreatePolicyScopeSnapshot(this->Makefile->StateSnapshot);
     this->Makefile->PushFunctionBlockerBarrier();
 
     this->GG = mf->GetGlobalGenerator();
@@ -4775,30 +4752,7 @@ const char* cmMakefile::GetDefineFlagsCMP0059() const
 cmPolicies::PolicyStatus
 cmMakefile::GetPolicyStatus(cmPolicies::PolicyID id) const
 {
-  cmPolicies::PolicyStatus status = cmPolicies::GetPolicyStatus(id);
-
-  if(status == cmPolicies::REQUIRED_ALWAYS ||
-     status == cmPolicies::REQUIRED_IF_USED)
-    {
-    return status;
-    }
-
-  cmLocalGenerator* lg = this->LocalGenerator;
-  while(lg)
-    {
-    cmMakefile const* mf = lg->GetMakefile();
-    for(PolicyStackType::const_reverse_iterator psi =
-        mf->PolicyStack.rbegin(); psi != mf->PolicyStack.rend(); ++psi)
-      {
-      if(psi->IsDefined(id))
-        {
-        status = psi->Get(id);
-        return status;
-        }
-      }
-    lg = lg->GetParent();
-    }
-  return status;
+  return this->StateSnapshot.GetPolicy(id);
 }
 
 //----------------------------------------------------------------------------
@@ -4847,15 +4801,7 @@ bool cmMakefile::SetPolicy(cmPolicies::PolicyID id,
     return false;
     }
 
-  // Update the policy stack from the top to the top-most strong entry.
-  bool previous_was_weak = true;
-  for(PolicyStackType::reverse_iterator psi = this->PolicyStack.rbegin();
-      previous_was_weak && psi != this->PolicyStack.rend(); ++psi)
-    {
-    psi->Set(id, status);
-    previous_was_weak = psi->Weak;
-    }
-
+  this->StateSnapshot.SetPolicy(id, status);
   return true;
 }
 
@@ -4864,32 +4810,28 @@ 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->PushPolicy(weak, pm);
-  this->Makefile->PushPolicyBarrier();
 }
 
 //----------------------------------------------------------------------------
 cmMakefile::PolicyPushPop::~PolicyPushPop()
 {
-  this->Makefile->PopPolicyBarrier(this->ReportError);
   this->Makefile->PopPolicy();
+  this->Makefile->PopPolicyBarrier(this->ReportError);
 }
 
 //----------------------------------------------------------------------------
 void cmMakefile::PushPolicy(bool weak, cmPolicies::PolicyMap const& pm)
 {
-  // Allocate a new stack entry.
-  this->PolicyStack.push_back(PolicyStackEntry(pm, weak));
+  this->StateSnapshot.PushPolicy(pm, weak);
 }
 
 //----------------------------------------------------------------------------
 void cmMakefile::PopPolicy()
 {
-  if(this->PolicyStack.size() > this->PolicyBarriers.back())
-    {
-    this->PolicyStack.pop_back();
-    }
-  else
+  if (!this->StateSnapshot.PopPolicy())
     {
     this->IssueMessage(cmake::FATAL_ERROR,
                        "cmake_policy POP without matching PUSH");
@@ -4897,17 +4839,9 @@ void cmMakefile::PopPolicy()
 }
 
 //----------------------------------------------------------------------------
-void cmMakefile::PushPolicyBarrier()
-{
-  this->PolicyBarriers.push_back(this->PolicyStack.size());
-}
-
-//----------------------------------------------------------------------------
 void cmMakefile::PopPolicyBarrier(bool reportError)
 {
-  // Remove any extra entries pushed on the barrier.
-  PolicyStackType::size_type barrier = this->PolicyBarriers.back();
-  while(this->PolicyStack.size() > barrier)
+  while (!this->StateSnapshot.CanPopPolicyScope())
     {
     if(reportError)
       {
@@ -4918,8 +4852,8 @@ void cmMakefile::PopPolicyBarrier(bool reportError)
     this->PopPolicy();
     }
 
-  // Remove the barrier.
-  this->PolicyBarriers.pop_back();
+  this->StateSnapshot = this->GetState()->Pop(this->StateSnapshot);
+  assert(this->StateSnapshot.IsValid());
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index c16ab3d..27e5bce 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -918,7 +918,6 @@ private:
   void PushPolicy(bool weak = false,
                   cmPolicies::PolicyMap const& pm = cmPolicies::PolicyMap());
   void PopPolicy();
-  void PushPolicyBarrier();
   void PopPolicyBarrier(bool reportError = true);
   friend class cmCMakePolicyCommand;
   class IncludeScope;
@@ -928,18 +927,6 @@ private:
   class BuildsystemFileScope;
   friend class BuildsystemFileScope;
 
-  // stack of policy settings
-  struct PolicyStackEntry: public cmPolicies::PolicyMap
-  {
-    typedef cmPolicies::PolicyMap derived;
-    PolicyStackEntry(bool w = false): derived(), Weak(w) {}
-    PolicyStackEntry(derived const& d, bool w = false): derived(d), Weak(w) {}
-    PolicyStackEntry(PolicyStackEntry const& r): derived(r), Weak(r.Weak) {}
-    bool Weak;
-  };
-  typedef std::vector<PolicyStackEntry> PolicyStackType;
-  PolicyStackType PolicyStack;
-  std::vector<PolicyStackType::size_type> PolicyBarriers;
 
   // CMP0053 == old
   cmake::MessageType ExpandVariablesInStringOld(
diff --git a/Source/cmState.cxx b/Source/cmState.cxx
index d8f8306..f425861 100644
--- a/Source/cmState.cxx
+++ b/Source/cmState.cxx
@@ -20,8 +20,10 @@
 
 struct cmState::SnapshotDataType
 {
-  cmState::PositionType CallStackParent;
   cmState::PositionType DirectoryParent;
+  cmLinkedTree<cmState::PolicyStackEntry>::iterator Policies;
+  cmLinkedTree<cmState::PolicyStackEntry>::iterator PolicyRoot;
+  cmLinkedTree<cmState::PolicyStackEntry>::iterator PolicyScope;
   cmState::SnapshotType SnapshotType;
   cmLinkedTree<std::string>::iterator ExecutionListFile;
   cmLinkedTree<cmState::BuildsystemDirectoryStateType>::iterator
@@ -33,8 +35,19 @@ struct cmState::SnapshotDataType
   std::vector<std::string>::size_type CompileOptionsPosition;
 };
 
+struct cmState::PolicyStackEntry: public cmPolicies::PolicyMap
+{
+  typedef cmPolicies::PolicyMap derived;
+  PolicyStackEntry(bool w = false): derived(), Weak(w) {}
+  PolicyStackEntry(derived const& d, bool w): derived(d), Weak(w) {}
+  PolicyStackEntry(PolicyStackEntry const& r): derived(r), Weak(r.Weak) {}
+  bool Weak;
+};
+
 struct cmState::BuildsystemDirectoryStateType
 {
+  cmState::PositionType DirectoryEnd;
+
   std::string Location;
   std::string OutputLocation;
 
@@ -240,6 +253,9 @@ cmState::Snapshot cmState::Reset()
   this->GlobalProperties.clear();
   this->PropertyDefinitions.clear();
 
+  PositionType pos = this->SnapshotData.Truncate();
+  this->ExecutionListFiles.Truncate();
+
   {
   cmLinkedTree<BuildsystemDirectoryStateType>::iterator it =
       this->BuildsystemDirectory.Truncate();
@@ -249,9 +265,15 @@ cmState::Snapshot cmState::Reset()
   it->CompileDefinitionsBacktraces.clear();
   it->CompileOptions.clear();
   it->CompileOptionsBacktraces.clear();
+  it->DirectoryEnd = pos;
   }
-  PositionType pos = this->SnapshotData.Truncate();
-  this->ExecutionListFiles.Truncate();
+
+  this->PolicyStack.Clear();
+  pos->Policies = this->PolicyStack.Root();
+  pos->PolicyRoot = this->PolicyStack.Root();
+  pos->PolicyScope = this->PolicyStack.Root();
+  assert(pos->Policies.IsValid());
+  assert(pos->PolicyRoot.IsValid());
 
   this->DefineProperty
     ("RULE_LAUNCH_COMPILE", cmProperty::DIRECTORY,
@@ -722,6 +744,12 @@ cmState::Snapshot cmState::CreateBaseSnapshot()
   pos->IncludeDirectoryPosition = 0;
   pos->CompileDefinitionsPosition = 0;
   pos->CompileOptionsPosition = 0;
+  pos->BuildSystemDirectory->DirectoryEnd = pos;
+  pos->Policies = this->PolicyStack.Root();
+  pos->PolicyRoot = this->PolicyStack.Root();
+  pos->PolicyScope = this->PolicyStack.Root();
+  assert(pos->Policies.IsValid());
+  assert(pos->PolicyRoot.IsValid());
   return cmState::Snapshot(this, pos);
 }
 
@@ -732,7 +760,6 @@ cmState::CreateBuildsystemDirectorySnapshot(Snapshot originSnapshot,
 {
   assert(originSnapshot.IsValid());
   PositionType pos = this->SnapshotData.Extend(originSnapshot.Position);
-  pos->CallStackParent = originSnapshot.Position;
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->DirectoryParent = originSnapshot.Position;
@@ -743,6 +770,12 @@ cmState::CreateBuildsystemDirectorySnapshot(Snapshot originSnapshot,
   pos->ExecutionListFile =
       this->ExecutionListFiles.Extend(
         originSnapshot.Position->ExecutionListFile);
+  pos->BuildSystemDirectory->DirectoryEnd = pos;
+  pos->Policies = originSnapshot.Position->Policies;
+  pos->PolicyRoot = originSnapshot.Position->Policies;
+  pos->PolicyScope = originSnapshot.Position->Policies;
+  assert(pos->Policies.IsValid());
+  assert(pos->PolicyRoot.IsValid());
   return cmState::Snapshot(this, pos);
 }
 
@@ -754,12 +787,13 @@ cmState::CreateFunctionCallSnapshot(cmState::Snapshot originSnapshot,
 {
   PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
                                                *originSnapshot.Position);
-  pos->CallStackParent = originSnapshot.Position;
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->SnapshotType = FunctionCallType;
   pos->ExecutionListFile = this->ExecutionListFiles.Extend(
         originSnapshot.Position->ExecutionListFile, fileName);
+  pos->BuildSystemDirectory->DirectoryEnd = pos;
+  pos->PolicyScope = originSnapshot.Position->Policies;
   return cmState::Snapshot(this, pos);
 }
 
@@ -772,12 +806,13 @@ cmState::CreateMacroCallSnapshot(cmState::Snapshot originSnapshot,
 {
   PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
                                                *originSnapshot.Position);
-  pos->CallStackParent = originSnapshot.Position;
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->SnapshotType = MacroCallType;
   pos->ExecutionListFile = this->ExecutionListFiles.Extend(
         originSnapshot.Position->ExecutionListFile, fileName);
+  pos->BuildSystemDirectory->DirectoryEnd = pos;
+  pos->PolicyScope = originSnapshot.Position->Policies;
   return cmState::Snapshot(this, pos);
 }
 
@@ -789,12 +824,13 @@ cmState::CreateCallStackSnapshot(cmState::Snapshot originSnapshot,
 {
   PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
                                                *originSnapshot.Position);
-  pos->CallStackParent = originSnapshot.Position;
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->SnapshotType = CallStackType;
   pos->ExecutionListFile = this->ExecutionListFiles.Extend(
         originSnapshot.Position->ExecutionListFile, fileName);
+  pos->BuildSystemDirectory->DirectoryEnd = pos;
+  pos->PolicyScope = originSnapshot.Position->Policies;
   return cmState::Snapshot(this, pos);
 }
 
@@ -806,12 +842,24 @@ cmState::CreateInlineListFileSnapshot(cmState::Snapshot originSnapshot,
 {
   PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
                                                *originSnapshot.Position);
-  pos->CallStackParent = originSnapshot.Position;
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->SnapshotType = InlineListFileType;
   pos->ExecutionListFile = this->ExecutionListFiles.Extend(
         originSnapshot.Position->ExecutionListFile, fileName);
+  pos->BuildSystemDirectory->DirectoryEnd = pos;
+  pos->PolicyScope = originSnapshot.Position->Policies;
+  return cmState::Snapshot(this, pos);
+}
+
+cmState::Snapshot
+cmState::CreatePolicyScopeSnapshot(cmState::Snapshot originSnapshot)
+{
+  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
+                                               *originSnapshot.Position);
+  pos->SnapshotType = PolicyScopeType;
+  pos->BuildSystemDirectory->DirectoryEnd = pos;
+  pos->PolicyScope = originSnapshot.Position->Policies;
   return cmState::Snapshot(this, pos);
 }
 
@@ -826,12 +874,9 @@ cmState::Snapshot cmState::Pop(cmState::Snapshot originSnapshot)
       prevPos->BuildSystemDirectory->CompileDefinitions.size();
   prevPos->CompileOptionsPosition =
       prevPos->BuildSystemDirectory->CompileOptions.size();
+  prevPos->BuildSystemDirectory->DirectoryEnd = prevPos;
 
-  if (prevPos == this->SnapshotData.Root())
-    {
-    return Snapshot(this, prevPos);
-    }
-  return Snapshot(this, originSnapshot.Position->CallStackParent);
+  return Snapshot(this, prevPos);
 }
 
 cmState::Snapshot::Snapshot(cmState* state)
@@ -847,6 +892,11 @@ cmState::Snapshot::Snapshot(cmState* state, PositionType position)
 
 }
 
+cmState::SnapshotType cmState::Snapshot::GetType() const
+{
+  return this->Position->SnapshotType;
+}
+
 const char* cmState::Directory::GetCurrentSource() const
 {
   return this->DirectoryState->Location.c_str();
@@ -964,13 +1014,22 @@ 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;
@@ -980,6 +1039,88 @@ cmState::Snapshot cmState::Snapshot::GetCallStackParent() const
   return snapshot;
 }
 
+void cmState::Snapshot::PushPolicy(cmPolicies::PolicyMap entry, bool weak)
+{
+  PositionType pos = this->Position;
+  pos->Policies =
+      this->State->PolicyStack.Extend(pos->Policies,
+                                      PolicyStackEntry(entry, weak));
+}
+
+bool cmState::Snapshot::PopPolicy()
+{
+  PositionType pos = this->Position;
+  if (pos->Policies == pos->PolicyScope)
+    {
+    return false;
+    }
+  ++pos->Policies;
+  return true;
+}
+
+bool cmState::Snapshot::CanPopPolicyScope()
+{
+  return this->Position->Policies == this->Position->PolicyScope;
+}
+
+void cmState::Snapshot::SetPolicy(cmPolicies::PolicyID id,
+                                  cmPolicies::PolicyStatus status)
+{
+  // Update the policy stack from the top to the top-most strong entry.
+  bool previous_was_weak = true;
+  for(cmLinkedTree<PolicyStackEntry>::iterator psi = this->Position->Policies;
+      previous_was_weak && psi != this->Position->PolicyRoot; ++psi)
+    {
+    psi->Set(id, status);
+    previous_was_weak = psi->Weak;
+    }
+}
+
+cmPolicies::PolicyStatus
+cmState::Snapshot::GetPolicy(cmPolicies::PolicyID id) const
+{
+  cmPolicies::PolicyStatus status = cmPolicies::GetPolicyStatus(id);
+
+  if(status == cmPolicies::REQUIRED_ALWAYS ||
+     status == cmPolicies::REQUIRED_IF_USED)
+    {
+    return status;
+    }
+
+  cmLinkedTree<BuildsystemDirectoryStateType>::iterator dir =
+      this->Position->BuildSystemDirectory;
+
+  while (true)
+    {
+    assert(dir.IsValid());
+    cmLinkedTree<PolicyStackEntry>::iterator leaf =
+        dir->DirectoryEnd->Policies;
+    cmLinkedTree<PolicyStackEntry>::iterator root =
+        dir->DirectoryEnd->PolicyRoot;
+    for( ; leaf != root; ++leaf)
+      {
+      if(leaf->IsDefined(id))
+        {
+        status = leaf->Get(id);
+        return status;
+        }
+      }
+    cmState::PositionType e = dir->DirectoryEnd;
+    cmState::PositionType p = e->DirectoryParent;
+    if (p == this->State->SnapshotData.Root())
+      {
+      break;
+      }
+    dir = p->BuildSystemDirectory;
+    }
+  return status;
+}
+
+bool cmState::Snapshot::HasDefinedPolicyCMP0011()
+{
+  return !this->Position->Policies->IsEmpty();
+}
+
 static const std::string cmPropertySentinal = std::string();
 
 template<typename T, typename U, typename V>
diff --git a/Source/cmState.h b/Source/cmState.h
index 0d5300f..07aa2a5 100644
--- a/Source/cmState.h
+++ b/Source/cmState.h
@@ -17,6 +17,7 @@
 #include "cmPropertyMap.h"
 #include "cmLinkedTree.h"
 #include "cmAlgorithms.h"
+#include "cmPolicies.h"
 
 class cmake;
 class cmCommand;
@@ -24,6 +25,7 @@ class cmCommand;
 class cmState
 {
   struct SnapshotDataType;
+  struct PolicyStackEntry;
   struct BuildsystemDirectoryStateType;
   typedef cmLinkedTree<SnapshotDataType>::iterator PositionType;
   friend class Snapshot;
@@ -37,7 +39,8 @@ public:
     FunctionCallType,
     MacroCallType,
     CallStackType,
-    InlineListFileType
+    InlineListFileType,
+    PolicyScopeType
   };
 
   class Directory;
@@ -56,9 +59,17 @@ public:
     bool IsValid() const;
     Snapshot GetBuildsystemDirectoryParent() const;
     Snapshot GetCallStackParent() const;
+    SnapshotType GetType() const;
 
     void InitializeFromParent();
 
+    void SetPolicy(cmPolicies::PolicyID id, cmPolicies::PolicyStatus status);
+    cmPolicies::PolicyStatus GetPolicy(cmPolicies::PolicyID id) const;
+    bool HasDefinedPolicyCMP0011();
+    void PushPolicy(cmPolicies::PolicyMap entry, bool weak);
+    bool PopPolicy();
+    bool CanPopPolicyScope();
+
     cmState* GetState() const;
 
     Directory GetDirectory() const;
@@ -147,6 +158,7 @@ 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,
@@ -254,6 +266,7 @@ private:
 
   cmLinkedTree<std::string> ExecutionListFiles;
 
+  cmLinkedTree<PolicyStackEntry> PolicyStack;
   cmLinkedTree<SnapshotDataType> SnapshotData;
 
   std::vector<std::string> SourceDirectoryComponents;