cmLocalGenerator: Require a valid cmState::Snapshot in the ctor.

Refactor the local generator creation API to accept a
cmState::Snapshot.  Adjust MakeLocalGenerator to use the 'current'
snapshot in cases where there is no parent.  Create the snapshot
for subdirectories in cmMakefile::AddSubdirectory.

This means that snapshots are now created at the point of extending the tree,
as appropriate, and independently of the cmLocalGenerator and cmMakefile they
represent the state for.

38 files changed, 111 insertions, 64 deletions

diff --git a/Source/cmGlobalBorlandMakefileGenerator.cxx b/Source/cmGlobalBorlandMakefileGenerator.cxx
index 7d05726..87665a0 100644
--- a/Source/cmGlobalBorlandMakefileGenerator.cxx
+++ b/Source/cmGlobalBorlandMakefileGenerator.cxx
@@ -44,10 +44,10 @@ void cmGlobalBorlandMakefileGenerator
 
 ///! Create a local generator appropriate to this Global Generator
 cmLocalGenerator *cmGlobalBorlandMakefileGenerator::CreateLocalGenerator(
-    cmLocalGenerator* parent)
+    cmLocalGenerator* parent, cmState::Snapshot snapshot)
 {
   cmLocalUnixMakefileGenerator3* lg =
-      new cmLocalUnixMakefileGenerator3(this, parent);
+      new cmLocalUnixMakefileGenerator3(this, parent, snapshot);
   lg->SetMakefileVariableSize(32);
   lg->SetMakeCommandEscapeTargetTwice(true);
   lg->SetBorlandMakeCurlyHack(true);
diff --git a/Source/cmGlobalBorlandMakefileGenerator.h b/Source/cmGlobalBorlandMakefileGenerator.h
index eac297e..2ec510d 100644
--- a/Source/cmGlobalBorlandMakefileGenerator.h
+++ b/Source/cmGlobalBorlandMakefileGenerator.h
@@ -36,7 +36,8 @@ public:
   static void GetDocumentation(cmDocumentationEntry& entry);
 
   ///! Create a local generator appropriate to this Global Generator
-  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent = 0);
+  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent,
+                                                 cmState::Snapshot snapshot);
 
   /**
    * Try to determine system information such as shared library
diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index 7cb5724..cd05c54 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -1884,15 +1884,22 @@ void cmGlobalGenerator::EnableInstallTarget()
 }
 
 cmLocalGenerator *
-cmGlobalGenerator::MakeLocalGenerator(cmLocalGenerator *parent)
+cmGlobalGenerator::MakeLocalGenerator(cmState::Snapshot snapshot,
+                                      cmLocalGenerator *parent)
 {
-  return this->CreateLocalGenerator(parent);
+  if (!snapshot.IsValid())
+    {
+    snapshot = this->CMakeInstance->GetCurrentSnapshot();
+    }
+
+  return this->CreateLocalGenerator(parent, snapshot);
 }
 
-cmLocalGenerator *
-cmGlobalGenerator::CreateLocalGenerator(cmLocalGenerator *parent)
+cmLocalGenerator*
+cmGlobalGenerator::CreateLocalGenerator(cmLocalGenerator* parent,
+                                        cmState::Snapshot snapshot)
 {
-  return new cmLocalGenerator(this, parent);
+  return new cmLocalGenerator(this, parent, snapshot);
 }
 
 void cmGlobalGenerator::EnableLanguagesFromGenerator(cmGlobalGenerator *gen,
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 98f87ed..979e971 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -21,6 +21,7 @@
 #include "cmExportSetMap.h" // For cmExportSetMap
 #include "cmGeneratorTarget.h"
 #include "cmGeneratorExpression.h"
+#include "cmState.h"
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 # include "cmFileLockPool.h"
@@ -56,7 +57,9 @@ public:
   cmGlobalGenerator(cmake* cm);
   virtual ~cmGlobalGenerator();
 
-  cmLocalGenerator* MakeLocalGenerator(cmLocalGenerator* parent = 0);
+  cmLocalGenerator* MakeLocalGenerator(
+      cmState::Snapshot snapshot = cmState::Snapshot(),
+      cmLocalGenerator* parent = 0);
 
   ///! Get the name for this generator
   virtual std::string GetName() const { return "Generic"; }
@@ -441,7 +444,8 @@ protected:
 
 private:
   ///! Create a local generator appropriate to this Global Generator
-  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent);
+  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent,
+                                                 cmState::Snapshot snapshot);
 
   cmMakefile* TryCompileOuterMakefile;
   float FirstTimeProgress;
diff --git a/Source/cmGlobalGhsMultiGenerator.cxx b/Source/cmGlobalGhsMultiGenerator.cxx
index 2bb0617..f764418 100644
--- a/Source/cmGlobalGhsMultiGenerator.cxx
+++ b/Source/cmGlobalGhsMultiGenerator.cxx
@@ -33,9 +33,10 @@ cmGlobalGhsMultiGenerator::~cmGlobalGhsMultiGenerator()
 }
 
 cmLocalGenerator *
-cmGlobalGhsMultiGenerator::CreateLocalGenerator(cmLocalGenerator* parent)
+cmGlobalGhsMultiGenerator::CreateLocalGenerator(cmLocalGenerator* parent,
+                                                cmState::Snapshot snapshot)
 {
-  return new cmLocalGhsMultiGenerator(this, parent);
+  return new cmLocalGhsMultiGenerator(this, parent, snapshot);
 }
 
 void cmGlobalGhsMultiGenerator::GetDocumentation(cmDocumentationEntry &entry)
diff --git a/Source/cmGlobalGhsMultiGenerator.h b/Source/cmGlobalGhsMultiGenerator.h
index 8b7ecf8..f1a3ed7 100644
--- a/Source/cmGlobalGhsMultiGenerator.h
+++ b/Source/cmGlobalGhsMultiGenerator.h
@@ -31,7 +31,8 @@ public:
   { return new cmGlobalGeneratorSimpleFactory<cmGlobalGhsMultiGenerator>(); }
 
   ///! create the correct local generator
-  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent = 0);
+  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent,
+                                                 cmState::Snapshot snapshot);
 
   /// @return the name of this generator.
   static std::string GetActualName() { return "Green Hills MULTI"; }
diff --git a/Source/cmGlobalNinjaGenerator.cxx b/Source/cmGlobalNinjaGenerator.cxx
index 2c5896c..10828e2 100644
--- a/Source/cmGlobalNinjaGenerator.cxx
+++ b/Source/cmGlobalNinjaGenerator.cxx
@@ -529,9 +529,10 @@ cmGlobalNinjaGenerator::cmGlobalNinjaGenerator(cmake* cm)
 // Virtual public methods.
 
 cmLocalGenerator*
-cmGlobalNinjaGenerator::CreateLocalGenerator(cmLocalGenerator* parent)
+cmGlobalNinjaGenerator::CreateLocalGenerator(cmLocalGenerator* parent,
+                                             cmState::Snapshot snapshot)
 {
-  return new cmLocalNinjaGenerator(this, parent);
+  return new cmLocalNinjaGenerator(this, parent, snapshot);
 }
 
 void cmGlobalNinjaGenerator
diff --git a/Source/cmGlobalNinjaGenerator.h b/Source/cmGlobalNinjaGenerator.h
index 88b7067..ffd1cdc 100644
--- a/Source/cmGlobalNinjaGenerator.h
+++ b/Source/cmGlobalNinjaGenerator.h
@@ -170,7 +170,8 @@ public:
   virtual ~cmGlobalNinjaGenerator() { }
 
   /// Overloaded methods. @see cmGlobalGenerator::CreateLocalGenerator()
-  virtual cmLocalGenerator* CreateLocalGenerator(cmLocalGenerator* parent = 0);
+  virtual cmLocalGenerator* CreateLocalGenerator(cmLocalGenerator* parent,
+                                                 cmState::Snapshot snapshot);
 
   /// Overloaded methods. @see cmGlobalGenerator::GetName().
   virtual std::string GetName() const {
diff --git a/Source/cmGlobalUnixMakefileGenerator3.cxx b/Source/cmGlobalUnixMakefileGenerator3.cxx
index 372e87a..4fe52dd 100644
--- a/Source/cmGlobalUnixMakefileGenerator3.cxx
+++ b/Source/cmGlobalUnixMakefileGenerator3.cxx
@@ -60,9 +60,10 @@ void cmGlobalUnixMakefileGenerator3
 
 ///! Create a local generator appropriate to this Global Generator
 cmLocalGenerator *
-cmGlobalUnixMakefileGenerator3::CreateLocalGenerator(cmLocalGenerator* parent)
+cmGlobalUnixMakefileGenerator3::CreateLocalGenerator(cmLocalGenerator* parent,
+                                                   cmState::Snapshot snapshot)
 {
-  return new cmLocalUnixMakefileGenerator3(this, parent);
+  return new cmLocalUnixMakefileGenerator3(this, parent, snapshot);
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGlobalUnixMakefileGenerator3.h b/Source/cmGlobalUnixMakefileGenerator3.h
index 686a4c9..a639ff0 100644
--- a/Source/cmGlobalUnixMakefileGenerator3.h
+++ b/Source/cmGlobalUnixMakefileGenerator3.h
@@ -68,7 +68,8 @@ public:
   static void GetDocumentation(cmDocumentationEntry& entry);
 
   ///! Create a local generator appropriate to this Global Generator3
-  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent = 0);
+  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent,
+                                                 cmState::Snapshot snapshot);
 
   /**
    * Try to determine system information such as shared library
diff --git a/Source/cmGlobalVisualStudio10Generator.cxx b/Source/cmGlobalVisualStudio10Generator.cxx
index 0835707..4e8ada4 100644
--- a/Source/cmGlobalVisualStudio10Generator.cxx
+++ b/Source/cmGlobalVisualStudio10Generator.cxx
@@ -307,9 +307,10 @@ void cmGlobalVisualStudio10Generator::WriteSLNHeader(std::ostream& fout)
 
 ///! Create a local generator appropriate to this Global Generator
 cmLocalGenerator *
-cmGlobalVisualStudio10Generator::CreateLocalGenerator(cmLocalGenerator* parent)
+cmGlobalVisualStudio10Generator::CreateLocalGenerator(cmLocalGenerator* parent,
+                                                    cmState::Snapshot snapshot)
 {
-  return new cmLocalVisualStudio10Generator(this, parent);
+  return new cmLocalVisualStudio10Generator(this, parent, snapshot);
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGlobalVisualStudio10Generator.h b/Source/cmGlobalVisualStudio10Generator.h
index 9faa603..74d5022 100644
--- a/Source/cmGlobalVisualStudio10Generator.h
+++ b/Source/cmGlobalVisualStudio10Generator.h
@@ -46,7 +46,8 @@ public:
     );
 
   ///! create the correct local generator
-  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent = 0);
+  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent,
+                                                 cmState::Snapshot snapshot);
 
   /**
    * Try to determine system information such as shared library
diff --git a/Source/cmGlobalVisualStudio6Generator.cxx b/Source/cmGlobalVisualStudio6Generator.cxx
index f420e4a..632141a 100644
--- a/Source/cmGlobalVisualStudio6Generator.cxx
+++ b/Source/cmGlobalVisualStudio6Generator.cxx
@@ -173,9 +173,10 @@ cmGlobalVisualStudio6Generator::GenerateBuildCommand(
 
 ///! Create a local generator appropriate to this Global Generator
 cmLocalGenerator *
-cmGlobalVisualStudio6Generator::CreateLocalGenerator(cmLocalGenerator* parent)
+cmGlobalVisualStudio6Generator::CreateLocalGenerator(cmLocalGenerator* parent,
+                                                   cmState::Snapshot snapshot)
 {
-  return new cmLocalVisualStudio6Generator(this, parent);
+  return new cmLocalVisualStudio6Generator(this, parent, snapshot);
 }
 
 
diff --git a/Source/cmGlobalVisualStudio6Generator.h b/Source/cmGlobalVisualStudio6Generator.h
index 2e61501..2460158 100644
--- a/Source/cmGlobalVisualStudio6Generator.h
+++ b/Source/cmGlobalVisualStudio6Generator.h
@@ -39,7 +39,8 @@ public:
   static void GetDocumentation(cmDocumentationEntry& entry);
 
   ///! Create a local generator appropriate to this Global Generator
-  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent = 0);
+  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent,
+                                                 cmState::Snapshot snapshot);
 
   /**
    * Try to determine system information such as shared library
diff --git a/Source/cmGlobalVisualStudio7Generator.cxx b/Source/cmGlobalVisualStudio7Generator.cxx
index 336328c..4dd54d0 100644
--- a/Source/cmGlobalVisualStudio7Generator.cxx
+++ b/Source/cmGlobalVisualStudio7Generator.cxx
@@ -279,10 +279,11 @@ void cmGlobalVisualStudio7Generator::GenerateBuildCommand(
 
 ///! Create a local generator appropriate to this Global Generator
 cmLocalGenerator *
-cmGlobalVisualStudio7Generator::CreateLocalGenerator(cmLocalGenerator* parent)
+cmGlobalVisualStudio7Generator::CreateLocalGenerator(cmLocalGenerator* parent,
+                                                   cmState::Snapshot snapshot)
 {
   cmLocalVisualStudio7Generator *lg =
-    new cmLocalVisualStudio7Generator(this, parent);
+    new cmLocalVisualStudio7Generator(this, parent, snapshot);
   return lg;
 }
 
diff --git a/Source/cmGlobalVisualStudio7Generator.h b/Source/cmGlobalVisualStudio7Generator.h
index cbd753b..c98d269 100644
--- a/Source/cmGlobalVisualStudio7Generator.h
+++ b/Source/cmGlobalVisualStudio7Generator.h
@@ -43,7 +43,8 @@ public:
   std::string const& GetPlatformName() const;
 
   ///! Create a local generator appropriate to this Global Generator
-  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent = 0);
+  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent,
+                                                 cmState::Snapshot snapshot);
 
   virtual bool SetSystemName(std::string const& s, cmMakefile* mf);
 
diff --git a/Source/cmGlobalXCodeGenerator.cxx b/Source/cmGlobalXCodeGenerator.cxx
index 302784d..7464e90 100644
--- a/Source/cmGlobalXCodeGenerator.cxx
+++ b/Source/cmGlobalXCodeGenerator.cxx
@@ -371,9 +371,10 @@ cmGlobalXCodeGenerator::GenerateBuildCommand(
 //----------------------------------------------------------------------------
 ///! Create a local generator appropriate to this Global Generator
 cmLocalGenerator *
-cmGlobalXCodeGenerator::CreateLocalGenerator(cmLocalGenerator* parent)
+cmGlobalXCodeGenerator::CreateLocalGenerator(cmLocalGenerator* parent,
+                                             cmState::Snapshot snapshot)
 {
-  return new cmLocalXCodeGenerator(this, parent);
+  return new cmLocalXCodeGenerator(this, parent, snapshot);
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGlobalXCodeGenerator.h b/Source/cmGlobalXCodeGenerator.h
index 42b6697..c36e4af 100644
--- a/Source/cmGlobalXCodeGenerator.h
+++ b/Source/cmGlobalXCodeGenerator.h
@@ -41,7 +41,8 @@ public:
   static void GetDocumentation(cmDocumentationEntry& entry);
 
   ///! Create a local generator appropriate to this Global Generator
-  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent = 0);
+  virtual cmLocalGenerator *CreateLocalGenerator(cmLocalGenerator* parent,
+                                                 cmState::Snapshot snapshot);
 
   /**
    * Try to determine system information such as shared library
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index d00b677..7d8596e 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -44,19 +44,16 @@
 #endif
 
 cmLocalGenerator::cmLocalGenerator(cmGlobalGenerator* gg,
-                                   cmLocalGenerator* parent)
+                                   cmLocalGenerator* parent,
+                                   cmState::Snapshot snapshot)
+  : StateSnapshot(snapshot)
 {
+  assert(snapshot.IsValid());
   this->GlobalGenerator = gg;
   this->Parent = parent;
   if (parent)
     {
     parent->AddChild(this);
-    this->StateSnapshot =
-        this->GetState()->CreateSnapshot(parent->StateSnapshot);
-    }
-  else
-    {
-    this->StateSnapshot = gg->GetCMakeInstance()->GetCurrentSnapshot();
     }
 
   this->Makefile = new cmMakefile(this);
diff --git a/Source/cmLocalGenerator.h b/Source/cmLocalGenerator.h
index 3fca225..44c9586 100644
--- a/Source/cmLocalGenerator.h
+++ b/Source/cmLocalGenerator.h
@@ -34,7 +34,8 @@ class cmCustomCommandGenerator;
 class cmLocalGenerator
 {
 public:
-  cmLocalGenerator(cmGlobalGenerator* gg, cmLocalGenerator* parent);
+  cmLocalGenerator(cmGlobalGenerator* gg, cmLocalGenerator* parent,
+                   cmState::Snapshot snapshot);
   virtual ~cmLocalGenerator();
 
   /// @return whether we are processing the top CMakeLists.txt file.
diff --git a/Source/cmLocalGhsMultiGenerator.cxx b/Source/cmLocalGhsMultiGenerator.cxx
index 025b464..870b9b9 100644
--- a/Source/cmLocalGhsMultiGenerator.cxx
+++ b/Source/cmLocalGhsMultiGenerator.cxx
@@ -17,8 +17,9 @@
 #include "cmGeneratedFileStream.h"
 
 cmLocalGhsMultiGenerator::cmLocalGhsMultiGenerator(cmGlobalGenerator* gg,
-                                                   cmLocalGenerator* parent)
-  : cmLocalGenerator(gg, parent)
+                                                   cmLocalGenerator* parent,
+                                                   cmState::Snapshot snapshot)
+  : cmLocalGenerator(gg, parent, snapshot)
 {
 }
 
diff --git a/Source/cmLocalGhsMultiGenerator.h b/Source/cmLocalGhsMultiGenerator.h
index 3157f11..f52ef39 100644
--- a/Source/cmLocalGhsMultiGenerator.h
+++ b/Source/cmLocalGhsMultiGenerator.h
@@ -25,7 +25,8 @@ class cmGeneratedFileStream;
 class cmLocalGhsMultiGenerator : public cmLocalGenerator
 {
 public:
-  cmLocalGhsMultiGenerator(cmGlobalGenerator* gg, cmLocalGenerator* parent);
+  cmLocalGhsMultiGenerator(cmGlobalGenerator* gg, cmLocalGenerator* parent,
+                           cmState::Snapshot snapshot);
 
   virtual ~cmLocalGhsMultiGenerator();
 
diff --git a/Source/cmLocalNinjaGenerator.cxx b/Source/cmLocalNinjaGenerator.cxx
index bcae486..c08c91f 100644
--- a/Source/cmLocalNinjaGenerator.cxx
+++ b/Source/cmLocalNinjaGenerator.cxx
@@ -23,8 +23,9 @@
 #include <assert.h>
 
 cmLocalNinjaGenerator::cmLocalNinjaGenerator(cmGlobalGenerator* gg,
-                                             cmLocalGenerator* parent)
-  : cmLocalGenerator(gg, parent)
+                                             cmLocalGenerator* parent,
+                                             cmState::Snapshot snapshot)
+  : cmLocalGenerator(gg, parent, snapshot)
   , ConfigName("")
   , HomeRelativeOutputPath("")
 {
diff --git a/Source/cmLocalNinjaGenerator.h b/Source/cmLocalNinjaGenerator.h
index 08b10e6..7ae97de 100644
--- a/Source/cmLocalNinjaGenerator.h
+++ b/Source/cmLocalNinjaGenerator.h
@@ -31,7 +31,8 @@ class cmake;
 class cmLocalNinjaGenerator : public cmLocalGenerator
 {
 public:
-  cmLocalNinjaGenerator(cmGlobalGenerator* gg, cmLocalGenerator* parent);
+  cmLocalNinjaGenerator(cmGlobalGenerator* gg, cmLocalGenerator* parent,
+                        cmState::Snapshot snapshot);
 
   virtual ~cmLocalNinjaGenerator();
 
diff --git a/Source/cmLocalUnixMakefileGenerator3.cxx b/Source/cmLocalUnixMakefileGenerator3.cxx
index b68dc51..3eea59b 100644
--- a/Source/cmLocalUnixMakefileGenerator3.cxx
+++ b/Source/cmLocalUnixMakefileGenerator3.cxx
@@ -80,8 +80,9 @@ static std::string cmSplitExtension(std::string const& in, std::string& base)
 
 //----------------------------------------------------------------------------
 cmLocalUnixMakefileGenerator3::
-cmLocalUnixMakefileGenerator3(cmGlobalGenerator* gg, cmLocalGenerator* parent)
-  : cmLocalGenerator(gg, parent)
+cmLocalUnixMakefileGenerator3(cmGlobalGenerator* gg, cmLocalGenerator* parent,
+                              cmState::Snapshot snapshot)
+  : cmLocalGenerator(gg, parent, snapshot)
 {
   this->MakefileVariableSize = 0;
   this->ColorMakefile = false;
diff --git a/Source/cmLocalUnixMakefileGenerator3.h b/Source/cmLocalUnixMakefileGenerator3.h
index 0b056ff..988d660 100644
--- a/Source/cmLocalUnixMakefileGenerator3.h
+++ b/Source/cmLocalUnixMakefileGenerator3.h
@@ -35,7 +35,8 @@ class cmLocalUnixMakefileGenerator3 : public cmLocalGenerator
 {
 public:
   cmLocalUnixMakefileGenerator3(cmGlobalGenerator* gg,
-                                cmLocalGenerator* parent);
+                                cmLocalGenerator* parent,
+                                cmState::Snapshot snapshot);
   virtual ~cmLocalUnixMakefileGenerator3();
 
   /**
diff --git a/Source/cmLocalVisualStudio10Generator.cxx b/Source/cmLocalVisualStudio10Generator.cxx
index 37b722a..ad6a020 100644
--- a/Source/cmLocalVisualStudio10Generator.cxx
+++ b/Source/cmLocalVisualStudio10Generator.cxx
@@ -63,8 +63,9 @@ class cmVS10XMLParser : public cmXMLParser
 //----------------------------------------------------------------------------
 cmLocalVisualStudio10Generator
 ::cmLocalVisualStudio10Generator(cmGlobalGenerator* gg,
-                                 cmLocalGenerator* parent):
-  cmLocalVisualStudio7Generator(gg, parent)
+                                 cmLocalGenerator* parent,
+                                 cmState::Snapshot snapshot):
+  cmLocalVisualStudio7Generator(gg, parent, snapshot)
 {
 }
 
diff --git a/Source/cmLocalVisualStudio10Generator.h b/Source/cmLocalVisualStudio10Generator.h
index afd52b9..c588aaf 100644
--- a/Source/cmLocalVisualStudio10Generator.h
+++ b/Source/cmLocalVisualStudio10Generator.h
@@ -26,7 +26,8 @@ class cmLocalVisualStudio10Generator : public cmLocalVisualStudio7Generator
 public:
   ///! Set cache only and recurse to false by default.
   cmLocalVisualStudio10Generator(cmGlobalGenerator* gg,
-                                 cmLocalGenerator* parent);
+                                 cmLocalGenerator* parent,
+                                 cmState::Snapshot snapshot);
 
   virtual ~cmLocalVisualStudio10Generator();
 
diff --git a/Source/cmLocalVisualStudio6Generator.cxx b/Source/cmLocalVisualStudio6Generator.cxx
index 7afb53a..ad34857 100644
--- a/Source/cmLocalVisualStudio6Generator.cxx
+++ b/Source/cmLocalVisualStudio6Generator.cxx
@@ -25,8 +25,9 @@
 
 cmLocalVisualStudio6Generator
 ::cmLocalVisualStudio6Generator(cmGlobalGenerator* gg,
-                                cmLocalGenerator* parent):
-  cmLocalVisualStudioGenerator(gg, parent)
+                                cmLocalGenerator* parent,
+                                cmState::Snapshot snapshot):
+  cmLocalVisualStudioGenerator(gg, parent, snapshot)
 {
 }
 
diff --git a/Source/cmLocalVisualStudio6Generator.h b/Source/cmLocalVisualStudio6Generator.h
index a6e0b3d..8f4d521 100644
--- a/Source/cmLocalVisualStudio6Generator.h
+++ b/Source/cmLocalVisualStudio6Generator.h
@@ -30,7 +30,8 @@ class cmLocalVisualStudio6Generator : public cmLocalVisualStudioGenerator
 public:
   ///! Set cache only and recurse to false by default.
   cmLocalVisualStudio6Generator(cmGlobalGenerator* gg,
-                                cmLocalGenerator* parent);
+                                cmLocalGenerator* parent,
+                                cmState::Snapshot snapshot);
 
   virtual ~cmLocalVisualStudio6Generator();
 
diff --git a/Source/cmLocalVisualStudio7Generator.cxx b/Source/cmLocalVisualStudio7Generator.cxx
index d2fb970..9c031cf 100644
--- a/Source/cmLocalVisualStudio7Generator.cxx
+++ b/Source/cmLocalVisualStudio7Generator.cxx
@@ -56,8 +56,9 @@ static void cmConvertToWindowsSlash(std::string& s)
 //----------------------------------------------------------------------------
 cmLocalVisualStudio7Generator
 ::cmLocalVisualStudio7Generator(cmGlobalGenerator* gg,
-                                cmLocalGenerator* parent):
-  cmLocalVisualStudioGenerator(gg, parent)
+                                cmLocalGenerator* parent,
+                                cmState::Snapshot snapshot):
+  cmLocalVisualStudioGenerator(gg, parent, snapshot)
 {
   this->Internal = new cmLocalVisualStudio7GeneratorInternals(this);
 }
diff --git a/Source/cmLocalVisualStudio7Generator.h b/Source/cmLocalVisualStudio7Generator.h
index 59c2144..43f3af9 100644
--- a/Source/cmLocalVisualStudio7Generator.h
+++ b/Source/cmLocalVisualStudio7Generator.h
@@ -36,7 +36,8 @@ class cmLocalVisualStudio7Generator : public cmLocalVisualStudioGenerator
 public:
   ///! Set cache only and recurse to false by default.
   cmLocalVisualStudio7Generator(cmGlobalGenerator* gg,
-                                cmLocalGenerator* parent);
+                                cmLocalGenerator* parent,
+                                cmState::Snapshot snapshot);
 
   virtual ~cmLocalVisualStudio7Generator();
 
diff --git a/Source/cmLocalVisualStudioGenerator.cxx b/Source/cmLocalVisualStudioGenerator.cxx
index f472bba..ca72939 100644
--- a/Source/cmLocalVisualStudioGenerator.cxx
+++ b/Source/cmLocalVisualStudioGenerator.cxx
@@ -20,8 +20,9 @@
 //----------------------------------------------------------------------------
 cmLocalVisualStudioGenerator
 ::cmLocalVisualStudioGenerator(cmGlobalGenerator* gg,
-                               cmLocalGenerator* parent)
-  : cmLocalGenerator(gg, parent)
+                               cmLocalGenerator* parent,
+                               cmState::Snapshot snapshot)
+  : cmLocalGenerator(gg, parent, snapshot)
 {
 }
 
diff --git a/Source/cmLocalVisualStudioGenerator.h b/Source/cmLocalVisualStudioGenerator.h
index df7d20c..d414651 100644
--- a/Source/cmLocalVisualStudioGenerator.h
+++ b/Source/cmLocalVisualStudioGenerator.h
@@ -32,7 +32,8 @@ class cmLocalVisualStudioGenerator : public cmLocalGenerator
 {
 public:
   cmLocalVisualStudioGenerator(cmGlobalGenerator* gg,
-                               cmLocalGenerator* parent);
+                               cmLocalGenerator* parent,
+                               cmState::Snapshot snapshot);
   virtual ~cmLocalVisualStudioGenerator();
 
   /** Construct a script from the given list of command lines.  */
diff --git a/Source/cmLocalXCodeGenerator.cxx b/Source/cmLocalXCodeGenerator.cxx
index a957c27..804dd7d 100644
--- a/Source/cmLocalXCodeGenerator.cxx
+++ b/Source/cmLocalXCodeGenerator.cxx
@@ -16,8 +16,9 @@
 
 //----------------------------------------------------------------------------
 cmLocalXCodeGenerator::cmLocalXCodeGenerator(cmGlobalGenerator* gg,
-                                             cmLocalGenerator* parent)
-  : cmLocalGenerator(gg, parent)
+                                             cmLocalGenerator* parent,
+                                             cmState::Snapshot snapshot)
+  : cmLocalGenerator(gg, parent, snapshot)
 {
   // the global generator does this, so do not
   // put these flags into the language flags
diff --git a/Source/cmLocalXCodeGenerator.h b/Source/cmLocalXCodeGenerator.h
index 54bc6df..26fff9c 100644
--- a/Source/cmLocalXCodeGenerator.h
+++ b/Source/cmLocalXCodeGenerator.h
@@ -24,7 +24,8 @@ class cmLocalXCodeGenerator : public cmLocalGenerator
 {
 public:
   ///! Set cache only and recurse to false by default.
-  cmLocalXCodeGenerator(cmGlobalGenerator* gg, cmLocalGenerator* parent);
+  cmLocalXCodeGenerator(cmGlobalGenerator* gg, cmLocalGenerator* parent,
+                        cmState::Snapshot snapshot);
 
   virtual ~cmLocalXCodeGenerator();
   virtual std::string GetTargetDirectory(cmTarget const& target) const;
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 3e8ae85..1d05873 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -1625,9 +1625,12 @@ void cmMakefile::AddSubDirectory(const std::string& srcPath,
     return;
     }
 
+  cmState::Snapshot newSnapshot = this->GetState()
+      ->CreateSnapshot(this->StateSnapshot);
+
   // create a new local generator and set its parent
   cmLocalGenerator *lg2 = this->GetGlobalGenerator()
-        ->MakeLocalGenerator(this->LocalGenerator);
+        ->MakeLocalGenerator(newSnapshot, this->LocalGenerator);
   this->GetGlobalGenerator()->AddLocalGenerator(lg2);
 
   // set the subdirs start dirs
diff --git a/Source/cmState.cxx b/Source/cmState.cxx
index 9ecd061..58885d3 100644
--- a/Source/cmState.cxx
+++ b/Source/cmState.cxx
@@ -661,6 +661,10 @@ void cmState::Snapshot::ComputeRelativePathTopBinary()
 
 cmState::Snapshot cmState::CreateSnapshot(Snapshot originSnapshot)
 {
+  if (!originSnapshot.IsValid())
+    {
+    originSnapshot.State = this;
+    }
   PositionType pos = this->ParentPositions.size();
   this->ParentPositions.push_back(originSnapshot.Position);
   this->Locations.resize(this->Locations.size() + 1);