genex: remove the need for backtraces

Rather than making dummy backtraces and passing them around, just make
backtraces optional.

20 files changed, 117 insertions, 125 deletions

diff --git a/Source/cmCustomCommand.cxx b/Source/cmCustomCommand.cxx
index 20908a5..ae702e5 100644
--- a/Source/cmCustomCommand.cxx
+++ b/Source/cmCustomCommand.cxx
@@ -33,7 +33,7 @@ cmCustomCommand::cmCustomCommand(const cmCustomCommand& r):
   WorkingDirectory(r.WorkingDirectory),
   EscapeAllowMakeVars(r.EscapeAllowMakeVars),
   EscapeOldStyle(r.EscapeOldStyle),
-  Backtrace(new cmListFileBacktrace(*r.Backtrace))
+  Backtrace(r.Backtrace)
 {
 }
 
@@ -54,11 +54,7 @@ cmCustomCommand& cmCustomCommand::operator=(cmCustomCommand const& r)
   this->EscapeAllowMakeVars = r.EscapeAllowMakeVars;
   this->EscapeOldStyle = r.EscapeOldStyle;
   this->ImplicitDepends = r.ImplicitDepends;
-
-  cmsys::auto_ptr<cmListFileBacktrace>
-    newBacktrace(new cmListFileBacktrace(*r.Backtrace));
-  delete this->Backtrace;
-  this->Backtrace = newBacktrace.release();
+  this->Backtrace = r.Backtrace;
 
   return *this;
 }
@@ -77,21 +73,19 @@ cmCustomCommand::cmCustomCommand(cmMakefile const* mf,
   Comment(comment?comment:""),
   WorkingDirectory(workingDirectory?workingDirectory:""),
   EscapeAllowMakeVars(false),
-  EscapeOldStyle(true),
-  Backtrace(new cmListFileBacktrace)
+  EscapeOldStyle(true)
 {
   this->EscapeOldStyle = true;
   this->EscapeAllowMakeVars = false;
   if(mf)
     {
-    *this->Backtrace = mf->GetBacktrace();
+    this->Backtrace = mf->GetBacktrace();
     }
 }
 
 //----------------------------------------------------------------------------
 cmCustomCommand::~cmCustomCommand()
 {
-  delete this->Backtrace;
 }
 
 //----------------------------------------------------------------------------
@@ -166,7 +160,7 @@ void cmCustomCommand::SetEscapeAllowMakeVars(bool b)
 //----------------------------------------------------------------------------
 cmListFileBacktrace const& cmCustomCommand::GetBacktrace() const
 {
-  return *this->Backtrace;
+  return this->Backtrace;
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmCustomCommand.h b/Source/cmCustomCommand.h
index b5d7e62..21dbefb 100644
--- a/Source/cmCustomCommand.h
+++ b/Source/cmCustomCommand.h
@@ -13,8 +13,8 @@
 #define cmCustomCommand_h
 
 #include "cmStandardIncludes.h"
+#include "cmListFileCache.h"
 class cmMakefile;
-class cmListFileBacktrace;
 
 /** \class cmCustomCommand
  * \brief A class to encapsulate a custom command
@@ -88,7 +88,7 @@ private:
   std::string WorkingDirectory;
   bool EscapeAllowMakeVars;
   bool EscapeOldStyle;
-  cmListFileBacktrace* Backtrace;
+  cmListFileBacktrace Backtrace;
   ImplicitDependsList ImplicitDepends;
 };
 
diff --git a/Source/cmCustomCommandGenerator.cxx b/Source/cmCustomCommandGenerator.cxx
index ebfbf7c..1bca6e6 100644
--- a/Source/cmCustomCommandGenerator.cxx
+++ b/Source/cmCustomCommandGenerator.cxx
@@ -21,7 +21,7 @@ cmCustomCommandGenerator::cmCustomCommandGenerator(
   cmCustomCommand const& cc, const std::string& config, cmMakefile* mf):
   CC(cc), Config(config), Makefile(mf), LG(mf->GetLocalGenerator()),
   OldStyle(cc.GetEscapeOldStyle()), MakeVars(cc.GetEscapeAllowMakeVars()),
-  GE(new cmGeneratorExpression(cc.GetBacktrace())), DependsDone(false)
+  GE(new cmGeneratorExpression(&cc.GetBacktrace())), DependsDone(false)
 {
 }
 
diff --git a/Source/cmExportFileGenerator.cxx b/Source/cmExportFileGenerator.cxx
index 2db4086..9f5eee5 100644
--- a/Source/cmExportFileGenerator.cxx
+++ b/Source/cmExportFileGenerator.cxx
@@ -377,8 +377,7 @@ void cmExportFileGenerator::PopulateIncludeDirectoriesInterface(
   const char *propName = "INTERFACE_INCLUDE_DIRECTORIES";
   const char *input = target->GetProperty(propName);
 
-  cmListFileBacktrace lfbt;
-  cmGeneratorExpression ge(lfbt);
+  cmGeneratorExpression ge;
 
   std::string dirs = cmGeneratorExpression::Preprocess(
                                             tei->InterfaceIncludeDirectories,
diff --git a/Source/cmExportTryCompileFileGenerator.cxx b/Source/cmExportTryCompileFileGenerator.cxx
index 3350d7c..eb8d193 100644
--- a/Source/cmExportTryCompileFileGenerator.cxx
+++ b/Source/cmExportTryCompileFileGenerator.cxx
@@ -57,10 +57,9 @@ std::string cmExportTryCompileFileGenerator::FindTargets(
     return std::string();
     }
 
-  cmListFileBacktrace lfbt;
-  cmGeneratorExpression ge(lfbt);
+  cmGeneratorExpression ge;
 
-  cmGeneratorExpressionDAGChecker dagChecker(lfbt,
+  cmGeneratorExpressionDAGChecker dagChecker(
                                       tgt->GetName(),
                                       propName, 0, 0);
 
diff --git a/Source/cmFileCommand.cxx b/Source/cmFileCommand.cxx
index 41ea357..655f3ba 100644
--- a/Source/cmFileCommand.cxx
+++ b/Source/cmFileCommand.cxx
@@ -3272,11 +3272,11 @@ void cmFileCommand::AddEvaluationFile(const std::string &inputName,
 {
   cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
 
-  cmGeneratorExpression outputGe(lfbt);
+  cmGeneratorExpression outputGe(&lfbt);
   cmsys::auto_ptr<cmCompiledGeneratorExpression> outputCge
                                                 = outputGe.Parse(outputExpr);
 
-  cmGeneratorExpression conditionGe(lfbt);
+  cmGeneratorExpression conditionGe(&lfbt);
   cmsys::auto_ptr<cmCompiledGeneratorExpression> conditionCge
                                               = conditionGe.Parse(condition);
 
diff --git a/Source/cmGeneratorExpression.cxx b/Source/cmGeneratorExpression.cxx
index d53bdd7..9a74569 100644
--- a/Source/cmGeneratorExpression.cxx
+++ b/Source/cmGeneratorExpression.cxx
@@ -24,7 +24,7 @@
 
 //----------------------------------------------------------------------------
 cmGeneratorExpression::cmGeneratorExpression(
-  cmListFileBacktrace const& backtrace):
+  cmListFileBacktrace const* backtrace):
   Backtrace(backtrace)
 {
 }
@@ -34,9 +34,9 @@ cmsys::auto_ptr<cmCompiledGeneratorExpression>
 cmGeneratorExpression::Parse(std::string const& input)
 {
   return cmsys::auto_ptr<cmCompiledGeneratorExpression>(
-                                      new cmCompiledGeneratorExpression(
-                                        this->Backtrace,
-                                        input));
+    new cmCompiledGeneratorExpression(
+      this->Backtrace ? *this->Backtrace : cmListFileBacktrace(),
+      input));
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGeneratorExpression.h b/Source/cmGeneratorExpression.h
index ef5360e..324d23c 100644
--- a/Source/cmGeneratorExpression.h
+++ b/Source/cmGeneratorExpression.h
@@ -41,7 +41,7 @@ class cmGeneratorExpression
 {
 public:
   /** Construct. */
-  cmGeneratorExpression(cmListFileBacktrace const& backtrace);
+  cmGeneratorExpression(cmListFileBacktrace const* backtrace = NULL);
   ~cmGeneratorExpression();
 
   cmsys::auto_ptr<cmCompiledGeneratorExpression> Parse(
@@ -70,7 +70,7 @@ private:
   cmGeneratorExpression(const cmGeneratorExpression &);
   void operator=(const cmGeneratorExpression &);
 
-  cmListFileBacktrace const& Backtrace;
+  cmListFileBacktrace const* Backtrace;
 };
 
 class cmCompiledGeneratorExpression
diff --git a/Source/cmGeneratorExpressionDAGChecker.cxx b/Source/cmGeneratorExpressionDAGChecker.cxx
index 7f8e694..531a471 100644
--- a/Source/cmGeneratorExpressionDAGChecker.cxx
+++ b/Source/cmGeneratorExpressionDAGChecker.cxx
@@ -24,6 +24,25 @@ cmGeneratorExpressionDAGChecker::cmGeneratorExpressionDAGChecker(
   : Parent(parent), Target(target), Property(property),
     Content(content), Backtrace(backtrace), TransitivePropertiesOnly(false)
 {
+  Initialize();
+}
+
+//----------------------------------------------------------------------------
+cmGeneratorExpressionDAGChecker::cmGeneratorExpressionDAGChecker(
+                const std::string &target,
+                const std::string &property,
+                const GeneratorExpressionContent *content,
+                cmGeneratorExpressionDAGChecker *parent)
+  : Parent(parent), Target(target), Property(property),
+    Content(content), TransitivePropertiesOnly(false)
+{
+  Initialize();
+}
+
+//----------------------------------------------------------------------------
+void
+cmGeneratorExpressionDAGChecker::Initialize()
+{
   const cmGeneratorExpressionDAGChecker *top = this;
   const cmGeneratorExpressionDAGChecker *p = this->Parent;
   while (p)
@@ -43,11 +62,12 @@ cmGeneratorExpressionDAGChecker::cmGeneratorExpressionDAGChecker(
 #undef TEST_TRANSITIVE_PROPERTY_METHOD
     {
     std::map<std::string, std::set<std::string> >::const_iterator it
-                                                    = top->Seen.find(target);
+                                              = top->Seen.find(this->Target);
     if (it != top->Seen.end())
       {
       const std::set<std::string> &propSet = it->second;
-      const std::set<std::string>::const_iterator i = propSet.find(property);
+      const std::set<std::string>::const_iterator i
+          = propSet.find(this->Property);
       if (i != propSet.end())
         {
         this->CheckResult = ALREADY_SEEN;
@@ -55,7 +75,7 @@ cmGeneratorExpressionDAGChecker::cmGeneratorExpressionDAGChecker(
         }
       }
     const_cast<cmGeneratorExpressionDAGChecker *>(top)
-                                            ->Seen[target].insert(property);
+      ->Seen[this->Target].insert(this->Property);
     }
 }
 
diff --git a/Source/cmGeneratorExpressionDAGChecker.h b/Source/cmGeneratorExpressionDAGChecker.h
index 7217a56..10f9fa7 100644
--- a/Source/cmGeneratorExpressionDAGChecker.h
+++ b/Source/cmGeneratorExpressionDAGChecker.h
@@ -46,6 +46,10 @@ struct cmGeneratorExpressionDAGChecker
                                   const std::string &property,
                                   const GeneratorExpressionContent *content,
                                   cmGeneratorExpressionDAGChecker *parent);
+  cmGeneratorExpressionDAGChecker(const std::string &target,
+                                  const std::string &property,
+                                  const GeneratorExpressionContent *content,
+                                  cmGeneratorExpressionDAGChecker *parent);
 
   enum Result {
     DAG,
@@ -76,6 +80,7 @@ struct cmGeneratorExpressionDAGChecker
 
 private:
   Result CheckGraph() const;
+  void Initialize();
 
 private:
   const cmGeneratorExpressionDAGChecker * const Parent;
diff --git a/Source/cmGeneratorExpressionEvaluationFile.cxx b/Source/cmGeneratorExpressionEvaluationFile.cxx
index 01d31d3..f9067cf 100644
--- a/Source/cmGeneratorExpressionEvaluationFile.cxx
+++ b/Source/cmGeneratorExpressionEvaluationFile.cxx
@@ -115,7 +115,7 @@ void cmGeneratorExpressionEvaluationFile::Generate()
     }
 
   cmListFileBacktrace lfbt = this->OutputFileExpr->GetBacktrace();
-  cmGeneratorExpression contentGE(lfbt);
+  cmGeneratorExpression contentGE(&lfbt);
   cmsys::auto_ptr<cmCompiledGeneratorExpression> inputExpression
                                               = contentGE.Parse(inputContent);
 
diff --git a/Source/cmGeneratorExpressionEvaluator.cxx b/Source/cmGeneratorExpressionEvaluator.cxx
index a15e3ff..c54922d 100644
--- a/Source/cmGeneratorExpressionEvaluator.cxx
+++ b/Source/cmGeneratorExpressionEvaluator.cxx
@@ -809,7 +809,7 @@ std::string getLinkedTargetsContent(const std::vector<cmTarget*> &targets,
                                   cmGeneratorExpressionDAGChecker *dagChecker,
                                   const std::string &interfacePropertyName)
 {
-  cmGeneratorExpression ge(context->Backtrace);
+  cmGeneratorExpression ge(&context->Backtrace);
 
   std::string sep;
   std::string depString;
@@ -1196,7 +1196,7 @@ static const struct TargetPropertyNode : public cmGeneratorExpressionNode
       {
       if (targetPropertyTransitiveWhitelist[i] == interfacePropertyName)
         {
-        cmGeneratorExpression ge(context->Backtrace);
+        cmGeneratorExpression ge(&context->Backtrace);
         cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(prop);
         std::string result = cge->Evaluate(context->Makefile,
                             context->Config,
diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 153c611..a7576ed 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -259,12 +259,10 @@ static void handleSystemIncludesDep(cmMakefile *mf, cmTarget* depTgt,
                                   std::vector<std::string>& result,
                                   bool excludeImported)
 {
-  cmListFileBacktrace lfbt;
-
   if (const char* dirs =
           depTgt->GetProperty("INTERFACE_SYSTEM_INCLUDE_DIRECTORIES"))
     {
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge;
     cmSystemTools::ExpandListArgument(ge.Parse(dirs)
                                       ->Evaluate(mf,
                                       config, false, headTarget,
@@ -278,7 +276,7 @@ static void handleSystemIncludesDep(cmMakefile *mf, cmTarget* depTgt,
   if (const char* dirs =
                 depTgt->GetProperty("INTERFACE_INCLUDE_DIRECTORIES"))
     {
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge;
     cmSystemTools::ExpandListArgument(ge.Parse(dirs)
                                       ->Evaluate(mf,
                                       config, false, headTarget,
@@ -457,8 +455,7 @@ bool cmGeneratorTarget::IsSystemIncludeDirectory(const std::string& dir,
       return false;
       }
 
-    cmListFileBacktrace lfbt;
-    cmGeneratorExpressionDAGChecker dagChecker(lfbt,
+    cmGeneratorExpressionDAGChecker dagChecker(
                                         this->GetName(),
                                         "SYSTEM_INCLUDE_DIRECTORIES", 0, 0);
 
@@ -470,7 +467,7 @@ bool cmGeneratorTarget::IsSystemIncludeDirectory(const std::string& dir,
         it = this->Target->GetSystemIncludeDirectories().begin();
         it != this->Target->GetSystemIncludeDirectories().end(); ++it)
       {
-      cmGeneratorExpression ge(lfbt);
+      cmGeneratorExpression ge;
       cmSystemTools::ExpandListArgument(ge.Parse(*it)
                                           ->Evaluate(this->Makefile,
                                           config, false, this->Target,
@@ -808,7 +805,7 @@ cmTargetTraceDependencies
 {
   // Transform command names that reference targets built in this
   // project to corresponding target-level dependencies.
-  cmGeneratorExpression ge(cc.GetBacktrace());
+  cmGeneratorExpression ge(&cc.GetBacktrace());
 
   // Add target-level dependencies referenced by generator expressions.
   std::set<cmTarget*> targets;
diff --git a/Source/cmInstallFilesGenerator.cxx b/Source/cmInstallFilesGenerator.cxx
index 6594218..b2be82e 100644
--- a/Source/cmInstallFilesGenerator.cxx
+++ b/Source/cmInstallFilesGenerator.cxx
@@ -12,6 +12,7 @@
 #include "cmInstallFilesGenerator.h"
 
 #include "cmGeneratorExpression.h"
+#include "cmMakefile.h"
 #include "cmSystemTools.h"
 
 //----------------------------------------------------------------------------
@@ -84,8 +85,7 @@ void cmInstallFilesGenerator::GenerateScriptForConfig(std::ostream& os,
                                                     Indent const& indent)
 {
   std::vector<std::string> files;
-  cmListFileBacktrace lfbt;
-  cmGeneratorExpression ge(lfbt);
+  cmGeneratorExpression ge;
   for(std::vector<std::string>::const_iterator i = this->Files.begin();
       i != this->Files.end(); ++i)
     {
diff --git a/Source/cmInstalledFile.cxx b/Source/cmInstalledFile.cxx
index 6860e00..7813fcc 100644
--- a/Source/cmInstalledFile.cxx
+++ b/Source/cmInstalledFile.cxx
@@ -33,7 +33,7 @@ cmInstalledFile::~cmInstalledFile()
 void cmInstalledFile::SetName(cmMakefile* mf, const std::string& name)
 {
   cmListFileBacktrace backtrace = mf->GetBacktrace();
-  cmGeneratorExpression ge(backtrace);
+  cmGeneratorExpression ge(&backtrace);
 
   this->Name = name;
   this->NameExpression = ge.Parse(name).release();
@@ -70,7 +70,7 @@ void cmInstalledFile::AppendProperty(cmMakefile const* mf,
   const std::string& prop, const char* value, bool /*asString*/)
 {
   cmListFileBacktrace backtrace = mf->GetBacktrace();
-  cmGeneratorExpression ge(backtrace);
+  cmGeneratorExpression ge(&backtrace);
 
   Property& property = this->Properties[prop];
   property.ValueExpressions.push_back(ge.Parse(value).release());
diff --git a/Source/cmMakefileTargetGenerator.cxx b/Source/cmMakefileTargetGenerator.cxx
index a08d731..77bf484 100644
--- a/Source/cmMakefileTargetGenerator.cxx
+++ b/Source/cmMakefileTargetGenerator.cxx
@@ -137,8 +137,7 @@ void cmMakefileTargetGenerator::WriteTargetBuildRules()
      this->Makefile->GetProperty
      ("ADDITIONAL_MAKE_CLEAN_FILES"))
     {
-    cmListFileBacktrace lfbt;
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge;
     cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
                                             ge.Parse(additional_clean_files);
 
diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index 56b98f7..4b5dc7a 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -710,11 +710,8 @@ void cmTarget::GetSourceFiles(std::vector<std::string> &files,
     this->DebugSourcesDone = true;
     }
 
-  cmListFileBacktrace lfbt;
-
-  cmGeneratorExpressionDAGChecker dagChecker(lfbt,
-                                              this->GetName(),
-                                              "SOURCES", 0, 0);
+  cmGeneratorExpressionDAGChecker dagChecker(this->GetName(),
+                                             "SOURCES", 0, 0);
 
   std::set<std::string> uniqueSrcs;
   bool contextDependentDirectSources = processSources(this,
@@ -739,7 +736,7 @@ void cmTarget::GetSourceFiles(std::vector<std::string> &files,
         continue;
         }
       {
-      cmGeneratorExpression ge(lfbt);
+      cmGeneratorExpression ge;
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
                                                         ge.Parse(it->Value);
       std::string targetResult = cge->Evaluate(this->Makefile, config,
@@ -758,7 +755,7 @@ void cmTarget::GetSourceFiles(std::vector<std::string> &files,
         // TARGET_PROPERTY expression.
         sourceGenex = "$<$<BOOL:" + it->Value + ">:" + sourceGenex + ">";
         }
-      cmGeneratorExpression ge(it->Backtrace);
+      cmGeneratorExpression ge(&it->Backtrace);
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(
                                                                 sourceGenex);
 
@@ -911,7 +908,7 @@ void cmTarget::AddTracedSources(std::vector<std::string> const& srcs)
     this->Internal->SourceFilesMap.clear();
     this->LinkImplementationLanguageIsContextDependent = true;
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(srcFiles);
     cge->SetEvaluateForBuildsystem(true);
     this->Internal->SourceEntries.push_back(
@@ -948,7 +945,7 @@ void cmTarget::AddSources(std::vector<std::string> const& srcs)
     this->Internal->SourceFilesMap.clear();
     this->LinkImplementationLanguageIsContextDependent = true;
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(srcFiles);
     cge->SetEvaluateForBuildsystem(true);
     this->Internal->SourceEntries.push_back(
@@ -1083,7 +1080,7 @@ cmSourceFile* cmTarget::AddSource(const std::string& src)
     this->Internal->SourceFilesMap.clear();
     this->LinkImplementationLanguageIsContextDependent = true;
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(src);
     cge->SetEvaluateForBuildsystem(true);
     this->Internal->SourceEntries.push_back(
@@ -1203,11 +1200,10 @@ void cmTarget::GetDirectLinkLibraries(const std::string& config,
   const char *prop = this->GetProperty("LINK_LIBRARIES");
   if (prop)
     {
-    cmListFileBacktrace lfbt;
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge;
     const cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(prop);
 
-    cmGeneratorExpressionDAGChecker dagChecker(lfbt,
+    cmGeneratorExpressionDAGChecker dagChecker(
                                         this->GetName(),
                                         "LINK_LIBRARIES", 0, 0);
     cmSystemTools::ExpandListArgument(cge->Evaluate(this->Makefile,
@@ -1238,11 +1234,10 @@ void cmTarget::GetInterfaceLinkLibraries(const std::string& config,
   const char *prop = this->GetProperty("INTERFACE_LINK_LIBRARIES");
   if (prop)
     {
-    cmListFileBacktrace lfbt;
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge;
     const cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(prop);
 
-    cmGeneratorExpressionDAGChecker dagChecker(lfbt,
+    cmGeneratorExpressionDAGChecker dagChecker(
                                         this->GetName(),
                                         "INTERFACE_LINK_LIBRARIES", 0, 0);
     cmSystemTools::ExpandListArgument(cge->Evaluate(this->Makefile,
@@ -1793,7 +1788,7 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
   if(prop == "INCLUDE_DIRECTORIES")
     {
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     deleteAndClear(this->Internal->IncludeDirectoriesEntries);
     cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(value);
     this->Internal->IncludeDirectoriesEntries.push_back(
@@ -1803,7 +1798,7 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
   if(prop == "COMPILE_OPTIONS")
     {
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     deleteAndClear(this->Internal->CompileOptionsEntries);
     cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(value);
     this->Internal->CompileOptionsEntries.push_back(
@@ -1813,7 +1808,7 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
   if(prop == "COMPILE_FEATURES")
     {
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     deleteAndClear(this->Internal->CompileFeaturesEntries);
     cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(value);
     this->Internal->CompileFeaturesEntries.push_back(
@@ -1823,7 +1818,7 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
   if(prop == "COMPILE_DEFINITIONS")
     {
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     deleteAndClear(this->Internal->CompileDefinitionsEntries);
     cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(value);
     this->Internal->CompileDefinitionsEntries.push_back(
@@ -1858,7 +1853,7 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
       }
     this->Internal->SourceFilesMap.clear();
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     this->Internal->SourceEntries.clear();
     cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(value);
     this->Internal->SourceEntries.push_back(
@@ -1892,7 +1887,7 @@ void cmTarget::AppendProperty(const std::string& prop, const char* value,
   if(prop == "INCLUDE_DIRECTORIES")
     {
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     this->Internal->IncludeDirectoriesEntries.push_back(
               new cmTargetInternals::TargetPropertyEntry(ge.Parse(value)));
     return;
@@ -1900,7 +1895,7 @@ void cmTarget::AppendProperty(const std::string& prop, const char* value,
   if(prop == "COMPILE_OPTIONS")
     {
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     this->Internal->CompileOptionsEntries.push_back(
               new cmTargetInternals::TargetPropertyEntry(ge.Parse(value)));
     return;
@@ -1908,7 +1903,7 @@ void cmTarget::AppendProperty(const std::string& prop, const char* value,
   if(prop == "COMPILE_FEATURES")
     {
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     this->Internal->CompileFeaturesEntries.push_back(
               new cmTargetInternals::TargetPropertyEntry(ge.Parse(value)));
     return;
@@ -1916,7 +1911,7 @@ void cmTarget::AppendProperty(const std::string& prop, const char* value,
   if(prop == "COMPILE_DEFINITIONS")
     {
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge(&lfbt);
     this->Internal->CompileDefinitionsEntries.push_back(
               new cmTargetInternals::TargetPropertyEntry(ge.Parse(value)));
     return;
@@ -1948,7 +1943,7 @@ void cmTarget::AppendProperty(const std::string& prop, const char* value,
       }
       this->Internal->SourceFilesMap.clear();
       cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
-      cmGeneratorExpression ge(lfbt);
+      cmGeneratorExpression ge(&lfbt);
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(value);
       this->Internal->SourceEntries.push_back(
                             new cmTargetInternals::TargetPropertyEntry(cge));
@@ -2014,7 +2009,7 @@ void cmTarget::AppendBuildInterfaceIncludes()
 void cmTarget::InsertInclude(const cmValueWithOrigin &entry,
                      bool before)
 {
-  cmGeneratorExpression ge(entry.Backtrace);
+  cmGeneratorExpression ge(&entry.Backtrace);
 
   std::vector<cmTargetInternals::TargetPropertyEntry*>::iterator position
                 = before ? this->Internal->IncludeDirectoriesEntries.begin()
@@ -2028,7 +2023,7 @@ void cmTarget::InsertInclude(const cmValueWithOrigin &entry,
 void cmTarget::InsertCompileOption(const cmValueWithOrigin &entry,
                      bool before)
 {
-  cmGeneratorExpression ge(entry.Backtrace);
+  cmGeneratorExpression ge(&entry.Backtrace);
 
   std::vector<cmTargetInternals::TargetPropertyEntry*>::iterator position
                 = before ? this->Internal->CompileOptionsEntries.begin()
@@ -2041,7 +2036,7 @@ void cmTarget::InsertCompileOption(const cmValueWithOrigin &entry,
 //----------------------------------------------------------------------------
 void cmTarget::InsertCompileDefinition(const cmValueWithOrigin &entry)
 {
-  cmGeneratorExpression ge(entry.Backtrace);
+  cmGeneratorExpression ge(&entry.Backtrace);
 
   this->Internal->CompileDefinitionsEntries.push_back(
       new cmTargetInternals::TargetPropertyEntry(ge.Parse(entry.Value)));
@@ -2082,14 +2077,13 @@ static void processIncludeDirectories(cmTarget const* tgt,
         }
       }
     std::string usedIncludes;
-    cmListFileBacktrace lfbt;
     for(std::vector<std::string>::iterator
           li = entryIncludes.begin(); li != entryIncludes.end(); ++li)
       {
       std::string targetName = (*it)->TargetName;
       std::string evaluatedTargetName;
       {
-      cmGeneratorExpression ge(lfbt);
+      cmGeneratorExpression ge;
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
                                                         ge.Parse(targetName);
       evaluatedTargetName = cge->Evaluate(mf, config, false, tgt, 0, 0);
@@ -2222,10 +2216,8 @@ cmTarget::GetIncludeDirectories(const std::string& config) const
 {
   std::vector<std::string> includes;
   std::set<std::string> uniqueIncludes;
-  cmListFileBacktrace lfbt;
 
-  cmGeneratorExpressionDAGChecker dagChecker(lfbt,
-                                             this->GetName(),
+  cmGeneratorExpressionDAGChecker dagChecker(this->GetName(),
                                              "INCLUDE_DIRECTORIES", 0, 0);
 
   std::vector<std::string> debugProperties;
@@ -2268,7 +2260,7 @@ cmTarget::GetIncludeDirectories(const std::string& config) const
         continue;
         }
       {
-      cmGeneratorExpression ge(lfbt);
+      cmGeneratorExpression ge;
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
                                                         ge.Parse(it->Value);
       std::string result = cge->Evaluate(this->Makefile, config,
@@ -2287,7 +2279,7 @@ cmTarget::GetIncludeDirectories(const std::string& config) const
         // TARGET_PROPERTY expression.
         includeGenex = "$<$<BOOL:" + it->Value + ">:" + includeGenex + ">";
         }
-      cmGeneratorExpression ge(it->Backtrace);
+      cmGeneratorExpression ge(&it->Backtrace);
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(
                                                               includeGenex);
 
@@ -2316,7 +2308,7 @@ cmTarget::GetIncludeDirectories(const std::string& config) const
 
         libDir = frameworkCheck.match(1);
 
-        cmGeneratorExpression ge(lfbt);
+        cmGeneratorExpression ge;
         cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
                   ge.Parse(libDir.c_str());
         this->Internal
@@ -2430,10 +2422,9 @@ void cmTarget::GetAutoUicOptions(std::vector<std::string> &result,
     {
     return;
     }
-  cmListFileBacktrace lfbt;
-  cmGeneratorExpression ge(lfbt);
+  cmGeneratorExpression ge;
 
-  cmGeneratorExpressionDAGChecker dagChecker(lfbt,
+  cmGeneratorExpressionDAGChecker dagChecker(
                                       this->GetName(),
                                       "AUTOUIC_OPTIONS", 0, 0);
   cmSystemTools::ExpandListArgument(ge.Parse(prop)
@@ -2450,11 +2441,9 @@ void cmTarget::GetCompileOptions(std::vector<std::string> &result,
                                  const std::string& config) const
 {
   std::set<std::string> uniqueOptions;
-  cmListFileBacktrace lfbt;
 
-  cmGeneratorExpressionDAGChecker dagChecker(lfbt,
-                                              this->GetName(),
-                                              "COMPILE_OPTIONS", 0, 0);
+  cmGeneratorExpressionDAGChecker dagChecker(this->GetName(),
+                                             "COMPILE_OPTIONS", 0, 0);
 
   std::vector<std::string> debugProperties;
   const char *debugProp =
@@ -2496,7 +2485,7 @@ void cmTarget::GetCompileOptions(std::vector<std::string> &result,
         continue;
         }
       {
-      cmGeneratorExpression ge(lfbt);
+      cmGeneratorExpression ge;
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
                                                         ge.Parse(it->Value);
       std::string targetResult = cge->Evaluate(this->Makefile, config,
@@ -2515,7 +2504,7 @@ void cmTarget::GetCompileOptions(std::vector<std::string> &result,
         // TARGET_PROPERTY expression.
         optionGenex = "$<$<BOOL:" + it->Value + ">:" + optionGenex + ">";
         }
-      cmGeneratorExpression ge(it->Backtrace);
+      cmGeneratorExpression ge(&it->Backtrace);
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(
                                                                 optionGenex);
 
@@ -2562,11 +2551,9 @@ void cmTarget::GetCompileDefinitions(std::vector<std::string> &list,
                                             const std::string& config) const
 {
   std::set<std::string> uniqueOptions;
-  cmListFileBacktrace lfbt;
 
-  cmGeneratorExpressionDAGChecker dagChecker(lfbt,
-                                              this->GetName(),
-                                              "COMPILE_DEFINITIONS", 0, 0);
+  cmGeneratorExpressionDAGChecker dagChecker(this->GetName(),
+                                             "COMPILE_DEFINITIONS", 0, 0);
 
   std::vector<std::string> debugProperties;
   const char *debugProp =
@@ -2608,7 +2595,7 @@ void cmTarget::GetCompileDefinitions(std::vector<std::string> &list,
         continue;
         }
       {
-      cmGeneratorExpression ge(lfbt);
+      cmGeneratorExpression ge;
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
                                                         ge.Parse(it->Value);
       std::string targetResult = cge->Evaluate(this->Makefile, config,
@@ -2627,7 +2614,7 @@ void cmTarget::GetCompileDefinitions(std::vector<std::string> &list,
         // TARGET_PROPERTY expression.
         defsGenex = "$<$<BOOL:" + it->Value + ">:" + defsGenex + ">";
         }
-      cmGeneratorExpression ge(it->Backtrace);
+      cmGeneratorExpression ge(&it->Backtrace);
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(
                                                                 defsGenex);
 
@@ -2655,7 +2642,7 @@ void cmTarget::GetCompileDefinitions(std::vector<std::string> &list,
             }
           case cmPolicies::OLD:
             {
-            cmGeneratorExpression ge(lfbt);
+            cmGeneratorExpression ge;
             cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
                                                         ge.Parse(configProp);
             this->Internal
@@ -2710,10 +2697,8 @@ void cmTarget::GetCompileFeatures(std::vector<std::string> &result,
                                   const std::string& config) const
 {
   std::set<std::string> uniqueFeatures;
-  cmListFileBacktrace lfbt;
 
-  cmGeneratorExpressionDAGChecker dagChecker(lfbt,
-                                             this->GetName(),
+  cmGeneratorExpressionDAGChecker dagChecker(this->GetName(),
                                              "COMPILE_FEATURES",
                                              0, 0);
 
@@ -2757,7 +2742,7 @@ void cmTarget::GetCompileFeatures(std::vector<std::string> &result,
         continue;
         }
       {
-      cmGeneratorExpression ge(lfbt);
+      cmGeneratorExpression ge;
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge =
                                                         ge.Parse(it->Value);
       std::string targetResult = cge->Evaluate(this->Makefile, config,
@@ -2776,7 +2761,7 @@ void cmTarget::GetCompileFeatures(std::vector<std::string> &result,
         // TARGET_PROPERTY expression.
         featureGenex = "$<$<BOOL:" + it->Value + ">:" + featureGenex + ">";
         }
-      cmGeneratorExpression ge(it->Backtrace);
+      cmGeneratorExpression ge(&it->Backtrace);
       cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(
                                                                 featureGenex);
 
@@ -5904,10 +5889,9 @@ void cmTarget::ComputeImportInfo(std::string const& desired_config,
     }
   if(propertyLibs)
     {
-    cmListFileBacktrace lfbt;
-    cmGeneratorExpression ge(lfbt);
+    cmGeneratorExpression ge;
 
-    cmGeneratorExpressionDAGChecker dagChecker(lfbt,
+    cmGeneratorExpressionDAGChecker dagChecker(
                                         this->GetName(),
                                         linkProp, 0, 0);
     cmSystemTools::ExpandListArgument(ge.Parse(propertyLibs)
@@ -6227,10 +6211,9 @@ void cmTarget::GetTransitivePropertyTargets(const std::string& config,
     }
 
   // The interface libraries have been explicitly set.
-  cmListFileBacktrace lfbt;
-  cmGeneratorExpression ge(lfbt);
-  cmGeneratorExpressionDAGChecker dagChecker(lfbt, this->GetName(),
-                                              linkIfaceProp, 0, 0);
+  cmGeneratorExpression ge;
+  cmGeneratorExpressionDAGChecker dagChecker(this->GetName(),
+                                             linkIfaceProp, 0, 0);
   dagChecker.SetTransitivePropertiesOnly();
   std::vector<std::string> libs;
   cmSystemTools::ExpandListArgument(ge.Parse(interfaceLibs)->Evaluate(
@@ -6339,9 +6322,8 @@ const char* cmTarget::ComputeLinkInterfaceLibraries(const std::string& config,
   if(explicitLibraries)
     {
     // The interface libraries have been explicitly set.
-    cmListFileBacktrace lfbt;
-    cmGeneratorExpression ge(lfbt);
-    cmGeneratorExpressionDAGChecker dagChecker(lfbt, this->GetName(),
+    cmGeneratorExpression ge;
+    cmGeneratorExpressionDAGChecker dagChecker(this->GetName(),
                                                linkIfaceProp, 0, 0);
     cmSystemTools::ExpandListArgument(ge.Parse(explicitLibraries)->Evaluate(
                                         this->Makefile,
@@ -6366,9 +6348,8 @@ const char* cmTarget::ComputeLinkInterfaceLibraries(const std::string& config,
       {
       // Compare the link implementation fallback link interface to the
       // preferred new link interface property and warn if different.
-      cmListFileBacktrace lfbt;
-      cmGeneratorExpression ge(lfbt);
-      cmGeneratorExpressionDAGChecker dagChecker(lfbt, this->GetName(),
+      cmGeneratorExpression ge;
+      cmGeneratorExpressionDAGChecker dagChecker(this->GetName(),
                                       "INTERFACE_LINK_LIBRARIES", 0, 0);
       std::vector<std::string> ifaceLibs;
       const char* newExplicitLibraries =
diff --git a/Source/cmTest.cxx b/Source/cmTest.cxx
index f0288b2..464ad60 100644
--- a/Source/cmTest.cxx
+++ b/Source/cmTest.cxx
@@ -21,20 +21,18 @@ cmTest::cmTest(cmMakefile* mf)
   this->Makefile = mf;
   this->OldStyle = true;
   this->Properties.SetCMakeInstance(mf->GetCMakeInstance());
-  this->Backtrace = new cmListFileBacktrace;
-  *this->Backtrace = this->Makefile->GetBacktrace();
+  this->Backtrace = this->Makefile->GetBacktrace();
 }
 
 //----------------------------------------------------------------------------
 cmTest::~cmTest()
 {
-  delete this->Backtrace;
 }
 
 //----------------------------------------------------------------------------
 cmListFileBacktrace const& cmTest::GetBacktrace() const
 {
-  return *this->Backtrace;
+  return this->Backtrace;
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmTest.h b/Source/cmTest.h
index a93eff5..c6e7e42 100644
--- a/Source/cmTest.h
+++ b/Source/cmTest.h
@@ -14,8 +14,8 @@
 
 #include "cmCustomCommand.h"
 #include "cmPropertyMap.h"
+#include "cmListFileCache.h"
 class cmMakefile;
-class cmListFileBacktrace;
 
 /** \class cmTest
  * \brief Represent a test
@@ -71,7 +71,7 @@ private:
   bool OldStyle;
 
   cmMakefile* Makefile;
-  cmListFileBacktrace* Backtrace;
+  cmListFileBacktrace Backtrace;
 };
 
 #endif
diff --git a/Source/cmTestGenerator.cxx b/Source/cmTestGenerator.cxx
index c1b1f8b..f87a535 100644
--- a/Source/cmTestGenerator.cxx
+++ b/Source/cmTestGenerator.cxx
@@ -70,7 +70,7 @@ void cmTestGenerator::GenerateScriptForConfig(std::ostream& os,
   this->TestGenerated = true;
 
   // Set up generator expression evaluation context.
-  cmGeneratorExpression ge(this->Test->GetBacktrace());
+  cmGeneratorExpression ge(&this->Test->GetBacktrace());
 
   // Start the test command.
   os << indent << "add_test(" << this->Test->GetName() << " ";