Genex: Store a backtrace, not a pointer to one.

The storage of a pointer means that the ownership and lifetime are
externally determined, which is harder to reason about. It also imposes
API constraints, requiring APIs to return references to backtraces.

This pointer storage was introduced in commit v3.1.0-rc1~425^2~3 (genex:
remove the need for backtraces, 2014-05-23).  As backtraces are now cheap
to copy around, just do that instead.

Source/cmCustomCommandGenerator.cxx

@@ -21,7 +21,7 @@ cmCustomCommandGenerator::cmCustomCommandGenerator(
   cmCustomCommand const& cc, const std::string& config, cmMakefile* mf):
   CC(cc), Config(config), Makefile(mf),
   OldStyle(cc.GetEscapeOldStyle()), MakeVars(cc.GetEscapeAllowMakeVars()),
-  GE(new cmGeneratorExpression(&cc.GetBacktrace())), DependsDone(false)
+  GE(new cmGeneratorExpression(cc.GetBacktrace())), DependsDone(false)
 {
 }
 

Source/cmFileCommand.cxx

@@ -3565,11 +3565,11 @@ 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);
 

Source/cmGeneratorExpression.cxx

@@ -23,7 +23,7 @@
 
 //----------------------------------------------------------------------------
 cmGeneratorExpression::cmGeneratorExpression(
-  cmListFileBacktrace const* backtrace):
+    const cmListFileBacktrace& backtrace):
   Backtrace(backtrace)
 {
 }
@@ -33,9 +33,7 @@ cmsys::auto_ptr<cmCompiledGeneratorExpression>
 cmGeneratorExpression::Parse(std::string const& input)
 {
   return cmsys::auto_ptr<cmCompiledGeneratorExpression>(
-    new cmCompiledGeneratorExpression(
+    new cmCompiledGeneratorExpression(this->Backtrace, input));
-      this->Backtrace ? *this->Backtrace : cmListFileBacktrace(),
-      input));
 }
 
 //----------------------------------------------------------------------------

Source/cmGeneratorExpression.h

@@ -42,7 +42,8 @@ class cmGeneratorExpression
 {
 public:
   /** Construct. */
-  cmGeneratorExpression(cmListFileBacktrace const* backtrace = NULL);
+  cmGeneratorExpression(
+      cmListFileBacktrace const& backtrace = cmListFileBacktrace());
   ~cmGeneratorExpression();
 
   cmsys::auto_ptr<cmCompiledGeneratorExpression> Parse(
@@ -71,7 +72,7 @@ private:
   cmGeneratorExpression(const cmGeneratorExpression &);
   void operator=(const cmGeneratorExpression &);
 
-  cmListFileBacktrace const* Backtrace;
+  cmListFileBacktrace Backtrace;
 };
 
 class cmCompiledGeneratorExpression

Source/cmGeneratorExpressionEvaluationFile.cxx

@@ -152,7 +152,7 @@ void cmGeneratorExpressionEvaluationFile::Generate()
     }
 
   cmListFileBacktrace lfbt = this->OutputFileExpr->GetBacktrace();
-  cmGeneratorExpression contentGE(&lfbt);
+  cmGeneratorExpression contentGE(lfbt);
   cmsys::auto_ptr<cmCompiledGeneratorExpression> inputExpression
                                               = contentGE.Parse(inputContent);
 

Source/cmGeneratorExpressionNode.cxx

@@ -21,7 +21,7 @@ std::string cmGeneratorExpressionNode::EvaluateDependentExpression(
     cmTarget const* headTarget, cmTarget const* currentTarget,
     cmGeneratorExpressionDAGChecker *dagChecker)
 {
-  cmGeneratorExpression ge(&context->Backtrace);
+  cmGeneratorExpression ge(context->Backtrace);
   cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(prop);
   cge->SetEvaluateForBuildsystem(context->EvaluateForBuildsystem);
   std::string result = cge->Evaluate(makefile,

Source/cmGeneratorTarget.cxx

@@ -878,7 +878,7 @@ 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;

Source/cmInstalledFile.cxx

@@ -44,7 +44,7 @@ cmInstalledFile::Property::~Property()
 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();
@@ -81,7 +81,7 @@ 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());

Source/cmTarget.cxx

@@ -916,7 +916,7 @@ 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(
@@ -956,7 +956,7 @@ 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(
@@ -1089,7 +1089,7 @@ 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(
@@ -1710,7 +1710,7 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
   else 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(
@@ -1719,7 +1719,7 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
   else 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(
@@ -1728,7 +1728,7 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
   else 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(
@@ -1737,7 +1737,7 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
   else 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(
@@ -1772,7 +1772,7 @@ 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(
@@ -1808,28 +1808,28 @@ void cmTarget::AppendProperty(const std::string& prop, const char* value,
   else 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)));
     }
   else 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)));
     }
   else 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)));
     }
   else 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)));
     }
@@ -1861,7 +1861,7 @@ 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));
@@ -1929,7 +1929,7 @@ 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()
@@ -1943,7 +1943,7 @@ 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()
@@ -1956,7 +1956,7 @@ 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)));
@@ -6162,7 +6162,7 @@ void cmTargetInternals::AddInterfaceEntries(
         {
         std::string genex =
           "$<TARGET_PROPERTY:" + *it + "," + prop + ">";
-        cmGeneratorExpression ge(&it->Backtrace);
+        cmGeneratorExpression ge(it->Backtrace);
         cmsys::auto_ptr<cmCompiledGeneratorExpression> cge = ge.Parse(genex);
         cge->SetEvaluateForBuildsystem(true);
         entries.push_back(
@@ -6258,7 +6258,7 @@ cmTargetInternals::ComputeLinkImplementationLibraries(
     cmGeneratorExpressionDAGChecker dagChecker(
                                         thisTarget->GetName(),
                                         "LINK_LIBRARIES", 0, 0);
-    cmGeneratorExpression ge(&le->Backtrace);
+    cmGeneratorExpression ge(le->Backtrace);
     cmsys::auto_ptr<cmCompiledGeneratorExpression> const cge =
       ge.Parse(le->Value);
     std::string const evaluated =

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() << " ";