4 files changed, 39 insertions, 37 deletions

diff --git a/Source/cmListFileCache.cxx b/Source/cmListFileCache.cxx
index d5d0184..f198ac3 100644
--- a/Source/cmListFileCache.cxx
+++ b/Source/cmListFileCache.cxx
@@ -400,13 +400,40 @@ bool cmListFileParser::AddArgument(cmListFileLexer_Token* token,
 
 cmListFileBacktrace::cmListFileBacktrace(cmState::Snapshot snapshot,
                                          cmCommandContext const& cc)
-  : Context(cc)
-  , Snapshot(snapshot)
+  : Snapshot(snapshot)
 {
-  if (this->Snapshot.IsValid())
+  if (!this->Snapshot.IsValid())
+    {
+    return;
+    }
+
+  // Record the entire call stack now so that the `Snapshot` we
+  // save for later refers to a long-lived scope.  This avoids
+  // having to keep short-lived scopes around just to extract
+  // their backtrace information later.
+
+  cmListFileContext lfc =
+    cmListFileContext::FromCommandContext(
+      cc, this->Snapshot.GetExecutionListFile());
+  this->push_back(lfc);
+
+  cmState::Snapshot parent = this->Snapshot.GetCallStackParent();
+  while (parent.IsValid())
     {
-    this->Snapshot.Keep();
+    lfc.Name = this->Snapshot.GetEntryPointCommand();
+    lfc.Line = this->Snapshot.GetEntryPointLine();
+    lfc.FilePath = parent.GetExecutionListFile();
+    if (lfc.FilePath.empty())
+      {
+      break;
+      }
+    this->push_back(lfc);
+
+    this->Snapshot = parent;
+    parent = parent.GetCallStackParent();
     }
+
+  this->Snapshot = this->Snapshot.GetCallStackBottom();
 }
 
 cmListFileBacktrace::~cmListFileBacktrace()
@@ -415,48 +442,30 @@ cmListFileBacktrace::~cmListFileBacktrace()
 
 void cmListFileBacktrace::PrintTitle(std::ostream& out) const
 {
-  if (!this->Snapshot.IsValid())
+  if (this->empty())
     {
     return;
     }
   cmOutputConverter converter(this->Snapshot);
-  cmListFileContext lfc =
-      cmListFileContext::FromCommandContext(
-        this->Context, this->Snapshot.GetExecutionListFile());
+  cmListFileContext lfc = this->front();
   lfc.FilePath = converter.Convert(lfc.FilePath, cmOutputConverter::HOME);
   out << (lfc.Line ? " at " : " in ") << lfc;
 }
 
 void cmListFileBacktrace::PrintCallStack(std::ostream& out) const
 {
-  if (!this->Snapshot.IsValid())
-    {
-    return;
-    }
-  cmState::Snapshot parent = this->Snapshot.GetCallStackParent();
-  if (!parent.IsValid() || parent.GetExecutionListFile().empty())
+  if (this->size() <= 1)
     {
     return;
     }
+  out << "Call Stack (most recent call first):\n";
 
   cmOutputConverter converter(this->Snapshot);
-  std::string commandName = this->Snapshot.GetEntryPointCommand();
-  long commandLine = this->Snapshot.GetEntryPointLine();
-
-  out << "Call Stack (most recent call first):\n";
-  while(parent.IsValid())
+  for (const_iterator i = this->begin() + 1; i != this->end(); ++i)
     {
-    cmListFileContext lfc;
-    lfc.Name = commandName;
-    lfc.Line = commandLine;
-
-    lfc.FilePath = converter.Convert(parent.GetExecutionListFile(),
-                                     cmOutputConverter::HOME);
+    cmListFileContext lfc = *i;
+    lfc.FilePath = converter.Convert(lfc.FilePath, cmOutputConverter::HOME);
     out << "  " << lfc << "\n";
-
-    commandName = parent.GetEntryPointCommand();
-    commandLine = parent.GetEntryPointLine();
-    parent = parent.GetCallStackParent();
     }
 }
 
diff --git a/Source/cmListFileCache.h b/Source/cmListFileCache.h
index 4d3055f..d3cab22 100644
--- a/Source/cmListFileCache.h
+++ b/Source/cmListFileCache.h
@@ -87,7 +87,7 @@ struct cmListFileFunction: public cmCommandContext
   std::vector<cmListFileArgument> Arguments;
 };
 
-class cmListFileBacktrace
+class cmListFileBacktrace: private std::vector<cmListFileContext>
 {
   public:
     cmListFileBacktrace(cmState::Snapshot snapshot = cmState::Snapshot(),
@@ -97,7 +97,6 @@ class cmListFileBacktrace
     void PrintTitle(std::ostream& out) const;
     void PrintCallStack(std::ostream& out) const;
   private:
-    cmCommandContext Context;
     cmState::Snapshot Snapshot;
 };
 
diff --git a/Source/cmState.cxx b/Source/cmState.cxx
index c48f9b1..bec5682 100644
--- a/Source/cmState.cxx
+++ b/Source/cmState.cxx
@@ -1098,11 +1098,6 @@ void cmState::Directory::SetCurrentBinary(std::string const& dir)
   this->Snapshot_.SetDefinition("CMAKE_CURRENT_BINARY_DIR", loc.c_str());
 }
 
-void cmState::Snapshot::Keep()
-{
-  this->Position->Keep = true;
-}
-
 void cmState::Snapshot::SetListFile(const std::string& listfile)
 {
   *this->Position->ExecutionListFile = listfile;
diff --git a/Source/cmState.h b/Source/cmState.h
index 0cce644..507d500 100644
--- a/Source/cmState.h
+++ b/Source/cmState.h
@@ -63,7 +63,6 @@ public:
     std::vector<std::string> ClosureKeys() const;
     bool RaiseScope(std::string const& var, const char* varDef);
 
-    void Keep();
     void SetListFile(std::string const& listfile);
 
     std::string GetExecutionListFile() const;