backtrace: Convert to local paths in IssueMessage

This is the only place we care show the FilePath to the user, so defer
the expensive relative path calculation until here.

1 files changed, 5 insertions, 0 deletions

diff --git a/Source/cmGeneratorExpressionEvaluator.h b/Source/cmGeneratorExpressionEvaluator.h
index eb76d7f157..0ffb860547 100644
--- a/Source/cmGeneratorExpressionEvaluator.h
+++ b/Source/cmGeneratorExpressionEvaluator.h
@@ -22,6 +22,11 @@ class cmTarget;
 //----------------------------------------------------------------------------
 struct cmGeneratorExpressionContext
 {
+  cmGeneratorExpressionContext()
+    : Backtrace(NULL)
+  {
+  }
+
   cmListFileBacktrace Backtrace;
   std::set<cmTarget*> DependTargets;
   std::set<cmTarget const*> AllTargets;