Introduce a limit on the depth of the template instantiation backtrace

we will print with each error that occurs during template
instantiation. When the backtrace is longer than that, we will print
N/2 of the innermost backtrace entries and N/2 of the outermost
backtrace entries, then skip the middle entries with a note such as:

  note: suppressed 2 template instantiation contexts; use
  -ftemplate-backtrace-limit=N to change the number of template
  instantiation entries shown

This should eliminate some excessively long backtraces that aren't
providing any value.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101882 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 1 deletions

diff --git a/include/clang/Frontend/DiagnosticOptions.h b/include/clang/Frontend/DiagnosticOptions.h
index d8ec14f9a3..797cb34023 100644
--- a/include/clang/Frontend/DiagnosticOptions.h
+++ b/include/clang/Frontend/DiagnosticOptions.h
@@ -39,7 +39,8 @@ public:
                                  /// deserialized by, e.g., the CIndex library.
 
   unsigned ErrorLimit;           /// Limit # errors emitted.
-  
+  unsigned TemplateBacktraceLimit; /// Limit depth of instantiation backtrace.
+
   /// The distance between tab stops.
   unsigned TabStop;
   enum { DefaultTabStop = 8, MaxTabStop = 100 };
@@ -73,6 +74,7 @@ public:
     VerifyDiagnostics = 0;
     BinaryOutput = 0;
     ErrorLimit = 0;
+    TemplateBacktraceLimit = 0;
   }
 };