When word-wrapping, be more defensive about a ridiculously small number of columns. Fixes <rdar://problem/6892178>

llvm-svn: 71870

2 files changed, 5 insertions, 3 deletions

diff --git a/clang/lib/Frontend/TextDiagnosticPrinter.cpp b/clang/lib/Frontend/TextDiagnosticPrinter.cpp
index f936807b6cf..09c29109f18 100644
--- a/clang/lib/Frontend/TextDiagnosticPrinter.cpp
+++ b/clang/lib/Frontend/TextDiagnosticPrinter.cpp
@@ -160,10 +160,12 @@ static void SelectInterestingSourceRegion(std::string &SourceLine,
 
   // If the end of the interesting region comes before we run out of
   // space in the terminal, start at the beginning of the line.
-  if (CaretEnd < Columns - 3)
+  if (Columns > 3 && CaretEnd < Columns - 3)
     CaretStart = 0;
 
-  unsigned TargetColumns = Columns - 8; // Give us extra room for the ellipses.
+  unsigned TargetColumns = Columns;
+  if (TargetColumns > 8)
+    TargetColumns -= 8; // Give us extra room for the ellipses.
   unsigned SourceLength = SourceLine.size();
   while ((CaretEnd - CaretStart) < TargetColumns) {
     bool ExpandedRegion = false;
diff --git a/clang/test/Misc/message-length.c b/clang/test/Misc/message-length.c
index d64b1bfc58a..ac5dab99ca5 100644
--- a/clang/test/Misc/message-length.c
+++ b/clang/test/Misc/message-length.c
@@ -4,7 +4,7 @@
 // FIXME: This diagnostic is getting truncated very poorly.
 // RUN: grep -e '^  ...// some long comment text and a brace, eh {} ' %t.msg &&
 // RUN: grep -e '^                                                 \^' %t.msg &&
-
+// RUN: clang -fsyntax-only -fmessage-length=1 %s &&
 // RUN: true
 
 // Hack so we can check things better, force the file name and line.