r303686 - [Frontend] Don't index into an empty string.

[Benjamin Kramer via cfe-commits]

Author: d0k
Date: Tue May 23 15:48:21 2017
New Revision: 303686

URL: http://llvm.org/viewvc/llvm-project?rev=303686&view=rev
Log:
[Frontend] Don't index into an empty string.

Found by msan!

Modified:
    cfe/trunk/lib/Frontend/TextDiagnostic.cpp

Modified: cfe/trunk/lib/Frontend/TextDiagnostic.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/TextDiagnostic.cpp?rev=303686&r1=303685&r2=303686&view=diff
==============================================================================
--- cfe/trunk/lib/Frontend/TextDiagnostic.cpp (original)
+++ cfe/trunk/lib/Frontend/TextDiagnostic.cpp Tue May 23 15:48:21 2017
@@ -1252,7 +1252,7 @@ void TextDiagnostic::emitSnippetAndCaret
     }
 
     // Finally, remove any blank spaces from the end of CaretLine.
-    while (CaretLine[CaretLine.size() - 1] == ' ')
+    while (!CaretLine.empty() && CaretLine[CaretLine.size() - 1] == ' ')
       CaretLine.erase(CaretLine.end() - 1);
 
     // Emit what we have computed.