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

Found by msan! git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@303686 91177308-0d34-0410-b5e6-96231b3b80d8
m-lopez · May 23, 2017 · 58d094a · 58d094a
1 parent 67b9708
commit 58d094a
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/lib/Frontend/TextDiagnostic.cpp b/lib/Frontend/TextDiagnostic.cpp
@@ -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.