r224210 - Lex: Don't crash if both conflict markers are on the same line

[David Majnemer]

Author: majnemer
Date: Sat Dec 13 22:53:11 2014
New Revision: 224210

URL: http://llvm.org/viewvc/llvm-project?rev=224210&view=rev
Log:
Lex: Don't crash if both conflict markers are on the same line

We would check if the terminator marker is on a newline.  However, the
logic would end up out-of-bounds if the terminator marker immediately
follows the start marker.

This fixes PR21820.

Modified:
    cfe/trunk/lib/Lex/Lexer.cpp
    cfe/trunk/test/Lexer/conflict-marker.c

Modified: cfe/trunk/lib/Lex/Lexer.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Lex/Lexer.cpp?rev=224210&r1=224209&r2=224210&view=diff
==============================================================================
--- cfe/trunk/lib/Lex/Lexer.cpp (original)
+++ cfe/trunk/lib/Lex/Lexer.cpp Sat Dec 13 22:53:11 2014
@@ -2588,8 +2588,8 @@ static const char *FindConflictEnd(const
   size_t Pos = RestOfBuffer.find(Terminator);
   while (Pos != StringRef::npos) {
     // Must occur at start of line.
-    if (RestOfBuffer[Pos-1] != '\r' &&
-        RestOfBuffer[Pos-1] != '\n') {
+    if (Pos == 0 ||
+        (RestOfBuffer[Pos - 1] != '\r' && RestOfBuffer[Pos - 1] != '\n')) {
       RestOfBuffer = RestOfBuffer.substr(Pos+TermLen);
       Pos = RestOfBuffer.find(Terminator);
       continue;

Modified: cfe/trunk/test/Lexer/conflict-marker.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Lexer/conflict-marker.c?rev=224210&r1=224209&r2=224210&view=diff
==============================================================================
--- cfe/trunk/test/Lexer/conflict-marker.c (original)
+++ cfe/trunk/test/Lexer/conflict-marker.c Sat Dec 13 22:53:11 2014
@@ -36,3 +36,5 @@ int foo() {
   y a = x;
   return x + a - z;
 }
+
+<<<<<<<>>>>>>> // expected-error {{expected identifier}}