r190984 - Fix use-after-free in r190980.

[Eli Friedman]

Author: efriedma
Date: Wed Sep 18 20:51:23 2013
New Revision: 190984

URL: http://llvm.org/viewvc/llvm-project?rev=190984&view=rev
Log:
Fix use-after-free in r190980.

Modified:
    cfe/trunk/lib/Lex/Lexer.cpp

Modified: cfe/trunk/lib/Lex/Lexer.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Lex/Lexer.cpp?rev=190984&r1=190983&r2=190984&view=diff
==============================================================================
--- cfe/trunk/lib/Lex/Lexer.cpp (original)
+++ cfe/trunk/lib/Lex/Lexer.cpp Wed Sep 18 20:51:23 2013
@@ -2823,9 +2823,12 @@ bool Lexer::Lex(Token &Result) {
 
   bool atPhysicalStartOfLine = IsAtPhysicalStartOfLine;
   IsAtPhysicalStartOfLine = false;
-  bool result = LexTokenInternal(Result, atPhysicalStartOfLine);
-  assert((result || !isLexingRawMode()) && "Raw lex must succeed");
-  return result;
+  bool isRawLex = isLexingRawMode();
+  (void) isRawLex;
+  bool returnedToken = LexTokenInternal(Result, atPhysicalStartOfLine);
+  // (After the LexTokenInternal call, the lexer might be destroyed.)
+  assert((returnedToken || !isRawLex) && "Raw lex must succeed");
+  return returnedToken;
 }
 
 /// LexTokenInternal - This implements a simple C family lexer.  It is an