Fix a potential null dereference in the pointer-to-bool evaluator; caught by

Eli Friedman.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@103297 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/ExprConstant.cpp

@@ -115,7 +115,7 @@ static bool EvalPointerValueAsBool(LValue& Value, bool& Result) {
 
   Result = Base || !Value.Offset.isZero();
 
-  const DeclRefExpr* DeclRef = dyn_cast<DeclRefExpr>(Base);
+  const DeclRefExpr* DeclRef = dyn_cast_or_null<DeclRefExpr>(Base);
   if (!DeclRef)
     return true;