Silence static analyzer issue by documenting that in this context

that a DeclRefExpr can never return a null decl.  We possibly should
hoist this into getDecl() itself.

llvm-svn: 165841

clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp

@@ -270,6 +270,7 @@ void WalkAST::checkLoopConditionForFloat(const ForStmt *FS) {
 
   // Emit the error.  First figure out which DeclRefExpr in the condition
   // referenced the compared variable.
+  assert(drInc->getDecl());
   const DeclRefExpr *drCond = vdLHS == drInc->getDecl() ? drLHS : drRHS;
 
   SmallVector<SourceRange, 2> ranges;