Add checker visitation hooks in ExprEngine::Visit() for common no-op expressions.  To be used later.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150723 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Core/ExprEngine.cpp b/lib/StaticAnalyzer/Core/ExprEngine.cpp
index b0ed181..6f588c5 100644
--- a/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -590,9 +590,14 @@
     case Stmt::CXXBoolLiteralExprClass:
     case Stmt::FloatingLiteralClass:
     case Stmt::SizeOfPackExprClass:
-    case Stmt::CXXNullPtrLiteralExprClass:
-      // No-op. Simply propagate the current state unchanged.
+    case Stmt::CXXNullPtrLiteralExprClass: {
+      Bldr.takeNodes(Pred);
+      ExplodedNodeSet preVisit;
+      getCheckerManager().runCheckersForPreStmt(preVisit, Pred, S, *this);
+      getCheckerManager().runCheckersForPostStmt(Dst, preVisit, S, *this);
+      Bldr.addNodes(Dst);
       break;
+    }
 
     case Stmt::ArraySubscriptExprClass:
       Bldr.takeNodes(Pred);