Revert r194540, it breaks various C++ programs.

llvm-svn: 195126
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 8ec58d4..22242a5 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -10619,17 +10619,8 @@
 
   switch (ConvTy) {
   case Compatible:
-    // See if a proper null pointer constant is to be assigned.
-    if (DstType->isAnyPointerType() && !SrcType->isAnyPointerType() &&
-        SrcExpr->isNullPointerConstant(Context,
-                                       Expr::NPC_NeverValueDependent) ==
-            Expr::NPCK_ZeroExpression &&
-        !isUnevaluatedContext())
-      Diag(SrcExpr->getExprLoc(), diag::warn_non_literal_null_pointer)
-        << DstType << SrcExpr->getSourceRange();
-
-    DiagnoseAssignmentEnum(DstType, SrcType, SrcExpr);
-    return false;
+      DiagnoseAssignmentEnum(DstType, SrcType, SrcExpr);
+      return false;
 
   case PointerToInt:
     DiagKind = diag::ext_typecheck_convert_pointer_int;