private void CheckNewModifier(Symbol symbol, bool isNew, DiagnosticBag diagnostics)
        {
            // for error cases
            if ((object)this.BaseTypeNoUseSiteDiagnostics == null)
            {
                return;
            }

            // Do not give warnings about missing 'new' modifier for implicitly declared members,
            // e.g. backing fields for auto-properties
            if (symbol.IsImplicitlyDeclared)
            {
                return;
            }

            int symbolArity = symbol.GetMemberArity();
            Location symbolLocation = symbol.Locations.FirstOrDefault();
            bool unused = false;

            NamedTypeSymbol currType = this.BaseTypeNoUseSiteDiagnostics;
            while ((object)currType != null)
            {
                foreach (var hiddenMember in currType.GetMembers(symbol.Name))
                {
                    if (hiddenMember.Kind == SymbolKind.Method && !((MethodSymbol)hiddenMember).CanBeHiddenByMemberKind(symbol.Kind))
                    {
                        continue;
                    }

                    HashSet<DiagnosticInfo> useSiteDiagnostics = null;
                    bool isAccessible = AccessCheck.IsSymbolAccessible(hiddenMember, this, ref useSiteDiagnostics);
                    diagnostics.Add(symbolLocation, useSiteDiagnostics);

                    if (isAccessible && hiddenMember.GetMemberArity() == symbolArity)
                    {
                        if (!isNew)
                        {
                            diagnostics.Add(ErrorCode.WRN_NewRequired, symbolLocation, symbol, hiddenMember);
                        }

                        AddHidingAbstractDiagnostic(symbol, symbolLocation, hiddenMember, diagnostics, ref unused);

                        return;
                    }
                }

                currType = currType.BaseTypeNoUseSiteDiagnostics;
            }

            if (isNew)
            {
                diagnostics.Add(ErrorCode.WRN_NewNotRequired, symbolLocation, symbol);
            }
        }