internal SourceCustomEventAccessorSymbol(
            SourceEventSymbol @event,
            AccessorDeclarationSyntax syntax,
            EventSymbol explicitlyImplementedEventOpt,
            string aliasQualifierOpt,
            DiagnosticBag diagnostics)
            : base(@event,
                   syntax.GetReference(),
                   syntax.Body.GetReferenceOrNull(),
                   ImmutableArray.Create(syntax.Keyword.GetLocation()))
        {
            Debug.Assert(syntax != null);
            Debug.Assert(syntax.Kind == SyntaxKind.AddAccessorDeclaration || syntax.Kind == SyntaxKind.RemoveAccessorDeclaration);

            bool isAdder = syntax.Kind == SyntaxKind.AddAccessorDeclaration;

            string name;
            ImmutableArray<MethodSymbol> explicitInterfaceImplementations;
            if ((object)explicitlyImplementedEventOpt == null)
            {
                name = SourceEventSymbol.GetAccessorName(@event.Name, isAdder);
                explicitInterfaceImplementations = ImmutableArray<MethodSymbol>.Empty;
            }
            else
            {
                MethodSymbol implementedAccessor = isAdder ? explicitlyImplementedEventOpt.AddMethod : explicitlyImplementedEventOpt.RemoveMethod;
                string accessorName = (object)implementedAccessor != null ? implementedAccessor.Name : SourceEventSymbol.GetAccessorName(explicitlyImplementedEventOpt.Name, isAdder);

                name = ExplicitInterfaceHelpers.GetMemberName(accessorName, explicitlyImplementedEventOpt.ContainingType, aliasQualifierOpt);
                explicitInterfaceImplementations = (object)implementedAccessor == null ? ImmutableArray<MethodSymbol>.Empty : ImmutableArray.Create<MethodSymbol>(implementedAccessor);
            }

            this.explicitInterfaceImplementations = explicitInterfaceImplementations;
            this.name = name;
            this.flags = MakeFlags(
                isAdder ? MethodKind.EventAdd : MethodKind.EventRemove,
                @event.Modifiers,
                returnsVoid: false, // until we learn otherwise (in LazyMethodChecks).
                isExtensionMethod: false,
                isMetadataVirtualIgnoringModifiers: explicitInterfaceImplementations.Any());

            if (@event.ContainingType.IsInterface)
            {
                diagnostics.Add(ErrorCode.ERR_EventPropertyInInterface, this.Location);
            }
            else
            {
                var bodyOpt = syntax.Body;
                if (bodyOpt != null)
                {
                    if (IsExtern && !IsAbstract)
                    {
                        diagnostics.Add(ErrorCode.ERR_ExternHasBody, this.Location, this);
                    }
                    else if (IsAbstract && !IsExtern)
                    {
                        diagnostics.Add(ErrorCode.ERR_AbstractHasBody, this.Location, this);
                    }
                    // Do not report error for IsAbstract && IsExtern. Dev10 reports CS0180 only
                    // in that case ("member cannot be both extern and abstract").
                }
            }

            this.name = GetOverriddenAccessorName(@event, isAdder) ?? this.name;
        }
        private SourcePropertyAccessorSymbol(
            NamedTypeSymbol containingType,
            string name,
            SourcePropertySymbol property,
            DeclarationModifiers propertyModifiers,
            ImmutableArray<MethodSymbol> explicitInterfaceImplementations,
            Location location,
            AccessorDeclarationSyntax syntax,
            MethodKind methodKind,
            bool isAutoPropertyAccessor,
            DiagnosticBag diagnostics) :
            base(containingType, syntax.GetReference(), syntax.Body?.GetReference(), location)
        {
            _property = property;
            _explicitInterfaceImplementations = explicitInterfaceImplementations;
            _name = name;
            _isAutoPropertyAccessor = isAutoPropertyAccessor;

            bool modifierErrors;
            var declarationModifiers = this.MakeModifiers(syntax, location, diagnostics, out modifierErrors);

            // Include modifiers from the containing property.
            propertyModifiers &= ~DeclarationModifiers.AccessibilityMask;
            if ((declarationModifiers & DeclarationModifiers.Private) != 0)
            {
                // Private accessors cannot be virtual.
                propertyModifiers &= ~DeclarationModifiers.Virtual;
            }
            declarationModifiers |= propertyModifiers & ~DeclarationModifiers.Indexer;

            // ReturnsVoid property is overridden in this class so
            // returnsVoid argument to MakeFlags is ignored.
            this.MakeFlags(methodKind, declarationModifiers, returnsVoid: false, isExtensionMethod: false,
                isMetadataVirtualIgnoringModifiers: explicitInterfaceImplementations.Any());

            var bodyOpt = syntax.Body;
            if (bodyOpt != null)
            {
                CheckModifiersForBody(location, diagnostics);
            }

            var info = ModifierUtils.CheckAccessibility(this.DeclarationModifiers);
            if (info != null)
            {
                diagnostics.Add(info, location);
            }

            if (!modifierErrors)
            {
                this.CheckModifiers(location, isAutoPropertyAccessor, diagnostics);
            }

            if (this.IsOverride)
            {
                MethodSymbol overriddenMethod = this.OverriddenMethod;
                if ((object)overriddenMethod != null)
                {
                    // If this accessor is overriding a method from metadata, it is possible that
                    // the name of the overridden method doesn't follow the C# get_X/set_X pattern.
                    // We should copy the name so that the runtime will recognize this as an override.
                    _name = overriddenMethod.Name;
                }
            }
        }
        private SourcePropertyAccessorSymbol(
            NamedTypeSymbol containingType,
            string name,
            SourcePropertySymbol property,
            DeclarationModifiers propertyModifiers,
            ImmutableArray<MethodSymbol> explicitInterfaceImplementations,
            Location location,
            AccessorDeclarationSyntax syntax,
            MethodKind methodKind,
            bool isAutoPropertyAccessor,
            DiagnosticBag diagnostics) :
            base(containingType, syntax.GetReference(), syntax.Body.GetReferenceOrNull(), location)
        {
            this.property = property;
            this.explicitInterfaceImplementations = explicitInterfaceImplementations;
            this.name = name;
            this.isAutoPropertyAccessor = isAutoPropertyAccessor;

            bool modifierErrors;
            var declarationModifiers = this.MakeModifiers(syntax, location, diagnostics, out modifierErrors);

            // Include modifiers from the containing property.
            propertyModifiers &= ~DeclarationModifiers.AccessibilityMask;
            if ((declarationModifiers & DeclarationModifiers.Private) != 0)
            {
                // Private accessors cannot be virtual.
                propertyModifiers &= ~DeclarationModifiers.Virtual;
            }
            declarationModifiers |= propertyModifiers;

            // ReturnsVoid property is overridden in this class so
            // returnsVoid argument to MakeFlags is ignored.
            this.flags = MakeFlags(methodKind, declarationModifiers, returnsVoid: false, isExtensionMethod: false,
                isMetadataVirtualIgnoringModifiers: explicitInterfaceImplementations.Any());

            var bodyOpt = syntax.Body;
            if (bodyOpt != null)
            {
                if (containingType.IsInterface)
                {
                    diagnostics.Add(ErrorCode.ERR_InterfaceMemberHasBody, location, this);
                }
                else if (IsExtern && !IsAbstract)
                {
                    diagnostics.Add(ErrorCode.ERR_ExternHasBody, location, this);
                }
                else if (IsAbstract && !IsExtern)
                {
                    diagnostics.Add(ErrorCode.ERR_AbstractHasBody, location, this);
                }
                // Do not report error for IsAbstract && IsExtern. Dev10 reports CS0180 only
                // in that case ("member cannot be both extern and abstract").
            }

            var info = ModifierUtils.CheckAccessibility(this.DeclarationModifiers);
            if (info != null)
            {
                diagnostics.Add(info, location);
            }

            if (!modifierErrors)
            {
                this.CheckModifiers(location, isAutoPropertyAccessor, diagnostics);
            }

            if (this.IsOverride)
            {
                MethodSymbol overriddenMethod = this.OverriddenMethod;
                if ((object)overriddenMethod != null)
                {
                    // If this accessor is overriding a method from metadata, it is possible that
                    // the name of the overridden method doesn't follow the C# get_X/set_X pattern.
                    // We should copy the name so that the runtime will recognize this as an override.
                    this.name = overriddenMethod.Name;
                }
            }
        }