Enable nullable on Avalonia.Diagnostics project

src/Avalonia.Base/Metadata/NullableAttributes.cs

@@ -1,6 +1,5 @@
 #pragma warning disable MA0048 // File name must match type name
 #define INTERNAL_NULLABLE_ATTRIBUTES
-#if NETSTANDARD2_0 ||  NETCOREAPP2_0 ||  NETCOREAPP2_1 ||  NETCOREAPP2_2 || NET45 || NET451 || NET452 || NET6 || NET461 || NET462 || NET47 || NET471 || NET472 || NET48
 
 // https://github.com/dotnet/corefx/blob/48363ac826ccf66fbe31a5dcb1dc2aab9a7dd768/src/Common/src/CoreLib/System/Diagnostics/CodeAnalysis/NullableAttributes.cs
 
@@ -10,6 +9,7 @@
 
 namespace System.Diagnostics.CodeAnalysis
 {
+#if NETSTANDARD2_0 || NETCOREAPP2_0 || NETCOREAPP2_1 || NETCOREAPP2_2 || NET45 || NET451 || NET452 || NET6 || NET461 || NET462 || NET47 || NET471 || NET472 || NET48
     /// <summary>Specifies that null is allowed as an input even if the corresponding type disallows it.</summary>
     [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
 #if INTERNAL_NULLABLE_ATTRIBUTES
@@ -136,5 +136,82 @@ sealed class DoesNotReturnIfAttribute : Attribute
         /// <summary>Gets the condition parameter value.</summary>
         public bool ParameterValue { get; }
     }
-}
+#endif // NETSTANDARD2_0 attributes
+
+#if NETSTANDARD2_1 || NETSTANDARD2_0 || NETCOREAPP2_0 || NETCOREAPP2_1 || NETCOREAPP2_2 || NETCOREAPP3_1 || NET45 || NET451 || NET452 || NET6 || NET461 || NET462 || NET47 || NET471 || NET472 || NET48
+    /// <summary>
+    /// Specifies that the method or property will ensure that the listed field and property members have
+    /// not-<see langword="null"/> values.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+#if INTERNAL_NULLABLE_ATTRIBUTES
+    internal
+#else
+    public
 #endif
+    sealed class MemberNotNullAttribute : Attribute
+    {
+        /// <summary>Gets field or property member names.</summary>
+        public string[] Members { get; }
+
+        /// <summary>Initializes the attribute with a field or property member.</summary>
+        /// <param name="member">The field or property member that is promised to be not-null.</param>
+        public MemberNotNullAttribute(string member)
+        {
+            Members = new[] { member };
+        }
+
+        /// <summary>Initializes the attribute with the list of field and property members.</summary>
+        /// <param name="members">The list of field and property members that are promised to be not-null.</param>
+        public MemberNotNullAttribute(params string[] members)
+        {
+            Members = members;
+        }
+    }
+
+    /// <summary>
+    /// Specifies that the method or property will ensure that the listed field and property members have
+    /// non-<see langword="null"/> values when returning with the specified return value condition.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+#if INTERNAL_NULLABLE_ATTRIBUTES
+    internal
+#else
+    public
+#endif
+    sealed class MemberNotNullWhenAttribute : Attribute
+    {
+        /// <summary>Gets the return value condition.</summary>
+        public bool ReturnValue { get; }
+
+        /// <summary>Gets field or property member names.</summary>
+        public string[] Members { get; }
+
+        /// <summary>Initializes the attribute with the specified return value condition and a field or property member.</summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value,
+        /// the associated parameter will not be <see langword="null"/>.
+        /// </param>
+        /// <param name="member">The field or property member that is promised to be not-<see langword="null"/>.</param>
+        public MemberNotNullWhenAttribute(bool returnValue, string member)
+        {
+            ReturnValue = returnValue;
+            Members = new[] { member };
+        }
+
+        /// <summary>Initializes the attribute with the specified return value condition and list of field and property members.
+        /// </summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value,
+        /// the associated parameter will not be <see langword="null"/>.
+        /// </param>
+        /// <param name="members">The list of field and property members that are promised to be not-null.</param>
+        public MemberNotNullWhenAttribute(bool returnValue, params string[] members)
+        {
+            ReturnValue = returnValue;
+            Members = members;
+        }
+    }
+#endif // NETSTANDARD2_1 attributes
+}
+

src/Avalonia.Diagnostics/Avalonia.Diagnostics.csproj

@@ -3,12 +3,16 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <RootNamespace>Avalonia</RootNamespace>
     <PackageId>Avalonia.Diagnostics</PackageId>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Update="**\*.xaml.cs">
       <DependentUpon>%(Filename)</DependentUpon>
     </Compile>
   </ItemGroup>
+  <ItemGroup>
+    <Compile Include="..\Avalonia.Base\Metadata\NullableAttributes.cs" Link="NullableAttributes.cs" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Avalonia.Controls.DataGrid\Avalonia.Controls.DataGrid.csproj" />
     <ProjectReference Include="..\Markup\Avalonia.Markup.Xaml\Avalonia.Markup.Xaml.csproj" />

src/Avalonia.Diagnostics/Diagnostics/Controls/ThicknessEditor.cs

@@ -10,8 +10,8 @@ internal class ThicknessEditor : ContentControl
             AvaloniaProperty.RegisterDirect<ThicknessEditor, Thickness>(nameof(Thickness), o => o.Thickness,
                 (o, v) => o.Thickness = v, defaultBindingMode: BindingMode.TwoWay);
 
-        public static readonly DirectProperty<ThicknessEditor, string> HeaderProperty =
-            AvaloniaProperty.RegisterDirect<ThicknessEditor, string>(nameof(Header), o => o.Header,
+        public static readonly DirectProperty<ThicknessEditor, string?> HeaderProperty =
+            AvaloniaProperty.RegisterDirect<ThicknessEditor, string?>(nameof(Header), o => o.Header,
                 (o, v) => o.Header = v);
 
         public static readonly DirectProperty<ThicknessEditor, bool> IsPresentProperty =
@@ -36,7 +36,7 @@ internal class ThicknessEditor : ContentControl
             AvaloniaProperty.Register<ThicknessEditor, IBrush>(nameof(Highlight));
 
         private Thickness _thickness;
-        private string _header;
+        private string? _header;
         private bool _isPresent = true;
         private double _left;
         private double _top;
@@ -50,7 +50,7 @@ public Thickness Thickness
             set => SetAndRaise(ThicknessProperty, ref _thickness, value);
         }
 
-        public string Header
+        public string? Header
         {
             get => _header;
             set => SetAndRaise(HeaderProperty, ref _header, value);

src/Avalonia.Diagnostics/Diagnostics/Converters/BoolToOpacityConverter.cs

@@ -8,12 +8,17 @@ internal class BoolToOpacityConverter : IValueConverter
     {
         public double Opacity { get; set; }
 
-        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
         {
-            return (bool)value ? 1d : Opacity;
+            if (value is bool boolean && boolean)
+            {
+                return 1d;
+            }
+
+            return Opacity;
         }
 
-        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
         {
             throw new NotImplementedException();
         }

src/Avalonia.Diagnostics/Diagnostics/Converters/EnumToCheckedConverter.cs

@@ -7,12 +7,12 @@ namespace Avalonia.Diagnostics.Converters
 {
     internal class EnumToCheckedConverter : IValueConverter
     {
-        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
         {
             return Equals(value, parameter);
         }
 
-        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
         {
             if (value is bool isChecked && isChecked)
             {

src/Avalonia.Diagnostics/Diagnostics/DevTools.cs

@@ -6,8 +6,6 @@
 using Avalonia.Input;
 using Avalonia.Interactivity;
 
-#nullable enable 
-
 namespace Avalonia.Diagnostics
 {
     public static class DevTools
@@ -24,7 +22,7 @@ public static IDisposable Attach(TopLevel root, KeyGesture gesture)
 
         public static IDisposable Attach(TopLevel root, DevToolsOptions options)
         {
-            void PreviewKeyDown(object sender, KeyEventArgs e)
+            void PreviewKeyDown(object? sender, KeyEventArgs e)
             {
                 if (options.Gesture.Matches(e))
                 {
@@ -71,10 +69,10 @@ public static IDisposable Open(TopLevel root, DevToolsOptions options)
             return Disposable.Create(() => window?.Close());
         }
 
-        private static void DevToolsClosed(object sender, EventArgs e)
+        private static void DevToolsClosed(object? sender, EventArgs e)
         {
-            var window = (MainWindow)sender;
-            s_open.Remove(window.Root);
+            var window = (MainWindow)sender!;
+            s_open.Remove(window.Root!);
             window.Closed -= DevToolsClosed;
         }
     }

src/Avalonia.Diagnostics/Diagnostics/Models/ConsoleContext.cs

@@ -22,8 +22,8 @@ public class ConsoleContext
 clear(): Clear the output history
 ";
 
-        public dynamic e { get; internal set; }
-        public dynamic root { get; internal set; }
+        public dynamic? e { get; internal set; }
+        public dynamic? root { get; internal set; }
 
         internal static object NoOutput { get; } = new object();
 

src/Avalonia.Diagnostics/Diagnostics/Models/EventChainLink.cs

@@ -7,9 +7,7 @@ internal class EventChainLink
     {
         public EventChainLink(object handler, bool handled, RoutingStrategies route)
         {
-            Contract.Requires<ArgumentNullException>(handler != null);
-
-            Handler = handler;
+            Handler = handler ?? throw new ArgumentNullException(nameof(handler));
             Handled = handled;
             Route = route;
         }

src/Avalonia.Diagnostics/Diagnostics/ViewLocator.cs

@@ -9,12 +9,12 @@ internal class ViewLocator : IDataTemplate
     {
         public IControl Build(object data)
         {
-            var name = data.GetType().FullName.Replace("ViewModel", "View");
+            var name = data.GetType().FullName!.Replace("ViewModel", "View");
             var type = Type.GetType(name);
 
             if (type != null)
             {
-                return (Control)Activator.CreateInstance(type);
+                return (Control)Activator.CreateInstance(type)!;
             }
             else
             {

src/Avalonia.Diagnostics/Diagnostics/ViewModels/AvaloniaPropertyViewModel.cs

@@ -1,17 +1,17 @@
-using System.ComponentModel;
-using Avalonia.Collections;
-
 namespace Avalonia.Diagnostics.ViewModels
 {
     internal class AvaloniaPropertyViewModel : PropertyViewModel
     {
         private readonly AvaloniaObject _target;
         private string _type;
-        private object _value;
+        private object? _value;
         private string _priority;
         private string _group;
 
+#nullable disable
+        // Remove "nullable disable" after MemberNotNull will work on our CI.
         public AvaloniaPropertyViewModel(AvaloniaObject o, AvaloniaProperty property)
+#nullable restore
         {
             _target = o;
             Property = property;
@@ -20,12 +20,6 @@ public AvaloniaPropertyViewModel(AvaloniaObject o, AvaloniaProperty property)
                 $"[{property.OwnerType.Name}.{property.Name}]" :
                 property.Name;
 
-            if (property.IsDirect)
-            {
-                _group = "Properties";
-                Priority = "Direct";
-            }
-
             Update();
         }
 
@@ -34,11 +28,7 @@ public AvaloniaPropertyViewModel(AvaloniaObject o, AvaloniaProperty property)
         public override string Name { get; }
         public bool IsAttached => Property.IsAttached;
 
-        public string Priority
-        {
-            get => _priority;
-            private set => RaiseAndSetIfChanged(ref _priority, value);
-        }
+        public string Priority => _priority;
 
         public override string Type => _type;
 
@@ -56,40 +46,37 @@ public override string Value
             }
         }
 
-        public override string Group
-        {
-            get => _group;
-        }
+        public override string Group => _group;
 
+        // [MemberNotNull(nameof(_type), nameof(_group), nameof(_priority))]
         public override void Update()
         {
             if (Property.IsDirect)
             {
                 RaiseAndSetIfChanged(ref _value, _target.GetValue(Property), nameof(Value));
-                RaiseAndSetIfChanged(ref _type, _value?.GetType().Name, nameof(Type));
+                RaiseAndSetIfChanged(ref _type, _value?.GetType().Name ?? Property.PropertyType.Name, nameof(Type));
+                RaiseAndSetIfChanged(ref _priority, "Direct", nameof(Priority));
+
+                _group = "Properties";
             }
             else
             {
                 var val = _target.GetDiagnostic(Property);
 
                 RaiseAndSetIfChanged(ref _value, val?.Value, nameof(Value));
-                RaiseAndSetIfChanged(ref _type, _value?.GetType().Name, nameof(Type));
+                RaiseAndSetIfChanged(ref _type, _value?.GetType().Name ?? Property.PropertyType.Name, nameof(Type));
 
                 if (val != null)
                 {
-                    SetGroup(IsAttached ? "Attached Properties" : "Properties");
-                    Priority = val.Priority.ToString();
+                    RaiseAndSetIfChanged(ref _priority, val.Priority.ToString(), nameof(Priority));
+                    RaiseAndSetIfChanged(ref _group, IsAttached ? "Attached Properties" : "Properties", nameof(Group));
                 }
                 else
                 {
-                    SetGroup(Priority = "Unset");
+                    RaiseAndSetIfChanged(ref _priority, "Unset", nameof(Priority));
+                    RaiseAndSetIfChanged(ref _group, "Unset", nameof(Group));
                 }
             }
         }
-
-        private void SetGroup(string group)
-        {
-            RaiseAndSetIfChanged(ref _group, group, nameof(Group));
-        }
     }
 }

src/Avalonia.Diagnostics/Diagnostics/ViewModels/ClrPropertyViewModel.cs

@@ -1,20 +1,22 @@
-using System.ComponentModel;
-using System.Reflection;
+using System.Reflection;
 
 namespace Avalonia.Diagnostics.ViewModels
 {
     internal class ClrPropertyViewModel : PropertyViewModel
     {
         private readonly object _target;
         private string _type;
-        private object _value;
+        private object? _value;
 
+#nullable disable
+        // Remove "nullable disable" after MemberNotNull will work on our CI.
         public ClrPropertyViewModel(object o, PropertyInfo property)
+#nullable restore
         {
             _target = o;
             Property = property;
 
-            if (!property.DeclaringType.IsInterface)
+            if (property.DeclaringType == null || !property.DeclaringType.IsInterface)
             {
                 Name = property.Name;
             }
@@ -47,11 +49,12 @@ public override string Value
             }
         }
 
+        // [MemberNotNull(nameof(_type))]
         public override void Update()
         {
             var val = Property.GetValue(_target);
             RaiseAndSetIfChanged(ref _value, val, nameof(Value));
-            RaiseAndSetIfChanged(ref _type, _value?.GetType().Name, nameof(Type));
+            RaiseAndSetIfChanged(ref _type, _value?.GetType().Name ?? Property.PropertyType.Name, nameof(Type));
         }
     }
 }