Switch attribute property setters to init-only

Author: Sergio0694

CommunityToolkit.Mvvm/ComponentModel/Attributes/INotifyPropertyChangedAttribute.cs

@@ -35,5 +35,5 @@ public sealed class INotifyPropertyChangedAttribute : Attribute
     /// the two <see cref="ObservableObject.OnPropertyChanged(PropertyChangedEventArgs)"/> overloads will be generated.
     /// The default value is <see langword="true"/>.
     /// </summary>
-    public bool IncludeAdditionalHelperMethods { get; set; } = true;
+    public bool IncludeAdditionalHelperMethods { get; init; } = true;
 }

CommunityToolkit.Mvvm/Input/Attributes/ICommandAttribute.cs

@@ -69,7 +69,7 @@ public sealed class ICommandAttribute : Attribute
     /// generated command can be executed at any given time. The referenced member needs to return
     /// a <see cref="bool"/> value, and has to have a signature compatible with the target command.
     /// </summary>
-    public string? CanExecute { get; set; }
+    public string? CanExecute { get; init; }
 
     /// <summary>
     /// Gets or sets a value indicating whether or not to allow concurrent executions for an asynchronous command.
@@ -78,5 +78,5 @@ public sealed class ICommandAttribute : Attribute
     /// when an execution is invoked while a previous one is still running. It is the same as creating an instance of
     /// these command types with a constructor such as <see cref="AsyncRelayCommand(Func{System.Threading.Tasks.Task}, bool)"/>.
     /// </summary>
-    public bool AllowConcurrentExecutions { get; set; } = true;
+    public bool AllowConcurrentExecutions { get; init; } = true;
 }

CommunityToolkit.Mvvm/Properties/Polyfills/System.Runtime.CompilerServices/IsExternalInit.cs

@@ -0,0 +1,20 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#if !NET6_0_OR_GREATER
+
+using System.ComponentModel;
+
+namespace System.Runtime.CompilerServices;
+
+/// <summary>
+/// Reserved to be used by the compiler for tracking metadata.
+/// This class should not be used by developers in source code.
+/// </summary>
+[EditorBrowsable(EditorBrowsableState.Never)]
+internal static class IsExternalInit
+{
+}
+
+#endif