Refactor WhenAnyValue usage to generic overloads (#4097)

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**What kind of change does this PR introduce?**
<!-- Bug fix, feature, docs update, ... -->

Update

**What is the new behavior?**
<!-- If this is a feature change -->

Replaces lambda-based WhenAnyValue calls with explicit generic overloads
across multiple platforms and components for improved AOT compatibility
and clarity. Adds SuppressMessage attributes to registration classes to
address trimming and AOT warnings where dynamic code or reflection is
not always used. Also updates project file to suppress IL2026 and IL3050
warnings for AOT tests.

**What might this PR break?**

New feature, part of a larger breaking change

**Please check if the PR fulfills these requirements**
- [ ] Tests for the changes have been added (for bug fixes / features)
- [ ] Docs have been added / updated (for bug fixes / features)

**Other information**:

Author: ChrisPulman

src/ReactiveUI.AOTTests/ReactiveUI.AOT.Tests.csproj

@@ -9,6 +9,7 @@
     <PublishAot>true</PublishAot>
     <InvariantGlobalization>true</InvariantGlobalization>
     <TrimMode>full</TrimMode>
+    <NoWarn>$(NoWarn);IL2026;IL3050;</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>

src/ReactiveUI.AOTTests/StringBasedObservationTests.cs

@@ -3,6 +3,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for full license information.
 
+using System.Diagnostics.CodeAnalysis;
 using System.Reactive.Concurrency;
 using System.Reactive.Linq;
 

src/ReactiveUI.AndroidX/Registrations.cs

@@ -17,6 +17,8 @@ public class Registrations : IWantsToRegisterStuff
 #if NET6_0_OR_GREATER
     [RequiresDynamicCode("Register uses methods that require dynamic code generation")]
     [RequiresUnreferencedCode("Register uses methods that may require unreferenced code")]
+    [SuppressMessage("Trimming", "IL2046:'RequiresUnreferencedCodeAttribute' annotations must match across all interface implementations or overrides.", Justification = "Not all paths use reflection")]
+    [SuppressMessage("AOT", "IL3051:'RequiresDynamicCodeAttribute' annotations must match across all interface implementations or overrides.", Justification = "Not all paths use reflection")]
 #endif
     public void Register(Action<Func<object>, Type> registerFunction)
     {

src/ReactiveUI.Blazor/ReactiveComponentBase.cs

@@ -92,7 +92,7 @@ protected override void OnAfterRender(bool firstRender)
         {
             // The following subscriptions are here because if they are done in OnInitialized, they conflict with certain JavaScript frameworks.
             var viewModelChanged =
-                this.WhenAnyValue(x => x.ViewModel)
+                this.WhenAnyValue<ReactiveComponentBase<T>, T?>(nameof(ViewModel))
                     .WhereNotNull()
                     .Publish()
                     .RefCount(2);

src/ReactiveUI.Blazor/ReactiveInjectableComponentBase.cs

@@ -94,7 +94,7 @@ protected override void OnAfterRender(bool firstRender)
         {
             // The following subscriptions are here because if they are done in OnInitialized, they conflict with certain JavaScript frameworks.
             var viewModelChanged =
-                this.WhenAnyValue(x => x.ViewModel)
+                this.WhenAnyValue<ReactiveInjectableComponentBase<T>, T?>(nameof(ViewModel))
                     .WhereNotNull()
                     .Publish()
                     .RefCount(2);

src/ReactiveUI.Blazor/ReactiveLayoutComponentBase.cs

@@ -91,7 +91,7 @@ protected override void OnAfterRender(bool isFirstRender)
         if (isFirstRender)
         {
             var viewModelChanged =
-                this.WhenAnyValue(x => x.ViewModel)
+                this.WhenAnyValue<ReactiveLayoutComponentBase<T>, T?>(nameof(ViewModel))
                     .WhereNotNull()
                     .Publish()
                     .RefCount(2);

src/ReactiveUI.Blazor/Registrations.cs

@@ -17,6 +17,8 @@ public class Registrations : IWantsToRegisterStuff
 #if NET6_0_OR_GREATER
     [RequiresDynamicCode("Register uses methods that require dynamic code generation")]
     [RequiresUnreferencedCode("Register uses methods that may require unreferenced code")]
+    [SuppressMessage("Trimming", "IL2046:'RequiresUnreferencedCodeAttribute' annotations must match across all interface implementations or overrides.", Justification = "Not all paths use reflection")]
+    [SuppressMessage("AOT", "IL3051:'RequiresDynamicCodeAttribute' annotations must match across all interface implementations or overrides.", Justification = "Not all paths use reflection")]
 #endif
     public void Register(Action<Func<object>, Type> registerFunction)
     {

src/ReactiveUI.Builder.WpfApp/ViewModels/ChatRoomViewModel.cs

@@ -33,7 +33,7 @@ public ChatRoomViewModel(IScreen hostScreen, ChatRoom room, string user)
         _room = room;
         _user = user;
 
-        var canSend = this.WhenAnyValue(x => x.MessageText, txt => !string.IsNullOrWhiteSpace(txt));
+        var canSend = this.WhenAnyValue<ChatRoomViewModel, bool, string>(nameof(MessageText), txt => !string.IsNullOrWhiteSpace(txt));
         SendMessage = ReactiveCommand.Create(SendMessageImpl, canSend);
 
         // Observe new incoming messages via MessageBus using the room name as the contract across instances

src/ReactiveUI.Builder.WpfApp/ViewModels/LobbyViewModel.cs

@@ -29,7 +29,7 @@ public LobbyViewModel(IScreen hostScreen)
         HostScreen = hostScreen;
         UrlPathSegment = "lobby";
 
-        var canCreate = this.WhenAnyValue(x => x.RoomName, rn => !string.IsNullOrWhiteSpace(rn));
+        var canCreate = this.WhenAnyValue<LobbyViewModel, bool, string>(nameof(RoomName), rn => !string.IsNullOrWhiteSpace(rn));
         CreateRoom = ReactiveCommand.Create(CreateRoomImpl, canCreate);
 
         DeleteRoom = ReactiveCommand.Create<ChatRoom>(DeleteRoomImpl);

src/ReactiveUI.Builder.WpfApp/Views/ChatRoomView.xaml.cs

@@ -5,6 +5,7 @@
 
 using System.Reactive.Disposables;
 using System.Windows;
+using ReactiveUI.Builder.WpfApp.ViewModels;
 
 namespace ReactiveUI.Builder.WpfApp.Views;
 
@@ -28,7 +29,7 @@ public ChatRoomView()
         this.WhenActivated(d =>
         {
             // Map ViewModel to DataContext for XAML bindings like {Binding RoomName}
-            this.WhenAnyValue(v => v.ViewModel).BindTo(this, v => v.DataContext).DisposeWith(d);
+            this.WhenAnyValue<ChatRoomView, ChatRoomViewModel>(nameof(ViewModel)).BindTo(this, v => v.DataContext).DisposeWith(d);
 
             this.Bind(ViewModel, vm => vm.MessageText, v => v.MessageBox.Text).DisposeWith(d);
             this.BindCommand(ViewModel, vm => vm.SendMessage, v => v.SendButton).DisposeWith(d);