Don't register controls with parent namescope.

This reverts the changes in #843 because they were causing problems, as described by #2512.

This should however not cause #829 to reappear because since #843 was merged we moved to Portable.Xaml and we're now registering controls with the root namescope in the XAML engine: b4577a1631/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaXamlObjectWriter.cs (L67)

Fixes #2512

src/Avalonia.Controls/Primitives/TemplatedControl.cs

@@ -357,7 +357,7 @@ namespace Avalonia.Controls.Primitives
 
             if (control.TemplatedParent == this)
             {
-                foreach (IControl child in control.GetVisualChildren())
+                foreach (IControl child in control.GetLogicalChildren())
                 {
                     RegisterNames(child, nameScope);
                 }

src/Avalonia.Styling/StyledElement.cs

@@ -677,23 +677,6 @@ namespace Avalonia
             if (Name != null)
             {
                 _nameScope?.Register(Name, this);
-
-                var visualParent = Parent as StyledElement;
-
-                if (this is INameScope && visualParent != null)
-                {
-                    // If we have e.g. a named UserControl in a window then we want that control
-                    // to be findable by name from the Window, so register with both name scopes.
-                    // This differs from WPF's behavior in that XAML manually registers controls 
-                    // with name scopes based on the XAML file in which the name attribute appears,
-                    // but we're trying to avoid XAML magic in Avalonia in order to made code-
-                    // created UIs easy. This will cause problems if a UserControl declares a name
-                    // in its XAML and that control is included multiple times in a parent control
-                    // (as the name will be duplicated), however at the moment I'm fine with saying
-                    // "don't do that".
-                    var parentNameScope = NameScope.FindNameScope(visualParent);
-                    parentNameScope?.Register(Name, this);
-                }
             }
         }
 

tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs

@@ -197,6 +197,22 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
             Assert.Equal("Foo", button.Content);
         }
 
+        [Fact]
+        public void Named_UserControl_Is_Added_To_Parent_NameScope()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var xaml = @"
+<Window xmlns='https://github.com/avaloniaui'>
+    <UserControl Name='foo'/>
+</Window>";
+
+                var control = AvaloniaXamlLoader.Parse<Window>(xaml);
+
+                Assert.NotNull(control.FindControl<UserControl>("foo"));
+            }
+        }
+
         [Fact]
         public void Direct_Content_In_ItemsControl_Is_Operational()
         {

tests/Avalonia.Styling.UnitTests/StyledElementTests.cs

@@ -273,13 +273,10 @@ namespace Avalonia.Styling.UnitTests
                 var root = new TestRoot();
                 var child = new Border();
 
-                ((ISupportInitialize)child).BeginInit();
+                child.BeginInit();
                 root.Child = child;
                 child.Name = "foo";
-                Assert.Null(root.FindControl<Border>("foo"));
-                ((ISupportInitialize)child).EndInit();
-
-                Assert.Same(root.FindControl<Border>("foo"), child);
+                child.EndInit();
             }
         }
 

tests/Avalonia.Styling.UnitTests/StyledElementTests_NameScope.cs

@@ -1,11 +1,6 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using System;
-using Avalonia.Controls.Presenters;
-using Avalonia.Controls.Templates;
-using Avalonia.Rendering;
-using Avalonia.Styling;
 using Avalonia.UnitTests;
 using Xunit;
 
@@ -70,23 +65,5 @@ namespace Avalonia.Controls.UnitTests
 
             Assert.Null(NameScope.GetNameScope((StyledElement)root.Presenter).Find("foo"));
         }
-
-        [Fact]
-        public void Control_That_Is_NameScope_Should_Register_With_Parent_NameScope()
-        {
-            UserControl userControl;
-            var root = new TestTemplatedRoot
-            {
-                Content = userControl = new UserControl
-                {
-                    Name = "foo",
-                }
-            };
-
-            root.ApplyTemplate();
-
-            Assert.Same(userControl, root.FindControl<UserControl>("foo"));
-            Assert.Same(userControl, userControl.FindControl<UserControl>("foo"));
-        }
     }
 }