Do not defer resources with name registration on them (#14703)

* Do not defer resources with name registration on them

* Fix transformers order

* Make NameScopeRegistrationVisitor usage more clear

* Reuse NameScopeRegistrationVisitor

* Make NameScopeRegistrationVisitor usage more intuitive

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/AvaloniaXamlIlCompiler.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
@@ -29,6 +30,10 @@ void InsertAfter<T>(params IXamlAstTransformer[] t)
             void InsertBefore<T>(params IXamlAstTransformer[] t)
                 => Transformers.InsertRange(Transformers.FindIndex(x => x is T), t);
 
+            void InsertBeforeMany(Type[] types, params IXamlAstTransformer[] t)
+                => Transformers.InsertRange(types
+                    .Select(type => Transformers.FindIndex(x => x.GetType() == type))
+                    .Min(), t);
 
             // Before everything else
 
@@ -69,10 +74,6 @@ void InsertBefore<T>(params IXamlAstTransformer[] t)
             InsertAfter<TypeReferenceResolver>(
                 new XDataTypeTransformer());
 
-            InsertBefore<DeferredContentTransformer>(
-                new AvaloniaXamlIlDeferredResourceTransformer()
-            );
-
             // After everything else
             InsertBefore<NewObjectTransformer>(
                 new AddNameScopeRegistration(),
@@ -82,6 +83,9 @@ void InsertBefore<T>(params IXamlAstTransformer[] t)
                 new AvaloniaXamlIlCompiledBindingsMetadataRemover()
                 );
 
+            InsertBeforeMany(new [] { typeof(DeferredContentTransformer), typeof(AvaloniaXamlIlCompiledBindingsMetadataRemover) },
+                new AvaloniaXamlIlDeferredResourceTransformer());
+
             Transformers.Add(new AvaloniaXamlIlControlTemplatePriorityTransformer());
             Transformers.Add(new AvaloniaXamlIlMetadataRemover());
             Transformers.Add(new AvaloniaXamlIlRootObjectScope());

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlControlTemplatePartsChecker.cs

@@ -2,6 +2,7 @@
 
 using System.Collections.Generic;
 using System.Linq;
+using Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Visitors;
 using XamlX;
 using XamlX.Ast;
 using XamlX.Transform;
@@ -25,7 +26,7 @@ public IXamlAstNode Transform(AstTransformationContext context, IXamlAstNode nod
         if (templateParts.Count == 0)
             return node;
 
-        var visitor = new TemplatePartVisitor();
+        var visitor = new NameScopeRegistrationVisitor();
         node.VisitChildren(visitor);
 
         foreach (var pair in templateParts)
@@ -99,40 +100,4 @@ public IXamlAstNode Transform(AstTransformationContext context, IXamlAstNode nod
 
         return dictionary;
     }
-
-    private class TemplatePartVisitor : Dictionary<string, (IXamlType type, IXamlLineInfo line)>, IXamlAstVisitor
-    {
-        private int _metadataScopeLevel = 0;
-        private Stack<IXamlAstNode> _parents = new();
-
-        IXamlAstNode IXamlAstVisitor.Visit(IXamlAstNode node)
-        {
-            if (_metadataScopeLevel == 1
-                && node is AvaloniaNameScopeRegistrationXamlIlNode nameScopeRegistration
-                && nameScopeRegistration.Name is XamlAstTextNode textNode)
-            {
-                this[textNode.Text] = (nameScopeRegistration.TargetType, textNode);
-            }
-
-            return node;
-        }
-
-        void IXamlAstVisitor.Push(IXamlAstNode node)
-        {
-            _parents.Push(node);
-            if (node is NestedScopeMetadataNode)
-            {
-                _metadataScopeLevel++;
-            }
-        }
-
-        void IXamlAstVisitor.Pop()
-        {
-            var oldParent = _parents.Pop();
-            if (oldParent is NestedScopeMetadataNode)
-            {
-                _metadataScopeLevel--;
-            }
-        }
-    } 
 }

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDeferredResourceTransformer.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Visitors;
 using XamlX.Ast;
 using XamlX.Emit;
 using XamlX.IL;
@@ -16,20 +17,19 @@ public IXamlAstNode Transform(AstTransformationContext context, IXamlAstNode nod
             if (!(node is XamlPropertyAssignmentNode pa) || pa.Values.Count != 2)
                 return node;
 
-            if (!ShouldBeDeferred(pa.Values[1]))
-                return node;
-
             var types = context.GetAvaloniaTypes();
 
-            if (pa.Property.DeclaringType == types.ResourceDictionary && pa.Property.Name == "Content")
+            if (pa.Property.DeclaringType == types.ResourceDictionary && pa.Property.Name == "Content"
+                && ShouldBeDeferred(pa.Values[1]))
             {
                 pa.Values[1] = new XamlDeferredContentNode(pa.Values[1], types.XamlIlTypes.Object, context.Configuration);
                 pa.PossibleSetters = new List<IXamlPropertySetter>
                 {
                     new XamlDirectCallPropertySetter(types.ResourceDictionaryDeferredAdd),
                 };
             }
-            else if (pa.Property.Name == "Resources" && pa.Property.Getter.ReturnType.Equals(types.IResourceDictionary))
+            else if (pa.Property.Name == "Resources" && pa.Property.Getter.ReturnType.Equals(types.IResourceDictionary)
+                && ShouldBeDeferred(pa.Values[1]))
             {
                 pa.Values[1] = new XamlDeferredContentNode(pa.Values[1], types.XamlIlTypes.Object, context.Configuration);
                 pa.PossibleSetters = new List<IXamlPropertySetter>
@@ -45,7 +45,23 @@ private static bool ShouldBeDeferred(IXamlAstValueNode node)
         {
             // XAML compiler is currently strict about value types, allowing them to be created only through converters.
             // At the moment it should be safe to not defer structs.
-            return !node.Type.GetClrType().IsValueType;
+            if (node.Type.GetClrType().IsValueType)
+            {
+                return false;
+            }
+
+            // Do not defer resources, if it has any x:Name registration, as it cannot be delayed.
+            // This visitor will count x:Name registrations, ignoring nested NestedScopeMetadataNode scopes.
+            // We set target scope level to 0, assuming that this resource node is a scope of itself.
+            var nameRegistrationsVisitor = new NameScopeRegistrationVisitor(
+                targetMetadataScopeLevel: 0);
+            node.Visit(nameRegistrationsVisitor);
+            if (nameRegistrationsVisitor.Count > 0)
+            {
+                return false;
+            }
+
+            return true;
         }
 
         class AdderSetter : IXamlILOptimizedEmitablePropertySetter, IEquatable<AdderSetter>

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Visitors/NameScopeRegistrationVisitor.cs

@@ -0,0 +1,51 @@
+using System.Collections.Generic;
+using Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers;
+using XamlX.Ast;
+using XamlX.TypeSystem;
+
+namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Visitors;
+
+internal class NameScopeRegistrationVisitor : Dictionary<string, (IXamlType type, IXamlLineInfo line)>, IXamlAstVisitor
+{
+    private readonly int _targetMetadataScopeLevel;
+    private readonly Stack<IXamlAstNode> _parents = new();
+    private int _metadataScopeLevel;
+
+    public NameScopeRegistrationVisitor(
+        int initialMetadataScopeLevel = 0,
+        int targetMetadataScopeLevel = 1)
+    {
+        _metadataScopeLevel = initialMetadataScopeLevel;
+        _targetMetadataScopeLevel = targetMetadataScopeLevel;
+    }
+
+    IXamlAstNode IXamlAstVisitor.Visit(IXamlAstNode node)
+    {
+        if (_metadataScopeLevel == _targetMetadataScopeLevel
+            && node is AvaloniaNameScopeRegistrationXamlIlNode nameScopeRegistration
+            && nameScopeRegistration.Name is XamlAstTextNode textNode)
+        {
+            this[textNode.Text] = (nameScopeRegistration.TargetType, textNode);
+        }
+
+        return node;
+    }
+
+    void IXamlAstVisitor.Push(IXamlAstNode node)
+    {
+        _parents.Push(node);
+        if (node is NestedScopeMetadataNode)
+        {
+            _metadataScopeLevel++;
+        }
+    }
+
+    void IXamlAstVisitor.Pop()
+    {
+        var oldParent = _parents.Pop();
+        if (oldParent is NestedScopeMetadataNode)
+        {
+            _metadataScopeLevel--;
+        }
+    }
+}

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

@@ -125,6 +125,28 @@ public void Item_Is_Added_To_Window_Resources_As_Deferred()
             }
         }
 
+        [Fact]
+        public void Named_Item_Is_Added_To_Resources_Should_Not_Be_Deferred()
+        {
+            // Since Named items can be accessed through the NameScope, we cannot delay their initialization.
+            using (StyledWindow())
+            {
+                var xaml = @"
+<Window xmlns='https://github.com/avaloniaui'
+        xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
+    <Window.Resources>
+        <Panel x:Name='MyPanel' x:Key='MyPanel' />
+    </Window.Resources>
+</Window>";
+                var window = (Window)AvaloniaRuntimeXamlLoader.Load(xaml);
+                var resources = (ResourceDictionary)window.Resources;
+
+                Assert.False(resources.ContainsDeferredKey("MyPanel"));
+                Assert.True(resources.ContainsKey("MyPanel"));
+                Assert.IsType<Panel>(window.Find<Panel>("MyPanel"));
+            }
+        }
+
         [Fact]
         public void Item_Is_Added_To_Window_MergedDictionaries_As_Deferred()
         {