Add AvaloniaListAttribute

src/Avalonia.Base/Metadata/AvaloniaListAttribute.cs

@@ -0,0 +1,23 @@
+using System;
+
+namespace Avalonia.Metadata;
+
+/// <summary>
+/// Defines how compiler should split avalonia list string value before parsing individual items.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = true)]
+public sealed class AvaloniaListAttribute : Attribute
+{
+    /// <summary>
+    /// Separator used to split input string.
+    /// Default value is ','.
+    /// </summary>
+    public string[]? Separators { get; init; }
+
+    /// <summary>
+    /// Split options used to split input string.
+    /// Default value is RemoveEmptyEntries with TrimEntries.
+    /// </summary>
+    // StringSplitOptions.TrimEntries = 2, but only on net6 target.
+    public StringSplitOptions SplitOptions { get; init; } = StringSplitOptions.RemoveEmptyEntries | (StringSplitOptions)2;
+}

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

@@ -337,6 +337,20 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
                     var separators = new[] { "," };
                     var splitOptions = StringSplitOptions.RemoveEmptyEntries | trimOption;
 
+                    var attribute = type.GetAllCustomAttributes().FirstOrDefault(a => a.Type == types.AvaloniaListAttribute);
+                    if (attribute is not null)
+                    {
+                        if (attribute.Properties.TryGetValue("Separators", out var separatorsArray))
+                        {
+                            separators = ((Array)separatorsArray)?.OfType<string>().ToArray();
+                        }
+
+                        if (attribute.Properties.TryGetValue("SplitOptions", out var splitOptionsObj))
+                        {
+                            splitOptions = (StringSplitOptions)splitOptionsObj;
+                        }
+                    }
+
                     items = text.Split(separators, splitOptions ^ trimOption);
                     // Compiler targets netstandard, so we need to emulate StringSplitOptions.TrimEntries, if it was requested.
                     if (splitOptions.HasFlag(trimOption))

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

@@ -33,6 +33,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         public IXamlType InheritDataTypeFromItemsAttribute { get; }
         public IXamlType MarkupExtensionOptionAttribute { get; }
         public IXamlType MarkupExtensionDefaultOptionAttribute { get; }
+        public IXamlType AvaloniaListAttribute { get; }
         public IXamlType AvaloniaList { get; }
         public IXamlType OnExtensionType { get; }
         public IXamlType UnsetValueType { get; }
@@ -143,6 +144,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             InheritDataTypeFromItemsAttribute = cfg.TypeSystem.GetType("Avalonia.Metadata.InheritDataTypeFromItemsAttribute");
             MarkupExtensionOptionAttribute = cfg.TypeSystem.GetType("Avalonia.Metadata.MarkupExtensionOptionAttribute");
             MarkupExtensionDefaultOptionAttribute = cfg.TypeSystem.GetType("Avalonia.Metadata.MarkupExtensionDefaultOptionAttribute");
+            AvaloniaListAttribute = cfg.TypeSystem.GetType("Avalonia.Metadata.AvaloniaListAttribute");
             AvaloniaList = cfg.TypeSystem.GetType("Avalonia.Collections.AvaloniaList`1");
             OnExtensionType = cfg.TypeSystem.GetType("Avalonia.Markup.Xaml.MarkupExtensions.On");
             AvaloniaObjectBindMethod = AvaloniaObjectExtensions.FindMethod("Bind", IDisposable, false, AvaloniaObject,

src/Markup/Avalonia.Markup.Xaml.Loader/xamlil.github

@@ -1 +1 @@
-Subproject commit 5d1025f30d0ed6d8f419d82959c148276301f393
+Subproject commit e5254eb1b2017f78a92acd466c8fa1e47401056b