Use EnabledDataValidation from metadata.

`DirectProperty` stored a `EnabledDataValidation`  flag in its metadata but also had an `IsDataValidationEnabled` property in `DirectPropertyBase` which was the one used by `AvaloniaObject`. Use the version from metadata so that it can be overridden and remove the flag from `DirectPropertyBase`.

src/Avalonia.Base/AvaloniaObject.cs

@@ -806,7 +806,9 @@ namespace Avalonia
                     break;
             }
 
-            if (p.IsDataValidationEnabled)
+            var metadata = p.GetMetadata(GetType());
+
+            if (metadata.EnableDataValidation == true)
             {
                 UpdateDataValidation(property, value);
             }

src/Avalonia.Base/AvaloniaProperty.cs

@@ -369,14 +369,14 @@ namespace Avalonia
 
             var metadata = new DirectPropertyMetadata<TValue>(
                 unsetValue: unsetValue,
-                defaultBindingMode: defaultBindingMode);
+                defaultBindingMode: defaultBindingMode,
+                enableDataValidation: enableDataValidation);
 
             var result = new DirectProperty<TOwner, TValue>(
                 name,
                 getter,
                 setter,
-                metadata,
-                enableDataValidation);
+                metadata);
             AvaloniaPropertyRegistry.Instance.Register(typeof(TOwner), result);
             return result;
         }

src/Avalonia.Base/DirectProperty.cs

@@ -23,16 +23,12 @@ namespace Avalonia
         /// <param name="getter">Gets the current value of the property.</param>
         /// <param name="setter">Sets the value of the property. May be null.</param>
         /// <param name="metadata">The property metadata.</param>
-        /// <param name="enableDataValidation">
-        /// Whether the property is interested in data validation.
-        /// </param>
         public DirectProperty(
             string name,
             Func<TOwner, TValue> getter,
             Action<TOwner, TValue> setter,
-            DirectPropertyMetadata<TValue> metadata,
-            bool enableDataValidation)
-            : base(name, typeof(TOwner), metadata, enableDataValidation)
+            DirectPropertyMetadata<TValue> metadata)
+            : base(name, typeof(TOwner), metadata)
         {
             Contract.Requires<ArgumentNullException>(getter != null);
 
@@ -47,16 +43,12 @@ namespace Avalonia
         /// <param name="getter">Gets the current value of the property.</param>
         /// <param name="setter">Sets the value of the property. May be null.</param>
         /// <param name="metadata">Optional overridden metadata.</param>
-        /// <param name="enableDataValidation">
-        /// Whether the property is interested in data validation.
-        /// </param>
         private DirectProperty(
             DirectPropertyBase<TValue> source,
             Func<TOwner, TValue> getter,
             Action<TOwner, TValue> setter,
-            DirectPropertyMetadata<TValue> metadata,
-            bool enableDataValidation)
-            : base(source, typeof(TOwner), metadata, enableDataValidation)
+            DirectPropertyMetadata<TValue> metadata)
+            : base(source, typeof(TOwner), metadata)
         {
             Contract.Requires<ArgumentNullException>(getter != null);
 
@@ -107,7 +99,8 @@ namespace Avalonia
         {
             var metadata = new DirectPropertyMetadata<TValue>(
                 unsetValue: unsetValue,
-                defaultBindingMode: defaultBindingMode);
+                defaultBindingMode: defaultBindingMode,
+                enableDataValidation: enableDataValidation);
 
             metadata.Merge(GetMetadata<TOwner>(), this);
 
@@ -115,8 +108,7 @@ namespace Avalonia
                 (DirectPropertyBase<TValue>)this,
                 getter,
                 setter,
-                metadata,
-                enableDataValidation);
+                metadata);
 
             AvaloniaPropertyRegistry.Instance.Register(typeof(TNewOwner), result);
             return result;
@@ -155,8 +147,7 @@ namespace Avalonia
                 this,
                 getter,
                 setter,
-                metadata,
-                enableDataValidation);
+                metadata);
 
             AvaloniaPropertyRegistry.Instance.Register(typeof(TNewOwner), result);
             return result;

src/Avalonia.Base/DirectPropertyBase.cs

@@ -23,17 +23,12 @@ namespace Avalonia
         /// <param name="name">The name of the property.</param>
         /// <param name="ownerType">The type of the class that registers the property.</param>
         /// <param name="metadata">The property metadata.</param>
-        /// <param name="enableDataValidation">
-        /// Whether the property is interested in data validation.
-        /// </param>
         protected DirectPropertyBase(
             string name,
             Type ownerType,
-            PropertyMetadata metadata,
-            bool enableDataValidation)
+            PropertyMetadata metadata)
             : base(name, ownerType, metadata)
         {
-            IsDataValidationEnabled = enableDataValidation;
         }
 
         /// <summary>
@@ -42,17 +37,12 @@ namespace Avalonia
         /// <param name="source">The property to copy.</param>
         /// <param name="ownerType">The new owner type.</param>
         /// <param name="metadata">Optional overridden metadata.</param>
-        /// <param name="enableDataValidation">
-        /// Whether the property is interested in data validation.
-        /// </param>
         protected DirectPropertyBase(
             AvaloniaProperty source,
             Type ownerType,
-            PropertyMetadata metadata,
-            bool enableDataValidation)
+            PropertyMetadata metadata)
             : base(source, ownerType, metadata)
         {
-            IsDataValidationEnabled = enableDataValidation;
         }
 
         /// <summary>
@@ -60,11 +50,6 @@ namespace Avalonia
         /// </summary>
         public abstract Type Owner { get; }
 
-        /// <summary>
-        /// Gets a value that indicates whether data validation is enabled for the property.
-        /// </summary>
-        public bool IsDataValidationEnabled { get; }
-
         /// <summary>
         /// Gets the value of the property on the instance.
         /// </summary>

tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Direct.cs

@@ -547,8 +547,7 @@ namespace Avalonia.Base.UnitTests
                 "foo",
                 o => "foo",
                 null,
-                new DirectPropertyMetadata<string>(defaultBindingMode: BindingMode.TwoWay),
-                false);
+                new DirectPropertyMetadata<string>(defaultBindingMode: BindingMode.TwoWay));
             var bar = foo.AddOwner<Class2>(o => "bar");
 
             Assert.Equal(BindingMode.TwoWay, bar.GetMetadata<Class1>().DefaultBindingMode);
@@ -562,8 +561,7 @@ namespace Avalonia.Base.UnitTests
                 "foo",
                 o => "foo",
                 null,
-                new DirectPropertyMetadata<string>(defaultBindingMode: BindingMode.TwoWay),
-                false);
+                new DirectPropertyMetadata<string>(defaultBindingMode: BindingMode.TwoWay));
             var bar = foo.AddOwner<Class2>(o => "bar", defaultBindingMode: BindingMode.OneWayToSource);
 
             Assert.Equal(BindingMode.TwoWay, bar.GetMetadata<Class1>().DefaultBindingMode);

tests/Avalonia.Base.UnitTests/DirectPropertyTests.cs

@@ -11,8 +11,7 @@ namespace Avalonia.Base.UnitTests
                 "test", 
                 o => null, 
                 null,
-                new DirectPropertyMetadata<string>(),
-                false);
+                new DirectPropertyMetadata<string>());
 
             Assert.True(target.IsDirect);
         }