fix: DataContext is wrongly propagated to all DependencyObject when s…

…et into a DependencyProperty

This might drives to invalid DataContext changes when an element only wants to keep a reference on a parent.
As the propagation is expected on almost all DP declared by the Framework, the inheritance is enabled by default for those properties (when using FrameworkPropertyMetadata), and disabled for properties defined in application (PropertyMetadata)

src/Uno.UI.Tests/DependencyProperty/Given_DependencyProperty.DataContext.cs

@@ -199,6 +199,38 @@ public void When_DataContext_Inherited_And_Parent_Changed()
 			Assert.AreEqual(42, SUT.DataContext);
 
 		}
+
+		[TestMethod]
+		public void When_DataContext_Inherited_And_Child_Removed()
+		{
+			var SUT = new MyControl();
+
+			var independentChild = new MyControl();
+			var parent = new Grid
+			{
+				Children = { independentChild, SUT },
+				DataContext = 42
+			};
+
+			// And here is the trick: the SUT does have a reference to the child
+			SUT.InnerControl = independentChild;
+
+			int parentCtxChanged = 0, childCtxChanged = 0, SUTCtxChanged = 0;
+			parent.RegisterPropertyChangedCallback(Control.DataContextProperty, (snd, dp) => parentCtxChanged++);
+			independentChild.RegisterPropertyChangedCallback(Control.DataContextProperty, (snd, dp) => childCtxChanged++);
+			SUT.RegisterPropertyChangedCallback(Control.DataContextProperty, (snd, dp) => SUTCtxChanged++);
+
+			Assert.AreEqual(42, SUT.DataContext);
+
+			// And here the issue: when we remove the SUT from the parent,
+			// it will propagate to the independentChild the DataContext change ... while it should not!
+			parent.Children.Remove(SUT);
+
+			Assert.AreEqual(null, SUT.DataContext);
+			Assert.AreEqual(0, parentCtxChanged);
+			Assert.AreEqual(1, SUTCtxChanged);
+			Assert.AreEqual(0, childCtxChanged);
+		}
 	}
 
 	public partial class MyBasicListType : DependencyObject
@@ -264,6 +296,18 @@ private void OnInnerObjectChanged(DependencyPropertyChangedEventArgs e)
 		}
 
 		#endregion
+	}
 
+	public partial class MyControl : Control
+	{
+		// Just a standard DP defined by a project / third party component
+		public static readonly DependencyProperty InnerControlProperty = DependencyProperty.Register(
+			"InnerControl", typeof(MyControl), typeof(MyControl), new PropertyMetadata(default(MyControl)));
+
+		public MyControl InnerControl
+		{
+			get { return (MyControl)GetValue(InnerControlProperty); }
+			set { SetValue(InnerControlProperty, value); }
+		}
 	}
 }

src/Uno.UI/UI/Xaml/DependencyObjectStore.Binder.cs

@@ -494,7 +494,7 @@ private void OnDependencyPropertyChanged(DependencyPropertyDetails propertyDetai
 
 			var (hasValueInherits, hasValueDoesNotInherit) = GetPropertyInheritanceConfiguration(propertyDetails);
 
-			if (!hasValueDoesNotInherit && (hasValueInherits || propertyDetails.Property.HasAutoDataContextInherit))
+			if (!hasValueDoesNotInherit && hasValueInherits)
 			{
 				if(args.NewValue is IDependencyObjectStoreProvider provider)
 				{

src/Uno.UI/UI/Xaml/FrameworkPropertyMetadata.cs

@@ -31,7 +31,7 @@ object defaultValue
 			FrameworkPropertyMetadataOptions options
 		) : base(defaultValue)
 		{
-			Options = options;
+			Options = options.WithDefault();
 		}
 
 		public FrameworkPropertyMetadata(
@@ -40,7 +40,7 @@ FrameworkPropertyMetadataOptions options
 			PropertyChangedCallback propertyChangedCallback
 		) : base(defaultValue, propertyChangedCallback)
 		{
-			Options = options;
+			Options = options.WithDefault();
 		}
 
 		internal FrameworkPropertyMetadata(
@@ -50,7 +50,7 @@ PropertyChangedCallback propertyChangedCallback
 			BackingFieldUpdateCallback backingFieldUpdateCallback
 		) : base(defaultValue, propertyChangedCallback, backingFieldUpdateCallback)
 		{
-			Options = options;
+			Options = options.WithDefault();
 		}
 
 		internal FrameworkPropertyMetadata(
@@ -66,7 +66,7 @@ BackingFieldUpdateCallback backingFieldUpdateCallback
 			BackingFieldUpdateCallback backingFieldUpdateCallback
 		) : base(defaultValue, null, backingFieldUpdateCallback)
 		{
-			Options = options;
+			Options = options.WithDefault();
 		}
 
 		internal FrameworkPropertyMetadata(
@@ -76,7 +76,7 @@ BackingFieldUpdateCallback backingFieldUpdateCallback
 			CoerceValueCallback coerceValueCallback
 		) : base(defaultValue, propertyChangedCallback, coerceValueCallback, null)
 		{
-			Options = options;
+			Options = options.WithDefault();
 		}
 
 		internal FrameworkPropertyMetadata(
@@ -87,7 +87,7 @@ CoerceValueCallback coerceValueCallback
 			BackingFieldUpdateCallback backingFieldUpdateCallback
 		) : base(defaultValue, propertyChangedCallback, coerceValueCallback, backingFieldUpdateCallback)
 		{
-			Options = options;
+			Options = options.WithDefault();
 		}
 
 		internal FrameworkPropertyMetadata(
@@ -128,11 +128,11 @@ CoerceValueCallback coerceValueCallback
 			UpdateSourceTrigger defaultUpdateSourceTrigger
 		) : base(defaultValue, propertyChangedCallback, coerceValueCallback, null)
 		{
-			Options = options;
+			Options = options.WithDefault();
 			DefaultUpdateSourceTrigger = defaultUpdateSourceTrigger;
 		}
-		
-		public FrameworkPropertyMetadataOptions Options { get; set; }
+
+		public FrameworkPropertyMetadataOptions Options { get; set; } = FrameworkPropertyMetadataOptions.Default;
 
 		public UpdateSourceTrigger DefaultUpdateSourceTrigger
 		{

src/Uno.UI/UI/Xaml/FrameworkPropertyMetadataOptions.cs

@@ -18,10 +18,6 @@ public enum FrameworkPropertyMetadataOptions
 		/// <summary>
 		/// Specifies that this property's value or values will inherit the DataContext of its or their parent.
 		/// </summary>
-		/// <remarks>
-		/// This property is ignored and ValueInheritsDataContext is interpreted as true for properties of type <see cref="DependencyObject"/>.
-		/// Use ValueDoesNotInheritDataContext to prevent this default behavior.
-		/// </remarks>
 		ValueInheritsDataContext = 1 << 1,
 
 		/// <summary>
@@ -33,7 +29,8 @@ public enum FrameworkPropertyMetadataOptions
 		/// Prevents this property's value or values from inheriting the DataContext of its or their parent.
 		/// </summary>
 		/// <remarks>
-		/// This is useful for properties of type <see cref="DependencyObject"/> for which ValueInheritsDataContext is always interpreted as true.
+		/// This is useful for framework properties of type <see cref="DependencyObject"/> for which ValueInheritsDataContext is enabled by default
+		/// (cf. <see cref="Default"/>).
 		/// </remarks>
 		ValueDoesNotInheritDataContext = 1 << 3,
 
@@ -62,5 +59,12 @@ public enum FrameworkPropertyMetadataOptions
 		/// </summary>
 		AffectsRender = 1 << 8,
 
+		/// <summary>
+		/// The default options set when creating a <see cref="FrameworkPropertyMetadata"/>.
+		/// </summary>
+		/// <remarks>
+		/// By default all DP declared by the framework will inherit the DataContext while DP declared by application won't.
+		/// </remarks>
+		Default = ValueInheritsDataContext,
 	}
 }

src/Uno.UI/UI/Xaml/FrameworkPropertyMetadataOptionsExtensions.cs

@@ -67,5 +67,12 @@ public static bool HasLogicalChild(this FrameworkPropertyMetadataOptions options
 		public static bool HasWeakStorage(this FrameworkPropertyMetadataOptions options)
 			=> (options & FrameworkPropertyMetadataOptions.WeakStorage) != 0;
 
+		/// <summary>
+		/// Defines the default flags for a FrameworkPropertyMetadata if not explicitly opt-out (cf. <see cref="FrameworkPropertyMetadataOptions.Default"/>).
+		/// </summary>
+		internal static FrameworkPropertyMetadataOptions WithDefault(this FrameworkPropertyMetadataOptions options)
+			=> (options & (FrameworkPropertyMetadataOptions.ValueDoesNotInheritDataContext | FrameworkPropertyMetadataOptions.ValueInheritsDataContext)) == default
+				? options | FrameworkPropertyMetadataOptions.ValueInheritsDataContext // == FrameworkPropertyMetadataOptions.Default
+				: options;
 	}
 }