[XamlC] Port #1035 to comiled bindings (#4454)

And share the TryConvert implementation to avoid future diverges

Xamarin.Forms.Core/BindingExpression.cs

@@ -164,7 +164,7 @@ namespace Xamarin.Forms
 				else
 					value = Binding.FallbackValue ?? property.DefaultValue;
 
-				if (!TryConvert(part, ref value, property.ReturnType, true))
+				if (!TryConvert(ref value, property, property.ReturnType, true))
 				{
 					Log.Warning("Binding", "{0} can not be converted to type '{1}'", value, property.ReturnType);
 					return;
@@ -176,7 +176,7 @@ namespace Xamarin.Forms
 			{
 				object value = Binding.GetTargetValue(target.GetValue(property), part.SetterType);
 
-				if (!TryConvert(part, ref value, part.SetterType, false))
+				if (!TryConvert(ref value, property, part.SetterType, false))
 				{
 					Log.Warning("Binding", "{0} can not be converted to type '{1}'", value, part.SetterType);
 					return;
@@ -415,16 +415,15 @@ namespace Xamarin.Forms
 		}
 		static Type[] DecimalTypes = new[] { typeof(float), typeof(decimal), typeof(double) };
 
-		bool TryConvert(BindingExpressionPart part, ref object value, Type convertTo, bool toTarget)
+		internal static bool TryConvert(ref object value, BindableProperty targetProperty, Type convertTo, bool toTarget)
 		{
 			if (value == null)
 				return true;
-			if ((toTarget && _targetProperty.TryConvert(ref value)) || (!toTarget && convertTo.IsInstanceOfType(value)))
+			if ((toTarget && targetProperty.TryConvert(ref value)) || (!toTarget && convertTo.IsInstanceOfType(value)))
 				return true;
 
 			object original = value;
-			try
-			{
+			try {
 				var stringValue = value as string ?? string.Empty;
 				// see: https://bugzilla.xamarin.com/show_bug.cgi?id=32871
 				// do not canonicalize "*.[.]"; "1." should not update bound BindableProperty
@@ -442,18 +441,7 @@ namespace Xamarin.Forms
 				value = Convert.ChangeType(value, convertTo, CultureInfo.InvariantCulture);
 				return true;
 			}
-			catch (InvalidCastException)
-			{
-				value = original;
-				return false;
-			}
-			catch (FormatException)
-			{
-				value = original;
-				return false;
-			}
-			catch (OverflowException)
-			{
+			catch (Exception ex) when (ex is InvalidCastException || ex is FormatException || ex is OverflowException) {
 				value = original;
 				return false;
 			}

Xamarin.Forms.Core/TypedBinding.cs

@@ -203,7 +203,7 @@ namespace Xamarin.Forms.Internals
 					} catch (Exception ex) when (ex is NullReferenceException || ex is KeyNotFoundException) {
 					}
 				}
-				if (!TryConvert(ref value, property, property.ReturnType, true)) {
+				if (!BindingExpression.TryConvert(ref value, property, property.ReturnType, true)) {
 					Log.Warning("Binding", "{0} can not be converted to type '{1}'", value, property.ReturnType);
 					return;
 				}
@@ -214,7 +214,7 @@ namespace Xamarin.Forms.Internals
 			var needsSetter = (mode == BindingMode.TwoWay && fromTarget) || mode == BindingMode.OneWayToSource;
 			if (needsSetter && _setter != null && isTSource) {
 				var value = GetTargetValue(target.GetValue(property), typeof(TProperty));
-				if (!TryConvert(ref value, property, typeof(TProperty), false)) {
+				if (!BindingExpression.TryConvert(ref value, property, typeof(TProperty), false)) {
 					Log.Warning("Binding", "{0} can not be converted to type '{1}'", value, typeof(TProperty));
 					return;
 				}
@@ -222,23 +222,6 @@ namespace Xamarin.Forms.Internals
 			}
 		}
 
-		static bool TryConvert(ref object value, BindableProperty targetProperty, Type convertTo, bool toTarget)
-		{
-			if (value == null)
-				return true;
-			if ((toTarget && targetProperty.TryConvert(ref value)) || (!toTarget && convertTo.IsInstanceOfType(value)))
-				return true;
-
-			object original = value;
-			try {
-				value = Convert.ChangeType(value, convertTo, CultureInfo.InvariantCulture);
-				return true;
-			} catch (Exception ex ) when (ex is InvalidCastException || ex is FormatException||ex is OverflowException) {
-				value = original;
-				return false;
-			}
-		}
-
 		class PropertyChangedProxy
 		{
 			public Func<TSource, object> PartGetter { get; }