[XamlC] use op_implicit where we should (#580)

* [XamlC] (passing) test for 48242

* [XamlC] (failing) test for 48242

* [XamlC] more op_implicit conversions

* additional test

* fix rebase

2 files changed, 19 insertions, 6 deletions

diff --git a/Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs b/Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs
index 397ea526..44678d26 100644
--- a/Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs
+++ b/Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs
@@ -857,6 +857,10 @@ namespace Xamarin.Forms.Build.Tasks
 			// Worst case scenario ? InvalidCastException at runtime
 			if (attached && varValue.VariableType.FullName == "System.Object") 
 				return true;
+			var implicitOperator = varValue.VariableType.GetImplicitOperatorTo(bpTypeRef, module);
+			if (implicitOperator != null)
+				return true;
+
 			return varValue.VariableType.InheritsFromOrImplements(bpTypeRef);
 		}
 
@@ -879,9 +883,17 @@ namespace Xamarin.Forms.Build.Tasks
 				foreach (var instruction in valueNode.PushConvertedValue(context, bpRef, valueNode.PushServiceProvider(context, bpRef:bpRef), true, false))
 					yield return instruction;
 			} else if (elementNode != null) {
-				yield return Instruction.Create(OpCodes.Ldloc, context.Variables [elementNode]);
-				if (context.Variables [elementNode].VariableType.IsValueType)
-					yield return Instruction.Create(OpCodes.Box, context.Variables [elementNode].VariableType);
+				var bpTypeRef = bpRef.GetBindablePropertyType(iXmlLineInfo, module);
+				var varDef = context.Variables[elementNode];
+				var varType = varDef.VariableType;
+				var implicitOperator = varDef.VariableType.GetImplicitOperatorTo(bpTypeRef, module);
+				yield return Instruction.Create(OpCodes.Ldloc, varDef);
+				if (implicitOperator != null) {
+					yield return Instruction.Create(OpCodes.Call, module.Import(implicitOperator));
+					varType = module.Import(bpTypeRef);
+				}
+				if (varType.IsValueType)
+					yield return Instruction.Create(OpCodes.Box, varType);
 			}
 
 			yield return Instruction.Create(OpCodes.Callvirt, module.Import(setValue));
diff --git a/Xamarin.Forms.Build.Tasks/TypeReferenceExtensions.cs b/Xamarin.Forms.Build.Tasks/TypeReferenceExtensions.cs
index f0a6cef7..d0ccbc59 100644
--- a/Xamarin.Forms.Build.Tasks/TypeReferenceExtensions.cs
+++ b/Xamarin.Forms.Build.Tasks/TypeReferenceExtensions.cs
@@ -204,9 +204,10 @@ namespace Xamarin.Forms.Build.Tasks
 		}
 
 		public static MethodReference GetImplicitOperatorTo(this TypeReference fromType, TypeReference toType, ModuleDefinition module)
-		{ 
-			var implicitOperators = fromType.GetMethods(md => md.IsPublic && md.IsStatic && md.IsSpecialName && md.Name == "op_Implicit",
-												module).ToList();
+		{
+			var implicitOperatorsOnFromType = fromType.GetMethods(md => md.IsPublic && md.IsStatic && md.IsSpecialName && md.Name == "op_Implicit", module);
+			var implicitOperatorsOnToType = toType.GetMethods(md => md.IsPublic && md.IsStatic && md.IsSpecialName && md.Name == "op_Implicit", module);
+			var implicitOperators = implicitOperatorsOnFromType.Concat(implicitOperatorsOnToType).ToList();
 			if (implicitOperators.Any()) {
 				foreach (var op in implicitOperators) {
 					var cast = op.Item1;