public static void EmitConvert(XamlEmitContextWithLocals <IXamlILEmitter, XamlILNodeEmitResult> context, IXamlLineInfo node, IXamlType what,
                                IXamlType to, Func <bool, IXamlILEmitter> ld)
 {
     if (what.Equals(to))
     {
         ld(false);
     }
     else if (what == XamlPseudoType.Null)
     {
         if (to.IsValueType)
         {
             if (to.GenericTypeDefinition?.Equals(context.Configuration.WellKnownTypes.NullableT) == true)
             {
                 using (var loc = context.GetLocalOfType(to))
                     ld(false)
                     .Pop()
                     .Ldloca(loc.Local)
                     .Emit(OpCodes.Initobj, to)
                     .Ldloc(loc.Local);
             }
             else
             {
                 throw new XamlLoadException("Unable to convert {x:Null} to " + to.GetFqn(), node);
             }
         }
         else
         {
             ld(false);
         }
     }
     else if (what.IsValueType && to.IsValueType)
     {
         if (to.IsNullableOf(what))
         {
             ld(false).Emit(OpCodes.Newobj,
                            to.Constructors.First(c =>
                                                  c.Parameters.Count == 1 && c.Parameters[0].Equals(what)));
         }
         else if (what.IsNullableOf(what))
         {
             ld(true)
             .EmitCall(what.FindMethod(m => m.Name == "get_Value"));
         }
         else
         {
             throw new XamlLoadException(
                       $"Don't know how to convert value type {what.GetFullName()} to value type {to.GetFullName()}",
                       node);
         }
     }
     else if (!to.IsValueType && what.IsValueType)
     {
         if (!to.IsAssignableFrom(what))
         {
             throw new XamlLoadException(
                       $"Don't know how to convert value type {what.GetFullName()} to reference type {to.GetFullName()}",
                       node);
         }
         ld(false).Box(what);
     }
     else if (to.IsValueType && !what.IsValueType)
     {
         if (!(what.Namespace == "System" && what.Name == "Object"))
         {
             throw new XamlLoadException(
                       $"Don't know how to convert reference type {what.GetFullName()} to value type {to.GetFullName()}",
                       node);
         }
         ld(false).Unbox_Any(to);
     }
     else
     {
         if (to.IsAssignableFrom(what))
         {
             // Downcast, always safe
             ld(false);
         }
         else if (what.IsInterface || what.IsAssignableFrom(to))
         {
             // Upcast or cast from interface, might throw InvalidCastException
             ld(false).Emit(OpCodes.Castclass, to);
         }
         else
         {
             // Types are completely unrelated, e. g. string to List<int> conversion attempt
             throw new XamlLoadException(
                       $"Don't know how to convert reference type {what.GetFullName()} to reference type {to.GetFullName()}",
                       node);
         }
     }
 }