Bug 46949 - Can not change binding type form ArrayList to Object
Summary: Can not change binding type form ArrayList to Object
Alias: None
Product: Android
Classification: Xamarin
Component: Bindings ()
Version: 7.0 (C8)
Hardware: PC Mac OS
: --- normal
Target Milestone: ---
Assignee: Atsushi Eno
Depends on:
Reported: 2016-11-14 19:40 UTC by Bill Holmes
Modified: 2017-07-07 21:15 UTC (History)
3 users (show)

Is this bug a regression?: ---
Last known good build:

Solution for testing (10.00 KB, application/zip)
2016-11-14 19:40 UTC, Bill Holmes

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Description Bill Holmes 2016-11-14 19:40:24 UTC
Created attachment 18459 [details]
Solution for testing

Can not change binding type form ArrayList to Object

Build the attached ArrayList.sln.  You will receive errors dealing with converting ArrayList and Object.  

This is a simplified version of a case where we find a base class returns Object yes the derived class returns an ArrayList.  We need to change the return type to an Object to satisfy the abstract base class.
Comment 3 Atsushi Eno 2017-01-05 09:03:21 UTC
This is a blend of limitations, misunderstanding of the binding generator tool, and wrong API design decision.

You can't automatically generate such a code.

Binding generator is not has no human beings behind and cannot automatically guess that the object of what you manually described as "managedReturn" type actually needs casts to the destination target type. You may specify WhateverNamespace.FooBarBaz, instead of Java.Lang.Object, and there is no automatic way to convert to IList<T>, so there are cases that you simply cannot do that.

This could have been avoided if we didn't design the API to generate IList<T> instead of Java.Util collections. But that cannot be changed anymore.
Comment 4 Jon Douglas [MSFT] 2017-07-07 21:15:59 UTC
Marking this bug as RESOLVED ANSWERED due to the comment in https://bugzilla.xamarin.com/show_bug.cgi?id=46949#c3 and the limitations present. If this is still a bug and can be addressed, please feel free to re-open this bug.