c++ - Windows Phone 8.1: C# Callback with IList variable fails to cast to IVector -

i have c# windows phone 8.1 visual studio (2013) project declares interface callback

    public interface icallback     {          /// <summary>         /// child callback must override method , fired when time comes         /// </summary>         /// <param name="files">the resultant files </param>         /// <param name="code">error code</param>          void gotfilelist(filetype type, ilist<fileinfo> files, errorcode code);     } 

i have c++/cx wrapper implements follows:

ref class  callbackimpl sealed : icallback { private:     callbackimpl(){}  public:      virtual void gotfilelist(filetype type, windows::foundation::collections::ivector<object^>^ files, errorcode code); } 

my problem on release build, when c# calls icallback::gotfilelist

_callback.gotfilelist(filetype, result ilist<fileinfo>, errorcode.ec_no_error); 

it throws exception system.invalidcastexception: specified cast not valid. exception refers casting ilist ivector.

debug fine; meaning, can add values internal ilist , call icallback::gotfilelist , ilist values in c++ ivector without problems.

i compared release/debug project properties (in projects: c# core lib, c++/cx wrapper , c++/cx application) , did not find difference can explain exception on release build only.

any ideas?

i found simple answer. since ilist of proprietary data type fileinfo fails cast ivector. changed interface function signature ilist<object> instead of ilist<fileinfo> (and ivector respectively in c++ wrapper), works.
here new code snippet:

public interface icallback {      /// <summary>     /// child callback must override method , fired when time comes     /// </summary>     /// <param name="files">the resultant files </param>     /// <param name="code">error code</param>      void gotfilelist(filetype type, ilist<object> files, errorcode code); } 

c++ wrapper:

ref class  callbackimpl sealed : icallback { private:     callbackimpl(){}  public:      virtual void gotfilelist(filetype type, windows::foundation::collections::ivector<object^>^ files, errorcode code); }