Bug#842464: alice: warns when used (Cpanel::JSON::XS vs. JSON::PP ?)

[Niko Tyni]

Package: alice
Version: 0.19-1
Severity: minor
User: debian-perl at lists.debian.org
Usertags: autopkgtest

The main module shipped in this package, App::Alice, recently started
issuing warnings when used.

  % perl -we 'use App::Alice'
  Subroutine JSON::PP::Boolean::(++ redefined at /usr/share/perl/5.24/overload.pm line 50.
  Subroutine JSON::PP::Boolean::(0+ redefined at /usr/share/perl/5.24/overload.pm line 50.
  Subroutine JSON::PP::Boolean::(-- redefined at /usr/share/perl/5.24/overload.pm line 50.
  
This only happens with --no-install-recommends; when libjson-xs-perl is
present (as recommended by libjson-perl), the warning goes away.

The change that triggered it on ci.debian.net seems to be libplack-perl
introducing a dependency on libhttp-entity-parser-perl. This pulls
in libjson-maybexs-perl, which depends on libcpanel-json-xs-perl |
libjson-xs-perl, and the interaction of the former with libjson-perl
seems glitchy:

  % perl -we 'use Cpanel::JSON::XS; use JSON'
  Subroutine JSON::PP::Boolean::(0+ redefined at /usr/share/perl/5.24/overload.pm line 50.
  Subroutine JSON::PP::Boolean::(++ redefined at /usr/share/perl/5.24/overload.pm line 50.
  Subroutine JSON::PP::Boolean::(-- redefined at /usr/share/perl/5.24/overload.pm line 50.
  Subroutine main::from_json redefined at -e line 1.
  Subroutine main::to_json redefined at -e line 1.
  Subroutine main::encode_json redefined at -e line 1.
  Subroutine main::decode_json redefined at -e line 1.
  Prototype mismatch: sub main::decode_json ($;$) vs none at -e line 1.
 
Not quite sure whose bug this really is.
<https://github.com/rurban/Cpanel-JSON-XS/issues/65> and
<https://github.com/makamaka/JSON/pull/17#issuecomment-253968217>
seem related.
-- 
Niko Tyni   ntyni at debian.org