Bug#810023: libconfig-model-dpkg-perl: Does not recognize/allow user-defined fields as per §5.7

[Ben Wiederhake]

Package: libconfig-model-dpkg-perl
Version: 2.069
Severity: normal

Dear Maintainer,

I'm trying to package something for Debian and use (among other tools)
cme to make sure that my d/control is sane.

There is some issue with the package, which means I would like to put
a comment into d/control. However, this is deprecated by some tools,
and also a bad idea: YAML-comments are not readily machine-parsable.

Thus I was happy to see that §5.7 explicitly allows user-defined tags,
and mentions "X-Comment" as an example; so I believe I'm acting in the
intention of that Policy.

However, cme (a program that uses libconfig-model-dpkg-perl)
does not allow this:

    $ cme check dpkg
    In control binary:invalid: (function 'create_element') unknown element
'X-Comment'. Either your file has an error or Dpkg::Control::Binary model is
lagging behind. In the latter case, please submit a bug report or fix the
model. See cme man page for details.
    Expected elements: 'Architecture','Multi-
Arch','Section','Priority','Essential','Depends','Recommends','Suggests','Enhances
','Pre-Depends','Breaks','Conflicts','Provides','Replaces','Built-Using
','Package-Type','Synopsis','Description','Homepage','Build-Profiles'

Please find a sample file attached.

Could this be changed so that user-defined tags
are recognized and handled as such?

Regards,
Ben Wiederhake

PS: In case anyone cares, it's about telegram-purple, RFS #809623 :
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=809623#20



-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (500, 'testing'), (500, 'oldstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.2.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=de_DE.utf8, LC_CTYPE=de_DE.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages libconfig-model-dpkg-perl depends on:
ii  devscripts                                   2.15.9
ii  libapt-pkg-perl                              0.1.29+b5
ii  libarray-intspan-perl                        2.003-1
ii  libconfig-model-perl                         2.075-1
ii  libexporter-lite-perl                        0.06-1
ii  liblog-log4perl-perl                         1.46-1
ii  libmouse-perl                                2.4.5-1+b1
ii  libparse-recdescent-perl                     1.967013+dfsg-1
ii  libsoftware-license-perl                     0.103010-4
ii  libtext-autoformat-perl                      1.740000-1
ii  libtext-levenshtein-damerau-perl             0.41-1
ii  liburi-perl                                  1.69-1
ii  libwww-perl                                  6.15-1
ii  lintian                                      2.5.39.1
ii  perl                                         5.22.1-3
ii  perl-modules-5.22 [libmodule-corelist-perl]  5.22.1-3

Versions of packages libconfig-model-dpkg-perl recommends:
pn  libconfig-model-tkui-perl  <none>

libconfig-model-dpkg-perl suggests no packages.

-- no debconf information
-------------- next part --------------
Source: invalid
Section: net
Priority: optional
Maintainer: Ben Wiederhake <Ben.Wiederhake at gmail.com>
Build-Depends:
 debhelper (>= 9)
Standards-Version: 3.9.6
Homepage: https://github.com/some/where
Vcs-Git: https://github.com/my/where
Vcs-Browser: https://github.com/my/where/tree/debian-develop

Package: invalid
Architecture: any
Depends:
 ${misc:Depends},
 ${shlibs:Depends}
Description: Invalid does nothing
 You shouldn't use this as your own. However, it has to look good for cme.
X-Comment: Traditionally, this would probably have been called 'hello-world',
 but I needed a reason to write a comment, so yeah.
 .
 This is a valid field as per Policy §5.7.
 ( https://www.debian.org/doc/debian-policy/ch-controlfields.html#s5.7 )