Bug#786470: debian-policy: [copyright-format] Add an optional “License-Grant” field

[Simon McVittie <smcv@debian.org>]

I think the License-Grant field is a useful addition to the format,
resolving some issues around whether License is meant to be the license,
the license grant or both, and I would like to be able to start using it.

I assume a normative change to the available fields, and to the meaning
of License, would make this be copyright format 1.1?

On Mon, 07 Aug 2017 at 10:00:32 +1000, Ben Finney wrote:
>  <programlisting>Files: *
>  Copyright: 1975-2010 Ulla Upstream
> +License-Grant:
> +    This program is free software; you can redistribute it and/or modify
> +    it under the terms of the GNU General Public License as published by
> +    the Free Software Foundation; either version 2 of the License, or
> +    (at your option) any later version.
>  License: GPL-2+

I would personally sort License: GPL-2+ before License-Grant, because
that means someone familiar with debian/copyright can usually skip to
the next paragraph without reading the license grant in detail!

> +      <para>
> +        The full license terms and conditions themselves – the license
> +        text – belongs in a
> +        <link linkend="license-field">License</link> field.
> +      </para>

What happens if the license grant *is* the full license, as with many
short permissive licenses, and in particular the BSD and MIT/X11 license
families? (I suspect the answer is meant to be "keep doing what you're
doing now" - break out the license-grant-and-license to a standalone
License paragraph if all instantiations are identical, or keep it in a
non-standalone License field per instantiation if they are not?)

Should Example 3, "Simple" be using the License-Grant too? If I understand
correctly, it should ideally become:

    Format: ...
    Upstream-Name: ...
    Source: ...

    Files: *
    Copyright: ...
    License-Grant:
     This program is free software; ...
    License: GPL-2+
     On Debian systems, ...

which I don't think makes it significantly less simple.

Or if the intention is to keep Example 3, "Simple" using the fields it
currently uses, it should probably be changed to something that uses the
MIT/X11 license, like in
<https://tracker.debian.org/media/packages/libg/libgfshare/copyright-2.0.0-2>
which is a real d/copyright that is as simple as this one.

Example 4, "Complex" should probably be updated to use License-Grant,
because quoting the GPL license grant in a standalone License paragraph
after License-Grant has been added seems counter-intuitive. I'm curious
to see how that would look, if we imagine Joe Hacker and Thomas Brown
had used the same form of words for their GPL-2+ license grants - does
the author of the copyright file have to choose between duplicating the
License-Grant or combining those two paragraphs, or is there some way
to deduplicate identical license grants without combining the paragraphs?

Perhaps standalone License paragraphs should be allowed to have a
License-Grant field, which applies to all references by name to
that license that do not declare their own License-Grant? Or perhaps
authors of d/copyright files should be encouraged to merge paragraphs
that have identical license grants but different Files and Copyright.

Regards,
    smcv