Bug#688251: Built-Using description too aggressive

[Jonathan Nieder <jrnieder@gmail.com>]

Hi,

Charles Plessy wrote:

> --- a/policy.sgml
> +++ b/policy.sgml
> @@ -5563,7 +5563,13 @@ Replaces: mail-transport-agent
>  	</p>
>  
>  	<p>
> -	  A <tt>Built-Using</tt> field must list the corresponding source
> +	  When the licensing terms of the incorporated parts require to provide
> +	  their source <footnote>
> +	  </footnote>,
> +	  a <tt>Built-Using</tt> field must list the corresponding source
>  	  package for any such binary package incorporated during the build

The above looks sensible.  As a small nit, it's not just the licensing
terms of the incorporated parts --- for example, if the incorporated
part were public domain but the code incorporating it had terms
requiring all corresponding source to be included with binaries,
it would probably still be wise to use Built-Using.

How about something like "When the license terms of a binary package
require providing the corresponding source incorporated from other
packages, [...]"?

> +	    As of September 2013, the current practice in Debian is to consider
> +	    that we can benefit from the GPL exceptions for the libc, GCC and
> +	    similar packages.

I can't agree with the above paragraph, mostly because I don't
understand it completely.  What GPL exception?

I am convinced it is legally fine to distribute a binary package of
Git because there is not a substantial amount of GPLv2-incompatible
code in the binary.  GCC's runtime exception doesn't help with that
at all, unfortunately (a GPLv2-incompatible license + GCC runtime
exception is still GPLv2-incompatible), but fortunately there is not
much GCC runtime code in the binary.

Of course that is only my own understanding, I am not an ftpmaster,
I am not a lawyer, etc etc.

Besides, this "As of September 2013" statement in policy feels quite
strange.

Would it be okay to leave out the footnote, or to say something more
practical like the following?

	<footnote>
	  <p>
	    For example, a cross-compiler package which Build-Depends on
	    gcc-5.2-source and whose source package consists of build rules
	    instead of compiler code should use "Built-Using: gcc-5.2
	    (= <version>)" to ensure the archive includes the corresponding
	    source for the produced binary.
	  </p>

	  <p>
	    Most packages do not need to use Built-Using, since the archive
	    maintenance tools already normally ensure that source for at least
	    one version of their build-time dependencies is present.
	  </p>
	</footnote>

Hope that helps,
Jonathan