Re: [PATCH] git-send-email: fix get_maintainer.pl regression

From: Alex Bennée <alex.bennee@linaro.org>
Date: Nov 22, 2017, 09:05 UTC
Message-ID: <87vai2wumy.fsf@linaro.org>
In-Reply-To: <q7h97euiradu.fsf@orange.lip.ens-lyon.fr>

Matthieu Moy <Matthieu.Moy@univ-lyon1.fr> writes:

Show 25 quoted lines

> Junio C Hamano <gitster@pobox.com> writes:
>
>> Was there any reason why Mail::Address was _inadequate_?
>
> I think the main reason was that Mail::Address is not a standard perl
> module, and not relying on it avoided one external dependency. AFAIK, we
> don't really have a good way to deal with Perl dependencies, so having a
> strong requirement on Mail::Address will probably end up in a runtime
> error for users who compile Git from source (people using a packaged
> version have their package manager to deal with this).
>
>> I know we had trouble with random garbage that are *not* addresses
>> people put on the in-body CC: trailer in the past, but I do not recall
>> if they are something Mail::Address would give worse result and we
>> need our workaround (hence our own substitute), or Mail::Address would
>> handle them just fine.
>
> For a long time, we used Mail::Address if it was available and I don't
> think we had issues with it.
>
> My point in cc907506 ("send-email: don't use Mail::Address, even if
> available", 2017-08-23) was not that Mail::Address was bad, but that
> changing our behavior depending on whether it was there or not was
> really bad. For example, the issue dealt with in this thread probably
> always existed, but it was present only for *some* users.

So I just did a little digging on my systems to illustrate the point. My work machine is Ubuntu, so has a packaged git via PPA. It depends on libmailtools-perl which includes the perl module and:

  apt-cache rdepends  libmailtools-perl | wc -l
  45

So for binary packaged systems it's not a big thing - libmailtools-perl seems to be quite widely relied on.

On my system at home, running Gentoo, while requiring "perl" doesn't explicitly pull in the Mail::Address dependency. As a result the git send-email stanza I was running at work manages to corrupt the addresses. If I manually install dev-perl/MailTools of course it silently starts working again.

Good job I never usually send patches from my home machine ;-)

My hacky guess about GIT's perl use calls is:

   find . -iname "*.perl" -or -iname "*.pm" -or -iname "*.pl" | xargs grep -h  "use .*::" | sort | uniq | wc -l
   88

So that is about 88 perl modules used in the code base. How many of them are not part of the core perl distribution?

Should the solution be to just make Mail::Address a hard dependency and not have the fallback?

-- Alex Bennée