Re: [PATCH 3/8] perl: generalize the Git::LoadCPAN facility

From: Todd Zullinger <tmz@pobox.com>
Date: Feb 15, 2018, 21:23 UTC
Message-ID: <20180215212338.GL27038@zaya.teonanacatl.net>
In-Reply-To: <87sha2f0j1.fsf@evledraar.gmail.com>

[I dropped bbourbie@slb.com from the Cc: list, as it bounced on my previous reply.]

Ævar Arnfjörð Bjarmason wrote:

> That makes sense, I'll incorporate that in a re-roll. I like
> NO_PERL_CPAN_FALLBACKS or just NO_CPAN_FALLBACKS better.

Either is an improvement. Starting with NO_PERL_ seems like a slightly better bikeshed color. :)

Show 13 quoted lines

> I'd really like to find some solution that works differently though,
> because with this approach we'll run the full test suite against a
> system where our fallbacks will be in place (although if the OS
> distributor has done as promised we won't use them), and then just
> remove this at 'make install' time, also meaning we'll re-gen it before
> running 'make install' again, only to rm it again.
> 
> The former issue we could deal with by munging the Git::LoadCPAN file so
> it knows about NO_PERL_CPAN_FALLBACKS, and will always refuse to use the
> fallbacks if that's set. That's a good idea anyway, because right now if
> you e.g. uninstall Error.pm on Debian (which strips the CPAN fallbacks)
> you get a cryptic "BUG: ..." message, it should instead say "we couldn't
> get this module the OS promised we'd have" or something to that effect.

Teaching Git::LoadCPAN to never fallback sounds like a good idea. At least then if the packager intended to avoid the fallbacks and didn't get it right the error message could be more useful.

Hopefully that's not a common problem for packagers though. (And adding the Makefile knob was intended to help make it easier for packagers to achieve this common goal.)

Show 14 quoted lines

> The latter is trickier, I don't see an easy way to coerce the Makefile
> into not copying the FromCPAN directory without going back to a
> hardcoded list again, the easiest thing is probably to turn that:
> 
>     $(TAR) cf - .)
> 
> Into:
> 
>     $(TAR) cf - $(find ... -not ....)
> 
> Or something like that to get all the stuff that isn't the Git/FromCPAN
> directory.
> 
> Other suggestions most welcome.

What about moving perl/Git/FromCPAN to perl/FromCPAN and then including perl/FromCPAN in LIB_PERL{,_GEN} only if NO_PERL_CPAN_FALLBACKS is unset?

 LIB_PERL := $(wildcard perl/Git.pm perl/Git/*.pm perl/Git/*/*.pm perl/Git/*/*/*.pm)
+ifndef NO_PERL_CPAN_FALLBACKS
+LIB_PERL += $(wildcard perl/FromCPAN/*.pm perl/FromCPAN/*/*.pm)
+endif
 LIB_PERL_GEN := $(patsubst perl/%.pm,perl/build/lib/%.pm,$(LIB_PERL))

I haven't tested that at all, so it could be broken in many ways.

Thanks,

-- 
Todd
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The nice thing about egotists is that they don't talk about other
people.
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