Re: [Problem] test_must_fail makes possibly questionable assumptions about exit_code.

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 28, 2018, 16:22 UTC
Message-ID: <xmqqk1uxm6db.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20180228074918.GA32127@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 27 quoted lines

> You're right. I cut down my example too much and dropped the necessary
> eval magic. Try this:
>
> -- >8 --
> SIG{__DIE__} = sub {
>   CORE::die @_ if $^S || !defined($^S);
>   print STDERR "fatal: @_";
>   exit 128;
> };
>
> eval {
>   die "inside eval";
> };
> print "eval status: $@" if $@;
>
> die "outside eval";
> -- 8< --
>
> Running that should produce:
>
> $ perl foo.pl; echo $?
> eval status: inside eval at foo.pl line 8.
> fatal: outside eval at foo.pl line 12.
> 128
>
> It may be getting a little too black-magic, though. Embedding in an eval
> is at least straightforward, if a bit more invasive.

I briefly wondered if this affects die that are called by code that we did not write (i.e. from core or cpan via "use/require"), but (1) we do want this to affect them, so that we die with status code known to us, and (2) the way this uses CORE::die or exit depending on the surrounding 'eval' would "fool" their uses just like we want it to fool our uses, which is exactly what we want.

So, it looks like a good "black magic" ;-).