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Date:   Fri, 13 Jan 2017 16:58:19 +0000
From:   Eric Wong <e@80x24.org>
To:     Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc:     Pat Pannuto <pat.pannuto@gmail.com>,
        Junio C Hamano <gitster@pobox.com>,
        Johannes Sixt <j6t@kdbg.org>, git@vger.kernel.org
Subject: Re: [PATCH 2/2] Use 'env' to find perl instead of fixed path
Message-ID: <20170113165819.GA6069@starla>
References: <20170112055140.29877-1-pat.pannuto@gmail.com>
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Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:
> I guess I do not understand, still, what the difference is between using
> -w and adding `use warnings` *very early* in the script... Could you give
> an example where it makes a difference?

"use warnings" won't leak across files/modules.  In the following
example, only the "useless use of join or string in void context"
from void.perl gets shown w/o -w.  The VoidExample.pm warning
can get lost.

----- VoidExample.pm ------
package VoidExample;
use strict;
# use warnings; # uncomment to trigger warning on next line:
join('', qw(a b c));

1;
------ void.perl ------
#!/usr/bin/perl
use strict;
use warnings;
use VoidExample;

join('', qw(a b c)); # warns
----------8<----------

$ perl -I . void.perl    # 1 warning
$ perl -w -I . void.perl # 2 warnings