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References: <20210423194230.1388945-1-lukeshu@lukeshu.com> <20210423194230.1388945-19-lukeshu@lukeshu.com>
 <CAPig+cTb-h=Qb9asvh+MVH2s5uj7szP_QOPpcm1bqdE6DK9V7g@mail.gmail.com> <87zgxoa7cj.wl-lukeshu@lukeshu.com>
In-Reply-To: <87zgxoa7cj.wl-lukeshu@lukeshu.com>
From:   Eric Sunshine <sunshine@sunshineco.com>
Date:   Sat, 24 Apr 2021 01:18:33 -0400
Message-ID: <CAPig+cQ_7eVgdYuci1JeVwU89VOeOU6kzZ9=yw1ySR9RXzjuTA@mail.gmail.com>
Subject: Re: [PATCH 18/30] subtree: use $* instead of $@ as appropriate
To:     Luke Shumaker <lukeshu@lukeshu.com>
Cc:     Git List <git@vger.kernel.org>,
        Avery Pennarun <apenwarr@gmail.com>,
        Charles Bailey <cbailey32@bloomberg.net>,
        Danny Lin <danny0838@gmail.com>,
        "David A . Greene" <greened@obbligato.org>,
        David Aguilar <davvid@gmail.com>,
        Jakub Suder <jakub.suder@gmail.com>,
        James Denholm <nod.helm@gmail.com>, Jeff King <peff@peff.net>,
        Jonathan Nieder <jrnieder@gmail.com>,
        Junio C Hamano <gitster@pobox.com>,
        =?UTF-8?B?Tmd1eeG7hW4gVGjDoWkgTmfhu41jIER1eQ==?= 
        <pclouds@gmail.com>, Roger L Strain <roger.strain@swri.org>,
        Techlive Zheng <techlivezheng@gmail.com>,
        Luke Shumaker <lukeshu@datawire.io>
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On Fri, Apr 23, 2021 at 7:50 PM Luke Shumaker <lukeshu@lukeshu.com> wrote:
> On Fri, 23 Apr 2021 14:40:31 -0600, Eric Sunshine wrote:
> > Nit: I have some trouble following what the commit message is actually
> > trying to say with "smash things" and "separate strings". It might be
> > simpler to say merely that use of "$@" in these particular instances
> > is overkill and possibly misleading to readers not familiar with the
> > finer details of $* vs. "$@".

Oof, I somehow misread the code this patch is touching and ended up
confusing myself, and the confusion bled into my review comments.
Sorry.

> How's this:
> ---
> subtree: use "$*" instead of "$@" as appropriate
>
> "$*" is for when you want to concatenate the args together,
> whitespace-separated; and "$@" is for when you want them to be separate
> strings.
>
> There are several places in subtree that erroneously use $@ when
> concatenating args together into an error message.
>
> For instance, if the args are argv[1]="dead" and argv[2]="beef", then
> the line
>
>     die "You must provide exactly one revision.  Got: '$@'"
>
> surely intends to call 'die' with the argument
>
>     argv[1]="You must provide exactly one revision.  Got: 'dead beef'"
>
> however, because the line used $@ instead of $*, it will actually call
> 'die' with the arguments
>
>     argv[1]="You must provide exactly one revision.  Got: 'dead"
>     argv[2]="beef'"
>
> This isn't a big deal, because 'die' concatenates its arguments together
> anyway (using "$*").  But that doesn't change the fact that it was a
> mistake to use $@ instead of $*, even though in the end $@ still ended
> up doing the right thing.

This explanation spells out the problem nicely.