From: Colin Stagner <ask+git@howdoi.land>
Date: Wed, 10 Sep 2025 03:00:18 GMT
Subject: Re: [PATCH v2] contrib/subtree: fix split with squashed subtrees
Message-ID: <641aaa9b-2b23-4faf-a13e-f6205e9ef5a2@howdoi.land>
In-Reply-To: <xmqqbjnjt67y.fsf@gitster.g>

On 9/9/25 21:02, Junio C Hamano wrote:
> Besides, "if test -n ${subtree_dir-}" without colon would be the
> more proper way for those who care about "set -u", wouldn't it?  It
> is not that you want to substitute with an empty string that comes
> between that "-" and "}" when subtree_dir is unset or set to empty.
> You are preparing for the case where the variable is truly not set,
> and the variable being set to an empty string is not something you
> are worried about.
Yes, "test -n ${subtree_dir-}" is definitely the more correct expression.

At the very real risk of embarrassing myself in public today... in the 
particular case of a "test -n," is there actually an appreciable 
difference? Either way, the output of the substitution is empty if the 
input is empty or undefined. Here, "test -n ${subtree_dir:-}" is merely 
less efficient. Right?

The difference between "${x:-}" vs "${x-}" really starts to matter if 
you want to permit the empty string (or not). It also matters if you 
call a command that has side effects.

(And in the context of this patch, neither are necessary.)