From: Jeff King <peff@peff.net>
Date: Sat, 03 Feb 2018 20:22:34 GMT
Subject: Re: contrib/completion/git-completion.bash: declare -g is not portable
Message-ID: <20180203202234.GA13374@sigill.intra.peff.net>
In-Reply-To: <87lgg9g8cr.fsf@linux-m68k.org>

On Sat, Feb 03, 2018 at 08:51:16PM +0100, Andreas Schwab wrote:

> On Feb 03 2018, Torsten Bögershausen <tboegi@web.de> wrote:
> 
> > What is "declare -g" good for ?
> 
>       -g        create global variables when used in a shell function; otherwise
>                 ignored
> 
>     When used in a function, `declare' makes NAMEs local, as with the `local'
>     command.  The `-g' option suppresses this behavior.

I think the bigger question is why one would use "declare -g" instead of
just assigning the variable with "var=value".

Glancing at the code, I suspect it is because the name of the variable
itself needs expanded. If that's the case, we could use eval instead,
like:

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 3cc815be0d..204d620ff7 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -297,7 +297,7 @@ __gitcomp_builtin ()
 	eval "options=\$$var"
 
 	if [ -z "$options" ]; then
-		declare -g "$var=$(__git ${cmd/_/ } --git-completion-helper)"
+		eval "$var=\$(__git \${cmd/_/ } --git-completion-helper)"
 		eval "options=\$$var"
 	fi
 

-Peff