Re: [PATCH] CodingGuidelines: quote assigned value with "local" and "export"

From: Jeff King <peff@peff.net>
Date: Apr 5, 2024, 17:48 UTC
Message-ID: <20240405174859.GE2529133@coredump.intra.peff.net>
In-Reply-To: <xmqqbk6nyej1.fsf_-_@gitster.g>

On Fri, Apr 05, 2024 at 09:12:34AM -0700, Junio C Hamano wrote:

Show 7 quoted lines

> Dash bug https://bugs.launchpad.net/ubuntu/+source/dash/+bug/139097
> lets the shell erroneously perform field splitting on the expansion
> of a command substitution during declaration of a local or an extern
> variable.
> 
> The explanation was stolen from ebee5580 (parallel-checkout: avoid
> dash local bug in tests, 2021-06-06).

Thanks for digging up that commit. I read the earlier part of the thread and went off on a wild goose chase in the archive. :)

Show 13 quoted lines

> + - Some versions of dash has broken variable assignment when prefixed
> +   with "local", "export", and "readonly", in that the value to be
> +   assigned goes through field splitting at $IFS unless quoted.  
> +
> +   DO NOT write:
> +
> +     local variable=$value           ;# wrong
> +     export variable=$(command args) ;# wrong
> +
> +   and instead write:
> +
> +     local variable="$value"
> +     export variable="$(command args)"

I think that is a good rule for "local", but I thought we did not allow "export foo=bar" at all, and required:

  foo=bar
  export foo

If that was only because of this bug, it would be nice to loosen the rules a bit.

-Peff