Re: syntax error in git-rebase while running t34* tests

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi,

On Tue, 10 May 2016, Jeff King wrote:

> On Tue, May 10, 2016 at 01:53:56PM -0700, Junio C Hamano wrote:
> 
> > Jeff King <peff@peff.net> writes:
> > 
> > > I think it is clear why it works. If $strategy_opts is empty, then the
> > > code we generate looks like:
> > >
> > >   for strategy_opt in
> > >   do
> > >           ...
> > >   done
> > 
> > Ah, of course.  Thanks.
> 
> Here it is as a patch and commit message.
> 
> -- >8 --
> Subject: [PATCH] rebase--interactive: avoid empty list in shell for-loop
> 
> The $strategy_opts variable contains a space-separated list
> of strategy options, each individually shell-quoted. To loop
> over each, we "unwrap" them by doing an eval like:
> 
>   eval '
>     for opt in '"$strategy_opts"'
>     do
>        ...
>     done
>   '
> 
> Note the quoting that means we expand $strategy_opts inline
> in the code to be evaluated (which is the right thing
> because we want the IFS-split and de-quoting). If the
> variable is empty, however, we ask the shell to eval the
> following code:
> 
>   for opt in
>   do
>      ...
>   done
> 
> without anything between "in" and "do".  Most modern shells
> are happy to treat that like a noop, but reportedly ksh88 on
> AIX considers it a syntax error. So let's catch the case
> that the variable is empty and skip the eval altogether
> (since we know the loop would be a noop anyway).
> 
> Reported-by: Armin Kunaschik <megabreit@googlemail.com>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
>  git-rebase--interactive.sh | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
> index 9ea3075..1c6dfb6 100644
> --- a/git-rebase--interactive.sh
> +++ b/git-rebase--interactive.sh
> @@ -82,6 +82,7 @@ rewritten_pending="$state_dir"/rewritten-pending
>  cr=$(printf "\015")
>  
>  strategy_args=${strategy:+--strategy=$strategy}
> +test -n "$strategy_opts" &&
>  eval '
>  	for strategy_opt in '"$strategy_opts"'
>  	do

Looks obviously correct to me.

I had a look at our other shell scripts and it looks as if there is only
one more candidate for this issue: git-bisect.sh has a couple of 'for arg
in "$@"' constructs. But from a cursory look, it appears that none of
these "$@" can be empty lists because at least one parameter is passed to
those functions (check_expected_revs() is only called from bisect_state()
with 1 or 2 parameters, bisect_skip() makes no sense without parameters,
and bisect_state() has another for loop if it got 2 parameters).

So I think we're fine.

Ciao,
Dscho