Re: [PATCH] completion: do not cache if --git-completion-helper fails

[Felipe Contreras <felipe.contreras@gmail.com>]

On Fri, Jun 7, 2019 at 5:02 AM SZEDER Gábor <szeder.dev@gmail.com> wrote:
>
> On Fri, Jun 07, 2019 at 04:30:34PM +0700, Nguyễn Thái Ngọc Duy wrote:
> > "git <cmd> --git-completion-helper" could fail if the command checks for
> > a repo before parse_options(). If the result is cached, later on when
> > the user moves to a worktree with repo, tab completion will still fail.
> >
> > Avoid this by detecting errors and not cache the completion output. We
> > can try again and hopefully succeed next time (e.g. when a repo is
> > found).
> >
> > Of course if --git-completion-helper fails permanently because of other
> > reasons (*), this will slow down completion. But I don't see any better
> > option to handle that case.
>
> I think a permanently failing 'git cmd --git-completion-helper'
> shouldn't really happen, unless there is a bug in the completion
> script or the git installation or similar exceptional situation.  And
> then that issue should be fixed, but I don't think we should worry
> about an extra subshell and git process in those situations.

Indeed. In think there's only sane option to make this work in all
situation; a reorganization.

Something like this should work:

struct command checkout_command = {
.name = "checkout",
.function = cmd_checkout,
.run_options = RUN_SETUP | NEED_WORK_TREE,
.help = N_("Switch branches or restore working tree files"),
.options = {
OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
...
},
}

This way we could run parse_options_show_gitcomp() from git.c and not
worry about whatever cmd_checkout() needs.

This has the added advantage that it gathers information about this
command that is stray in multiple sources (git.c, command-list.h), and
it makes builtin.h cleaner too.

Plus, we could rework the way -h works too.

-- 
Felipe Contreras