Re: Bug report - sparse-checkout ignores prefix when run in subdirectories

[Elijah Newren <newren@gmail.com>]

On Wed, Jan 5, 2022 at 2:38 PM Junio C Hamano <gitster@pobox.com> wrote:
>
> Lessley Dennington <lessleydennington@gmail.com> writes:
>
> > Hello everyone! See the following bug report pertaining to sparse-checkout
> > when run outside top-level directories.
>
> In a bug report it is fine, but "outside top-level" usually means
> above the top-level of the working tree.  Here, I think you meant
> running in a subdirectory of the top-level.
>
> Perhaps something along this line?
>
>  builtin/sparse-checkout.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git c/builtin/sparse-checkout.c w/builtin/sparse-checkout.c
> index 45e838d8f8..4e5efbb85e 100644
> --- c/builtin/sparse-checkout.c
> +++ w/builtin/sparse-checkout.c
> @@ -753,6 +753,16 @@ static int sparse_checkout_set(int argc, const char **argv, const char *prefix)
>         if (!core_sparse_checkout_cone && argc == 0) {
>                 argv = default_patterns;
>                 argc = default_patterns_nr;
> +       } else if (argc && prefix && *prefix) {
> +               /*
> +                * The args are not pathspecs, so unfortunately we
> +                * cannot imitate how cmd_add() uses parse_pathspec().
> +                */
> +               int i;
> +               int prefix_len = strlen(prefix);
> +
> +               for (i = 0; i < argc; i++)
> +                       argv[i] = prefix_path(prefix, prefix_len, argv[i]);
>         }

This looks good (sparse_checkout_add() needs a similar fix), at least
for cone mode.  There might be a small pickle here that I didn't think
about before.  --cone mode always uses directories, so we expect
people to provide directory names.  Because of that, I think it's fair
to expect the arguments passed to `set` or `add` to be paths relative
to the current working directory.  In contrast, for non-cone mode we
do not expect pathnames but gitignore-style globs.  And when we get
gitignore-style globs, we don't know if they were intended relative to
the current working directory or the toplevel, because we only have
one $GIT_DIR/info/sparse-checkout file versus many .gitignore files.
So, should "**.py" go directly into the sparse-checkout file as-is, or
be translated to "my/current/subdir/**.py" first?

Maybe translating is always fine, or maybe we want to throw an error
when: (not using cone mode and prefix is non-empty and any patterns
are provided).

Thoughts?

>
>         return modify_pattern_list(argc, argv, set_opts.use_stdin, REPLACE);