Re: [PATCHv5 8/8] clone: recursive and reference option triggers submodule alternates

> When `--recursive` and `--reference` is given, it is reasonable to
> expect that the submodules are created with references to the submodules
> of the given alternate for the superproject.
>
>   An initial attempt to do this was presented to the mailing list, which
>   used flags that are passed around ("--super-reference") that instructed
>   the submodule clone to look for a reference in the submodules of the
>   referenced superproject. This is not well thought out, as any further
>   `submodule update` should also respect the initial setup.
>
>   When a new  submodule is added to the superproject and the alternate
>   of the superproject does not know about that submodule yet, we rather
>   error out informing the user instead of being unclear if we did or did
>   not use a submodules alternate.
>
> To solve this problem introduce new options that store the configuration
> for what the user wanted originally.
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
>  Documentation/config.txt       | 12 ++++++
>  builtin/clone.c                | 19 +++++++++
>  builtin/submodule--helper.c    | 87 ++++++++++++++++++++++++++++++++++++++++++
>  t/t7408-submodule-reference.sh | 43 +++++++++++++++++++++
>  4 files changed, 161 insertions(+)
>
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index bc1c433..602f43a 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -2837,6 +2837,18 @@ submodule.fetchJobs::
>         in parallel. A value of 0 will give some reasonable default.
>         If unset, it defaults to 1.
>
> +submodule.alternateLocation::
> +       Specifies how the submodules obtain alternates when submodules are
> +       cloned. Possible values are `no`, `superproject`.
> +       By default `no` is assumed, which doesn't add references. When the
> +       value is set to `superproject` the submodule to be cloned computes
> +       its alternates location relative to the superprojects alternate.
> +
> +submodule.alternateErrorStrategy
> +       Specifies how to treat errors with the alternates for a submodule
> +       as computed via `submodule.alternateLocation`. Possible values are
> +       `ignore`, `info`, `die`.
> +
>  tag.forceSignAnnotated::
>         A boolean to specify whether annotated tags created should be GPG signed.
>         If `--annotate` is specified on the command line, it takes
> diff --git a/builtin/clone.c b/builtin/clone.c
> index 0182665..404c5e8 100644
> --- a/builtin/clone.c
> +++ b/builtin/clone.c
> @@ -947,6 +947,25 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
>                 else
>                         fprintf(stderr, _("Cloning into '%s'...\n"), dir);
>         }
> +
> +       if (option_recursive) {
> +               if (option_required_reference.nr &&
> +                   option_optional_reference.nr)
> +                       die(_("clone --recursive is not compatible with "
> +                             "both --reference and --reference-if-able"));