Re: [PATCH] diff: allow --recurse-submodules as an synonym for --submodule

[Jonathan Nieder <jrnieder@gmail.com>]

Stefan Beller wrote:

> Many commands have flags to recurse into submodules, which is named
> --recurse-submodules. The diff family also has a submodule recursion flag,
> but that is named differently. Add a synonym --recurse-submodules, which
> means the same as the --submodule flag, such that across all git commands
> supporting submodules we have the --recurse-submodules flag available.
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
>  Documentation/diff-options.txt | 1 +
>  diff.c                         | 2 ++
>  2 files changed, 3 insertions(+)

Makes sense.

[...]
> --- a/Documentation/diff-options.txt
> +++ b/Documentation/diff-options.txt
> @@ -227,6 +227,7 @@ linkgit:git-config[1]).
>  	of the `--diff-filter` option on what the status letters mean.
>  
>  --submodule[=<format>]::
> +--recurse-submodules[=<format>]::
>  	Specify how differences in submodules are shown.  When specifying
>  	`--submodule=short` the 'short' format is used.  This format just
>  	shows the names of the commits at the beginning and end of the range.
> diff --git a/diff.c b/diff.c
> index 145cfbae592..d3d5a989bd1 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -5023,6 +5023,8 @@ int diff_opt_parse(struct diff_options *options,
>  		handle_ignore_submodules_arg(options, arg);
>  	} else if (skip_to_optional_arg_default(arg, "--submodule", &arg, "log"))
>  		return parse_submodule_opt(options, arg);
> +	else if (skip_to_optional_arg_default(arg, "--recurse-submodules", &arg, "log"))
> +		return parse_submodule_opt(options, arg);

It seems like various commands are gaining --recurse-submodules options
taking different kinds of arguments:

- clone takes --recurse-submodules=<pathspec>
- fetch takes --recurse-submodules=<mode>
- after this patch, diff takes --recurse-submodules=<mode>

Is there a unifying principle?  Can Documentation/gitsubmodules.txt
say a word or two about what kind of argument values the user should
expect to be accepted by these options?

Thanks,
Jonathan