Re: [GSoC][PATCH v5] submodule: port subcommand 'set-branch' from shell to C

> Convert submodule subcommand 'set-branch' to a builtin and call it via
> 'git-submodule.sh'.
> 
> Mentored-by: Christian Couder <chriscool@tuxfamily.org>
> Mentored-by: Kaartic Sivaraam <kaartic.sivaraam@gmail.com>
> Helped-by: Denton Liu <liu.denton@gmail.com>
> Helped-by: Eric Sunshine <sunshine@sunshineco.com>
> Helped-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
> Signed-off-by: Shourya Shukla <shouryashukla.oo@gmail.com>
> ---
> Here is the v5 of the subcommand. Thank you Danh for the feedback! I
> apologise for not replying on time. I have taken into account Danh's
> suggestions on the `quiet` option as well as done the fixup Dscho
> suggested (fixed by Junio here:
> https://github.com/gitster/git/commit/77ba62f66ff8e3de54d81c240542edb42a2711c7)
> 
>   builtin/submodule--helper.c | 44 +++++++++++++++++++++++++++++++++++++
>   git-submodule.sh            | 32 +++------------------------
>   2 files changed, 47 insertions(+), 29 deletions(-)
> 
> diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
> index f50745a03f..a974e17571 100644
> --- a/builtin/submodule--helper.c
> +++ b/builtin/submodule--helper.c
> @@ -2284,6 +2284,49 @@ static int module_set_url(int argc, const char **argv, const char *prefix)
>   	return 0;
>   }
>   
> +static int module_set_branch(int argc, const char **argv, const char *prefix)
> +{
> +	int opt_default = 0, ret;
> +	const char *opt_branch = NULL;
> +	const char *path;
> +	char *config_name;
> +
> +	/*
> +	 * We accept the `quiet` option for uniformity across subcommands,
> +	 * though there is nothing to make less verbose in this subcommand.
> +	 */
> +	struct option options[] = {
> +		OPT_NOOP_NOARG('q', "quiet"),
> +		OPT_BOOL('d', "default", &opt_default,
> +			N_("set the default tracking branch to master")),
> +		OPT_STRING('b', "branch", &opt_branch, N_("branch"),
> +			N_("set the default tracking branch")),
> +		OPT_END()
> +	};
> +	const char *const usage[] = {
> +		N_("git submodule--helper set-branch [-q|--quiet] (-d|--default) <path>"),
> +		N_("git submodule--helper set-branch [-q|--quiet] (-b|--branch) <branch> <path>"),
> +		NULL
> +	};

>  Optional parts are enclosed in square brackets:
>    [<extra>]
>    (Zero or one <extra>.)
> 
>    --exec-path[=<path>]
>    (Option with an optional argument.  Note that the "=" is inside the
>    brackets.)
> 
>    [<patch>...]
>    (Zero or more of <patch>.  Note that the dots are inside, not
>    outside the brackets.)
> 
>  Multiple alternatives are indicated with vertical bars:
>    [-q | --quiet]
>    [--utf8 | --no-utf8]
> 
>  Parentheses are used for grouping:
>    [(<rev> | <range>)...]
>    (Any number of either <rev> or <range>.  Parens are needed to make
>    it clear that "..." pertains to both <rev> and <range>.)
> 
>    [(-p <parent>)...]
>    (Any number of option -p, each with one <parent> argument.)
> 
>    git remote set-head <name> (-a | -d | <branch>)
>    (One and only one of "-a", "-d" or "<branch>" _must_ (no square
>    brackets) be provided.)