Re: [PATCH v2 18/18] sparse-checkout: provide a new reapply subcommand

> From: Elijah Newren <newren@gmail.com>
> 
> If commands like merge or rebase materialize files as part of their work,
> or a previous sparse-checkout command failed to update individual files
> due to dirty changes, users may want a command to simply 'reapply' the
> sparsity rules.  Provide one.
> 
> Signed-off-by: Elijah Newren <newren@gmail.com>
> ---
>  Documentation/git-sparse-checkout.txt | 10 ++++++++++
>  builtin/sparse-checkout.c             | 10 +++++++++-
>  2 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/git-sparse-checkout.txt b/Documentation/git-sparse-checkout.txt
> index c0342e53938..1a3ace60820 100644
> --- a/Documentation/git-sparse-checkout.txt
> +++ b/Documentation/git-sparse-checkout.txt
> @@ -70,6 +70,16 @@ C-style quoted strings.
>  	`core.sparseCheckoutCone` is enabled, the given patterns are interpreted
>  	as directory names as in the 'set' subcommand.
>  
> +'reapply::
> +	Reapply the sparsity pattern rules to paths in the working tree.
> +	Commands like merge or rebase can materialize paths to do their
> +	work (e.g. in order to show you a conflict), and other
> +	sparse-checkout commands might fail to sparsify an individual file
> +	(e.g. because it has unstaged changes or conflicts).  In such
> +	cases, it can make sense to run `git sparse-checkout reapply` later
> +	after cleaning up affected paths (e.g. resolving conflicts, undoing
> +	or committing changes, etc.).
> +
>  'disable'::
>  	Disable the `core.sparseCheckout` config setting, and restore the
>  	working directory to include all files. Leaves the sparse-checkout
> diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
> index aa81199f85d..95d08824172 100644
> --- a/builtin/sparse-checkout.c
> +++ b/builtin/sparse-checkout.c
> @@ -18,7 +18,7 @@
>  static const char *empty_base = "";
>  
>  static char const * const builtin_sparse_checkout_usage[] = {
> -	N_("git sparse-checkout (init|list|set|add|disable) <options>"),
> +	N_("git sparse-checkout (init|list|set|add|reapply|disable) <options>"),
>  	NULL
>  };
>  
> @@ -554,6 +554,12 @@ static int sparse_checkout_set(int argc, const char **argv, const char *prefix,
>  	return modify_pattern_list(argc, argv, m);
>  }
>  
> +static int sparse_checkout_reapply(int argc, const char **argv)
> +{
> +	repo_read_index(the_repository);
> +	return update_working_directory(NULL);
> +}
> +
>  static int sparse_checkout_disable(int argc, const char **argv)
>  {
>  	struct pattern_list pl;
> @@ -603,6 +609,8 @@ int cmd_sparse_checkout(int argc, const char **argv, const char *prefix)
>  			return sparse_checkout_set(argc, argv, prefix, REPLACE);
>  		if (!strcmp(argv[0], "add"))
>  			return sparse_checkout_set(argc, argv, prefix, ADD);
> +		if (!strcmp(argv[0], "reapply"))
> +			return sparse_checkout_reapply(argc, argv);
>  		if (!strcmp(argv[0], "disable"))
>  			return sparse_checkout_disable(argc, argv);
>  	}