Subject: Re: [PATCH, RFC] checkout: Attempt to checkout submodules

From: Junio C Hamano <[email-masked]>
Date: Thu, 19 Mar 2015 11:53:10 -0700

Trevor Saunders <[email-masked]> writes:

> If a user does git checkout HEAD -- path/to/submodule they'd expect the
> submodule to be checked out to the commit that submodule is at in HEAD.

Hmmm.

Is it a good idea to do that unconditionally by hard-coding the
behaviour like this patch does?

Is it a good idea that hard-coded behaviour is "checkout [-f]"?

I think "git submodule update" is the command people use when they
want to "match" the working trees of submodules, and via the
configuration mechanism submodule.*.update, people can choose what
they mean by "match"ing.  Some people want to checkout the commit
specified in the superproject tree by detaching HEAD at it.  Some
people want to integrate by merging or rebasing.

> This is the most brute force possible way of try to do that, and so its
> probably broken in some cases.  However I'm not terribly familiar with
> git's internals and I'm not sure if this is even wanted so I'm starting
> simple.  If people want this to work I can try and do something better.
>
> Signed-off-by: Trevor Saunders <[email-masked]>
> ---
>  entry.c | 22 ++++++++++++++++++++--
>  1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/entry.c b/entry.c
> index 1eda8e9..2dbf5b9 100644
> --- a/entry.c
> +++ b/entry.c
> @@ -1,6 +1,8 @@
>  #include "cache.h"
> +#include "argv-array.h"
>  #include "blob.h"
>  #include "dir.h"
> +#include "run-command.h"
>  #include "streaming.h"
>  
>  static void create_directories(const char *path, int path_len,
> @@ -277,9 +279,25 @@ int checkout_entry(struct cache_entry *ce,
>  		 * just do the right thing)
>  		 */
>  		if (S_ISDIR(st.st_mode)) {
> -			/* If it is a gitlink, leave it alone! */
> -			if (S_ISGITLINK(ce->ce_mode))
> +			if (S_ISGITLINK(ce->ce_mode)) {
> +				struct argv_array args = ARGV_ARRAY_INIT;
> +				char sha1[41];
> +
> +				argv_array_push(&args, "checkout");
> +
> +				if (state->force)
> +					argv_array_push(&args, "-f");
> +
> +				memcpy(sha1, sha1_to_hex(ce->sha1), 41);
> +				argv_array_push(&args, sha1);
> +				
> +				run_command_v_opt_cd_env(args.argv,
> +					       		 RUN_GIT_CMD, ce->name,
> +							 NULL);
> +				argv_array_clear(&args);
> +
>  				return 0;
> +			}
>  			if (!state->force)
>  				return error("%s is a directory", path.buf);
>  			remove_subtree(&path);