Re: [PATCH] stash: add 'rename' subcommand

> From: =?UTF-8?q?Emin=20=C3=96zata?= <eminozata@proton.me>
> 
> There is no way to change the message of a stash entry after the
> fact.  The only option is dropping the entry and re-storing it by
> hand, which moves it to the top of the stash list and gets fiddly
> for deeper entries.
> 
> Add 'git stash rename <message> [<stash>]', defaulting to the
> latest entry like the other subcommands do.  It reads the object id
> and reflog message of the target entry and of the entries above it,
> drops them all like 'git stash drop' would, and stores them back in
> the same order, with the new message going to the target.  Position,
> contents and the reflog chain stay as they were.
> 
> The command checks every entry it is about to rewrite and refuses
> to start if one of them does not look like a stash commit, which
> can only happen when refs/stash was written to by hand.  Finding
> that out halfway through the sequence would lose entries.  Should a
> write-back fail anyway, the entry's object id is reported so it can
> be recovered with 'git stash store', and the command only reports
> success when the reflog ended up in the requested state.
> 
> This was proposed before: in 2010, as a "git reflog update" command
> that edited reflog entries in place [1].  When it came up again in
> 2013 [2], Junio rejected it on the grounds that reflogs are
> append-only recovery logs, and that whoever really cares about a
> stash message can pop and re-stash [3].  Michael Haggerty pointed
> out in that thread that refs/stash does not fit the description:
> its reflog is the primary data store for stash entries, and 'git
> stash drop' rewrites it all the time [4].  So this patch stays away
> from the reflog machinery entirely and does the suggested
> pop-and-re-stash workaround mechanically, without the detour
> through the working tree.

> diff --git a/Documentation/git-stash.adoc b/Documentation/git-stash.adoc
> index 50bb89f483..03f2e03096 100644
> --- a/Documentation/git-stash.adoc
> +++ b/Documentation/git-stash.adoc
> @@ -163,6 +164,12 @@ with no conflicts.
>  	created by `export`, and add them to the list of stashes.  To replace the
>  	existing stashes, use `clear` first.
>  
> +`rename [-q | --quiet] <message> [<stash>]`::
> +	Change the message of a single stash entry.  The entry keeps its
> +	position and its contents.  _<stash>_ must name an entry by
> +	index (e.g. `stash@{1}`); renaming refreshes the reflog
> +	timestamps of the entry and of the entries above it.

> diff --git a/builtin/stash.c b/builtin/stash.c
> index c4809f299a..94e66d6074 100644
> --- a/builtin/stash.c
> +++ b/builtin/stash.c
> @@ -1190,6 +1204,166 @@ out:

> +static int do_rename_stash(struct stash_info *info, size_t idx,
> +			   const char *msg, int quiet)
> +{
> +	struct rename_data data = { .want = idx + 1 };
> +	size_t i, missing = 0;
> +	int ret = -1;
> +
> +	refs_for_each_reflog_ent_reverse(get_main_ref_store(the_repository),
> +					 ref_stash, collect_rename_entries,
> +					 &data);
> +	if (data.nr <= idx) {
> +		error(_("%s does not exist"), info->revision.buf);
> +		goto cleanup;
> +	}
> +
> +	if (!oideq(&info->w_commit, &data.entries[idx].oid)) {
> +		error(_("%s changed concurrently; try again"),
> +		      info->revision.buf);
> +		goto cleanup;
> +	}
> +
> +	/* refuse up front; do_store_stash() would die halfway through */
> +	for (i = 0; i < data.nr; i++) {
> +		struct commit *stash = lookup_commit_reference(the_repository,
> +							       &data.entries[i].oid);
> +
> +		if (!stash || check_stash_topology(the_repository, stash)) {
> +			error(_("%s does not look like a stash commit"),
> +			      oid_to_hex(&data.entries[i].oid));
> +			goto cleanup;
> +		}
> +	}

> +
> +	while (missing <= idx) {
> +		if (drop_reflog_entry("stash@{0}"))
> +			goto restore;
> +		missing++;
> +	}