diff mbox series

[v2,5/8] sequencer: do not require `allow_empty` for redundant commit options

Message ID 20240210074859.552497-6-brianmlyles@gmail.com (mailing list archive)
State New, archived
Headers show
Series [1/4] sequencer: Do not require `allow_empty` for redundant commit options | expand

Commit Message

Brian Lyles Feb. 10, 2024, 7:43 a.m. UTC
A consumer of the sequencer that wishes to take advantage of either the
`keep_redundant_commits` or `drop_redundant_commits` feature must also
specify `allow_empty`. However, these refer to two distinct types of
empty commits:

- `allow_empty` refers specifically to commits which start empty
- `keep_redundant_commits` refers specifically to commits that do not
  start empty, but become empty due to the content already existing in
  the target history

Conceptually, there is no reason that the behavior for handling one of
these should be entangled with the other. It is particularly unintuitive
to require `allow_empty` in order for `drop_redundant_commits` to have
an effect: in order to prevent redundant commits automatically,
initially-empty commits would need to be kept automatically as well.

Instead, rewrite the `allow_empty()` logic to remove the over-arching
requirement that `allow_empty` be specified in order to reach any of the
keep/drop behaviors. Only if the commit was originally empty will
`allow_empty` have an effect.

Note that no behavioral changes should result from this commit -- it
merely sets the stage for future commits. In one such future commit, an
`--empty` option will be added to git-cherry-pick(1), meaning that
`drop_redundant_commits` will be used by that command.

Signed-off-by: Brian Lyles <brianmlyles@gmail.com>
---

This is the first half of the first commit[1] in v1, which has now been
split up. While the next commit may be considered somewhat
controversial, this part of the change should not be.

[1]: https://lore.kernel.org/git/20240119060721.3734775-2-brianmlyles@gmail.com/

 sequencer.c | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

Comments

Phillip Wood Feb. 22, 2024, 4:35 p.m. UTC | #1
Hi Brian

On 10/02/2024 07:43, Brian Lyles wrote:
> A consumer of the sequencer that wishes to take advantage of either the
> `keep_redundant_commits` or `drop_redundant_commits` feature must also
> specify `allow_empty`. However, these refer to two distinct types of
> empty commits:
> 
> - `allow_empty` refers specifically to commits which start empty
> - `keep_redundant_commits` refers specifically to commits that do not
>    start empty, but become empty due to the content already existing in
>    the target history
> 
> Conceptually, there is no reason that the behavior for handling one of
> these should be entangled with the other. It is particularly unintuitive
> to require `allow_empty` in order for `drop_redundant_commits` to have
> an effect: in order to prevent redundant commits automatically,
> initially-empty commits would need to be kept automatically as well.
> 
> Instead, rewrite the `allow_empty()` logic to remove the over-arching
> requirement that `allow_empty` be specified in order to reach any of the
> keep/drop behaviors. Only if the commit was originally empty will
> `allow_empty` have an effect.
> 
> Note that no behavioral changes should result from this commit -- it
> merely sets the stage for future commits.

Thanks for clarifying that. I think splitting this change out is a good 
idea. The patch looks good.

Best Wishes

Phillip

> In one such future commit, an
> `--empty` option will be added to git-cherry-pick(1), meaning that
> `drop_redundant_commits` will be used by that command.
> 
> Signed-off-by: Brian Lyles <brianmlyles@gmail.com>
> ---
> 
> This is the first half of the first commit[1] in v1, which has now been
> split up. While the next commit may be considered somewhat
> controversial, this part of the change should not be.
> 
> [1]: https://lore.kernel.org/git/20240119060721.3734775-2-brianmlyles@gmail.com/
> 
>   sequencer.c | 23 +++++++----------------
>   1 file changed, 7 insertions(+), 16 deletions(-)
> 
> diff --git a/sequencer.c b/sequencer.c
> index b1b19512de..3f41863dae 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -1725,34 +1725,25 @@ static int allow_empty(struct repository *r,
>   	int index_unchanged, originally_empty;
> 
>   	/*
> -	 * Four cases:
> +	 * For a commit that is initially empty, allow_empty determines if it
> +	 * should be kept or not
>   	 *
> -	 * (1) we do not allow empty at all and error out.
> -	 *
> -	 * (2) we allow ones that were initially empty, and
> -	 *     just drop the ones that become empty
> -	 *
> -	 * (3) we allow ones that were initially empty, but
> -	 *     halt for the ones that become empty;
> -	 *
> -	 * (4) we allow both.
> +	 * For a commit that becomes empty, keep_redundant_commits and
> +	 * drop_redundant_commits determine whether the commit should be kept or
> +	 * dropped. If neither is specified, halt.
>   	 */
> -	if (!opts->allow_empty)
> -		return 0; /* let "git commit" barf as necessary */
> -
>   	index_unchanged = is_index_unchanged(r);
>   	if (index_unchanged < 0)
>   		return index_unchanged;
>   	if (!index_unchanged)
>   		return 0; /* we do not have to say --allow-empty */
> 
> -	if (opts->keep_redundant_commits)
> -		return 1;
> -
>   	originally_empty = is_original_commit_empty(commit);
>   	if (originally_empty < 0)
>   		return originally_empty;
>   	if (originally_empty)
> +		return opts->allow_empty;
> +	else if (opts->keep_redundant_commits)
>   		return 1;
>   	else if (opts->drop_redundant_commits)
>   		return 2;
diff mbox series

Patch

diff --git a/sequencer.c b/sequencer.c
index b1b19512de..3f41863dae 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1725,34 +1725,25 @@  static int allow_empty(struct repository *r,
 	int index_unchanged, originally_empty;

 	/*
-	 * Four cases:
+	 * For a commit that is initially empty, allow_empty determines if it
+	 * should be kept or not
 	 *
-	 * (1) we do not allow empty at all and error out.
-	 *
-	 * (2) we allow ones that were initially empty, and
-	 *     just drop the ones that become empty
-	 *
-	 * (3) we allow ones that were initially empty, but
-	 *     halt for the ones that become empty;
-	 *
-	 * (4) we allow both.
+	 * For a commit that becomes empty, keep_redundant_commits and
+	 * drop_redundant_commits determine whether the commit should be kept or
+	 * dropped. If neither is specified, halt.
 	 */
-	if (!opts->allow_empty)
-		return 0; /* let "git commit" barf as necessary */
-
 	index_unchanged = is_index_unchanged(r);
 	if (index_unchanged < 0)
 		return index_unchanged;
 	if (!index_unchanged)
 		return 0; /* we do not have to say --allow-empty */

-	if (opts->keep_redundant_commits)
-		return 1;
-
 	originally_empty = is_original_commit_empty(commit);
 	if (originally_empty < 0)
 		return originally_empty;
 	if (originally_empty)
+		return opts->allow_empty;
+	else if (opts->keep_redundant_commits)
 		return 1;
 	else if (opts->drop_redundant_commits)
 		return 2;