"Phillip Wood via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes:
> From: Phillip Wood <phillip.wood@xxxxxxxxxxxxx>
>
> Separate out calculating the merge base between onto and head from the
> check for whether we can fast-forward or not. This means we can skip
> the fast-forward checks when the rebase is forced and avoid
> calculating the merge-base twice when --keep-base is given.
>
> Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx>
> ---
> Note the unnecessary braces around "if (keep_base)" are added here
> reduce the churn on the next commit.
> ---
> builtin/rebase.c | 35 +++++++++++++++++++++++------------
> 1 file changed, 23 insertions(+), 12 deletions(-)
>
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 6cf9c95f4e1..86ea731ca3a 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -871,13 +871,9 @@ static int can_fast_forward(struct commit *onto, struct commit *upstream,
> struct commit_list *merge_bases = NULL;
> int res = 0;
>
> - merge_bases = get_merge_bases(onto, head);
> - if (!merge_bases || merge_bases->next) {
> - oidcpy(merge_base, null_oid());
> + if (is_null_oid(merge_base))
> goto done;
> - }
>
> - oidcpy(merge_base, &merge_bases->item->object.oid);
> if (!oideq(merge_base, &onto->object.oid))
> goto done;
Looking at the change in "git show -W", it seems that this function
no longer touches merge_bases at all, other than initializing it to
NULL at the beginning and then calling free_commit_list() on it at
the end. Shouldn't it be removed?
> @@ -902,6 +898,20 @@ done:
> return res && is_linear_history(onto, head);
> }
>
> +static void fill_merge_base(struct rebase_options *options,
> + struct object_id *merge_base)
> +{
> + struct commit_list *merge_bases = NULL;
> +
> + merge_bases = get_merge_bases(options->onto, options->orig_head);
> + if (!merge_bases || merge_bases->next)
> + oidcpy(merge_base, null_oid());
> + else
> + oidcpy(merge_base, &merge_bases->item->object.oid);
> +
> + free_commit_list(merge_bases);
> +}
> +
> static int parse_opt_am(const struct option *opt, const char *arg, int unset)
> {
> struct rebase_options *opts = opt->value;
> @@ -1668,7 +1678,11 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
> die(_("Does not point to a valid commit '%s'"),
> options.onto_name);
> }
> -
> + if (keep_base) {
> + oidcpy(&merge_base, &options.onto->object.oid);
> + } else {
> + fill_merge_base(&options, &merge_base);
> + }
No need for braces around single-statement block on either side.
This is not a new issue introduced by this patch per-se, but
"merge_base" is becoming less and less accurate description of what
this variable really is. Perhaps it is a good time to rename it?
It is "the base commit to rebuild the history on top of", aka "onto
commit", isn't it? We often use merge-base between the upstream and
our tip of the history for it, but the variable often does not even
hold the merge-base in it, not because we cannot compute a single
merge-base but because depending on the operation mode we do not
want to use merge-base for further operation using that variable.
