Re: [PATCH v3 3/4] format-patch: introduce --base=auto option

[Junio C Hamano <gitster@pobox.com>]

Xiaolong Ye <xiaolong.ye@intel.com> writes:

> Introduce --base=auto to record the base commit info automatically, the base_commit
> will be the merge base of tip commit of the upstream branch and revision-range
> specified in cmdline.

This line is probably a bit too long.

>
> Helped-by: Junio C Hamano <gitster@pobox.com>
> Helped-by: Wu Fengguang <fengguang.wu@intel.com>
> Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com>
> ---
>  Documentation/git-format-patch.txt |  4 ++++
>  builtin/log.c                      | 31 +++++++++++++++++++++++++++----
>  2 files changed, 31 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
> index 067d562..d8fe651 100644
> --- a/Documentation/git-format-patch.txt
> +++ b/Documentation/git-format-patch.txt
> @@ -290,6 +290,10 @@ you can use `--suffix=-patch` to get `0001-description-of-my-change-patch`.
>  	patches for A, B and C, and the identifiers for P, X, Y, Z are appended
>  	at the end of the _first_ message.
>  
> +	If set '--base=auto' in cmdline, it will track base commit automatically,
> +	the base commit will be the merge base of tip commit of the remote-tracking
> +	branch and revision-range specified in cmdline.
> +
>  --root::
>  	Treat the revision argument as a <revision range>, even if it
>  	is just a single commit (that would normally be treated as a
> diff --git a/builtin/log.c b/builtin/log.c
> index 03cbab0..c5efe73 100644
> --- a/builtin/log.c
> +++ b/builtin/log.c
> @@ -1200,6 +1200,9 @@ static void prepare_bases(struct base_tree_info *bases,
>  	struct rev_info revs;
>  	struct diff_options diffopt;
>  	struct object_id *patch_id;
> +	struct branch *curr_branch;
> +	struct commit_list *base_list;
> +	const char *upstream;
>  	unsigned char sha1[20];
>  	int i;
>  
> @@ -1207,10 +1210,30 @@ static void prepare_bases(struct base_tree_info *bases,
>  	DIFF_OPT_SET(&diffopt, RECURSIVE);
>  	diff_setup_done(&diffopt);
>  
> -	base = lookup_commit_reference_by_name(base_commit);
> -	if (!base)
> -		die(_("Unknown commit %s"), base_commit);
> -	oidcpy(&bases->base_commit, &base->object.oid);
> +	if (!strcmp(base_commit, "auto")) {
> +		curr_branch = branch_get(NULL);

Can branch_get() return NULL?  Which ...

> +		upstream = branch_get_upstream(curr_branch, NULL);

... would cause branch_get_upstream() to give you an error (which
you ignore)?  I guess that is OK because upstream will safely be set
to NULL in that case.

> +		if (upstream) {
> +			if (get_sha1(upstream, sha1))
> +				die(_("Failed to resolve '%s' as a valid ref."), upstream);
> +			commit = lookup_commit_or_die(sha1, "upstream base");
> +			base_list = get_merge_bases_many(commit, total, list);
> +			if (!bases)
> +				die(_("Could not find merge base."));
> +			base = base_list->item;
> +			free_commit_list(base_list);

What should happen when there are multiple merge bases?  The code
picks one at random and ignores the remainder, if I am reading this
correctly.

> +			oidcpy(&bases->base_commit, &base->object.oid);
> +		} else {
> +			die(_("Failed to get upstream, if you want to record base commit automatically,\n"
> +			      "please use git branch --set-upstream-to to track a remote branch.\n"
> +			      "Or you could specify base commit by --base=<base-commit-id> manually."));
> +		}
> +	} else {
> +		base = lookup_commit_reference_by_name(base_commit);
> +		if (!base)
> +			die(_("Unknown commit %s"), base_commit);
> +		oidcpy(&bases->base_commit, &base->object.oid);
> +	}
>  
>  	init_revisions(&revs, NULL);
>  	revs.max_parents = 1;