Re: [PATCH v2 5/5] format-patch: pick up branch description when no ref is specified

Nguyễn Thái Ngọc Duy  [off-list ref] writes:

This hashcmp() is to make sure that the tip we _guessed_ with
dwim_ref() that the user meant matches what we are going to use, so
I do not think disabling the check is a good idea.

You could (and I think you should) do something like this:

	if (0 <= positive) {
        	ref = rev->cmdline.rev[positive].name;
                tip_sha1 = rev->cmdline.rev[positive].item->sha1;
	} else if (... defaulted to implied HEAD? ...) {
		ref = "HEAD";
                tip_sha1 = rev->pending.objects[0].item->sha1;
	} else {
		return NULL;
	}

        if (dwim_ref(...) && !prefixcmp(full_ref, "refs/heads/") &&
            !hashcmp(tip_sha1, branch_sha1))

to preserve that safety instead.

We only try to get branch name in "format-patch origin" case or
similar and not "format-patch -22" where HEAD is automatically
added. Without correct branch name, branch description cannot be
added. Make sure we always get branch name.

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 On Thu, Jan 3, 2013 at 10:49 PM, Junio C Hamano [off-list ref] wrote:
 > You could (and I think you should) do something like this:
 >
 >         if (0 <= positive) {
 >                 ref = rev->cmdline.rev[positive].name;
 >                 tip_sha1 = rev->cmdline.rev[positive].item->sha1;
 >         } else if (... defaulted to implied HEAD? ...) {
 >                 ref = "HEAD";
 >                 tip_sha1 = rev->pending.objects[0].item->sha1;
 >         } else {
 >                 return NULL;
 >         }
 >
 >         if (dwim_ref(...) && !prefixcmp(full_ref, "refs/heads/") &&
 >             !hashcmp(tip_sha1, branch_sha1))
 >
 > to preserve that safety instead.

 Good idea. Done.

 builtin/log.c           | 18 +++++++++++++++---
 t/t4014-format-patch.sh |  7 +++++++
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/builtin/log.c b/builtin/log.c
index 039bf67..72a368a 100644
--- a/builtin/log.c
+++ b/builtin/log.c

@@ -1016,6 +1016,7 @@ static char *find_branch_name(struct rev_info *rev)
 {
 	int i, positive = -1;
 	unsigned char branch_sha1[20];
+	const unsigned char *tip_sha1;
 	const char *ref;
 	char *full_ref, *branch = NULL;
 

@@ -1027,12 +1028,23 @@ static char *find_branch_name(struct rev_info *rev)
 		else
 			return NULL;
 	}
-	if (positive < 0)
+	if (0 <= positive) {
+		ref = rev->cmdline.rev[positive].name;
+		tip_sha1 = rev->cmdline.rev[positive].item->sha1;
+	} else if (!rev->cmdline.nr && rev->pending.nr == 1 &&
+		   !strcmp(rev->pending.objects[0].name, "HEAD")) {
+		/*
+		 * No actual ref from command line, but "HEAD" from
+		 * rev->def was added in setup_revisions()
+		 * e.g. format-patch --cover-letter -12
+		 */
+		ref = "HEAD";
+		tip_sha1 = rev->pending.objects[0].item->sha1;
+	} else
 		return NULL;
-	ref = rev->cmdline.rev[positive].name;
 	if (dwim_ref(ref, strlen(ref), branch_sha1, &full_ref) &&
 	    !prefixcmp(full_ref, "refs/heads/") &&
-	    !hashcmp(rev->cmdline.rev[positive].item->sha1, branch_sha1))
+	    !hashcmp(tip_sha1, branch_sha1))
 		branch = xstrdup(full_ref + strlen("refs/heads/"));
 	free(full_ref);
 	return branch;

diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 903a797..7e52941 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh

@@ -998,4 +998,11 @@ test_expect_success 'cover letter using branch description (5)' '
 	grep hello actual >/dev/null
 '
 
+test_expect_success 'cover letter using branch description (6)' '
+	git checkout rebuild-1 &&
+	test_config branch.rebuild-1.description hello &&
+	git format-patch --stdout --cover-letter -2 >actual &&
+	grep hello actual >/dev/null
+'
+
 test_done

-- 
1.8.0.rc2.23.g1fb49df