Subject: [BUGFIX/RFC] git-show: fix 'git show -s' to not add extra terminator after merge commit

From: Max Kirillov <[email-masked]>
Date: Mon, 12 May 2014 02:25:05 +0300

When "git show -s" is called for merge commit it prints extra newline
between any merge commit and the next one. This looks especially ugly for
--oneline and other single-line formats. Looks very much like a bug.

The code in question exists since commit 3969cf7db1. Probably the
correct condition should be in fact
"opt->output_format & DIFF_FORMAT_DIFFSTAT", but this
condition was also removed from show_log call before,
so I'm not sure about it.

Test "t7007-show" is also modified to cover this case.
---
Hi.

This actually has broken some number of existing tests
(their fix not included), and might break some existing
scripts which already expect this extra newline.

So, is it yet not too late to fix this?
 combine-diff.c  | 2 +-
 t/t7007-show.sh | 8 ++++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/combine-diff.c b/combine-diff.c
index 3b92c448..d2924de 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -1331,7 +1331,7 @@ void diff_tree_combined(const unsigned char *sha1,
 		if (show_log_first && i == 0) {
 			show_log(rev);
 
-			if (rev->verbose_header && opt->output_format)
+			if (rev->verbose_header && opt->output_format && opt->output_format != DIFF_FORMAT_NO_OUTPUT)
 				printf("%s%c", diff_line_prefix(opt),
 				       opt->line_termination);
 		}
diff --git a/t/t7007-show.sh b/t/t7007-show.sh
index e41fa00..d76c7db 100755
--- a/t/t7007-show.sh
+++ b/t/t7007-show.sh
@@ -25,6 +25,7 @@ test_expect_success 'set up a bit of history' '
 	git checkout -b side HEAD^^ &&
 	test_commit side2 &&
 	test_commit side3
+	test_merge merge main3
 '
 
 test_expect_success 'showing two commits' '
@@ -109,8 +110,11 @@ test_expect_success 'showing range' '
 '
 
 test_expect_success '-s suppresses diff' '
-	echo main3 >expect &&
-	git show -s --format=%s main3 >actual &&
+	cat >expect <<-EOF &&
+	merge
+	main3
+	EOF
+	git show -s --format=%s merge main3 >actual &&
 	test_cmp expect actual
 '
 
-- 
1.8.5.2.421.g4cdf8d0