[PATCH v2] format-patch: respect --stat in cover letter's diffstat

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Commit 43662b23ab (format-patch: keep cover-letter diffstat wrapped in
72 columns - 2018-01-24) uncondtionally sets stat width to 72 when
generating diffstat for the cover letter, ignoring --stat from command
line. But it should only do so when stat width is still default
(i.e. stat_width == 0).

In order to fix this, we should only set stat_width if stat_width is
zero. But it will never be. Commit 071dd0ba43 (format-patch: reduce
patch diffstat width to 72 - 2018-02-01) makes sure that default stat
width will be 72 (ignoring $COLUMNS, but could still be overriden by
--stat). So all we need to do here is drop the assignment.

Reported-by: Laszlo Ersek <lersek@redhat.com>
Helped-by: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/log.c          |  2 --
 t/t4052-stat-output.sh | 48 +++++++++++++++++++++++++++++-------------
 2 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/builtin/log.c b/builtin/log.c
index 061d4fd864..1a39c6e52a 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1009,8 +1009,6 @@ static void show_diffstat(struct rev_info *rev,
 
 	memcpy(&opts, &rev->diffopt, sizeof(opts));
 	opts.output_format = DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
-	opts.stat_width = MAIL_DEFAULT_WRAP;
-
 	diff_setup_done(&opts);
 
 	diff_tree_oid(get_commit_tree_oid(origin),
diff --git a/t/t4052-stat-output.sh b/t/t4052-stat-output.sh
index 6e2cf933f7..28c053849a 100755
--- a/t/t4052-stat-output.sh
+++ b/t/t4052-stat-output.sh
@@ -44,42 +44,50 @@ show --stat
 log -1 --stat
 EOF
 
-while read cmd args
+cat >expect.60 <<-'EOF'
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaaaa | 1 +
+EOF
+cat >expect.6030 <<-'EOF'
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaa | 1 +
+EOF
+cat >expect2.60 <<-'EOF'
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaaaa | 1 +
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaaaa | 1 +
+EOF
+cat >expect2.6030 <<-'EOF'
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaa | 1 +
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaa | 1 +
+EOF
+while read expect cmd args
 do
-	cat >expect <<-'EOF'
-	 ...aaaaaaaaaaaaaaaaaaaaaaaaaaaaa | 1 +
-	EOF
 	test_expect_success "$cmd --stat=width: a long name is given more room when the bar is short" '
 		git $cmd $args --stat=40 >output &&
 		grep " | " output >actual &&
-		test_cmp expect actual
+		test_cmp $expect.60 actual
 	'
 
 	test_expect_success "$cmd --stat-width=width with long name" '
 		git $cmd $args --stat-width=40 >output &&
 		grep " | " output >actual &&
-		test_cmp expect actual
+		test_cmp $expect.60 actual
 	'
 
-	cat >expect <<-'EOF'
-	 ...aaaaaaaaaaaaaaaaaaaaaaaaaaa | 1 +
-	EOF
 	test_expect_success "$cmd --stat=...,name-width with long name" '
 		git $cmd $args --stat=60,30 >output &&
 		grep " | " output >actual &&
-		test_cmp expect actual
+		test_cmp $expect.6030 actual
 	'
 
 	test_expect_success "$cmd --stat-name-width with long name" '
 		git $cmd $args --stat-name-width=30 >output &&
 		grep " | " output >actual &&
-		test_cmp expect actual
+		test_cmp $expect.6030 actual
 	'
 done <<\EOF
-format-patch -1 --stdout
-diff HEAD^ HEAD --stat
-show --stat
-log -1 --stat
+expect2 format-patch --cover-letter -1 --stdout
+expect diff HEAD^ HEAD --stat
+expect show --stat
+expect log -1 --stat
 EOF
 
 
@@ -95,6 +103,16 @@ test_expect_success 'preparation for big change tests' '
 	git commit -m message abcd
 '
 
+cat >expect72 <<'EOF'
+ abcd | 1000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ abcd | 1000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+EOF
+test_expect_success "format-patch --cover-letter ignores COLUMNS (big change)" '
+	COLUMNS=200 git format-patch -1 --stdout --cover-letter >output &&
+	grep " | " output >actual &&
+	test_cmp expect72 actual
+'
+
 cat >expect72 <<'EOF'
  abcd | 1000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 EOF
-- 
2.19.1.1005.gac84295441