[PATCH v2] format-patch: fix From header in cover letter

[Mirko Faina <mroik@delayed.space>]

"git format-patch" takes "--from=<user ident>" command line option and
uses the given ident for patch e-mails, but this is not applied to the
cover letter, the option is ignored and the committer ident of the
current user is used.

Teach the make_cover_letter() function to honor the option, instead of
always using the current committer identity.

Signed-off-by: Mirko Faina <mroik@delayed.space>
---
I'm sorry about the poor quality of the previous commit message, I
realise it did a poor job at explaining what the patch did.

I've applied the changes you suggested and wrote the test.
Thank you for the review.

 builtin/log.c           |  6 +++---
 t/t4014-format-patch.sh | 12 ++++++++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/builtin/log.c b/builtin/log.c
index d43ca693bf..42648dda54 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1332,7 +1332,7 @@ static void make_cover_letter(struct rev_info *rev, int use_separate_file,
 			      int quiet,
 			      const struct format_config *cfg)
 {
-	const char *committer;
+	const char *from;
 	struct shortlog log;
 	struct strbuf sb = STRBUF_INIT;
 	int i;
@@ -1345,7 +1345,7 @@ static void make_cover_letter(struct rev_info *rev, int use_separate_file,
 	if (!cmit_fmt_is_mail(rev->commit_format))
 		die(_("cover letter needs email format"));
 
-	committer = git_committer_info(0);
+	from = cfg->from ? cfg->from : git_committer_info(0);
 
 	if (use_separate_file &&
 	    open_next_file(NULL, rev->numbered_files ? NULL : "cover-letter", rev, quiet))
@@ -1368,7 +1368,7 @@ static void make_cover_letter(struct rev_info *rev, int use_separate_file,
 	pp.date_mode.type = DATE_RFC2822;
 	pp.rev = rev;
 	pp.encode_email_headers = rev->encode_email_headers;
-	pp_user_info(&pp, NULL, &sb, committer, encoding);
+	pp_user_info(&pp, NULL, &sb, from, encoding);
 	prepare_cover_text(&pp, description_file, branch_name, &sb,
 			   encoding, need_8bit_cte, cfg);
 	fprintf(rev->diffopt.file, "%s\n", sb.buf);
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 21d6d0cd9e..cb04a9c47b 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -1472,6 +1472,18 @@ test_expect_success '--from uses committer ident' '
 	test_cmp expect patch.head
 '
 
+test_expect_success '--from applies to cover letter' '
+	echo "This is a test text" >file_to_commit &&
+	git format-patch -1 --stdout --cover-letter --from="Foo Bar <author@example.com>" >patch &&
+	cat >expect <<-\EOF &&
+	From: Foo Bar <author@example.com>
+	From: Foo Bar <author@example.com>
+	From: A U Thor <author@example.com>
+	EOF
+	sed -ne "/^From:/p; /^[[:space:]]$/d" patch >patch.head &&
+	test_cmp expect patch.head
+'
+
 test_expect_success '--from omits redundant in-body header' '
 	git format-patch -1 --stdout --from="A U Thor <author@example.com>" >patch &&
 	cat >expect <<-\EOF &&
-- 
2.53.0