[PATCH 2/2] send-email: add support for --mailmap

[Jacob Keller <jacob.e.keller@intel.com>]

From: Jacob Keller <jacob.keller@gmail.com>

In certain cases, a user may be generating a patch for an old commit
which now has an out-of-date author or other identity. For example,
consider a team member who contributes to an internal fork of a project,
and then later leaves the company.

It may be desired to submit this change upstream, but the author
identity now points to an invalid email address which will bounce. This
is likely to annoy users who respond to the email on the public mailing
list.

This can be manually corrected, but requires a bit of effort, as it may
require --suppress-cc or otherwise formatting a patch separately and
manually removing any unintended email addresses.

Git already has support for the mailmap, which allows mapping addresses
for old commits to new canonical names and addresses.

Teach git send-email the --mailmap option. When supplied, use git
check-mailmap (with the --no-brackets mode) as a final stage when
processing address lists. This will convert all addresses to their
canonical name and email according to the mailmap file.

A mailmap file can then be configured to point the invalid addresses
either to their current canonical email (if they still participate in
the open source project), or possibly to new owner within the company.

This enables the sender to avoid accidentally listing an invalid address
when sending such a change.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
---
 git-send-email.perl   | 14 ++++++++++++++
 t/t9001-send-email.sh | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/git-send-email.perl b/git-send-email.perl
index 72044e5ef3a8..9a081e9f9b41 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -46,6 +46,8 @@ sub usage {
     --compose-encoding      <str>  * Encoding to assume for introduction.
     --8bit-encoding         <str>  * Encoding to assume 8bit mails if undeclared
     --transfer-encoding     <str>  * Transfer encoding to use (quoted-printable, 8bit, base64)
+    --[no-]mailmap                 * Use mailmap file to map all email addresses to canonical
+                                     real names and email addresses.
 
   Sending:
     --envelope-sender       <str>  * Email envelope sender.
@@ -278,6 +280,7 @@ sub do_edit {
 my $chain_reply_to = 0;
 my $use_xmailer = 1;
 my $validate = 1;
+my $mailmap = 0;
 my $target_xfer_encoding = 'auto';
 my $forbid_sendmail_variables = 1;
 
@@ -524,6 +527,8 @@ sub config_regexp {
 		    "thread!" => \$thread,
 		    "validate!" => \$validate,
 		    "transfer-encoding=s" => \$target_xfer_encoding,
+		    "mailmap!" => \$mailmap,
+		    "use-mailmap!" => \$mailmap,
 		    "format-patch!" => \$format_patch,
 		    "8bit-encoding=s" => \$auto_8bit_encoding,
 		    "compose-encoding=s" => \$compose_encoding,
@@ -1085,6 +1090,14 @@ sub expand_one_alias {
 our ($message_id, %mail, $subject, $in_reply_to, $references, $message,
 	$needs_confirm, $message_num, $ask_default);
 
+sub mailmap_address_list {
+	my @addr_list = @_;
+	if ($mailmap and @addr_list) {
+		@addr_list = Git::command('check-mailmap', '--no-brackets', @_);
+	}
+	return @addr_list;
+}
+
 sub extract_valid_address {
 	my $address = shift;
 	my $local_part_regexp = qr/[^<>"\s@]+/;
@@ -1294,6 +1307,7 @@ sub process_address_list {
 	@addr_list = expand_aliases(@addr_list);
 	@addr_list = sanitize_address_list(@addr_list);
 	@addr_list = validate_address_list(@addr_list);
+	@addr_list = mailmap_address_list(@addr_list);
 	return @addr_list;
 }
 
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index 64a4ab3736ef..185697d22563 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -2379,6 +2379,55 @@ test_expect_success $PREREQ 'leading and trailing whitespaces are removed' '
 	test_cmp expected-list actual-list
 '
 
+test_expect_success $PREREQ 'mailmap support with --to' '
+	clean_fake_sendmail &&
+	test_config mailmap.file "mailmap.test" &&
+	cat >mailmap.test <<-EOF &&
+	Some Body <someone@example.com> <someone@example.org>
+	EOF
+	git format-patch --stdout -1 >a.patch &&
+	git send-email \
+		--from="Example <nobody@example.com>" \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		--to=someone@example.org \
+		--mailmap \
+		a.patch \
+		2>errors >out &&
+	grep "^!someone@example\.com!$" commandline1
+'
+
+test_expect_success $PREREQ 'mailmap support in To header' '
+	clean_fake_sendmail &&
+	test_config mailmap.file "mailmap.test" &&
+	cat >mailmap.test <<-EOF &&
+	<someone@example.com> <someone@example.org>
+	EOF
+	git format-patch --stdout -1 --to=someone@example.org >a.patch &&
+	git send-email \
+		--from="Example <nobody@example.com>" \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		--mailmap \
+		a.patch \
+		2>errors >out &&
+	grep "^!someone@example\.com!$" commandline1
+'
+
+test_expect_success $PREREQ 'mailmap support in Cc header' '
+	clean_fake_sendmail &&
+	test_config mailmap.file "mailmap.test" &&
+	cat >mailmap.test <<-EOF &&
+	<someone@example.com> <someone@example.org>
+	EOF
+	git format-patch --stdout -1 --cc=someone@example.org >a.patch &&
+	git send-email \
+		--from="Example <nobody@example.com>" \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		--mailmap \
+		a.patch \
+		2>errors >out &&
+	grep "^!someone@example\.com!$" commandline1
+'
+
 test_expect_success $PREREQ 'test using command name with --sendmail-cmd' '
 	clean_fake_sendmail &&
 	PATH="$PWD:$PATH" \

-- 
2.46.0.124.g2dc1a81c8933