[PATCH v4] git-contacts: allow inputting patch via stdin

[Brigham Campbell <me@brighamcampbell.com>]

Make git-contacts accept patch contents via stdin for better
interoperability with other utilities. Read from stdin when the user
passes `-` at least once:

$ git contacts - <patch

Signed-off-by: Brigham Campbell <me@brighamcampbell.com>
---
Junio, you suggested that I make git-contacts process files and stdin
with respect to the order in which they appear in argv. I instead
removed the implication that git-contacts processes input in any
particular order.

Even before this patch, git-contacts parses files first, then git
rev-lists second, regardless of their order in argv. If we instead want
git-contacts to parse arguments in the same order that they're passed,
that's a change which should occur in a separate patch.

I'm happy to write that patch if you'd like.
---
Changes in v4:
- Don't imply that git-contacts processes input in any particular order
- Link to v3: https://patch.msgid.link/20260923-git-contacts-stdin-v3-1-56dd43c64d56@brighamcampbell.com

Changes in v3:
- Make user pass '-' instead of an empty argv and non-TTY stdin
- Link to v2: https://patch.msgid.link/20260915-git-contacts-stdin-v2-1-2005061d907a@brighamcampbell.com

Changes in v2:
- Minor variable cleanup / un-spaghettification
- Include update to usage comment
- Remove Cc trailers from commit message
- Link to v1: https://patch.msgid.link/20260914-git-contacts-stdin-v1-1-9ac628e6fd20@brighamcampbell.com

To: git@vger.kernel.org
Cc: Junio C Hamano <gitster@pobox.com>
Cc: Patrick Steinhardt <ps@pks.im>
---
 contrib/contacts/git-contacts | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/contrib/contacts/git-contacts b/contrib/contacts/git-contacts
index 85ad732fc0..df7b920d9e 100755
--- a/contrib/contacts/git-contacts
+++ b/contrib/contacts/git-contacts
@@ -162,9 +162,11 @@ if (!@ARGV) {
 	die "No input revisions or patch files\n";
 }
 
-my (@files, @rev_args);
+my ($read_from_stdin, @files, @rev_args);
 for (@ARGV) {
-	if (-e) {
+	if ($_ eq '-') {
+		$read_from_stdin = 1;
+	} elsif (-e) {
 		push @files, $_;
 	} else {
 		push @rev_args, $_;
@@ -172,6 +174,9 @@ for (@ARGV) {
 }
 
 my %sources;
+if ($read_from_stdin) {
+	scan_patches(\%sources, undef, \*STDIN);
+}
 for (@files) {
 	scan_patch_file(\%sources, $_);
 }

---
base-commit: 0f8e75abebff0877cae681a3d5ff31ac47f54220
change-id: 20260914-git-contacts-stdin-1e829930e19b

Thanks!
-- 
Brigham Campbell
https://brighamcampbell.com