commit: Add -f, --fixes <commit> option to add Fixes: linejt/commit-fixes-footer

Linux Kernel Summit 2013 decided on a commit message convention to
identify commits containing bugs fixed by a commit: a "Fixes:" line,
included in the standard commit footer (along with "Signed-off-by:" if
present), containing an abbreviated commit hash (at least 12 characters
to keep it valid for a long time) and the subject of the commit (for
human readers).  This helps people (or automated tools) determine how
far to backport a commit.

Add a command line option for git commit to automatically construct the
"Fixes:" line for a commit.  This avoids the need to manually construct
that line by copy-pasting the commit hash and subject.

Also works with --amend to modify an existing commit's message.  To add
a Fixes line to an earlier commit in a series, use rebase -i and add the
following line after the existing commit:
x git commit --amend --no-edit --fixes $commit_containing_bug

Generalize append_signoff to support appending arbitrary extra lines to
a commit in the signoff block; this avoids duplicating the logic to find
or construct that block.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 36 insertions, 1 deletions

diff --git a/t/t7502-commit.sh b/t/t7502-commit.sh
index 6313da2cdd..d00f2f1cb1 100755
--- a/t/t7502-commit.sh
+++ b/t/t7502-commit.sh
@@ -137,13 +137,48 @@ test_expect_success 'partial removal' '
 
 '
 
+signoff_ident () {
+	git var GIT_COMMITTER_IDENT | sed -e "s/>.*/>/"
+}
+
 test_expect_success 'sign off' '
 
 	>positive &&
 	git add positive &&
 	git commit -s -m "thank you" &&
 	actual=$(git cat-file commit HEAD | sed -ne "s/Signed-off-by: //p") &&
-	expected=$(git var GIT_COMMITTER_IDENT | sed -e "s/>.*/>/") &&
+	expected=$(signoff_ident) &&
+	test "z$actual" = "z$expected"
+
+'
+
+fixes_for_commits () {
+	git -c core.abbrev=12 show -s --format="Fixes: %h (%s)" "$@"
+}
+
+test_expect_success '--fixes' '
+
+	echo >>positive &&
+	git add positive &&
+	git commit --fixes HEAD -m "fix bug" &&
+	actual=$(git cat-file commit HEAD | sed -e "1,/^\$/d") &&
+	expected=$(echo fix bug; echo; fixes_for_commits HEAD^) &&
+	test "z$actual" = "z$expected"
+
+'
+
+test_expect_success 'multiple --fixes with signoff' '
+
+	echo >>positive &&
+	git add positive &&
+	git commit --fixes HEAD^ --fixes HEAD -s -m "signed bugfix" &&
+	actual=$(git cat-file commit HEAD | sed -e "1,/^\$/d") &&
+	expected=$(
+		echo signed bugfix
+		echo
+		echo "Signed-off-by: $(signoff_ident)"
+		fixes_for_commits HEAD^^ HEAD^
+	) &&
 	test "z$actual" = "z$expected"
 
 '