[PATCH] Teach merge the '[-e|--edit]' option

[Jay Soffian <jaysoffian@gmail.com>]

Implement "git merge [-e|--edit]" as "git merge --no-commit && git commit"
as a convenience for the user.

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
---
 Documentation/merge-options.txt |    6 ++++++
 builtin/merge.c                 |   14 ++++++++++++++
 t/t7600-merge.sh                |   15 +++++++++++++++
 3 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/Documentation/merge-options.txt b/Documentation/merge-options.txt
index b613d4ed08..6bd0b041c3 100644
--- a/Documentation/merge-options.txt
+++ b/Documentation/merge-options.txt
@@ -7,6 +7,12 @@ With --no-commit perform the merge but pretend the merge
 failed and do not autocommit, to give the user a chance to
 inspect and further tweak the merge result before committing.
 
+--edit::
+-e::
++
+	Invoke editor before committing successful merge to further
+	edit the default merge message.
+
 --ff::
 --no-ff::
 	Do not generate a merge commit if the merge resolved as
diff --git a/builtin/merge.c b/builtin/merge.c
index ee56974371..815e151487 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -46,6 +46,7 @@ static const char * const builtin_merge_usage[] = {
 
 static int show_diffstat = 1, shortlog_len, squash;
 static int option_commit = 1, allow_fast_forward = 1;
+static int option_edit = 0;
 static int fast_forward_only;
 static int allow_trivial = 1, have_message;
 static struct strbuf merge_msg;
@@ -190,6 +191,8 @@ static struct option builtin_merge_options[] = {
 		"create a single commit instead of doing a merge"),
 	OPT_BOOLEAN(0, "commit", &option_commit,
 		"perform a commit if the merge succeeds (default)"),
+	OPT_BOOLEAN('e', "edit", &option_edit,
+		"edit message before committing"),
 	OPT_BOOLEAN(0, "ff", &allow_fast_forward,
 		"allow fast-forward (default)"),
 	OPT_BOOLEAN(0, "ff-only", &fast_forward_only,
@@ -1092,6 +1095,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		option_commit = 0;
 	}
 
+	/* if not committing, edit is nonsensical */
+	if (!option_commit)
+		option_edit = 0;
+	/* if editing, invoke 'git commit -e' after successful merge */
+	if (option_edit)
+		option_commit = 0;
+
 	if (!allow_fast_forward && fast_forward_only)
 		die(_("You cannot combine --no-ff with --ff-only."));
 
@@ -1447,6 +1457,10 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	}
 
 	if (merge_was_ok) {
+		if (option_edit) {
+			const char *args[] = {"commit", "-e", NULL};
+			return run_command_v_opt(args, RUN_GIT_CMD);
+		}
 		fprintf(stderr, _("Automatic merge went well; "
 			"stopped before committing as requested\n"));
 		return 0;
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 87aac835a1..8c6b811718 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -643,4 +643,19 @@ test_expect_success 'amending no-ff merge commit' '
 
 test_debug 'git log --graph --decorate --oneline --all'
 
+cat >editor <<\EOF
+#!/bin/sh
+# strip comments and blank lines from end of message
+sed -e '/^#/d' < "$1" | sed -e :a -e '/^\n*$/{$d;N;ba' -e '}' > expected
+EOF
+chmod 755 editor
+
+test_expect_success 'merge --no-ff --edit' '
+	git reset --hard c0 &&
+	EDITOR=./editor git merge --no-ff --edit c1 &&
+	verify_parents $c0 $c1 &&
+	git cat-file commit HEAD | sed "1,/^$/d" > actual &&
+	test_cmp actual expected
+'
+
 test_done
-- 
1.7.7.147.g00fdf