[PATCH v2] Add option to git-commit to allow empty log messages

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change git-commit(1) to accept a --allow-empty-message option
analogous to the existing --allow-empty option which allows empty
trees. This is mainly for compatability with foreign SCM systems.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-commit.txt          |    6 +++++
 builtin/commit.c                      |    7 +++--
 t/t7510-commit-allow-empty-message.sh |   41 +++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 3 deletions(-)
 create mode 100755 t/t7510-commit-allow-empty-message.sh

diff --git a/Documentation/git-commit.txt b/Documentation/git-commit.txt
index 64fb458..aa18bee 100644
--- a/Documentation/git-commit.txt
+++ b/Documentation/git-commit.txt
@@ -131,6 +131,12 @@ OPTIONS
 	from making such a commit.  This option bypasses the safety, and
 	is primarily for use by foreign scm interface scripts.
 
+--allow-empty-message::
+       Like --allow-empty this command is primarily for use by foreign
+       scm interface scripts. It allows you to create a commit with an
+       empty commit message without using plumbing commands like
+       linkgit:git-commit-tree[1].
+
 --cleanup=<mode>::
 	This option sets how the commit message is cleaned up.
 	The  '<mode>' can be one of 'verbatim', 'whitespace', 'strip',
diff --git a/builtin/commit.c b/builtin/commit.c
index c5ab683..7fd963e 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -65,8 +65,8 @@ static const char *template_file;
 static char *edit_message, *use_message;
 static char *author_name, *author_email, *author_date;
 static int all, edit_flag, also, interactive, only, amend, signoff;
-static int quiet, verbose, no_verify, allow_empty, dry_run, renew_authorship;
-static int no_post_rewrite;
+static int quiet, verbose, no_verify, allow_empty, allow_empty_message, dry_run;
+static int no_post_rewrite, renew_authorship;
 static char *untracked_files_arg, *force_date;
 /*
  * The default commit message cleanup mode will remove the lines
@@ -141,6 +141,7 @@ static struct option builtin_commit_options[] = {
 	OPT_BOOLEAN(0, "no-post-rewrite", &no_post_rewrite, "bypass post-rewrite hook"),
 	{ OPTION_STRING, 'u', "untracked-files", &untracked_files_arg, "mode", "show untracked files, optional modes: all, normal, no. (Default: all)", PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
 	OPT_BOOLEAN(0, "allow-empty", &allow_empty, "ok to record an empty change"),
+	OPT_BOOLEAN(0, "allow-empty-message", &allow_empty_message, "ok to record a change with an empty message"),
 	/* end commit contents options */
 
 	OPT_END()
@@ -1293,7 +1294,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 
 	if (cleanup_mode != CLEANUP_NONE)
 		stripspace(&sb, cleanup_mode == CLEANUP_ALL);
-	if (message_is_empty(&sb)) {
+	if (message_is_empty(&sb) && !allow_empty_message) {
 		rollback_index_files();
 		fprintf(stderr, "Aborting commit due to empty commit message.\n");
 		exit(1);
diff --git a/t/t7510-commit-allow-empty-message.sh b/t/t7510-commit-allow-empty-message.sh
new file mode 100755
index 0000000..d7dc0da
--- /dev/null
+++ b/t/t7510-commit-allow-empty-message.sh
@@ -0,0 +1,41 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Ævar Arnfjörð Bjarmason
+#
+
+test_description='git commit --allow-empty-message'
+
+. ./test-lib.sh
+
+commit_msg_is () {
+	test "`git log --pretty=format:%s%b -1`" = "$1"
+}
+
+# A sanity check to see if commit is working at all.
+test_expect_success 'a basic commit in an empty tree should succeed' '
+	(
+		echo content > foo &&
+		git add foo &&
+		git commit -m "initial commit"
+	) &&
+	commit_msg_is "initial commit"
+'
+
+test_expect_success 'Commit no message with --allow-empty-message' '
+	(
+		echo "more content" >> foo &&
+		git add foo &&
+		printf "" | git commit --allow-empty-message
+	) &&
+	commit_msg_is ""
+'
+
+test_expect_success 'Commit a message with --allow-empty-message' '
+	(
+		echo "even more content" >> foo &&
+		git add foo &&
+		git commit --allow-empty-message -m"hello there"
+	) &&
+	commit_msg_is "hello there"
+'
+test_done
-- 
1.7.0.4.298.gc81d