Allow edit of empty message with commit --amend

"git commit --amend" used on a commit with an empty message fails
unless -m is given, whether or not --allow-empty-message is
specified.

Allow it to proceed to the editor with an empty commit message.
Unless --allow-empty-message is in force, it will still abort later
if an empty message is saved from the editor (this check was
already necessary to prevent a non-empty commit message being edited
to an empty one).

Add a test for --amend --edit of an empty commit message which fails
without this fix, as it's a rare case that won't get frequently
tested otherwise.

Signed-off-by: Chris Webb <chris@arachsys.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/commit.c b/builtin/commit.c
index eae5a29aeb4248b972f97632026993c25d5e03da..4b4e7e797f407953b097f05784b55d320f4c4a52 100644 (file)
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -690,7 +690,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
                hook_arg1 = "message";
        } else if (use_message) {
                buffer = strstr(use_message_buffer, "\n\n");
-               if (!buffer || buffer[2] == '\0')
+               if (!use_editor && (!buffer || buffer[2] == '\0'))
                        die(_("commit has empty message"));
                strbuf_add(&sb, buffer + 2, strlen(buffer + 2));
                hook_arg1 = "commit";

diff --git a/t/t7501-commit.sh b/t/t7501-commit.sh
index 8bb38337a9796142bc091c2b108f7f9e79b0f377..19593f8fbabf944a3319da8630d80b804d98ca91 100755 (executable)
--- a/t/t7501-commit.sh
+++ b/t/t7501-commit.sh
@@ -124,6 +124,21 @@ test_expect_success '--amend --edit' '
        test_cmp expect msg
 '
 
+test_expect_success '--amend --edit of empty message' '
+       cat >replace <<-\EOF &&
+       #!/bin/sh
+       echo "amended" >"$1"
+       EOF
+       chmod 755 replace &&
+       git commit --allow-empty --allow-empty-message -m "" &&
+       echo more bongo >file &&
+       git add file &&
+       EDITOR=./replace git commit --edit --amend &&
+       git diff-tree -s --format=%s HEAD >msg &&
+       ./replace expect &&
+       test_cmp expect msg
+'
+
 test_expect_success '-m --edit' '
        echo amended >expect &&
        git commit --allow-empty -m buffer &&