[PATCH v13 0/3] am: support --empty=(die|drop|keep) option and --allow-empty option to handle empty patches

Since that git has supported the --always option for the git-format-patch
command to create a patch with an empty commit message, git-am should
support applying and committing with empty patches.

----------------------------------------------------------------------------

Changes since v1:

 1. add a case when not passing the --always option.
 2. rename the --always option to --allow-empty.

----------------------------------------------------------------------------

Changes since v2:

 1. rename the --allow-empty option to --empty-commit.
 2. introduce three different strategies (die|skip|asis) when trying to
    record empty patches as empty commits.

----------------------------------------------------------------------------

Changes since v3:

 1. generate the missed file for test cases.
 2. grep -f cannot be used under Mac OS.

----------------------------------------------------------------------------

Changes since v4:

 1. rename the --empty-commit option to --empty.
 2. rename three different strategies (die|skip|asis) to die, drop and keep
    correspondingly.

----------------------------------------------------------------------------

Changes since v5:

 1. throw an error when passing --empty option without value.

----------------------------------------------------------------------------

Changes since v6:

 1. add i18n resources.

----------------------------------------------------------------------------

Changes since v7:

 1. update code according to the seen branch.
 2. fix the wrong document of git-am.
 3. sign off commits by a real name.

----------------------------------------------------------------------------

Changes since v8:

 1. update the committer's name with my real name to fix DCO of GGG.

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Changes since v9:

 1. imitate the signed name format of
    https://lore.kernel.org/git/pull.1143.git.git.1637347813367.gitgitgadget@gmail.com (local)
    .

----------------------------------------------------------------------------

Changes since v11:

 1. introduce an interactive option --allow-empty for git-am to record empty
    patches in the middle of an am session.

----------------------------------------------------------------------------

Changes since v12:

 1. record the empty patch as an empty commit only when there are no
    changes.
 2. fix indentation problems.
 3. simplify "to keep recording" to "to record".
 4. add a test case for skipping empty patches via the --skip option.

徐沛文 (Aleen) (3):
  doc: git-format-patch: describe the option --always
  am: support --empty=<option> to handle empty patches
  am: support --allow-empty to record specific empty patches

 Documentation/git-am.txt           | 14 ++++-
 Documentation/git-format-patch.txt |  6 ++-
 builtin/am.c                       | 82 +++++++++++++++++++++++++-----
 t/t4150-am.sh                      | 73 ++++++++++++++++++++++++++
 t/t7512-status-help.sh             |  1 +
 wt-status.c                        |  3 ++
 6 files changed, 164 insertions(+), 15 deletions(-)


base-commit: abe6bb3905392d5eb6b01fa6e54d7e784e0522aa
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1076%2Faleen42%2Fnext-v13
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1076/aleen42/next-v13
Pull-Request: https://github.com/gitgitgadget/git/pull/1076

Range-diff vs v12:

 1:  a524ca6adfa = 1:  a524ca6adfa doc: git-format-patch: describe the option --always
 2:  a3e850bab7d = 2:  a3e850bab7d am: support --empty=<option> to handle empty patches
 3:  d44dac09c87 ! 3:  08bd397ae7a am: support --allow-empty to record specific empty patches
     @@ Documentation/git-am.txt: default.   You can use `--no-utf8` to override this.
       	Defaults to `raw`.
       
      +--allow-empty::
     -+	Keep recording the empty patch as an empty commit with
     ++	Record the empty patch as an empty commit with
      +	the contents of the e-mail message as its log.
      +
       DISCUSSION
     @@ builtin/am.c: static void am_run(struct am_state *state, int resume)
       			case DIE_EMPTY_COMMIT:
      -				printf_ln(_("Patch is empty."));
      +				printf_ln(_("Patch is empty.\n"
     -+							"If you want to keep recording it, run \"git am --allow-empty\"."));
     ++					    "If you want to record it as an empty commit, run \"git am --allow-empty\"."));
       				die_user_resolve(state);
       				break;
       			}
     @@ builtin/am.c: next:
        * all the hard work, and we do not have to do any patch application. Just
      - * trust and commit what the user has in the index and working tree.
      + * trust and commit what the user has in the index and working tree. If `allow_empty`
     -+ * is true, commit as an empty commit.
     ++ * is true, commit as an empty commit when there is no changes.
        */
      -static void am_resolve(struct am_state *state)
      +static void am_resolve(struct am_state *state, int allow_empty)
       {
     -+	if (allow_empty) {
     -+		goto commit;
     -+	}
     -+
       	validate_resume_state(state);
       
       	say(state, stdout, _("Applying: %.*s"), linelen(state->msg), state->msg);
     -@@ builtin/am.c: static void am_resolve(struct am_state *state)
     - 
     - 	repo_rerere(the_repository, 0);
       
     -+commit:
     - 	do_commit(state);
     + 	if (!repo_index_has_changes(the_repository, NULL, NULL)) {
     +-		printf_ln(_("No changes - did you forget to use 'git add'?\n"
     +-			"If there is nothing left to stage, chances are that something else\n"
     +-			"already introduced the same changes; you might want to skip this patch."));
     +-		die_user_resolve(state);
     ++		if (allow_empty)
     ++			printf_ln(_("No changes - record it as an empty commit."));
     ++		else {
     ++			printf_ln(_("No changes - did you forget to use 'git add'?\n"
     ++				    "If there is nothing left to stage, chances are that something else\n"
     ++				    "already introduced the same changes; you might want to skip this patch."));
     ++			die_user_resolve(state);
     ++		}
     + 	}
       
     - next:
     + 	if (unmerged_cache()) {
      @@ builtin/am.c: enum resume_type {
       	RESUME_SKIP,
       	RESUME_ABORT,
     @@ builtin/am.c: int cmd_am(int argc, const char **argv, const char *prefix)
       		  PARSE_OPT_CMDMODE | PARSE_OPT_OPTARG | PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP,
       		  parse_opt_show_current_patch, RESUME_SHOW_PATCH },
      +		OPT_CMDMODE(0, "allow-empty", &resume.mode,
     -+			N_("keep recording the empty patch as empty commits"),
     ++			N_("record the empty patch as an empty commit"),
      +			RESUME_ALLOW_EMPTY),
       		OPT_BOOL(0, "committer-date-is-author-date",
       			&state.committer_date_is_author_date,
     @@ builtin/am.c: int cmd_am(int argc, const char **argv, const char *prefix)
       		break;
       	case RESUME_RESOLVED:
      -		am_resolve(&state);
     -+		am_resolve(&state, 0);
     -+		break;
      +	case RESUME_ALLOW_EMPTY:
     -+		am_resolve(&state, 1);
     ++		am_resolve(&state, resume.mode == RESUME_ALLOW_EMPTY ? 1 : 0);
       		break;
       	case RESUME_SKIP:
       		am_skip(&state);
     @@ t/t4150-am.sh: test_expect_success 'record as an empty commit when meeting e-mai
       	test_cmp actual expected
       '
       
     ++test_expect_success 'skip an empty patch in the middle of an am session' '
     ++	git checkout empty-commit^ &&
     ++	test_must_fail git am empty-commit.patch >err &&
     ++	grep "Patch is empty." err &&
     ++	grep "If you want to record it as an empty commit, run \"git am --allow-empty\"." err &&
     ++	git am --skip &&
     ++	test_path_is_missing .git/rebase-apply &&
     ++	git rev-parse empty-commit^ >expected &&
     ++	git rev-parse HEAD >actual &&
     ++	test_cmp expected actual
     ++'
      +
     -+test_expect_success 'record as an empty commit in the middle of an am session' '
     ++test_expect_success 'record an empty patch as an empty commit in the middle of an am session' '
      +	git checkout empty-commit^ &&
      +	test_must_fail git am empty-commit.patch >err &&
      +	grep "Patch is empty." err &&
     -+	grep "If you want to keep recording it, run \"git am --allow-empty\"." err &&
     ++	grep "If you want to record it as an empty commit, run \"git am --allow-empty\"." err &&
      +	git am --allow-empty &&
     ++	test_path_is_missing .git/rebase-apply &&
      +	git show empty-commit --format="%s" >expected &&
      +	git show HEAD --format="%s" >actual &&
      +	test_cmp actual expected
     @@ t/t7512-status-help.sh: test_expect_success 'status in an am session: empty patc
       On branch am_empty
       You are in the middle of an am session.
       The current patch is empty.
     -+  (use "git am --allow-empty" to keep recording this empty patch)
     ++  (use "git am --allow-empty" to record this patch as an empty commit)
         (use "git am --skip" to skip this patch)
         (use "git am --abort" to restore the original branch)
       
     @@ wt-status.c: static void show_am_in_progress(struct wt_status *s,
       				_("  (fix conflicts and then run \"git am --continue\")"));
      +		else
      +			status_printf_ln(s, color,
     -+				_("  (use \"git am --allow-empty\" to keep recording this empty patch)"));
     ++				_("  (use \"git am --allow-empty\" to record this patch as an empty commit)"));
       		status_printf_ln(s, color,
       			_("  (use \"git am --skip\" to skip this patch)"));
       		status_printf_ln(s, color,

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