Merge branch 'nd/rebase-show-current-patch'

The new "--show-current-patch" option gives an end-user facing way
to get the diff being applied when "git rebase" (and "git am")
stops with a conflict.

* nd/rebase-show-current-patch:
  rebase: introduce and use pseudo-ref REBASE_HEAD
  rebase: add --show-current-patch
  am: add --show-current-patch

Documentation/git-am.txt

@@ -16,7 +16,7 @@ SYNOPSIS
 	 [--exclude=<path>] [--include=<path>] [--reject] [-q | --quiet]
 	 [--[no-]scissors] [-S[<keyid>]] [--patch-format=<format>]
 	 [(<mbox> | <Maildir>)...]
-'git am' (--continue | --skip | --abort | --quit)
+'git am' (--continue | --skip | --abort | --quit | --show-current-patch)
 
 DESCRIPTION
 -----------
@@ -171,6 +171,10 @@ default.   You can use `--no-utf8` to override this.
 	Abort the patching operation but keep HEAD and the index
 	untouched.
 
+--show-current-patch::
+	Show the patch being applied when "git am" is stopped because
+	of conflicts.
+
 DISCUSSION
 ----------
 

Documentation/git-rebase.txt

@@ -12,7 +12,7 @@ SYNOPSIS
 	[<upstream> [<branch>]]
 'git rebase' [-i | --interactive] [options] [--exec <cmd>] [--onto <newbase>]
 	--root [<branch>]
-'git rebase' --continue | --skip | --abort | --quit | --edit-todo
+'git rebase' --continue | --skip | --abort | --quit | --edit-todo | --show-current-patch
 
 DESCRIPTION
 -----------
@@ -255,6 +255,11 @@ leave out at most one of A and B, in which case it defaults to HEAD.
 --edit-todo::
 	Edit the todo list during an interactive rebase.
 
+--show-current-patch::
+	Show the current patch in an interactive rebase or when rebase
+	is stopped because of conflicts. This is the equivalent of
+	`git show REBASE_HEAD`.
+
 -m::
 --merge::
 	Use merging strategies to rebase.  When the recursive (default) merge

builtin/am.c

@@ -1011,6 +1011,7 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 
 	if (mkdir(state->dir, 0777) < 0 && errno != EEXIST)
 		die_errno(_("failed to create directory '%s'"), state->dir);
+	delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
 
 	if (split_mail(state, patch_format, paths, keep_cr) < 0) {
 		am_destroy(state);
@@ -1110,6 +1111,7 @@ static void am_next(struct am_state *state)
 
 	oidclr(&state->orig_commit);
 	unlink(am_path(state, "original-commit"));
+	delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
 
 	if (!get_oid("HEAD", &head))
 		write_state_text(state, "abort-safety", oid_to_hex(&head));
@@ -1441,6 +1443,8 @@ static int parse_mail_rebase(struct am_state *state, const char *mail)
 
 	oidcpy(&state->orig_commit, &commit_oid);
 	write_state_text(state, "original-commit", oid_to_hex(&commit_oid));
+	update_ref("am", "REBASE_HEAD", &commit_oid,
+		   NULL, REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 
 	return 0;
 }
@@ -1831,8 +1835,7 @@ static void am_run(struct am_state *state, int resume)
 			git_config_get_bool("advice.amworkdir", &advice_amworkdir);
 
 			if (advice_amworkdir)
-				printf_ln(_("The copy of the patch that failed is found in: %s"),
-						am_path(state, "patch"));
+				printf_ln(_("Use 'git am --show-current-patch' to see the failed patch"));
 
 			die_user_resolve(state);
 		}
@@ -2121,6 +2124,34 @@ static void am_abort(struct am_state *state)
 	am_destroy(state);
 }
 
+static int show_patch(struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+	const char *patch_path;
+	int len;
+
+	if (!is_null_oid(&state->orig_commit)) {
+		const char *av[4] = { "show", NULL, "--", NULL };
+		char *new_oid_str;
+		int ret;
+
+		av[1] = new_oid_str = xstrdup(oid_to_hex(&state->orig_commit));
+		ret = run_command_v_opt(av, RUN_GIT_CMD);
+		free(new_oid_str);
+		return ret;
+	}
+
+	patch_path = am_path(state, msgnum(state));
+	len = strbuf_read_file(&sb, patch_path, 0);
+	if (len < 0)
+		die_errno(_("failed to read '%s'"), patch_path);
+
+	setup_pager();
+	write_in_full(1, sb.buf, sb.len);
+	strbuf_release(&sb);
+	return 0;
+}
+
 /**
  * parse_options() callback that validates and sets opt->value to the
  * PATCH_FORMAT_* enum value corresponding to `arg`.
@@ -2150,7 +2181,8 @@ enum resume_mode {
 	RESUME_RESOLVED,
 	RESUME_SKIP,
 	RESUME_ABORT,
-	RESUME_QUIT
+	RESUME_QUIT,
+	RESUME_SHOW_PATCH
 };
 
 static int git_am_config(const char *k, const char *v, void *cb)
@@ -2172,6 +2204,7 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 	int patch_format = PATCH_FORMAT_UNKNOWN;
 	enum resume_mode resume = RESUME_FALSE;
 	int in_progress;
+	int ret = 0;
 
 	const char * const usage[] = {
 		N_("git am [<options>] [(<mbox> | <Maildir>)...]"),
@@ -2253,6 +2286,9 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		OPT_CMDMODE(0, "quit", &resume,
 			N_("abort the patching operation but keep HEAD where it is."),
 			RESUME_QUIT),
+		OPT_CMDMODE(0, "show-current-patch", &resume,
+			N_("show the patch being applied."),
+			RESUME_SHOW_PATCH),
 		OPT_BOOL(0, "committer-date-is-author-date",
 			&state.committer_date_is_author_date,
 			N_("lie about committer date")),
@@ -2367,11 +2403,14 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		am_rerere_clear();
 		am_destroy(&state);
 		break;
+	case RESUME_SHOW_PATCH:
+		ret = show_patch(&state);
+		break;
 	default:
 		die("BUG: invalid resume value");
 	}
 
 	am_state_release(&state);
 
-	return 0;
+	return ret;
 }

contrib/completion/git-completion.bash

@@ -439,7 +439,7 @@ __git_refs ()
 			track=""
 			;;
 		*)
-			for i in HEAD FETCH_HEAD ORIG_HEAD MERGE_HEAD; do
+			for i in HEAD FETCH_HEAD ORIG_HEAD MERGE_HEAD REBASE_HEAD; do
 				case "$i" in
 				$match*)
 					if [ -e "$dir/$i" ]; then
@@ -1077,7 +1077,7 @@ _git_am ()
 {
 	__git_find_repo_path
 	if [ -d "$__git_repo_path"/rebase-apply ]; then
-		__gitcomp "--skip --continue --resolved --abort --quit"
+		__gitcomp "--skip --continue --resolved --abort --quit --show-current-patch"
 		return
 	fi
 	case "$cur" in
@@ -1992,11 +1992,11 @@ _git_rebase ()
 {
 	__git_find_repo_path
 	if [ -f "$__git_repo_path"/rebase-merge/interactive ]; then
-		__gitcomp "--continue --skip --abort --quit --edit-todo"
+		__gitcomp "--continue --skip --abort --quit --edit-todo --show-current-patch"
 		return
 	elif [ -d "$__git_repo_path"/rebase-apply ] || \
 	     [ -d "$__git_repo_path"/rebase-merge ]; then
-		__gitcomp "--continue --skip --abort --quit"
+		__gitcomp "--continue --skip --abort --quit --show-current-patch"
 		return
 	fi
 	__git_complete_strategy && return

git-rebase--am.sh

@@ -27,6 +27,9 @@ skip)
 	move_to_original_branch
 	return
 	;;
+show-current-patch)
+	exec git am --show-current-patch
+	;;
 esac
 
 if test -z "$rebase_root"

git-rebase--interactive.sh

@@ -199,12 +199,14 @@ make_patch () {
 
 die_with_patch () {
 	echo "$1" > "$state_dir"/stopped-sha
+	git update-ref REBASE_HEAD "$1"
 	make_patch "$1"
 	die "$2"
 }
 
 exit_with_patch () {
 	echo "$1" > "$state_dir"/stopped-sha
+	git update-ref REBASE_HEAD "$1"
 	make_patch $1
 	git rev-parse --verify HEAD > "$amend"
 	gpg_sign_opt_quoted=${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")}
@@ -844,6 +846,9 @@ To continue rebase after editing, run:
 
 	exit
 	;;
+show-current-patch)
+	exec git show REBASE_HEAD --
+	;;
 esac
 
 comment_for_reflog start
@@ -859,6 +864,7 @@ fi
 
 orig_head=$(git rev-parse --verify HEAD) || die "$(gettext "No HEAD?")"
 mkdir -p "$state_dir" || die "$(eval_gettext "Could not create temporary \$state_dir")"
+rm -f "$(git rev-parse --git-path REBASE_HEAD)"
 
 : > "$state_dir"/interactive || die "$(gettext "Could not mark as interactive")"
 write_basic_state

git-rebase--merge.sh

@@ -58,6 +58,7 @@ call_merge () {
 	echo "$msgnum" >"$state_dir/msgnum"
 	cmt="$(cat "$state_dir/cmt.$msgnum")"
 	echo "$cmt" > "$state_dir/current"
+	git update-ref REBASE_HEAD "$cmt"
 	hd=$(git rev-parse --verify HEAD)
 	cmt_name=$(git symbolic-ref HEAD 2> /dev/null || echo HEAD)
 	eval GITHEAD_$cmt='"${cmt_name##refs/heads/}~$(($end - $msgnum))"'
@@ -138,11 +139,15 @@ skip)
 	finish_rb_merge
 	return
 	;;
+show-current-patch)
+	exec git show REBASE_HEAD --
+	;;
 esac
 
 mkdir -p "$state_dir"
 echo "$onto_name" > "$state_dir/onto_name"
 write_basic_state
+rm -f "$(git rev-parse --git-path REBASE_HEAD)"
 
 msgnum=0
 for cmt in $(git rev-list --reverse --no-merges "$revisions")

git-rebase.sh

@@ -46,6 +46,7 @@ abort!             abort and check out the original branch
 skip!              skip current patch and continue
 edit-todo!         edit the todo list during an interactive rebase
 quit!              abort but keep HEAD where it is
+show-current-patch! show the patch file being applied or merged
 "
 . git-sh-setup
 set_reflog_action rebase
@@ -183,6 +184,7 @@ You can run "git stash pop" or "git stash drop" at any time.
 }
 
 finish_rebase () {
+	rm -f "$(git rev-parse --git-path REBASE_HEAD)"
 	apply_autostash &&
 	{ git gc --auto || true; } &&
 	rm -rf "$state_dir"
@@ -247,7 +249,7 @@ do
 	--verify)
 		ok_to_skip_pre_rebase=
 		;;
-	--continue|--skip|--abort|--quit|--edit-todo)
+	--continue|--skip|--abort|--quit|--edit-todo|--show-current-patch)
 		test $total_argc -eq 2 || usage
 		action=${1##--}
 		;;
@@ -417,6 +419,10 @@ quit)
 edit-todo)
 	run_specific_rebase
 	;;
+show-current-patch)
+	run_specific_rebase
+	die "BUG: run_specific_rebase is not supposed to return here"
+	;;
 esac
 
 # Make sure no rebase is in progress

sequencer.c

@@ -2314,6 +2314,9 @@ static int make_patch(struct commit *commit, struct replay_opts *opts)
 	p = short_commit_name(commit);
 	if (write_message(p, strlen(p), rebase_path_stopped_sha(), 1) < 0)
 		return -1;
+	if (update_ref("rebase", "REBASE_HEAD", &commit->object.oid,
+		       NULL, REF_NO_DEREF, UPDATE_REFS_MSG_ON_ERR))
+		res |= error(_("could not update %s"), "REBASE_HEAD");
 
 	strbuf_addf(&buf, "%s/patch", get_dir(opts));
 	memset(&log_tree_opt, 0, sizeof(log_tree_opt));
@@ -2565,6 +2568,7 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
 			unlink(rebase_path_author_script());
 			unlink(rebase_path_stopped_sha());
 			unlink(rebase_path_amend());
+			delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
 		}
 		if (item->command <= TODO_SQUASH) {
 			if (is_rebase_i(opts))

t/t3400-rebase.sh

@@ -277,4 +277,38 @@ EOF
 	test_cmp From_.msg out
 '
 
+test_expect_success 'rebase--am.sh and --show-current-patch' '
+	test_create_repo conflict-apply &&
+	(
+		cd conflict-apply &&
+		test_commit init &&
+		echo one >>init.t &&
+		git commit -a -m one &&
+		echo two >>init.t &&
+		git commit -a -m two &&
+		git tag two &&
+		test_must_fail git rebase --onto init HEAD^ &&
+		GIT_TRACE=1 git rebase --show-current-patch >/dev/null 2>stderr &&
+		grep "show.*$(git rev-parse two)" stderr
+	)
+'
+
+test_expect_success 'rebase--merge.sh and --show-current-patch' '
+	test_create_repo conflict-merge &&
+	(
+		cd conflict-merge &&
+		test_commit init &&
+		echo one >>init.t &&
+		git commit -a -m one &&
+		echo two >>init.t &&
+		git commit -a -m two &&
+		git tag two &&
+		test_must_fail git rebase --merge --onto init HEAD^ &&
+		git rebase --show-current-patch >actual.patch &&
+		GIT_TRACE=1 git rebase --show-current-patch >/dev/null 2>stderr &&
+		grep "show.*REBASE_HEAD" stderr &&
+		test "$(git rev-parse REBASE_HEAD)" = "$(git rev-parse two)"
+	)
+'
+
 test_done

t/t3404-rebase-interactive.sh

@@ -225,6 +225,14 @@ test_expect_success 'stop on conflicting pick' '
 	test 0 = $(grep -c "^[^#]" < .git/rebase-merge/git-rebase-todo)
 '
 
+test_expect_success 'show conflicted patch' '
+	GIT_TRACE=1 git rebase --show-current-patch >/dev/null 2>stderr &&
+	grep "show.*REBASE_HEAD" stderr &&
+	# the original stopped-sha1 is abbreviated
+	stopped_sha1="$(git rev-parse $(cat ".git/rebase-merge/stopped-sha"))" &&
+	test "$(git rev-parse REBASE_HEAD)" = "$stopped_sha1"
+'
+
 test_expect_success 'abort' '
 	git rebase --abort &&
 	test $(git rev-parse new-branch1) = $(git rev-parse HEAD) &&

t/t4150-am.sh

@@ -662,6 +662,11 @@ test_expect_success 'am pauses on conflict' '
 	test -d .git/rebase-apply
 '
 
+test_expect_success 'am --show-current-patch' '
+	git am --show-current-patch >actual.patch &&
+	test_cmp .git/rebase-apply/0001 actual.patch
+'
+
 test_expect_success 'am --skip works' '
 	echo goodbye >expected &&
 	git am --skip &&