Merge branch 'dl/merge-autostash'

"git merge" learns the "--autostash" option.

* dl/merge-autostash: (22 commits)
  pull: pass --autostash to merge
  t5520: make test_pull_autostash() accept expect_parent_num
  merge: teach --autostash option
  sequencer: implement apply_autostash_oid()
  sequencer: implement save_autostash()
  sequencer: unlink autostash in apply_autostash()
  sequencer: extract perform_autostash() from rebase
  rebase: generify create_autostash()
  rebase: extract create_autostash()
  reset: extract reset_head() from rebase
  rebase: generify reset_head()
  rebase: use apply_autostash() from sequencer.c
  sequencer: rename stash_sha1 to stash_oid
  sequencer: make apply_autostash() accept a path
  rebase: use read_oneliner()
  sequencer: make read_oneliner() extern
  sequencer: configurably warn on non-existent files
  sequencer: make read_oneliner() accept flags
  sequencer: make file exists check more efficient
  sequencer: stop leaking buf
  ...

Documentation/config/merge.txt

@@ -70,6 +70,16 @@ merge.stat::
 	Whether to print the diffstat between ORIG_HEAD and the merge result
 	at the end of the merge.  True by default.
 
+merge.autoStash::
+	When set to true, automatically create a temporary stash entry
+	before the operation begins, and apply it after the operation
+	ends.  This means that you can run merge on a dirty worktree.
+	However, use with care: the final stash application after a
+	successful merge might result in non-trivial conflicts.
+	This option can be overridden by the `--no-autostash` and
+	`--autostash` options of linkgit:git-merge[1].
+	Defaults to false.
+
 merge.tool::
 	Controls which merge tool is used by linkgit:git-mergetool[1].
 	The list below shows the valid built-in values.

Documentation/git-merge.txt

@@ -94,7 +94,8 @@ will be appended to the specified message.
 
 --abort::
 	Abort the current conflict resolution process, and
-	try to reconstruct the pre-merge state.
+	try to reconstruct the pre-merge state. If an autostash entry is
+	present, apply it to the worktree.
 +
 If there were uncommitted worktree changes present when the merge
 started, 'git merge --abort' will in some cases be unable to
@@ -102,11 +103,15 @@ reconstruct these changes. It is therefore recommended to always
 commit or stash your changes before running 'git merge'.
 +
 'git merge --abort' is equivalent to 'git reset --merge' when
-`MERGE_HEAD` is present.
+`MERGE_HEAD` is present unless `MERGE_AUTOSTASH` is also present in
+which case 'git merge --abort' applies the stash entry to the worktree
+whereas 'git reset --merge' will save the stashed changes in the stash
+reflog.
 
 --quit::
 	Forget about the current merge in progress. Leave the index
-	and the working tree as-is.
+	and the working tree as-is. If `MERGE_AUTOSTASH` is present, the
+	stash entry will be saved to the stash reflog.
 
 --continue::
 	After a 'git merge' stops due to conflicts you can conclude the

Documentation/git-pull.txt

@@ -134,15 +134,6 @@ unless you have read linkgit:git-rebase[1] carefully.
 --no-rebase::
 	Override earlier --rebase.
 
---autostash::
---no-autostash::
-	Before starting rebase, stash local modifications away (see
-	linkgit:git-stash[1]) if needed, and apply the stash entry when
-	done. `--no-autostash` is useful to override the `rebase.autoStash`
-	configuration variable (see linkgit:git-config[1]).
-+
-This option is only valid when "--rebase" is used.
-
 Options related to fetching
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

Documentation/merge-options.txt

@@ -160,6 +160,14 @@ ifndef::git-pull[]
 
 endif::git-pull[]
 
+--autostash::
+--no-autostash::
+	Automatically create a temporary stash entry before the operation
+	begins, and apply it after the operation ends.  This means
+	that you can run the operation on a dirty worktree.  However, use
+	with care: the final stash application after a successful
+	merge might result in non-trivial conflicts.
+
 --allow-unrelated-histories::
 	By default, `git merge` command refuses to merge histories
 	that do not share a common ancestor.  This option can be

Makefile

@@ -610,8 +610,8 @@ SCRIPT_SH += git-web--browse.sh
 SCRIPT_LIB += git-mergetool--lib
 SCRIPT_LIB += git-parse-remote
 SCRIPT_LIB += git-rebase--preserve-merges
-SCRIPT_LIB += git-sh-setup
 SCRIPT_LIB += git-sh-i18n
+SCRIPT_LIB += git-sh-setup
 
 SCRIPT_PERL += git-add--interactive.perl
 SCRIPT_PERL += git-archimport.perl
@@ -679,9 +679,9 @@ PROGRAM_OBJS += daemon.o
 PROGRAM_OBJS += fast-import.o
 PROGRAM_OBJS += http-backend.o
 PROGRAM_OBJS += imap-send.o
+PROGRAM_OBJS += remote-testsvn.o
 PROGRAM_OBJS += sh-i18n--envsubst.o
 PROGRAM_OBJS += shell.o
-PROGRAM_OBJS += remote-testsvn.o
 
 # Binary suffix, set to .exe for Windows builds
 X =
@@ -703,15 +703,16 @@ TEST_BUILTINS_OBJS += test-dump-untracked-cache.o
 TEST_BUILTINS_OBJS += test-example-decorate.o
 TEST_BUILTINS_OBJS += test-genrandom.o
 TEST_BUILTINS_OBJS += test-genzeros.o
+TEST_BUILTINS_OBJS += test-hash-speed.o
 TEST_BUILTINS_OBJS += test-hash.o
 TEST_BUILTINS_OBJS += test-hashmap.o
-TEST_BUILTINS_OBJS += test-hash-speed.o
 TEST_BUILTINS_OBJS += test-index-version.o
 TEST_BUILTINS_OBJS += test-json-writer.o
 TEST_BUILTINS_OBJS += test-lazy-init-name-hash.o
 TEST_BUILTINS_OBJS += test-match-trees.o
 TEST_BUILTINS_OBJS += test-mergesort.o
 TEST_BUILTINS_OBJS += test-mktemp.o
+TEST_BUILTINS_OBJS += test-oid-array.o
 TEST_BUILTINS_OBJS += test-oidmap.o
 TEST_BUILTINS_OBJS += test-online-cpus.o
 TEST_BUILTINS_OBJS += test-parse-options.o
@@ -732,7 +733,6 @@ TEST_BUILTINS_OBJS += test-run-command.o
 TEST_BUILTINS_OBJS += test-scrap-cache-tree.o
 TEST_BUILTINS_OBJS += test-serve-v2.o
 TEST_BUILTINS_OBJS += test-sha1.o
-TEST_BUILTINS_OBJS += test-oid-array.o
 TEST_BUILTINS_OBJS += test-sha256.o
 TEST_BUILTINS_OBJS += test-sigchain.o
 TEST_BUILTINS_OBJS += test-strcmp-offset.o
@@ -742,10 +742,10 @@ TEST_BUILTINS_OBJS += test-submodule-nested-repo-config.o
 TEST_BUILTINS_OBJS += test-subprocess.o
 TEST_BUILTINS_OBJS += test-trace2.o
 TEST_BUILTINS_OBJS += test-urlmatch-normalization.o
-TEST_BUILTINS_OBJS += test-xml-encode.o
 TEST_BUILTINS_OBJS += test-wildmatch.o
 TEST_BUILTINS_OBJS += test-windows-named-pipe.o
 TEST_BUILTINS_OBJS += test-write-cache.o
+TEST_BUILTINS_OBJS += test-xml-encode.o
 
 # Do not add more tests here unless they have extra dependencies. Add
 # them in TEST_BUILTINS_OBJS above.
@@ -782,10 +782,10 @@ OTHER_PROGRAMS = git$X
 
 # what test wrappers are needed and 'install' will install, in bindir
 BINDIR_PROGRAMS_NEED_X += git
-BINDIR_PROGRAMS_NEED_X += git-upload-pack
 BINDIR_PROGRAMS_NEED_X += git-receive-pack
-BINDIR_PROGRAMS_NEED_X += git-upload-archive
 BINDIR_PROGRAMS_NEED_X += git-shell
+BINDIR_PROGRAMS_NEED_X += git-upload-archive
+BINDIR_PROGRAMS_NEED_X += git-upload-pack
 
 BINDIR_PROGRAMS_NO_X += git-cvsserver
 
@@ -825,9 +825,9 @@ LIB_OBJS += advice.o
 LIB_OBJS += alias.o
 LIB_OBJS += alloc.o
 LIB_OBJS += apply.o
-LIB_OBJS += archive.o
 LIB_OBJS += archive-tar.o
 LIB_OBJS += archive-zip.o
+LIB_OBJS += archive.o
 LIB_OBJS += argv-array.o
 LIB_OBJS += attr.o
 LIB_OBJS += base85.o
@@ -843,9 +843,9 @@ LIB_OBJS += checkout.o
 LIB_OBJS += color.o
 LIB_OBJS += column.o
 LIB_OBJS += combine-diff.o
-LIB_OBJS += commit.o
 LIB_OBJS += commit-graph.o
 LIB_OBJS += commit-reach.o
+LIB_OBJS += commit.o
 LIB_OBJS += compat/obstack.o
 LIB_OBJS += compat/terminal.o
 LIB_OBJS += config.o
@@ -859,17 +859,17 @@ LIB_OBJS += ctype.o
 LIB_OBJS += date.o
 LIB_OBJS += decorate.o
 LIB_OBJS += delta-islands.o
+LIB_OBJS += diff-delta.o
+LIB_OBJS += diff-lib.o
+LIB_OBJS += diff-no-index.o
+LIB_OBJS += diff.o
 LIB_OBJS += diffcore-break.o
 LIB_OBJS += diffcore-delta.o
 LIB_OBJS += diffcore-order.o
 LIB_OBJS += diffcore-pickaxe.o
 LIB_OBJS += diffcore-rename.o
-LIB_OBJS += diff-delta.o
-LIB_OBJS += diff-lib.o
-LIB_OBJS += diff-no-index.o
-LIB_OBJS += diff.o
-LIB_OBJS += dir.o
 LIB_OBJS += dir-iterator.o
+LIB_OBJS += dir.o
 LIB_OBJS += editor.o
 LIB_OBJS += entry.o
 LIB_OBJS += environment.o
@@ -888,7 +888,6 @@ LIB_OBJS += gpg-interface.o
 LIB_OBJS += graph.o
 LIB_OBJS += grep.o
 LIB_OBJS += hashmap.o
-LIB_OBJS += linear-assignment.o
 LIB_OBJS += help.o
 LIB_OBJS += hex.o
 LIB_OBJS += ident.o
@@ -898,9 +897,10 @@ LIB_OBJS += kwset.o
 LIB_OBJS += levenshtein.o
 LIB_OBJS += line-log.o
 LIB_OBJS += line-range.o
-LIB_OBJS += list-objects.o
-LIB_OBJS += list-objects-filter.o
+LIB_OBJS += linear-assignment.o
 LIB_OBJS += list-objects-filter-options.o
+LIB_OBJS += list-objects-filter.o
+LIB_OBJS += list-objects.o
 LIB_OBJS += ll-merge.o
 LIB_OBJS += lockfile.o
 LIB_OBJS += log-tree.o
@@ -909,32 +909,32 @@ LIB_OBJS += mailinfo.o
 LIB_OBJS += mailmap.o
 LIB_OBJS += match-trees.o
 LIB_OBJS += mem-pool.o
-LIB_OBJS += merge.o
 LIB_OBJS += merge-blobs.o
 LIB_OBJS += merge-recursive.o
+LIB_OBJS += merge.o
 LIB_OBJS += mergesort.o
 LIB_OBJS += midx.o
 LIB_OBJS += name-hash.o
 LIB_OBJS += negotiator/default.o
 LIB_OBJS += negotiator/skipping.o
-LIB_OBJS += notes.o
 LIB_OBJS += notes-cache.o
 LIB_OBJS += notes-merge.o
 LIB_OBJS += notes-utils.o
+LIB_OBJS += notes.o
 LIB_OBJS += object.o
+LIB_OBJS += oid-array.o
 LIB_OBJS += oidmap.o
 LIB_OBJS += oidset.o
-LIB_OBJS += oid-array.o
-LIB_OBJS += packfile.o
-LIB_OBJS += pack-bitmap.o
 LIB_OBJS += pack-bitmap-write.o
+LIB_OBJS += pack-bitmap.o
 LIB_OBJS += pack-check.o
 LIB_OBJS += pack-objects.o
 LIB_OBJS += pack-revindex.o
 LIB_OBJS += pack-write.o
+LIB_OBJS += packfile.o
 LIB_OBJS += pager.o
-LIB_OBJS += parse-options.o
 LIB_OBJS += parse-options-cb.o
+LIB_OBJS += parse-options.o
 LIB_OBJS += patch-delta.o
 LIB_OBJS += patch-ids.o
 LIB_OBJS += path.o
@@ -952,8 +952,9 @@ LIB_OBJS += quote.o
 LIB_OBJS += range-diff.o
 LIB_OBJS += reachable.o
 LIB_OBJS += read-cache.o
-LIB_OBJS += rebase.o
 LIB_OBJS += rebase-interactive.o
+LIB_OBJS += rebase.o
+LIB_OBJS += ref-filter.o
 LIB_OBJS += reflog-walk.o
 LIB_OBJS += refs.o
 LIB_OBJS += refs/files-backend.o
@@ -961,12 +962,12 @@ LIB_OBJS += refs/iterator.o
 LIB_OBJS += refs/packed-backend.o
 LIB_OBJS += refs/ref-cache.o
 LIB_OBJS += refspec.o
-LIB_OBJS += ref-filter.o
 LIB_OBJS += remote.o
 LIB_OBJS += replace-object.o
 LIB_OBJS += repo-settings.o
 LIB_OBJS += repository.o
 LIB_OBJS += rerere.o
+LIB_OBJS += reset.o
 LIB_OBJS += resolve-undo.o
 LIB_OBJS += revision.o
 LIB_OBJS += run-command.o
@@ -975,8 +976,8 @@ LIB_OBJS += sequencer.o
 LIB_OBJS += serve.o
 LIB_OBJS += server-info.o
 LIB_OBJS += setup.o
-LIB_OBJS += sha1-lookup.o
 LIB_OBJS += sha1-file.o
+LIB_OBJS += sha1-lookup.o
 LIB_OBJS += sha1-name.o
 LIB_OBJS += shallow.o
 LIB_OBJS += sideband.o
@@ -986,9 +987,9 @@ LIB_OBJS += stable-qsort.o
 LIB_OBJS += strbuf.o
 LIB_OBJS += streaming.o
 LIB_OBJS += string-list.o
-LIB_OBJS += submodule.o
-LIB_OBJS += submodule-config.o
 LIB_OBJS += sub-process.o
+LIB_OBJS += submodule-config.o
+LIB_OBJS += submodule.o
 LIB_OBJS += symlinks.o
 LIB_OBJS += tag.o
 LIB_OBJS += tempfile.o
@@ -1007,11 +1008,11 @@ LIB_OBJS += trace2/tr2_tgt_normal.o
 LIB_OBJS += trace2/tr2_tgt_perf.o
 LIB_OBJS += trace2/tr2_tls.o
 LIB_OBJS += trailer.o
-LIB_OBJS += transport.o
 LIB_OBJS += transport-helper.o
+LIB_OBJS += transport.o
 LIB_OBJS += tree-diff.o
-LIB_OBJS += tree.o
 LIB_OBJS += tree-walk.o
+LIB_OBJS += tree.o
 LIB_OBJS += unpack-trees.o
 LIB_OBJS += upload-pack.o
 LIB_OBJS += url.o
@@ -1051,9 +1052,9 @@ BUILTIN_OBJS += builtin/checkout.o
 BUILTIN_OBJS += builtin/clean.o
 BUILTIN_OBJS += builtin/clone.o
 BUILTIN_OBJS += builtin/column.o
+BUILTIN_OBJS += builtin/commit-graph.o
 BUILTIN_OBJS += builtin/commit-tree.o
 BUILTIN_OBJS += builtin/commit.o
-BUILTIN_OBJS += builtin/commit-graph.o
 BUILTIN_OBJS += builtin/config.o
 BUILTIN_OBJS += builtin/count-objects.o
 BUILTIN_OBJS += builtin/credential.o
@@ -1084,13 +1085,13 @@ BUILTIN_OBJS += builtin/ls-remote.o
 BUILTIN_OBJS += builtin/ls-tree.o
 BUILTIN_OBJS += builtin/mailinfo.o
 BUILTIN_OBJS += builtin/mailsplit.o
-BUILTIN_OBJS += builtin/merge.o
 BUILTIN_OBJS += builtin/merge-base.o
 BUILTIN_OBJS += builtin/merge-file.o
 BUILTIN_OBJS += builtin/merge-index.o
 BUILTIN_OBJS += builtin/merge-ours.o
 BUILTIN_OBJS += builtin/merge-recursive.o
 BUILTIN_OBJS += builtin/merge-tree.o
+BUILTIN_OBJS += builtin/merge.o
 BUILTIN_OBJS += builtin/mktag.o
 BUILTIN_OBJS += builtin/mktree.o
 BUILTIN_OBJS += builtin/multi-pack-index.o
@@ -1110,9 +1111,9 @@ BUILTIN_OBJS += builtin/read-tree.o
 BUILTIN_OBJS += builtin/rebase.o
 BUILTIN_OBJS += builtin/receive-pack.o
 BUILTIN_OBJS += builtin/reflog.o
-BUILTIN_OBJS += builtin/remote.o
 BUILTIN_OBJS += builtin/remote-ext.o
 BUILTIN_OBJS += builtin/remote-fd.o
+BUILTIN_OBJS += builtin/remote.o
 BUILTIN_OBJS += builtin/repack.o
 BUILTIN_OBJS += builtin/replace.o
 BUILTIN_OBJS += builtin/rerere.o
@@ -2331,16 +2332,16 @@ reconfigure config.mak.autogen: config.status
 endif
 
 XDIFF_OBJS += xdiff/xdiffi.o
-XDIFF_OBJS += xdiff/xprepare.o
-XDIFF_OBJS += xdiff/xutils.o
 XDIFF_OBJS += xdiff/xemit.o
+XDIFF_OBJS += xdiff/xhistogram.o
 XDIFF_OBJS += xdiff/xmerge.o
 XDIFF_OBJS += xdiff/xpatience.o
-XDIFF_OBJS += xdiff/xhistogram.o
+XDIFF_OBJS += xdiff/xprepare.o
+XDIFF_OBJS += xdiff/xutils.o
 
+VCSSVN_OBJS += vcs-svn/fast_export.o
 VCSSVN_OBJS += vcs-svn/line_buffer.o
 VCSSVN_OBJS += vcs-svn/sliding_window.o
-VCSSVN_OBJS += vcs-svn/fast_export.o
 VCSSVN_OBJS += vcs-svn/svndiff.o
 VCSSVN_OBJS += vcs-svn/svndump.o
 
@@ -3148,9 +3149,10 @@ endif
 #
 ALL_COMMANDS = $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS)
 ALL_COMMANDS += git
+ALL_COMMANDS += git-citool
+ALL_COMMANDS += git-gui
 ALL_COMMANDS += gitk
 ALL_COMMANDS += gitweb
-ALL_COMMANDS += git-gui git-citool
 
 .PHONY: check-docs
 check-docs::

branch.c

@@ -344,6 +344,7 @@ void remove_merge_branch_state(struct repository *r)
 	unlink(git_path_merge_rr(r));
 	unlink(git_path_merge_msg(r));
 	unlink(git_path_merge_mode(r));
+	save_autostash(git_path_merge_autostash(r));
 }
 
 void remove_branch_state(struct repository *r, int verbose)

builtin/commit.c

@@ -1721,6 +1721,8 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 				     &oid, flags);
 	}
 
+	apply_autostash(git_path_merge_autostash(the_repository));
+
 	UNLEAK(err);
 	UNLEAK(sb);
 	return 0;

builtin/merge.c

@@ -82,6 +82,7 @@ static int show_progress = -1;
 static int default_to_upstream = 1;
 static int signoff;
 static const char *sign_commit;
+static int autostash;
 static int no_verify;
 
 static struct strategy all_strategy[] = {
@@ -286,6 +287,7 @@ static struct option builtin_merge_options[] = {
 	OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
 	{ OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key-id"),
 	  N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
+	OPT_AUTOSTASH(&autostash),
 	OPT_BOOL(0, "overwrite-ignore", &overwrite_ignore, N_("update ignored files (default)")),
 	OPT_BOOL(0, "signoff", &signoff, N_("add Signed-off-by:")),
 	OPT_BOOL(0, "no-verify", &no_verify, N_("bypass pre-merge-commit and commit-msg hooks")),
@@ -475,6 +477,7 @@ static void finish(struct commit *head_commit,
 	/* Run a post-merge hook */
 	run_hook_le(NULL, "post-merge", squash ? "1" : "0", NULL);
 
+	apply_autostash(git_path_merge_autostash(the_repository));
 	strbuf_release(&reflog_message);
 }
 
@@ -636,6 +639,9 @@ static int git_merge_config(const char *k, const char *v, void *cb)
 		return 0;
 	} else if (!strcmp(k, "gpg.mintrustlevel")) {
 		check_trust_level = 0;
+	} else if (!strcmp(k, "merge.autostash")) {
+		autostash = git_config_bool(k, v);
+		return 0;
 	}
 
 	status = fmt_merge_msg_config(k, v, cb);
@@ -1283,6 +1289,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	if (abort_current_merge) {
 		int nargc = 2;
 		const char *nargv[] = {"reset", "--merge", NULL};
+		struct strbuf stash_oid = STRBUF_INIT;
 
 		if (orig_argc != 2)
 			usage_msg_opt(_("--abort expects no arguments"),
@@ -1291,8 +1298,17 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		if (!file_exists(git_path_merge_head(the_repository)))
 			die(_("There is no merge to abort (MERGE_HEAD missing)."));
 
+		if (read_oneliner(&stash_oid, git_path_merge_autostash(the_repository),
+		    READ_ONELINER_SKIP_IF_EMPTY))
+			unlink(git_path_merge_autostash(the_repository));
+
 		/* Invoke 'git reset --merge' */
 		ret = cmd_reset(nargc, nargv, prefix);
+
+		if (stash_oid.len)
+			apply_autostash_oid(stash_oid.buf);
+
+		strbuf_release(&stash_oid);
 		goto done;
 	}
 
@@ -1515,6 +1531,10 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			goto done;
 		}
 
+		if (autostash)
+			create_autostash(the_repository,
+					 git_path_merge_autostash(the_repository),
+					 "merge");
 		if (checkout_fast_forward(the_repository,
 					  &head_commit->object.oid,
 					  &commit->object.oid,
@@ -1581,6 +1601,11 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	if (fast_forward == FF_ONLY)
 		die(_("Not possible to fast-forward, aborting."));
 
+	if (autostash)
+		create_autostash(the_repository,
+				 git_path_merge_autostash(the_repository),
+				 "merge");
+
 	/* We are going to make a new commit. */
 	git_committer_info(IDENT_STRICT);
 

builtin/pull.c

@@ -164,7 +164,7 @@ static struct option pull_options[] = {
 		N_("verify that the named commit has a valid GPG signature"),
 		PARSE_OPT_NOARG),
 	OPT_BOOL(0, "autostash", &opt_autostash,
-		N_("automatically stash/stash pop before and after rebase")),
+		N_("automatically stash/stash pop before and after")),
 	OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 		N_("merge strategy to use"),
 		0),
@@ -695,6 +695,10 @@ static int run_merge(void)
 	argv_array_pushv(&args, opt_strategy_opts.argv);
 	if (opt_gpg_sign)
 		argv_array_push(&args, opt_gpg_sign);
+	if (opt_autostash == 0)
+		argv_array_push(&args, "--no-autostash");
+	else if (opt_autostash == 1)
+		argv_array_push(&args, "--autostash");
 	if (opt_allow_unrelated_histories > 0)
 		argv_array_push(&args, "--allow-unrelated-histories");
 
@@ -942,9 +946,6 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (get_oid("HEAD", &orig_head))
 		oidclr(&orig_head);
 
-	if (!opt_rebase && opt_autostash != -1)
-		die(_("--[no-]autostash option is only valid with --rebase."));
-
 	autostash = config_autostash;
 	if (opt_rebase) {
 		if (opt_autostash != -1)

builtin/rebase.c

@@ -27,6 +27,9 @@
 #include "branch.h"
 #include "sequencer.h"
 #include "rebase-interactive.h"
+#include "reset.h"
+
+#define DEFAULT_REFLOG_ACTION "rebase"
 
 static char const * const builtin_rebase_usage[] = {
 	N_("git rebase [-i] [options] [--exec <cmd>] "
@@ -590,15 +593,6 @@ static const char *state_dir_path(const char *filename, struct rebase_options *o
 	return path.buf;
 }
 
-/* Read one file, then strip line endings */
-static int read_one(const char *path, struct strbuf *buf)
-{
-	if (strbuf_read_file(buf, path, 0) < 0)
-		return error_errno(_("could not read '%s'"), path);
-	strbuf_trim_trailing_newline(buf);
-	return 0;
-}
-
 /* Initialize the rebase options from the state directory. */
 static int read_basic_state(struct rebase_options *opts)
 {
@@ -606,8 +600,10 @@ static int read_basic_state(struct rebase_options *opts)
 	struct strbuf buf = STRBUF_INIT;
 	struct object_id oid;
 
-	if (read_one(state_dir_path("head-name", opts), &head_name) ||
-	    read_one(state_dir_path("onto", opts), &buf))
+	if (!read_oneliner(&head_name, state_dir_path("head-name", opts),
+			   READ_ONELINER_WARN_MISSING) ||
+	    !read_oneliner(&buf, state_dir_path("onto", opts),
+			   READ_ONELINER_WARN_MISSING))
 		return -1;
 	opts->head_name = starts_with(head_name.buf, "refs/") ?
 		xstrdup(head_name.buf) : NULL;
@@ -623,9 +619,11 @@ static int read_basic_state(struct rebase_options *opts)
 	 */
 	strbuf_reset(&buf);
 	if (file_exists(state_dir_path("orig-head", opts))) {
-		if (read_one(state_dir_path("orig-head", opts), &buf))
+		if (!read_oneliner(&buf, state_dir_path("orig-head", opts),
+				   READ_ONELINER_WARN_MISSING))
 			return -1;
-	} else if (read_one(state_dir_path("head", opts), &buf))
+	} else if (!read_oneliner(&buf, state_dir_path("head", opts),
+				  READ_ONELINER_WARN_MISSING))
 		return -1;
 	if (get_oid(buf.buf, &opts->orig_head))
 		return error(_("invalid orig-head: '%s'"), buf.buf);
@@ -645,8 +643,8 @@ static int read_basic_state(struct rebase_options *opts)
 
 	if (file_exists(state_dir_path("allow_rerere_autoupdate", opts))) {
 		strbuf_reset(&buf);
-		if (read_one(state_dir_path("allow_rerere_autoupdate", opts),
-			    &buf))
+		if (!read_oneliner(&buf, state_dir_path("allow_rerere_autoupdate", opts),
+				   READ_ONELINER_WARN_MISSING))
 			return -1;
 		if (!strcmp(buf.buf, "--rerere-autoupdate"))
 			opts->allow_rerere_autoupdate = RERERE_AUTOUPDATE;
@@ -659,8 +657,8 @@ static int read_basic_state(struct rebase_options *opts)
 
 	if (file_exists(state_dir_path("gpg_sign_opt", opts))) {
 		strbuf_reset(&buf);
-		if (read_one(state_dir_path("gpg_sign_opt", opts),
-			    &buf))
+		if (!read_oneliner(&buf, state_dir_path("gpg_sign_opt", opts),
+				   READ_ONELINER_WARN_MISSING))
 			return -1;
 		free(opts->gpg_sign_opt);
 		opts->gpg_sign_opt = xstrdup(buf.buf);
@@ -668,7 +666,8 @@ static int read_basic_state(struct rebase_options *opts)
 
 	if (file_exists(state_dir_path("strategy", opts))) {
 		strbuf_reset(&buf);
-		if (read_one(state_dir_path("strategy", opts), &buf))
+		if (!read_oneliner(&buf, state_dir_path("strategy", opts),
+				   READ_ONELINER_WARN_MISSING))
 			return -1;
 		free(opts->strategy);
 		opts->strategy = xstrdup(buf.buf);
@@ -676,7 +675,8 @@ static int read_basic_state(struct rebase_options *opts)
 
 	if (file_exists(state_dir_path("strategy_opts", opts))) {
 		strbuf_reset(&buf);
-		if (read_one(state_dir_path("strategy_opts", opts), &buf))
+		if (!read_oneliner(&buf, state_dir_path("strategy_opts", opts),
+				   READ_ONELINER_WARN_MISSING))
 			return -1;
 		free(opts->strategy_opts);
 		opts->strategy_opts = xstrdup(buf.buf);
@@ -719,51 +719,6 @@ static int rebase_write_basic_state(struct rebase_options *opts)
 	return 0;
 }
 
-static int apply_autostash(struct rebase_options *opts)
-{
-	const char *path = state_dir_path("autostash", opts);
-	struct strbuf autostash = STRBUF_INIT;
-	struct child_process stash_apply = CHILD_PROCESS_INIT;
-
-	if (!file_exists(path))
-		return 0;
-
-	if (read_one(path, &autostash))
-		return error(_("Could not read '%s'"), path);
-	/* Ensure that the hash is not mistaken for a number */
-	strbuf_addstr(&autostash, "^0");
-	argv_array_pushl(&stash_apply.args,
-			 "stash", "apply", autostash.buf, NULL);
-	stash_apply.git_cmd = 1;
-	stash_apply.no_stderr = stash_apply.no_stdout =
-		stash_apply.no_stdin = 1;
-	if (!run_command(&stash_apply))
-		printf(_("Applied autostash.\n"));
-	else {
-		struct argv_array args = ARGV_ARRAY_INIT;
-		int res = 0;
-
-		argv_array_pushl(&args,
-				 "stash", "store", "-m", "autostash", "-q",
-				 autostash.buf, NULL);
-		if (run_command_v_opt(args.argv, RUN_GIT_CMD))
-			res = error(_("Cannot store %s"), autostash.buf);
-		argv_array_clear(&args);
-		strbuf_release(&autostash);
-		if (res)
-			return res;
-
-		fprintf(stderr,
-			_("Applying autostash resulted in conflicts.\n"
-			  "Your changes are safe in the stash.\n"
-			  "You can run \"git stash pop\" or \"git stash drop\" "
-			  "at any time.\n"));
-	}
-
-	strbuf_release(&autostash);
-	return 0;
-}
-
 static int finish_rebase(struct rebase_options *opts)
 {
 	struct strbuf dir = STRBUF_INIT;
@@ -771,7 +726,7 @@ static int finish_rebase(struct rebase_options *opts)
 	int ret = 0;
 
 	delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
-	apply_autostash(opts);
+	apply_autostash(state_dir_path("autostash", opts));
 	close_object_store(the_repository->objects);
 	/*
 	 * We ignore errors in 'gc --auto', since the
@@ -816,144 +771,6 @@ static void add_var(struct strbuf *buf, const char *name, const char *value)
 	}
 }
 
-#define GIT_REFLOG_ACTION_ENVIRONMENT "GIT_REFLOG_ACTION"
-
-#define RESET_HEAD_DETACH (1<<0)
-#define RESET_HEAD_HARD (1<<1)
-#define RESET_HEAD_RUN_POST_CHECKOUT_HOOK (1<<2)
-#define RESET_HEAD_REFS_ONLY (1<<3)
-#define RESET_ORIG_HEAD (1<<4)
-
-static int reset_head(struct object_id *oid, const char *action,
-		      const char *switch_to_branch, unsigned flags,
-		      const char *reflog_orig_head, const char *reflog_head)
-{
-	unsigned detach_head = flags & RESET_HEAD_DETACH;
-	unsigned reset_hard = flags & RESET_HEAD_HARD;
-	unsigned run_hook = flags & RESET_HEAD_RUN_POST_CHECKOUT_HOOK;
-	unsigned refs_only = flags & RESET_HEAD_REFS_ONLY;
-	unsigned update_orig_head = flags & RESET_ORIG_HEAD;
-	struct object_id head_oid;
-	struct tree_desc desc[2] = { { NULL }, { NULL } };
-	struct lock_file lock = LOCK_INIT;
-	struct unpack_trees_options unpack_tree_opts;
-	struct tree *tree;
-	const char *reflog_action;
-	struct strbuf msg = STRBUF_INIT;
-	size_t prefix_len;
-	struct object_id *orig = NULL, oid_orig,
-		*old_orig = NULL, oid_old_orig;
-	int ret = 0, nr = 0;
-
-	if (switch_to_branch && !starts_with(switch_to_branch, "refs/"))
-		BUG("Not a fully qualified branch: '%s'", switch_to_branch);
-
-	if (!refs_only && hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0) {
-		ret = -1;
-		goto leave_reset_head;
-	}
-
-	if ((!oid || !reset_hard) && get_oid("HEAD", &head_oid)) {
-		ret = error(_("could not determine HEAD revision"));
-		goto leave_reset_head;
-	}
-
-	if (!oid)
-		oid = &head_oid;
-
-	if (refs_only)
-		goto reset_head_refs;
-
-	memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
-	setup_unpack_trees_porcelain(&unpack_tree_opts, action);
-	unpack_tree_opts.head_idx = 1;
-	unpack_tree_opts.src_index = the_repository->index;
-	unpack_tree_opts.dst_index = the_repository->index;
-	unpack_tree_opts.fn = reset_hard ? oneway_merge : twoway_merge;
-	unpack_tree_opts.update = 1;
-	unpack_tree_opts.merge = 1;
-	init_checkout_metadata(&unpack_tree_opts.meta, switch_to_branch, oid, NULL);
-	if (!detach_head)
-		unpack_tree_opts.reset = 1;
-
-	if (repo_read_index_unmerged(the_repository) < 0) {
-		ret = error(_("could not read index"));
-		goto leave_reset_head;
-	}
-
-	if (!reset_hard && !fill_tree_descriptor(the_repository, &desc[nr++], &head_oid)) {
-		ret = error(_("failed to find tree of %s"),
-			    oid_to_hex(&head_oid));
-		goto leave_reset_head;
-	}
-
-	if (!fill_tree_descriptor(the_repository, &desc[nr++], oid)) {
-		ret = error(_("failed to find tree of %s"), oid_to_hex(oid));
-		goto leave_reset_head;
-	}
-
-	if (unpack_trees(nr, desc, &unpack_tree_opts)) {
-		ret = -1;
-		goto leave_reset_head;
-	}
-
-	tree = parse_tree_indirect(oid);
-	prime_cache_tree(the_repository, the_repository->index, tree);
-
-	if (write_locked_index(the_repository->index, &lock, COMMIT_LOCK) < 0) {
-		ret = error(_("could not write index"));
-		goto leave_reset_head;
-	}
-
-reset_head_refs:
-	reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
-	strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action : "rebase");
-	prefix_len = msg.len;
-
-	if (update_orig_head) {
-		if (!get_oid("ORIG_HEAD", &oid_old_orig))
-			old_orig = &oid_old_orig;
-		if (!get_oid("HEAD", &oid_orig)) {
-			orig = &oid_orig;
-			if (!reflog_orig_head) {
-				strbuf_addstr(&msg, "updating ORIG_HEAD");
-				reflog_orig_head = msg.buf;
-			}
-			update_ref(reflog_orig_head, "ORIG_HEAD", orig,
-				   old_orig, 0, UPDATE_REFS_MSG_ON_ERR);
-		} else if (old_orig)
-			delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
-	}
-
-	if (!reflog_head) {
-		strbuf_setlen(&msg, prefix_len);
-		strbuf_addstr(&msg, "updating HEAD");
-		reflog_head = msg.buf;
-	}
-	if (!switch_to_branch)
-		ret = update_ref(reflog_head, "HEAD", oid, orig,
-				 detach_head ? REF_NO_DEREF : 0,
-				 UPDATE_REFS_MSG_ON_ERR);
-	else {
-		ret = update_ref(reflog_head, switch_to_branch, oid,
-				 NULL, 0, UPDATE_REFS_MSG_ON_ERR);
-		if (!ret)
-			ret = create_symref("HEAD", switch_to_branch,
-					    reflog_head);
-	}
-	if (run_hook)
-		run_hook_le(NULL, "post-checkout",
-			    oid_to_hex(orig ? orig : &null_oid),
-			    oid_to_hex(oid), "1", NULL);
-
-leave_reset_head:
-	strbuf_release(&msg);
-	rollback_lock_file(&lock);
-	while (nr)
-		free((void *)desc[--nr].buffer);
-	return ret;
-}
-
 static int move_to_original_branch(struct rebase_options *opts)
 {
 	struct strbuf orig_head_reflog = STRBUF_INIT, head_reflog = STRBUF_INIT;
@@ -969,8 +786,10 @@ static int move_to_original_branch(struct rebase_options *opts)
 		    opts->head_name, oid_to_hex(&opts->onto->object.oid));
 	strbuf_addf(&head_reflog, "rebase finished: returning to %s",
 		    opts->head_name);
-	ret = reset_head(NULL, "", opts->head_name, RESET_HEAD_REFS_ONLY,
-			 orig_head_reflog.buf, head_reflog.buf);
+	ret = reset_head(the_repository, NULL, "", opts->head_name,
+			 RESET_HEAD_REFS_ONLY,
+			 orig_head_reflog.buf, head_reflog.buf,
+			 DEFAULT_REFLOG_ACTION);
 
 	strbuf_release(&orig_head_reflog);
 	strbuf_release(&head_reflog);
@@ -1058,8 +877,9 @@ static int run_am(struct rebase_options *opts)
 		free(rebased_patches);
 		argv_array_clear(&am.args);
 
-		reset_head(&opts->orig_head, "checkout", opts->head_name, 0,
-			   "HEAD", NULL);
+		reset_head(the_repository, &opts->orig_head, "checkout",
+			   opts->head_name, 0,
+			   "HEAD", NULL, DEFAULT_REFLOG_ACTION);
 		error(_("\ngit encountered an error while preparing the "
 			"patches to replay\n"
 			"these revisions:\n"
@@ -1218,7 +1038,7 @@ finished_rebase:
 	} else if (status == 2) {
 		struct strbuf dir = STRBUF_INIT;
 
-		apply_autostash(opts);
+		apply_autostash(state_dir_path("autostash", opts));
 		strbuf_addstr(&dir, opts->state_dir);
 		remove_dir_recursively(&dir, 0);
 		strbuf_release(&dir);
@@ -1459,7 +1279,6 @@ static int check_exec_cmd(const char *cmd)
 	return 0;
 }
 
-
 int cmd_rebase(int argc, const char **argv, const char *prefix)
 {
 	struct rebase_options options = REBASE_OPTIONS_INIT;
@@ -1562,8 +1381,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		{ OPTION_STRING, 'S', "gpg-sign", &gpg_sign, N_("key-id"),
 			N_("GPG-sign commits"),
 			PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
-		OPT_BOOL(0, "autostash", &options.autostash,
-			 N_("automatically stash/stash pop before and after")),
+		OPT_AUTOSTASH(&options.autostash),
 		OPT_STRING_LIST('x', "exec", &exec, N_("exec"),
 				N_("add exec lines after each commit of the "
 				   "editable list")),
@@ -1720,8 +1538,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		rerere_clear(the_repository, &merge_rr);
 		string_list_clear(&merge_rr, 1);
 
-		if (reset_head(NULL, "reset", NULL, RESET_HEAD_HARD,
-			       NULL, NULL) < 0)
+		if (reset_head(the_repository, NULL, "reset", NULL, RESET_HEAD_HARD,
+			       NULL, NULL, DEFAULT_REFLOG_ACTION) < 0)
 			die(_("could not discard worktree changes"));
 		remove_branch_state(the_repository, 0);
 		if (read_basic_state(&options))
@@ -1738,9 +1556,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 
 		if (read_basic_state(&options))
 			exit(1);
-		if (reset_head(&options.orig_head, "reset",
+		if (reset_head(the_repository, &options.orig_head, "reset",
 			       options.head_name, RESET_HEAD_HARD,
-			       NULL, NULL) < 0)
+			       NULL, NULL, DEFAULT_REFLOG_ACTION) < 0)
 			die(_("could not move back to %s"),
 			    oid_to_hex(&options.orig_head));
 		remove_branch_state(the_repository, 0);
@@ -2098,49 +1916,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		die(_("could not read index"));
 
 	if (options.autostash) {
-		struct lock_file lock_file = LOCK_INIT;
-		int fd;
-
-		fd = hold_locked_index(&lock_file, 0);
-		refresh_cache(REFRESH_QUIET);
-		if (0 <= fd)
-			repo_update_index_if_able(the_repository, &lock_file);
-		rollback_lock_file(&lock_file);
-
-		if (has_unstaged_changes(the_repository, 1) ||
-		    has_uncommitted_changes(the_repository, 1)) {
-			const char *autostash =
-				state_dir_path("autostash", &options);
-			struct child_process stash = CHILD_PROCESS_INIT;
-			struct object_id oid;
-
-			argv_array_pushl(&stash.args,
-					 "stash", "create", "autostash", NULL);
-			stash.git_cmd = 1;
-			stash.no_stdin = 1;
-			strbuf_reset(&buf);
-			if (capture_command(&stash, &buf, GIT_MAX_HEXSZ))
-				die(_("Cannot autostash"));
-			strbuf_trim_trailing_newline(&buf);
-			if (get_oid(buf.buf, &oid))
-				die(_("Unexpected stash response: '%s'"),
-				    buf.buf);
-			strbuf_reset(&buf);
-			strbuf_add_unique_abbrev(&buf, &oid, DEFAULT_ABBREV);
-
-			if (safe_create_leading_directories_const(autostash))
-				die(_("Could not create directory for '%s'"),
-				    options.state_dir);
-			write_file(autostash, "%s", oid_to_hex(&oid));
-			printf(_("Created autostash: %s\n"), buf.buf);
-			if (reset_head(NULL, "reset --hard",
-				       NULL, RESET_HEAD_HARD, NULL, NULL) < 0)
-				die(_("could not reset --hard"));
-
-			if (discard_index(the_repository->index) < 0 ||
-				repo_read_index(the_repository) < 0)
-				die(_("could not read index"));
-		}
+		create_autostash(the_repository, state_dir_path("autostash", &options),
+				 DEFAULT_REFLOG_ACTION);
 	}
 
 	if (require_clean_work_tree(the_repository, "rebase",
@@ -2174,10 +1951,12 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 				strbuf_addf(&buf, "%s: checkout %s",
 					    getenv(GIT_REFLOG_ACTION_ENVIRONMENT),
 					    options.switch_to);
-				if (reset_head(&options.orig_head, "checkout",
+				if (reset_head(the_repository,
+					       &options.orig_head, "checkout",
 					       options.head_name,
 					       RESET_HEAD_RUN_POST_CHECKOUT_HOOK,
-					       NULL, buf.buf) < 0) {
+					       NULL, buf.buf,
+					       DEFAULT_REFLOG_ACTION) < 0) {
 					ret = !!error(_("could not switch to "
 							"%s"),
 						      options.switch_to);
@@ -2249,10 +2028,10 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 
 	strbuf_addf(&msg, "%s: checkout %s",
 		    getenv(GIT_REFLOG_ACTION_ENVIRONMENT), options.onto_name);
-	if (reset_head(&options.onto->object.oid, "checkout", NULL,
+	if (reset_head(the_repository, &options.onto->object.oid, "checkout", NULL,
 		       RESET_HEAD_DETACH | RESET_ORIG_HEAD |
 		       RESET_HEAD_RUN_POST_CHECKOUT_HOOK,
-		       NULL, msg.buf))
+		       NULL, msg.buf, DEFAULT_REFLOG_ACTION))
 		die(_("Could not detach HEAD"));
 	strbuf_release(&msg);
 
@@ -2267,8 +2046,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		strbuf_addf(&msg, "rebase finished: %s onto %s",
 			options.head_name ? options.head_name : "detached HEAD",
 			oid_to_hex(&options.onto->object.oid));
-		reset_head(NULL, "Fast-forwarded", options.head_name,
-			   RESET_HEAD_REFS_ONLY, "HEAD", msg.buf);
+		reset_head(the_repository, NULL, "Fast-forwarded", options.head_name,
+			   RESET_HEAD_REFS_ONLY, "HEAD", msg.buf,
+			   DEFAULT_REFLOG_ACTION);
 		strbuf_release(&msg);
 		ret = !!finish_rebase(&options);
 		goto cleanup;

parse-options.h

@@ -336,5 +336,6 @@ int parse_opt_passthru_argv(const struct option *, const char *, int);
 #define OPT_CLEANUP(v) OPT_STRING(0, "cleanup", v, N_("mode"), N_("how to strip spaces and #comments from message"))
 #define OPT_PATHSPEC_FROM_FILE(v) OPT_FILENAME(0, "pathspec-from-file", v, N_("read pathspec from file"))
 #define OPT_PATHSPEC_FILE_NUL(v)  OPT_BOOL(0, "pathspec-file-nul", v, N_("with --pathspec-from-file, pathspec elements are separated with NUL character"))
+#define OPT_AUTOSTASH(v) OPT_BOOL(0, "autostash", v, N_("automatically stash/stash pop before and after"))
 
 #endif

path.c

@@ -1535,5 +1535,6 @@ REPO_GIT_PATH_FUNC(merge_msg, "MERGE_MSG")
 REPO_GIT_PATH_FUNC(merge_rr, "MERGE_RR")
 REPO_GIT_PATH_FUNC(merge_mode, "MERGE_MODE")
 REPO_GIT_PATH_FUNC(merge_head, "MERGE_HEAD")
+REPO_GIT_PATH_FUNC(merge_autostash, "MERGE_AUTOSTASH")
 REPO_GIT_PATH_FUNC(fetch_head, "FETCH_HEAD")
 REPO_GIT_PATH_FUNC(shallow, "shallow")

path.h

@@ -177,11 +177,12 @@ struct path_cache {
 	const char *merge_rr;
 	const char *merge_mode;
 	const char *merge_head;
+	const char *merge_autostash;
 	const char *fetch_head;
 	const char *shallow;
 };
 
-#define PATH_CACHE_INIT { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }
+#define PATH_CACHE_INIT { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }
 
 const char *git_path_cherry_pick_head(struct repository *r);
 const char *git_path_revert_head(struct repository *r);
@@ -190,6 +191,7 @@ const char *git_path_merge_msg(struct repository *r);
 const char *git_path_merge_rr(struct repository *r);
 const char *git_path_merge_mode(struct repository *r);
 const char *git_path_merge_head(struct repository *r);
+const char *git_path_merge_autostash(struct repository *r);
 const char *git_path_fetch_head(struct repository *r);
 const char *git_path_shallow(struct repository *r);
 

reset.c

@@ -0,0 +1,141 @@
+#include "git-compat-util.h"
+#include "cache-tree.h"
+#include "lockfile.h"
+#include "refs.h"
+#include "reset.h"
+#include "run-command.h"
+#include "tree-walk.h"
+#include "tree.h"
+#include "unpack-trees.h"
+
+int reset_head(struct repository *r, struct object_id *oid, const char *action,
+	       const char *switch_to_branch, unsigned flags,
+	       const char *reflog_orig_head, const char *reflog_head,
+	       const char *default_reflog_action)
+{
+	unsigned detach_head = flags & RESET_HEAD_DETACH;
+	unsigned reset_hard = flags & RESET_HEAD_HARD;
+	unsigned run_hook = flags & RESET_HEAD_RUN_POST_CHECKOUT_HOOK;
+	unsigned refs_only = flags & RESET_HEAD_REFS_ONLY;
+	unsigned update_orig_head = flags & RESET_ORIG_HEAD;
+	struct object_id head_oid;
+	struct tree_desc desc[2] = { { NULL }, { NULL } };
+	struct lock_file lock = LOCK_INIT;
+	struct unpack_trees_options unpack_tree_opts;
+	struct tree *tree;
+	const char *reflog_action;
+	struct strbuf msg = STRBUF_INIT;
+	size_t prefix_len;
+	struct object_id *orig = NULL, oid_orig,
+		*old_orig = NULL, oid_old_orig;
+	int ret = 0, nr = 0;
+
+	if (switch_to_branch && !starts_with(switch_to_branch, "refs/"))
+		BUG("Not a fully qualified branch: '%s'", switch_to_branch);
+
+	if (!refs_only && repo_hold_locked_index(r, &lock, LOCK_REPORT_ON_ERROR) < 0) {
+		ret = -1;
+		goto leave_reset_head;
+	}
+
+	if ((!oid || !reset_hard) && get_oid("HEAD", &head_oid)) {
+		ret = error(_("could not determine HEAD revision"));
+		goto leave_reset_head;
+	}
+
+	if (!oid)
+		oid = &head_oid;
+
+	if (refs_only)
+		goto reset_head_refs;
+
+	memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
+	setup_unpack_trees_porcelain(&unpack_tree_opts, action);
+	unpack_tree_opts.head_idx = 1;
+	unpack_tree_opts.src_index = r->index;
+	unpack_tree_opts.dst_index = r->index;
+	unpack_tree_opts.fn = reset_hard ? oneway_merge : twoway_merge;
+	unpack_tree_opts.update = 1;
+	unpack_tree_opts.merge = 1;
+	init_checkout_metadata(&unpack_tree_opts.meta, switch_to_branch, oid, NULL);
+	if (!detach_head)
+		unpack_tree_opts.reset = 1;
+
+	if (repo_read_index_unmerged(r) < 0) {
+		ret = error(_("could not read index"));
+		goto leave_reset_head;
+	}
+
+	if (!reset_hard && !fill_tree_descriptor(r, &desc[nr++], &head_oid)) {
+		ret = error(_("failed to find tree of %s"),
+			    oid_to_hex(&head_oid));
+		goto leave_reset_head;
+	}
+
+	if (!fill_tree_descriptor(r, &desc[nr++], oid)) {
+		ret = error(_("failed to find tree of %s"), oid_to_hex(oid));
+		goto leave_reset_head;
+	}
+
+	if (unpack_trees(nr, desc, &unpack_tree_opts)) {
+		ret = -1;
+		goto leave_reset_head;
+	}
+
+	tree = parse_tree_indirect(oid);
+	prime_cache_tree(r, r->index, tree);
+
+	if (write_locked_index(r->index, &lock, COMMIT_LOCK) < 0) {
+		ret = error(_("could not write index"));
+		goto leave_reset_head;
+	}
+
+reset_head_refs:
+	reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
+	strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action : default_reflog_action);
+	prefix_len = msg.len;
+
+	if (update_orig_head) {
+		if (!get_oid("ORIG_HEAD", &oid_old_orig))
+			old_orig = &oid_old_orig;
+		if (!get_oid("HEAD", &oid_orig)) {
+			orig = &oid_orig;
+			if (!reflog_orig_head) {
+				strbuf_addstr(&msg, "updating ORIG_HEAD");
+				reflog_orig_head = msg.buf;
+			}
+			update_ref(reflog_orig_head, "ORIG_HEAD", orig,
+				   old_orig, 0, UPDATE_REFS_MSG_ON_ERR);
+		} else if (old_orig)
+			delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
+	}
+
+	if (!reflog_head) {
+		strbuf_setlen(&msg, prefix_len);
+		strbuf_addstr(&msg, "updating HEAD");
+		reflog_head = msg.buf;
+	}
+	if (!switch_to_branch)
+		ret = update_ref(reflog_head, "HEAD", oid, orig,
+				 detach_head ? REF_NO_DEREF : 0,
+				 UPDATE_REFS_MSG_ON_ERR);
+	else {
+		ret = update_ref(reflog_head, switch_to_branch, oid,
+				 NULL, 0, UPDATE_REFS_MSG_ON_ERR);
+		if (!ret)
+			ret = create_symref("HEAD", switch_to_branch,
+					    reflog_head);
+	}
+	if (run_hook)
+		run_hook_le(NULL, "post-checkout",
+			    oid_to_hex(orig ? orig : &null_oid),
+			    oid_to_hex(oid), "1", NULL);
+
+leave_reset_head:
+	strbuf_release(&msg);
+	rollback_lock_file(&lock);
+	while (nr)
+		free((void *)desc[--nr].buffer);
+	return ret;
+
+}

reset.h

@@ -0,0 +1,20 @@
+#ifndef RESET_H
+#define RESET_H
+
+#include "hash.h"
+#include "repository.h"
+
+#define GIT_REFLOG_ACTION_ENVIRONMENT "GIT_REFLOG_ACTION"
+
+#define RESET_HEAD_DETACH (1<<0)
+#define RESET_HEAD_HARD (1<<1)
+#define RESET_HEAD_RUN_POST_CHECKOUT_HOOK (1<<2)
+#define RESET_HEAD_REFS_ONLY (1<<3)
+#define RESET_ORIG_HEAD (1<<4)
+
+int reset_head(struct repository *r, struct object_id *oid, const char *action,
+	       const char *switch_to_branch, unsigned flags,
+	       const char *reflog_orig_head, const char *reflog_head,
+	       const char *default_reflog_action);
+
+#endif

sequencer.c

@@ -32,6 +32,7 @@
 #include "alias.h"
 #include "commit-reach.h"
 #include "rebase-interactive.h"
+#include "reset.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
@@ -419,25 +420,15 @@ static int write_message(const void *buf, size_t len, const char *filename,
 	return 0;
 }
 
-/*
- * Reads a file that was presumably written by a shell script, i.e. with an
- * end-of-line marker that needs to be stripped.
- *
- * Note that only the last end-of-line marker is stripped, consistent with the
- * behavior of "$(cat path)" in a shell script.
- *
- * Returns 1 if the file was read, 0 if it could not be read or does not exist.
- */
-static int read_oneliner(struct strbuf *buf,
-	const char *path, int skip_if_empty)
+int read_oneliner(struct strbuf *buf,
+	const char *path, unsigned flags)
 {
 	int orig_len = buf->len;
 
-	if (!file_exists(path))
-		return 0;
-
 	if (strbuf_read_file(buf, path, 0) < 0) {
-		warning_errno(_("could not read '%s'"), path);
+		if ((flags & READ_ONELINER_WARN_MISSING) ||
+		    (errno != ENOENT && errno != ENOTDIR))
+			warning_errno(_("could not read '%s'"), path);
 		return 0;
 	}
 
@@ -447,7 +438,7 @@ static int read_oneliner(struct strbuf *buf,
 		buf->buf[buf->len] = '\0';
 	}
 
-	if (skip_if_empty && buf->len == orig_len)
+	if ((flags & READ_ONELINER_SKIP_IF_EMPTY) && buf->len == orig_len)
 		return 0;
 
 	return 1;
@@ -2504,8 +2495,10 @@ static int read_populate_opts(struct replay_opts *opts)
 {
 	if (is_rebase_i(opts)) {
 		struct strbuf buf = STRBUF_INIT;
+		int ret = 0;
 
-		if (read_oneliner(&buf, rebase_path_gpg_sign_opt(), 1)) {
+		if (read_oneliner(&buf, rebase_path_gpg_sign_opt(),
+				  READ_ONELINER_SKIP_IF_EMPTY)) {
 			if (!starts_with(buf.buf, "-S"))
 				strbuf_reset(&buf);
 			else {
@@ -2515,7 +2508,8 @@ static int read_populate_opts(struct replay_opts *opts)
 			strbuf_reset(&buf);
 		}
 
-		if (read_oneliner(&buf, rebase_path_allow_rerere_autoupdate(), 1)) {
+		if (read_oneliner(&buf, rebase_path_allow_rerere_autoupdate(),
+				  READ_ONELINER_SKIP_IF_EMPTY)) {
 			if (!strcmp(buf.buf, "--rerere-autoupdate"))
 				opts->allow_rerere_auto = RERERE_AUTOUPDATE;
 			else if (!strcmp(buf.buf, "--no-rerere-autoupdate"))
@@ -2544,10 +2538,11 @@ static int read_populate_opts(struct replay_opts *opts)
 			opts->keep_redundant_commits = 1;
 
 		read_strategy_opts(opts, &buf);
-		strbuf_release(&buf);
+		strbuf_reset(&buf);
 
 		if (read_oneliner(&opts->current_fixups,
-				  rebase_path_current_fixups(), 1)) {
+				  rebase_path_current_fixups(),
+				  READ_ONELINER_SKIP_IF_EMPTY)) {
 			const char *p = opts->current_fixups.buf;
 			opts->current_fixup_count = 1;
 			while ((p = strchr(p, '\n'))) {
@@ -2557,12 +2552,16 @@ static int read_populate_opts(struct replay_opts *opts)
 		}
 
 		if (read_oneliner(&buf, rebase_path_squash_onto(), 0)) {
-			if (get_oid_hex(buf.buf, &opts->squash_onto) < 0)
-				return error(_("unusable squash-onto"));
+			if (get_oid_hex(buf.buf, &opts->squash_onto) < 0) {
+				ret = error(_("unusable squash-onto"));
+				goto done_rebase_i;
+			}
 			opts->have_squash_onto = 1;
 		}
 
-		return 0;
+done_rebase_i:
+		strbuf_release(&buf);
+		return ret;
 	}
 
 	if (!file_exists(git_path_opts_file()))
@@ -3677,25 +3676,71 @@ static enum todo_command peek_command(struct todo_list *todo_list, int offset)
 	return -1;
 }
 
-static int apply_autostash(struct replay_opts *opts)
+void create_autostash(struct repository *r, const char *path,
+		      const char *default_reflog_action)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct lock_file lock_file = LOCK_INIT;
+	int fd;
+
+	fd = repo_hold_locked_index(r, &lock_file, 0);
+	refresh_index(r->index, REFRESH_QUIET, NULL, NULL, NULL);
+	if (0 <= fd)
+		repo_update_index_if_able(r, &lock_file);
+	rollback_lock_file(&lock_file);
+
+	if (has_unstaged_changes(r, 1) ||
+	    has_uncommitted_changes(r, 1)) {
+		struct child_process stash = CHILD_PROCESS_INIT;
+		struct object_id oid;
+
+		argv_array_pushl(&stash.args,
+				 "stash", "create", "autostash", NULL);
+		stash.git_cmd = 1;
+		stash.no_stdin = 1;
+		strbuf_reset(&buf);
+		if (capture_command(&stash, &buf, GIT_MAX_HEXSZ))
+			die(_("Cannot autostash"));
+		strbuf_trim_trailing_newline(&buf);
+		if (get_oid(buf.buf, &oid))
+			die(_("Unexpected stash response: '%s'"),
+			    buf.buf);
+		strbuf_reset(&buf);
+		strbuf_add_unique_abbrev(&buf, &oid, DEFAULT_ABBREV);
+
+		if (safe_create_leading_directories_const(path))
+			die(_("Could not create directory for '%s'"),
+			    path);
+		write_file(path, "%s", oid_to_hex(&oid));
+		printf(_("Created autostash: %s\n"), buf.buf);
+		if (reset_head(r, NULL, "reset --hard",
+			       NULL, RESET_HEAD_HARD, NULL, NULL,
+			       default_reflog_action) < 0)
+			die(_("could not reset --hard"));
+
+		if (discard_index(r->index) < 0 ||
+			repo_read_index(r) < 0)
+			die(_("could not read index"));
+	}
+	strbuf_release(&buf);
+}
+
+static int apply_save_autostash_oid(const char *stash_oid, int attempt_apply)
 {
-	struct strbuf stash_sha1 = STRBUF_INIT;
 	struct child_process child = CHILD_PROCESS_INIT;
 	int ret = 0;
 
-	if (!read_oneliner(&stash_sha1, rebase_path_autostash(), 1)) {
-		strbuf_release(&stash_sha1);
-		return 0;
+	if (attempt_apply) {
+		child.git_cmd = 1;
+		child.no_stdout = 1;
+		child.no_stderr = 1;
+		argv_array_push(&child.args, "stash");
+		argv_array_push(&child.args, "apply");
+		argv_array_push(&child.args, stash_oid);
+		ret = run_command(&child);
 	}
-	strbuf_trim(&stash_sha1);
 
-	child.git_cmd = 1;
-	child.no_stdout = 1;
-	child.no_stderr = 1;
-	argv_array_push(&child.args, "stash");
-	argv_array_push(&child.args, "apply");
-	argv_array_push(&child.args, stash_sha1.buf);
-	if (!run_command(&child))
+	if (attempt_apply && !ret)
 		fprintf(stderr, _("Applied autostash.\n"));
 	else {
 		struct child_process store = CHILD_PROCESS_INIT;
@@ -3706,21 +3751,57 @@ static int apply_autostash(struct replay_opts *opts)
 		argv_array_push(&store.args, "-m");
 		argv_array_push(&store.args, "autostash");
 		argv_array_push(&store.args, "-q");
-		argv_array_push(&store.args, stash_sha1.buf);
+		argv_array_push(&store.args, stash_oid);
 		if (run_command(&store))
-			ret = error(_("cannot store %s"), stash_sha1.buf);
+			ret = error(_("cannot store %s"), stash_oid);
 		else
 			fprintf(stderr,
-				_("Applying autostash resulted in conflicts.\n"
+				_("%s\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"));
+				  " \"git stash drop\" at any time.\n"),
+				attempt_apply ?
+				_("Applying autostash resulted in conflicts.") :
+				_("Autostash exists; creating a new stash entry."));
 	}
 
-	strbuf_release(&stash_sha1);
 	return ret;
 }
 
+static int apply_save_autostash(const char *path, int attempt_apply)
+{
+	struct strbuf stash_oid = STRBUF_INIT;
+	int ret = 0;
+
+	if (!read_oneliner(&stash_oid, path,
+			   READ_ONELINER_SKIP_IF_EMPTY)) {
+		strbuf_release(&stash_oid);
+		return 0;
+	}
+	strbuf_trim(&stash_oid);
+
+	ret = apply_save_autostash_oid(stash_oid.buf, attempt_apply);
+
+	unlink(path);
+	strbuf_release(&stash_oid);
+	return ret;
+}
+
+int save_autostash(const char *path)
+{
+	return apply_save_autostash(path, 0);
+}
+
+int apply_autostash(const char *path)
+{
+	return apply_save_autostash(path, 1);
+}
+
+int apply_autostash_oid(const char *stash_oid)
+{
+	return apply_save_autostash_oid(stash_oid, 1);
+}
+
 static const char *reflog_message(struct replay_opts *opts,
 	const char *sub_action, const char *fmt, ...)
 {
@@ -3776,7 +3857,7 @@ static int checkout_onto(struct repository *r, struct replay_opts *opts,
 		return error(_("%s: not a valid OID"), orig_head);
 
 	if (run_git_checkout(r, opts, oid_to_hex(onto), action)) {
-		apply_autostash(opts);
+		apply_autostash(rebase_path_autostash());
 		sequencer_remove_state(opts);
 		return error(_("could not detach HEAD"));
 	}
@@ -4095,7 +4176,7 @@ cleanup_head_ref:
 				run_command(&hook);
 			}
 		}
-		apply_autostash(opts);
+		apply_autostash(rebase_path_autostash());
 
 		if (!opts->quiet) {
 			if (!opts->verbose)
@@ -4313,7 +4394,8 @@ int sequencer_continue(struct repository *r, struct replay_opts *opts)
 		struct strbuf buf = STRBUF_INIT;
 		struct object_id oid;
 
-		if (read_oneliner(&buf, rebase_path_stopped_sha(), 1) &&
+		if (read_oneliner(&buf, rebase_path_stopped_sha(),
+				  READ_ONELINER_SKIP_IF_EMPTY) &&
 		    !get_oid_committish(buf.buf, &oid))
 			record_in_rewritten(&oid, peek_command(&todo_list, 0));
 		strbuf_release(&buf);
@@ -5118,7 +5200,7 @@ int complete_action(struct repository *r, struct replay_opts *opts, unsigned fla
 		todo_list_add_exec_commands(todo_list, commands);
 
 	if (count_commands(todo_list) == 0) {
-		apply_autostash(opts);
+		apply_autostash(rebase_path_autostash());
 		sequencer_remove_state(opts);
 
 		return error(_("nothing to do"));
@@ -5129,12 +5211,12 @@ int complete_action(struct repository *r, struct replay_opts *opts, unsigned fla
 	if (res == -1)
 		return -1;
 	else if (res == -2) {
-		apply_autostash(opts);
+		apply_autostash(rebase_path_autostash());
 		sequencer_remove_state(opts);
 
 		return -1;
 	} else if (res == -3) {
-		apply_autostash(opts);
+		apply_autostash(rebase_path_autostash());
 		sequencer_remove_state(opts);
 		todo_list_release(&new_todo);
 

sequencer.h

@@ -191,6 +191,12 @@ void commit_post_rewrite(struct repository *r,
 			 const struct commit *current_head,
 			 const struct object_id *new_head);
 
+void create_autostash(struct repository *r, const char *path,
+		      const char *default_reflog_action);
+int save_autostash(const char *path);
+int apply_autostash(const char *path);
+int apply_autostash_oid(const char *stash_oid);
+
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
 void print_commit_summary(struct repository *repo,
@@ -198,6 +204,20 @@ void print_commit_summary(struct repository *repo,
 			  const struct object_id *oid,
 			  unsigned int flags);
 
+#define READ_ONELINER_SKIP_IF_EMPTY (1 << 0)
+#define READ_ONELINER_WARN_MISSING (1 << 1)
+
+/*
+ * Reads a file that was presumably written by a shell script, i.e. with an
+ * end-of-line marker that needs to be stripped.
+ *
+ * Note that only the last end-of-line marker is stripped, consistent with the
+ * behavior of "$(cat path)" in a shell script.
+ *
+ * Returns 1 if the file was read, 0 if it could not be read or does not exist.
+ */
+int read_oneliner(struct strbuf *buf,
+	const char *path, unsigned flags);
 int read_author_script(const char *path, char **name, char **email, char **date,
 		       int allow_missing);
 void parse_strategy_opts(struct replay_opts *opts, char *raw_opts);

t/t3033-merge-toplevel.sh

@@ -142,6 +142,17 @@ test_expect_success 'refuse two-project merge by default' '
 	test_must_fail git merge five
 '
 
+test_expect_success 'refuse two-project merge by default, quit before --autostash happens' '
+	t3033_reset &&
+	git reset --hard four &&
+	echo change >>one.t &&
+	git diff >expect &&
+	test_must_fail git merge --autostash five 2>err &&
+	test_i18ngrep ! "stash" err &&
+	git diff >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'two-project merge with --allow-unrelated-histories' '
 	t3033_reset &&
 	git reset --hard four &&
@@ -149,4 +160,15 @@ test_expect_success 'two-project merge with --allow-unrelated-histories' '
 	git diff --exit-code five
 '
 
+test_expect_success 'two-project merge with --allow-unrelated-histories with --autostash' '
+	t3033_reset &&
+	git reset --hard four &&
+	echo change >>one.t &&
+	git diff one.t >expect &&
+	git merge --allow-unrelated-histories --autostash five 2>err &&
+	test_i18ngrep "Applied autostash." err &&
+	git diff one.t >actual &&
+	test_cmp expect actual
+'
+
 test_done

t/t5520-pull.sh

@@ -10,11 +10,13 @@ modify () {
 }
 
 test_pull_autostash () {
+	expect_parent_num="$1" &&
+	shift &&
 	git reset --hard before-rebase &&
 	echo dirty >new_file &&
 	git add new_file &&
 	git pull "$@" . copy &&
-	test_cmp_rev HEAD^ copy &&
+	test_cmp_rev HEAD^"$expect_parent_num" copy &&
 	echo dirty >expect &&
 	test_cmp expect new_file &&
 	echo "modified again" >expect &&
@@ -26,7 +28,7 @@ test_pull_autostash_fail () {
 	echo dirty >new_file &&
 	git add new_file &&
 	test_must_fail git pull "$@" . copy 2>err &&
-	test_i18ngrep "uncommitted changes." err
+	test_i18ngrep "\(uncommitted changes.\)\|\(overwritten by merge:\)" err
 }
 
 test_expect_success setup '
@@ -369,22 +371,22 @@ test_expect_success '--rebase fails with multiple branches' '
 
 test_expect_success 'pull --rebase succeeds with dirty working directory and rebase.autostash set' '
 	test_config rebase.autostash true &&
-	test_pull_autostash --rebase
+	test_pull_autostash 1 --rebase
 '
 
 test_expect_success 'pull --rebase --autostash & rebase.autostash=true' '
 	test_config rebase.autostash true &&
-	test_pull_autostash --rebase --autostash
+	test_pull_autostash 1 --rebase --autostash
 '
 
 test_expect_success 'pull --rebase --autostash & rebase.autostash=false' '
 	test_config rebase.autostash false &&
-	test_pull_autostash --rebase --autostash
+	test_pull_autostash 1 --rebase --autostash
 '
 
 test_expect_success 'pull --rebase --autostash & rebase.autostash unset' '
 	test_unconfig rebase.autostash &&
-	test_pull_autostash --rebase --autostash
+	test_pull_autostash 1 --rebase --autostash
 '
 
 test_expect_success 'pull --rebase --no-autostash & rebase.autostash=true' '
@@ -402,13 +404,40 @@ test_expect_success 'pull --rebase --no-autostash & rebase.autostash unset' '
 	test_pull_autostash_fail --rebase --no-autostash
 '
 
-for i in --autostash --no-autostash
-do
-	test_expect_success "pull $i (without --rebase) is illegal" '
-		test_must_fail git pull $i . copy 2>err &&
-		test_i18ngrep "only valid with --rebase" err
-	'
-done
+test_expect_success 'pull succeeds with dirty working directory and merge.autostash set' '
+	test_config merge.autostash true &&
+	test_pull_autostash 2
+'
+
+test_expect_success 'pull --autostash & merge.autostash=true' '
+	test_config merge.autostash true &&
+	test_pull_autostash 2 --autostash
+'
+
+test_expect_success 'pull --autostash & merge.autostash=false' '
+	test_config merge.autostash false &&
+	test_pull_autostash 2 --autostash
+'
+
+test_expect_success 'pull --autostash & merge.autostash unset' '
+	test_unconfig merge.autostash &&
+	test_pull_autostash 2 --autostash
+'
+
+test_expect_success 'pull --no-autostash & merge.autostash=true' '
+	test_config merge.autostash true &&
+	test_pull_autostash_fail --no-autostash
+'
+
+test_expect_success 'pull --no-autostash & merge.autostash=false' '
+	test_config merge.autostash false &&
+	test_pull_autostash_fail --no-autostash
+'
+
+test_expect_success 'pull --no-autostash & merge.autostash unset' '
+	test_unconfig merge.autostash &&
+	test_pull_autostash_fail --no-autostash
+'
 
 test_expect_success 'pull.rebase' '
 	git reset --hard before-rebase &&
@@ -422,7 +451,7 @@ test_expect_success 'pull.rebase' '
 
 test_expect_success 'pull --autostash & pull.rebase=true' '
 	test_config pull.rebase true &&
-	test_pull_autostash --autostash
+	test_pull_autostash 1 --autostash
 '
 
 test_expect_success 'pull --no-autostash & pull.rebase=true' '

t/t7600-merge.sh

@@ -29,15 +29,19 @@ Testing basic merge operations/option parsing.
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-gpg.sh
 
-printf '%s\n' 1 2 3 4 5 6 7 8 9 >file
-printf '%s\n' '1 X' 2 3 4 5 6 7 8 9 >file.1
-printf '%s\n' 1 2 3 4 '5 X' 6 7 8 9 >file.5
-printf '%s\n' 1 2 3 4 5 6 7 8 '9 X' >file.9
-printf '%s\n' 1 2 3 4 5 6 7 8 '9 Y' >file.9y
-printf '%s\n' '1 X' 2 3 4 5 6 7 8 9 >result.1
-printf '%s\n' '1 X' 2 3 4 '5 X' 6 7 8 9 >result.1-5
-printf '%s\n' '1 X' 2 3 4 '5 X' 6 7 8 '9 X' >result.1-5-9
-printf '%s\n' 1 2 3 4 5 6 7 8 '9 Z' >result.9z
+test_write_lines 1 2 3 4 5 6 7 8 9 >file
+cp file file.orig
+test_write_lines '1 X' 2 3 4 5 6 7 8 9 >file.1
+test_write_lines 1 2 '3 X' 4 5 6 7 8 9 >file.3
+test_write_lines 1 2 3 4 '5 X' 6 7 8 9 >file.5
+test_write_lines 1 2 3 4 5 6 7 8 '9 X' >file.9
+test_write_lines 1 2 3 4 5 6 7 8 '9 Y' >file.9y
+test_write_lines '1 X' 2 3 4 5 6 7 8 9 >result.1
+test_write_lines '1 X' 2 3 4 '5 X' 6 7 8 9 >result.1-5
+test_write_lines '1 X' 2 3 4 5 6 7 8 '9 X' >result.1-9
+test_write_lines '1 X' 2 3 4 '5 X' 6 7 8 '9 X' >result.1-5-9
+test_write_lines '1 X' 2 '3 X' 4 '5 X' 6 7 8 '9 X' >result.1-3-5-9
+test_write_lines 1 2 3 4 5 6 7 8 '9 Z' >result.9z
 
 create_merge_msgs () {
 	echo "Merge tag 'c2'" >msg.1-5 &&
@@ -81,7 +85,7 @@ verify_head () {
 }
 
 verify_parents () {
-	printf '%s\n' "$@" >parents.expected &&
+	test_write_lines "$@" >parents.expected &&
 	>parents.actual &&
 	i=1 &&
 	while test $i -le $#
@@ -95,7 +99,7 @@ verify_parents () {
 }
 
 verify_mergeheads () {
-	printf '%s\n' "$@" >mergehead.expected &&
+	test_write_lines "$@" >mergehead.expected &&
 	while read sha1 rest
 	do
 		git rev-parse $sha1
@@ -675,6 +679,134 @@ test_expect_success 'refresh the index before merging' '
 	git merge c3
 '
 
+test_expect_success 'merge with --autostash' '
+	git reset --hard c1 &&
+	git merge-file file file.orig file.9 &&
+	git merge --autostash c2 2>err &&
+	test_i18ngrep "Applied autostash." err &&
+	git show HEAD:file >merge-result &&
+	test_cmp result.1-5 merge-result &&
+	test_cmp result.1-5-9 file
+'
+
+test_expect_success 'merge with merge.autoStash' '
+	test_config merge.autoStash true &&
+	git reset --hard c1 &&
+	git merge-file file file.orig file.9 &&
+	git merge c2 2>err &&
+	test_i18ngrep "Applied autostash." err &&
+	git show HEAD:file >merge-result &&
+	test_cmp result.1-5 merge-result &&
+	test_cmp result.1-5-9 file
+'
+
+test_expect_success 'fast-forward merge with --autostash' '
+	git reset --hard c0 &&
+	git merge-file file file.orig file.5 &&
+	git merge --autostash c1 2>err &&
+	test_i18ngrep "Applied autostash." err &&
+	test_cmp result.1-5 file
+'
+
+test_expect_success 'octopus merge with --autostash' '
+	git reset --hard c1 &&
+	git merge-file file file.orig file.3 &&
+	git merge --autostash c2 c3 2>err &&
+	test_i18ngrep "Applied autostash." err &&
+	git show HEAD:file >merge-result &&
+	test_cmp result.1-5-9 merge-result &&
+	test_cmp result.1-3-5-9 file
+'
+
+test_expect_success 'conflicted merge with --autostash, --abort restores stash' '
+	git reset --hard c3 &&
+	cp file.1 file &&
+	test_must_fail git merge --autostash c7 &&
+	git merge --abort 2>err &&
+	test_i18ngrep "Applied autostash." err &&
+	test_cmp file.1 file
+'
+
+test_expect_success 'completed merge (git commit) with --no-commit and --autostash' '
+	git reset --hard c1 &&
+	git merge-file file file.orig file.9 &&
+	git diff >expect &&
+	git merge --no-commit --autostash c2 &&
+	git stash show -p MERGE_AUTOSTASH >actual &&
+	test_cmp expect actual &&
+	git commit 2>err &&
+	test_i18ngrep "Applied autostash." err &&
+	git show HEAD:file >merge-result &&
+	test_cmp result.1-5 merge-result &&
+	test_cmp result.1-5-9 file
+'
+
+test_expect_success 'completed merge (git merge --continue) with --no-commit and --autostash' '
+	git reset --hard c1 &&
+	git merge-file file file.orig file.9 &&
+	git diff >expect &&
+	git merge --no-commit --autostash c2 &&
+	git stash show -p MERGE_AUTOSTASH >actual &&
+	test_cmp expect actual &&
+	git merge --continue 2>err &&
+	test_i18ngrep "Applied autostash." err &&
+	git show HEAD:file >merge-result &&
+	test_cmp result.1-5 merge-result &&
+	test_cmp result.1-5-9 file
+'
+
+test_expect_success 'aborted merge (merge --abort) with --no-commit and --autostash' '
+	git reset --hard c1 &&
+	git merge-file file file.orig file.9 &&
+	git diff >expect &&
+	git merge --no-commit --autostash c2 &&
+	git stash show -p MERGE_AUTOSTASH >actual &&
+	test_cmp expect actual &&
+	git merge --abort 2>err &&
+	test_i18ngrep "Applied autostash." err &&
+	git diff >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'aborted merge (reset --hard) with --no-commit and --autostash' '
+	git reset --hard c1 &&
+	git merge-file file file.orig file.9 &&
+	git diff >expect &&
+	git merge --no-commit --autostash c2 &&
+	git stash show -p MERGE_AUTOSTASH >actual &&
+	test_cmp expect actual &&
+	git reset --hard 2>err &&
+	test_i18ngrep "Autostash exists; creating a new stash entry." err &&
+	git diff --exit-code
+'
+
+test_expect_success 'quit merge with --no-commit and --autostash' '
+	git reset --hard c1 &&
+	git merge-file file file.orig file.9 &&
+	git diff >expect &&
+	git merge --no-commit --autostash c2 &&
+	git stash show -p MERGE_AUTOSTASH >actual &&
+	test_cmp expect actual &&
+	git diff HEAD >expect &&
+	git merge --quit 2>err &&
+	test_i18ngrep "Autostash exists; creating a new stash entry." err &&
+	git diff HEAD >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'merge with conflicted --autostash changes' '
+	git reset --hard c1 &&
+	git merge-file file file.orig file.9y &&
+	git diff >expect &&
+	test_when_finished "test_might_fail git stash drop" &&
+	git merge --autostash c3 2>err &&
+	test_i18ngrep "Applying autostash resulted in conflicts." err &&
+	git show HEAD:file >merge-result &&
+	test_cmp result.1-9 merge-result &&
+	git stash show -p >actual &&
+	test_cmp expect actual
+'
+
 cat >expected.branch <<\EOF
 Merge branch 'c5-branch' (early part)
 EOF