contrib/examples/git-merge.sh - git - Git at Google

 #!/bin/sh
 #
 # Copyright (c) 2005 Junio C Hamano
 #

 OPTIONS_KEEPDASHDASH=
 OPTIONS_SPEC="\
 git merge [options] <remote>...
 git merge [options] <msg> HEAD <remote>
 --
 stat                 show a diffstat at the end of the merge
 n                    don't show a diffstat at the end of the merge
 summary              (synonym to --stat)
 log                  add list of one-line log to merge commit message
 squash               create a single commit instead of doing a merge
 commit               perform a commit if the merge succeeds (default)
 ff                   allow fast-forward (default)
 ff-only              abort if fast-forward is not possible
 rerere-autoupdate    update index with any reused conflict resolution
 s,strategy=          merge strategy to use
 X=                   option for selected merge strategy
 m,message=           message to be used for the merge commit (if any)
 "

 SUBDIRECTORY_OK=Yes
 . git-sh-setup
 require_work_tree
 cd_to_toplevel

 test -z "$(git ls-files -u)" ||
 	die "Merge is not possible because you have unmerged files."

 ! test -e "$GIT_DIR/MERGE_HEAD" ||
 	die 'You have not concluded your merge (MERGE_HEAD exists).'

 LF='
 '

 all_strategies='recur recursive octopus resolve stupid ours subtree'
 all_strategies="$all_strategies recursive-ours recursive-theirs"
 not_strategies='base file index tree'
 default_twohead_strategies='recursive'
 default_octopus_strategies='octopus'
 no_fast_forward_strategies='subtree ours'
 no_trivial_strategies='recursive recur subtree ours recursive-ours recursive-theirs'
 use_strategies=
 xopt=

 allow_fast_forward=t
 fast_forward_only=
 allow_trivial_merge=t
 squash= no_commit= log_arg= rr_arg=

 dropsave() {
 	rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
 		 "$GIT_DIR/MERGE_STASH" "$GIT_DIR/MERGE_MODE" || exit 1
 }

 savestate() {
 	# Stash away any local modifications.
 	git stash create >"$GIT_DIR/MERGE_STASH"
 }

 restorestate() {
         if test -f "$GIT_DIR/MERGE_STASH"
 	then
 		git reset --hard $head >/dev/null
 		git stash apply $(cat "$GIT_DIR/MERGE_STASH")
 		git update-index --refresh >/dev/null
 	fi
 }

 finish_up_to_date () {
 	case "$squash" in
 	t)
 		echo "$1 (nothing to squash)" ;;
 	'')
 		echo "$1" ;;
 	esac
 	dropsave
 }

 squash_message () {
 	echo Squashed commit of the following:
 	echo
 	git log --no-merges --pretty=medium ^"$head" $remoteheads
 }

 finish () {
 	if test '' = "$2"
 	then
 		rlogm="$GIT_REFLOG_ACTION"
 	else
 		echo "$2"
 		rlogm="$GIT_REFLOG_ACTION: $2"
 	fi
 	case "$squash" in
 	t)
 		echo "Squash commit -- not updating HEAD"
 		squash_message >"$GIT_DIR/SQUASH_MSG"
 		;;
 	'')
 		case "$merge_msg" in
 		'')
 			echo "No merge message -- not updating HEAD"
 			;;
 		*)
 			git update-ref -m "$rlogm" HEAD "$1" "$head" || exit 1
 			git gc --auto
 			;;
 		esac
 		;;
 	esac
 	case "$1" in
 	'')
 		;;
 	?*)
 		if test "$show_diffstat" = t
 		then
 			# We want color (if set), but no pager
 			GIT_PAGER='' git diff --stat --summary -M "$head" "$1"
 		fi
 		;;
 	esac

 	# Run a post-merge hook
         if test -x "$GIT_DIR"/hooks/post-merge
         then
 	    case "$squash" in
 	    t)
                 "$GIT_DIR"/hooks/post-merge 1
 		;;
 	    '')
                 "$GIT_DIR"/hooks/post-merge 0
 		;;
 	    esac
         fi
 }

 merge_name () {
 	remote="$1"
 	rh=$(git rev-parse --verify "$remote^0" 2>/dev/null) || return
 	if truname=$(expr "$remote" : '\(.*\)~[0-9]*$') &&
 		git show-ref -q --verify "refs/heads/$truname" 2>/dev/null
 	then
 		echo "$rh		branch '$truname' (early part) of ."
 		return
 	fi
 	if found_ref=$(git rev-parse --symbolic-full-name --verify \
 							"$remote" 2>/dev/null)
 	then
 		expanded=$(git check-ref-format --branch "$remote") ||
 			exit
 		if test "${found_ref#refs/heads/}" != "$found_ref"
 		then
 			echo "$rh		branch '$expanded' of ."
 			return
 		elif test "${found_ref#refs/remotes/}" != "$found_ref"
 		then
 			echo "$rh		remote branch '$expanded' of ."
 			return
 		fi
 	fi
 	if test "$remote" = "FETCH_HEAD" && test -r "$GIT_DIR/FETCH_HEAD"
 	then
 		sed -e 's/	not-for-merge	/		/' -e 1q \
 			"$GIT_DIR/FETCH_HEAD"
 		return
 	fi
 	echo "$rh		commit '$remote'"
 }

 parse_config () {
 	while test $# != 0; do
 		case "$1" in
 		-n|--no-stat|--no-summary)
 			show_diffstat=false ;;
 		--stat|--summary)
 			show_diffstat=t ;;
 		--log|--no-log)
 			log_arg=$1 ;;
 		--squash)
 			test "$allow_fast_forward" = t ||
 				die "You cannot combine --squash with --no-ff."
 			squash=t no_commit=t ;;
 		--no-squash)
 			squash= no_commit= ;;
 		--commit)
 			no_commit= ;;
 		--no-commit)
 			no_commit=t ;;
 		--ff)
 			allow_fast_forward=t ;;
 		--no-ff)
 			test "$squash" != t ||
 				die "You cannot combine --squash with --no-ff."
 			test "$fast_forward_only" != t ||
 				die "You cannot combine --ff-only with --no-ff."
 			allow_fast_forward=f ;;
 		--ff-only)
 			test "$allow_fast_forward" != f ||
 				die "You cannot combine --ff-only with --no-ff."
 			fast_forward_only=t ;;
 		--rerere-autoupdate|--no-rerere-autoupdate)
 			rr_arg=$1 ;;
 		-s|--strategy)
 			shift
 			case " $all_strategies " in
 			*" $1 "*)
 				use_strategies="$use_strategies$1 "
 				;;
 			*)
 				case " $not_strategies " in
 				*" $1 "*)
 					false
 				esac &&
 				type "git-merge-$1" >/dev/null 2>&1 ||
 					die "available strategies are: $all_strategies"
 				use_strategies="$use_strategies$1 "
 				;;
 			esac
 			;;
 		-X)
 			shift
 			xopt="${xopt:+$xopt }$(git rev-parse --sq-quote "--$1")"
 			;;
 		-m|--message)
 			shift
 			merge_msg="$1"
 			have_message=t
 			;;
 		--)
 			shift
 			break ;;
 		*)	usage ;;
 		esac
 		shift
 	done
 	args_left=$#
 }

 test $# != 0 || usage

 have_message=

 if branch=$(git-symbolic-ref -q HEAD)
 then
 	mergeopts=$(git config "branch.${branch#refs/heads/}.mergeoptions")
 	if test -n "$mergeopts"
 	then
 		parse_config $mergeopts --
 	fi
 fi

 parse_config "$@"
 while test $args_left -lt $#; do shift; done

 if test -z "$show_diffstat"; then
     test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
     test "$(git config --bool merge.stat)" = false && show_diffstat=false
     test -z "$show_diffstat" && show_diffstat=t
 fi

 # This could be traditional "merge <msg> HEAD <commit>..."  and the
 # way we can tell it is to see if the second token is HEAD, but some
 # people might have misused the interface and used a commit-ish that
 # is the same as HEAD there instead.  Traditional format never would
 # have "-m" so it is an additional safety measure to check for it.

 if test -z "$have_message" &&
 	second_token=$(git rev-parse --verify "$2^0" 2>/dev/null) &&
 	head_commit=$(git rev-parse --verify "HEAD" 2>/dev/null) &&
 	test "$second_token" = "$head_commit"
 then
 	merge_msg="$1"
 	shift
 	head_arg="$1"
 	shift
 elif ! git rev-parse --verify HEAD >/dev/null 2>&1
 then
 	# If the merged head is a valid one there is no reason to
 	# forbid "git merge" into a branch yet to be born.  We do
 	# the same for "git pull".
 	if test 1 -ne $#
 	then
 		echo >&2 "Can merge only exactly one commit into empty head"
 		exit 1
 	fi

 	test "$squash" != t ||
 		die "Squash commit into empty head not supported yet"
 	test "$allow_fast_forward" = t ||
 		die "Non-fast-forward into an empty head does not make sense"
 	rh=$(git rev-parse --verify "$1^0") ||
 		die "$1 - not something we can merge"

 	git update-ref -m "initial pull" HEAD "$rh" "" &&
 	git read-tree --reset -u HEAD
 	exit

 else
 	# We are invoked directly as the first-class UI.
 	head_arg=HEAD

 	# All the rest are the commits being merged; prepare
 	# the standard merge summary message to be appended to
 	# the given message.  If remote is invalid we will die
 	# later in the common codepath so we discard the error
 	# in this loop.
 	merge_msg="$(
 		for remote
 		do
 			merge_name "$remote"
 		done |
 		if test "$have_message" = t
 		then
 			git fmt-merge-msg -m "$merge_msg" $log_arg
 		else
 			git fmt-merge-msg $log_arg
 		fi
 	)"
 fi
 head=$(git rev-parse --verify "$head_arg"^0) || usage

 # All the rest are remote heads
 test "$#" = 0 && usage ;# we need at least one remote head.
 set_reflog_action "merge $*"

 remoteheads=
 for remote
 do
 	remotehead=$(git rev-parse --verify "$remote"^0 2>/dev/null) ||
 	    die "$remote - not something we can merge"
 	remoteheads="${remoteheads}$remotehead "
 	eval GITHEAD_$remotehead='"$remote"'
 	export GITHEAD_$remotehead
 done
 set x $remoteheads ; shift

 case "$use_strategies" in
 '')
 	case "$#" in
 	1)
 		var="$(git config --get pull.twohead)"
 		if test -n "$var"
 		then
 			use_strategies="$var"
 		else
 			use_strategies="$default_twohead_strategies"
 		fi ;;
 	*)
 		var="$(git config --get pull.octopus)"
 		if test -n "$var"
 		then
 			use_strategies="$var"
 		else
 			use_strategies="$default_octopus_strategies"
 		fi ;;
 	esac
 	;;
 esac

 for s in $use_strategies
 do
 	for ss in $no_fast_forward_strategies
 	do
 		case " $s " in
 		*" $ss "*)
 			allow_fast_forward=f
 			break
 			;;
 		esac
 	done
 	for ss in $no_trivial_strategies
 	do
 		case " $s " in
 		*" $ss "*)
 			allow_trivial_merge=f
 			break
 			;;
 		esac
 	done
 done

 case "$#" in
 1)
 	common=$(git merge-base --all $head "$@")
 	;;
 *)
 	common=$(git merge-base --all --octopus $head "$@")
 	;;
 esac
 echo "$head" >"$GIT_DIR/ORIG_HEAD"

 case "$allow_fast_forward,$#,$common,$no_commit" in
 ?,*,'',*)
 	# No common ancestors found. We need a real merge.
 	;;
 ?,1,"$1",*)
 	# If head can reach all the merge then we are up to date.
 	# but first the most common case of merging one remote.
 	finish_up_to_date "Already up-to-date."
 	exit 0
 	;;
 t,1,"$head",*)
 	# Again the most common case of merging one remote.
 	echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
 	git update-index --refresh 2>/dev/null
 	msg="Fast-forward"
 	if test -n "$have_message"
 	then
 		msg="$msg (no commit created; -m option ignored)"
 	fi
 	new_head=$(git rev-parse --verify "$1^0") &&
 	git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
 	finish "$new_head" "$msg" || exit
 	dropsave
 	exit 0
 	;;
 ?,1,?*"$LF"?*,*)
 	# We are not doing octopus and not fast-forward.  Need a
 	# real merge.
 	;;
 ?,1,*,)
 	# We are not doing octopus, not fast-forward, and have only
 	# one common.
 	git update-index --refresh 2>/dev/null
 	case "$allow_trivial_merge,$fast_forward_only" in
 	t,)
 		# See if it is really trivial.
 		git var GIT_COMMITTER_IDENT >/dev/null || exit
 		echo "Trying really trivial in-index merge..."
 		if git read-tree --trivial -m -u -v $common $head "$1" &&
 		   result_tree=$(git write-tree)
 		then
 			echo "Wonderful."
 			result_commit=$(
 				printf '%s\n' "$merge_msg" |
 				git commit-tree $result_tree -p HEAD -p "$1"
 			) || exit
 			finish "$result_commit" "In-index merge"
 			dropsave
 			exit 0
 		fi
 		echo "Nope."
 	esac
 	;;
 *)
 	# An octopus.  If we can reach all the remote we are up to date.
 	up_to_date=t
 	for remote
 	do
 		common_one=$(git merge-base --all $head $remote)
 		if test "$common_one" != "$remote"
 		then
 			up_to_date=f
 			break
 		fi
 	done
 	if test "$up_to_date" = t
 	then
 		finish_up_to_date "Already up-to-date. Yeeah!"
 		exit 0
 	fi
 	;;
 esac

 if test "$fast_forward_only" = t
 then
 	die "Not possible to fast-forward, aborting."
 fi

 # We are going to make a new commit.
 git var GIT_COMMITTER_IDENT >/dev/null || exit

 # At this point, we need a real merge.  No matter what strategy
 # we use, it would operate on the index, possibly affecting the
 # working tree, and when resolved cleanly, have the desired tree
 # in the index -- this means that the index must be in sync with
 # the $head commit.  The strategies are responsible to ensure this.

 case "$use_strategies" in
 ?*' '?*)
     # Stash away the local changes so that we can try more than one.
     savestate
     single_strategy=no
     ;;
 *)
     rm -f "$GIT_DIR/MERGE_STASH"
     single_strategy=yes
     ;;
 esac

 result_tree= best_cnt=-1 best_strategy= wt_strategy=
 merge_was_ok=
 for strategy in $use_strategies
 do
     test "$wt_strategy" = '' || {
 	echo "Rewinding the tree to pristine..."
 	restorestate
     }
     case "$single_strategy" in
     no)
 	echo "Trying merge strategy $strategy..."
 	;;
     esac

     # Remember which strategy left the state in the working tree
     wt_strategy=$strategy

     eval 'git-merge-$strategy '"$xopt"' $common -- "$head_arg" "$@"'
     exit=$?
     if test "$no_commit" = t && test "$exit" = 0
     then
         merge_was_ok=t
 	exit=1 ;# pretend it left conflicts.
     fi

     test "$exit" = 0 || {

 	# The backend exits with 1 when conflicts are left to be resolved,
 	# with 2 when it does not handle the given merge at all.

 	if test "$exit" -eq 1
 	then
 	    cnt=$({
 		git diff-files --name-only
 		git ls-files --unmerged
 	    } | wc -l)
 	    if test $best_cnt -le 0 || test $cnt -le $best_cnt
 	    then
 		best_strategy=$strategy
 		best_cnt=$cnt
 	    fi
 	fi
 	continue
     }

     # Automerge succeeded.
     result_tree=$(git write-tree) && break
 done

 # If we have a resulting tree, that means the strategy module
 # auto resolved the merge cleanly.
 if test '' != "$result_tree"
 then
     if test "$allow_fast_forward" = "t"
     then
 	parents=$(git merge-base --independent "$head" "$@")
     else
 	parents=$(git rev-parse "$head" "$@")
     fi
     parents=$(echo "$parents" | sed -e 's/^/-p /')
     result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
     finish "$result_commit" "Merge made by $wt_strategy."
     dropsave
     exit 0
 fi

 # Pick the result from the best strategy and have the user fix it up.
 case "$best_strategy" in
 '')
 	restorestate
 	case "$use_strategies" in
 	?*' '?*)
 		echo >&2 "No merge strategy handled the merge."
 		;;
 	*)
 		echo >&2 "Merge with strategy $use_strategies failed."
 		;;
 	esac
 	exit 2
 	;;
 "$wt_strategy")
 	# We already have its result in the working tree.
 	;;
 *)
 	echo "Rewinding the tree to pristine..."
 	restorestate
 	echo "Using the $best_strategy to prepare resolving by hand."
 	git-merge-$best_strategy $common -- "$head_arg" "$@"
 	;;
 esac

 if test "$squash" = t
 then
 	finish
 else
 	for remote
 	do
 		echo $remote
 	done >"$GIT_DIR/MERGE_HEAD"
 	printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG" ||
 		die "Could not write to $GIT_DIR/MERGE_MSG"
 	if test "$allow_fast_forward" != t
 	then
 		printf "%s" no-ff
 	else
 		:
 	fi >"$GIT_DIR/MERGE_MODE" ||
 		die "Could not write to $GIT_DIR/MERGE_MODE"
 fi

 if test "$merge_was_ok" = t
 then
 	echo >&2 \
 	"Automatic merge went well; stopped before committing as requested"
 	exit 0
 else
 	{
 	    echo '
 Conflicts:
 '
 		git ls-files --unmerged |
 		sed -e 's/^[^	]*	/	/' |
 		uniq
 	} >>"$GIT_DIR/MERGE_MSG"
 	git rerere $rr_arg
 	die "Automatic merge failed; fix conflicts and then commit the result."
 fi
	#!/bin/sh
	#
	# Copyright (c) 2005 Junio C Hamano
	#

	OPTIONS_KEEPDASHDASH=
	OPTIONS_SPEC="\
	git merge [options] <remote>...
	git merge [options] <msg> HEAD <remote>
	--
	stat show a diffstat at the end of the merge
	n don't show a diffstat at the end of the merge
	summary (synonym to --stat)
	log add list of one-line log to merge commit message
	squash create a single commit instead of doing a merge
	commit perform a commit if the merge succeeds (default)
	ff allow fast-forward (default)
	ff-only abort if fast-forward is not possible
	rerere-autoupdate update index with any reused conflict resolution
	s,strategy= merge strategy to use
	X= option for selected merge strategy
	m,message= message to be used for the merge commit (if any)
	"

	SUBDIRECTORY_OK=Yes
	. git-sh-setup
	require_work_tree
	cd_to_toplevel

	test -z "$(git ls-files -u)" \|\|
	die "Merge is not possible because you have unmerged files."

	! test -e "$GIT_DIR/MERGE_HEAD" \|\|
	die 'You have not concluded your merge (MERGE_HEAD exists).'

	LF='
	'

	all_strategies='recur recursive octopus resolve stupid ours subtree'
	all_strategies="$all_strategies recursive-ours recursive-theirs"
	not_strategies='base file index tree'
	default_twohead_strategies='recursive'
	default_octopus_strategies='octopus'
	no_fast_forward_strategies='subtree ours'
	no_trivial_strategies='recursive recur subtree ours recursive-ours recursive-theirs'
	use_strategies=
	xopt=

	allow_fast_forward=t
	fast_forward_only=
	allow_trivial_merge=t
	squash= no_commit= log_arg= rr_arg=

	dropsave() {
	rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
	"$GIT_DIR/MERGE_STASH" "$GIT_DIR/MERGE_MODE" \|\| exit 1
	}

	savestate() {
	# Stash away any local modifications.
	git stash create >"$GIT_DIR/MERGE_STASH"
	}

	restorestate() {
	if test -f "$GIT_DIR/MERGE_STASH"
	then
	git reset --hard $head >/dev/null
	git stash apply $(cat "$GIT_DIR/MERGE_STASH")
	git update-index --refresh >/dev/null
	fi
	}

	finish_up_to_date () {
	case "$squash" in
	t)
	echo "$1 (nothing to squash)" ;;
	'')
	echo "$1" ;;
	esac
	dropsave
	}

	squash_message () {
	echo Squashed commit of the following:
	echo
	git log --no-merges --pretty=medium ^"$head" $remoteheads
	}

	finish () {
	if test '' = "$2"
	then
	rlogm="$GIT_REFLOG_ACTION"
	else
	echo "$2"
	rlogm="$GIT_REFLOG_ACTION: $2"
	fi
	case "$squash" in
	t)
	echo "Squash commit -- not updating HEAD"
	squash_message >"$GIT_DIR/SQUASH_MSG"
	;;
	'')
	case "$merge_msg" in
	'')
	echo "No merge message -- not updating HEAD"
	;;
	*)
	git update-ref -m "$rlogm" HEAD "$1" "$head" \|\| exit 1
	git gc --auto
	;;
	esac
	;;
	esac
	case "$1" in
	'')
	;;
	?*)
	if test "$show_diffstat" = t
	then
	# We want color (if set), but no pager
	GIT_PAGER='' git diff --stat --summary -M "$head" "$1"
	fi
	;;
	esac

	# Run a post-merge hook
	if test -x "$GIT_DIR"/hooks/post-merge
	then
	case "$squash" in
	t)
	"$GIT_DIR"/hooks/post-merge 1
	;;
	'')
	"$GIT_DIR"/hooks/post-merge 0
	;;
	esac
	fi
	}

	merge_name () {
	remote="$1"
	rh=$(git rev-parse --verify "$remote^0" 2>/dev/null) \|\| return
	if truname=$(expr "$remote" : '\(.\)~[0-9]$') &&
	git show-ref -q --verify "refs/heads/$truname" 2>/dev/null
	then
	echo "$rh branch '$truname' (early part) of ."
	return
	fi
	if found_ref=$(git rev-parse --symbolic-full-name --verify \
	"$remote" 2>/dev/null)
	then
	expanded=$(git check-ref-format --branch "$remote") \|\|
	exit
	if test "${found_ref#refs/heads/}" != "$found_ref"
	then
	echo "$rh branch '$expanded' of ."
	return
	elif test "${found_ref#refs/remotes/}" != "$found_ref"
	then
	echo "$rh remote branch '$expanded' of ."
	return
	fi
	fi
	if test "$remote" = "FETCH_HEAD" && test -r "$GIT_DIR/FETCH_HEAD"
	then
	sed -e 's/ not-for-merge / /' -e 1q \
	"$GIT_DIR/FETCH_HEAD"
	return
	fi
	echo "$rh commit '$remote'"
	}

	parse_config () {
	while test $# != 0; do
	case "$1" in
	-n\|--no-stat\|--no-summary)
	show_diffstat=false ;;
	--stat\|--summary)
	show_diffstat=t ;;
	--log\|--no-log)
	log_arg=$1 ;;
	--squash)
	test "$allow_fast_forward" = t \|\|
	die "You cannot combine --squash with --no-ff."
	squash=t no_commit=t ;;
	--no-squash)
	squash= no_commit= ;;
	--commit)
	no_commit= ;;
	--no-commit)
	no_commit=t ;;
	--ff)
	allow_fast_forward=t ;;
	--no-ff)
	test "$squash" != t \|\|
	die "You cannot combine --squash with --no-ff."
	test "$fast_forward_only" != t \|\|
	die "You cannot combine --ff-only with --no-ff."
	allow_fast_forward=f ;;
	--ff-only)
	test "$allow_fast_forward" != f \|\|
	die "You cannot combine --ff-only with --no-ff."
	fast_forward_only=t ;;
	--rerere-autoupdate\|--no-rerere-autoupdate)
	rr_arg=$1 ;;
	-s\|--strategy)
	shift
	case " $all_strategies " in
	" $1 ")
	use_strategies="$use_strategies$1 "
	;;
	*)
	case " $not_strategies " in
	" $1 ")
	false
	esac &&
	type "git-merge-$1" >/dev/null 2>&1 \|\|
	die "available strategies are: $all_strategies"
	use_strategies="$use_strategies$1 "
	;;
	esac
	;;
	-X)
	shift
	xopt="${xopt:+$xopt }$(git rev-parse --sq-quote "--$1")"
	;;
	-m\|--message)
	shift
	merge_msg="$1"
	have_message=t
	;;
	--)
	shift
	break ;;
	*) usage ;;
	esac
	shift
	done
	args_left=$#
	}

	test $# != 0 \|\| usage

	have_message=

	if branch=$(git-symbolic-ref -q HEAD)
	then
	mergeopts=$(git config "branch.${branch#refs/heads/}.mergeoptions")
	if test -n "$mergeopts"
	then
	parse_config $mergeopts --
	fi
	fi

	parse_config "$@"
	while test $args_left -lt $#; do shift; done

	if test -z "$show_diffstat"; then
	test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
	test "$(git config --bool merge.stat)" = false && show_diffstat=false
	test -z "$show_diffstat" && show_diffstat=t
	fi

	# This could be traditional "merge <msg> HEAD <commit>..." and the
	# way we can tell it is to see if the second token is HEAD, but some
	# people might have misused the interface and used a commit-ish that
	# is the same as HEAD there instead. Traditional format never would
	# have "-m" so it is an additional safety measure to check for it.

	if test -z "$have_message" &&
	second_token=$(git rev-parse --verify "$2^0" 2>/dev/null) &&
	head_commit=$(git rev-parse --verify "HEAD" 2>/dev/null) &&
	test "$second_token" = "$head_commit"
	then
	merge_msg="$1"
	shift
	head_arg="$1"
	shift
	elif ! git rev-parse --verify HEAD >/dev/null 2>&1
	then
	# If the merged head is a valid one there is no reason to
	# forbid "git merge" into a branch yet to be born. We do
	# the same for "git pull".
	if test 1 -ne $#
	then
	echo >&2 "Can merge only exactly one commit into empty head"
	exit 1
	fi

	test "$squash" != t \|\|
	die "Squash commit into empty head not supported yet"
	test "$allow_fast_forward" = t \|\|
	die "Non-fast-forward into an empty head does not make sense"
	rh=$(git rev-parse --verify "$1^0") \|\|
	die "$1 - not something we can merge"

	git update-ref -m "initial pull" HEAD "$rh" "" &&
	git read-tree --reset -u HEAD
	exit

	else
	# We are invoked directly as the first-class UI.
	head_arg=HEAD

	# All the rest are the commits being merged; prepare
	# the standard merge summary message to be appended to
	# the given message. If remote is invalid we will die
	# later in the common codepath so we discard the error
	# in this loop.
	merge_msg="$(
	for remote
	do
	merge_name "$remote"
	done \|
	if test "$have_message" = t
	then
	git fmt-merge-msg -m "$merge_msg" $log_arg
	else
	git fmt-merge-msg $log_arg
	fi
	)"
	fi
	head=$(git rev-parse --verify "$head_arg"^0) \|\| usage

	# All the rest are remote heads
	test "$#" = 0 && usage ;# we need at least one remote head.
	set_reflog_action "merge $*"

	remoteheads=
	for remote
	do
	remotehead=$(git rev-parse --verify "$remote"^0 2>/dev/null) \|\|
	die "$remote - not something we can merge"
	remoteheads="${remoteheads}$remotehead "
	eval GITHEAD_$remotehead='"$remote"'
	export GITHEAD_$remotehead
	done
	set x $remoteheads ; shift

	case "$use_strategies" in
	'')
	case "$#" in
	1)
	var="$(git config --get pull.twohead)"
	if test -n "$var"
	then
	use_strategies="$var"
	else
	use_strategies="$default_twohead_strategies"
	fi ;;
	*)
	var="$(git config --get pull.octopus)"
	if test -n "$var"
	then
	use_strategies="$var"
	else
	use_strategies="$default_octopus_strategies"
	fi ;;
	esac
	;;
	esac

	for s in $use_strategies
	do
	for ss in $no_fast_forward_strategies
	do
	case " $s " in
	" $ss ")
	allow_fast_forward=f
	break
	;;
	esac
	done
	for ss in $no_trivial_strategies
	do
	case " $s " in
	" $ss ")
	allow_trivial_merge=f
	break
	;;
	esac
	done
	done

	case "$#" in
	1)
	common=$(git merge-base --all $head "$@")
	;;
	*)
	common=$(git merge-base --all --octopus $head "$@")
	;;
	esac
	echo "$head" >"$GIT_DIR/ORIG_HEAD"

	case "$allow_fast_forward,$#,$common,$no_commit" in
	?,,'',)
	# No common ancestors found. We need a real merge.
	;;
	?,1,"$1",*)
	# If head can reach all the merge then we are up to date.
	# but first the most common case of merging one remote.
	finish_up_to_date "Already up-to-date."
	exit 0
	;;
	t,1,"$head",*)
	# Again the most common case of merging one remote.
	echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
	git update-index --refresh 2>/dev/null
	msg="Fast-forward"
	if test -n "$have_message"
	then
	msg="$msg (no commit created; -m option ignored)"
	fi
	new_head=$(git rev-parse --verify "$1^0") &&
	git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
	finish "$new_head" "$msg" \|\| exit
	dropsave
	exit 0
	;;
	?,1,?"$LF"?,*)
	# We are not doing octopus and not fast-forward. Need a
	# real merge.
	;;
	?,1,*,)
	# We are not doing octopus, not fast-forward, and have only
	# one common.
	git update-index --refresh 2>/dev/null
	case "$allow_trivial_merge,$fast_forward_only" in
	t,)
	# See if it is really trivial.
	git var GIT_COMMITTER_IDENT >/dev/null \|\| exit
	echo "Trying really trivial in-index merge..."
	if git read-tree --trivial -m -u -v $common $head "$1" &&
	result_tree=$(git write-tree)
	then
	echo "Wonderful."
	result_commit=$(
	printf '%s\n' "$merge_msg" \|
	git commit-tree $result_tree -p HEAD -p "$1"
	) \|\| exit
	finish "$result_commit" "In-index merge"
	dropsave
	exit 0
	fi
	echo "Nope."
	esac
	;;
	*)
	# An octopus. If we can reach all the remote we are up to date.
	up_to_date=t
	for remote
	do
	common_one=$(git merge-base --all $head $remote)
	if test "$common_one" != "$remote"
	then
	up_to_date=f
	break
	fi
	done
	if test "$up_to_date" = t
	then
	finish_up_to_date "Already up-to-date. Yeeah!"
	exit 0
	fi
	;;
	esac

	if test "$fast_forward_only" = t
	then
	die "Not possible to fast-forward, aborting."
	fi

	# We are going to make a new commit.
	git var GIT_COMMITTER_IDENT >/dev/null \|\| exit

	# At this point, we need a real merge. No matter what strategy
	# we use, it would operate on the index, possibly affecting the
	# working tree, and when resolved cleanly, have the desired tree
	# in the index -- this means that the index must be in sync with
	# the $head commit. The strategies are responsible to ensure this.

	case "$use_strategies" in
	?' '?)
	# Stash away the local changes so that we can try more than one.
	savestate
	single_strategy=no
	;;
	*)
	rm -f "$GIT_DIR/MERGE_STASH"
	single_strategy=yes
	;;
	esac

	result_tree= best_cnt=-1 best_strategy= wt_strategy=
	merge_was_ok=
	for strategy in $use_strategies
	do
	test "$wt_strategy" = '' \|\| {
	echo "Rewinding the tree to pristine..."
	restorestate
	}
	case "$single_strategy" in
	no)
	echo "Trying merge strategy $strategy..."
	;;
	esac

	# Remember which strategy left the state in the working tree
	wt_strategy=$strategy

	eval 'git-merge-$strategy '"$xopt"' $common -- "$head_arg" "$@"'
	exit=$?
	if test "$no_commit" = t && test "$exit" = 0
	then
	merge_was_ok=t
	exit=1 ;# pretend it left conflicts.
	fi

	test "$exit" = 0 \|\| {

	# The backend exits with 1 when conflicts are left to be resolved,
	# with 2 when it does not handle the given merge at all.

	if test "$exit" -eq 1
	then
	cnt=$({
	git diff-files --name-only
	git ls-files --unmerged
	} \| wc -l)
	if test $best_cnt -le 0 \|\| test $cnt -le $best_cnt
	then
	best_strategy=$strategy
	best_cnt=$cnt
	fi
	fi
	continue
	}

	# Automerge succeeded.
	result_tree=$(git write-tree) && break
	done

	# If we have a resulting tree, that means the strategy module
	# auto resolved the merge cleanly.
	if test '' != "$result_tree"
	then
	if test "$allow_fast_forward" = "t"
	then
	parents=$(git merge-base --independent "$head" "$@")
	else
	parents=$(git rev-parse "$head" "$@")
	fi
	parents=$(echo "$parents" \| sed -e 's/^/-p /')
	result_commit=$(printf '%s\n' "$merge_msg" \| git commit-tree $result_tree $parents) \|\| exit
	finish "$result_commit" "Merge made by $wt_strategy."
	dropsave
	exit 0
	fi

	# Pick the result from the best strategy and have the user fix it up.
	case "$best_strategy" in
	'')
	restorestate
	case "$use_strategies" in
	?' '?)
	echo >&2 "No merge strategy handled the merge."
	;;
	*)
	echo >&2 "Merge with strategy $use_strategies failed."
	;;
	esac
	exit 2
	;;
	"$wt_strategy")
	# We already have its result in the working tree.
	;;
	*)
	echo "Rewinding the tree to pristine..."
	restorestate
	echo "Using the $best_strategy to prepare resolving by hand."
	git-merge-$best_strategy $common -- "$head_arg" "$@"
	;;
	esac

	if test "$squash" = t
	then
	finish
	else
	for remote
	do
	echo $remote
	done >"$GIT_DIR/MERGE_HEAD"
	printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG" \|\|
	die "Could not write to $GIT_DIR/MERGE_MSG"
	if test "$allow_fast_forward" != t
	then
	printf "%s" no-ff
	else
	:
	fi >"$GIT_DIR/MERGE_MODE" \|\|
	die "Could not write to $GIT_DIR/MERGE_MODE"
	fi

	if test "$merge_was_ok" = t
	then
	echo >&2 \
	"Automatic merge went well; stopped before committing as requested"
	exit 0
	else
	{
	echo '
	Conflicts:
	'
	git ls-files --unmerged \|
	sed -e 's/^[^ ]* / /' \|
	uniq
	} >>"$GIT_DIR/MERGE_MSG"
	git rerere $rr_arg
	die "Automatic merge failed; fix conflicts and then commit the result."
	fi