git/git-merge.sh
Junio C Hamano 228e2eb67e merge and reset: adjust for "reset --hard" messages
An earlier commit made "reset --hard" chattier but leaking its
message from "git rebase" (which calls it when first rewinding
the current branch to prepare replaying our own changes) without
explanation was confusing, so add an extra message to mention
it.  Inside restorestate in merge (which is rarely exercised
codepath, where more than one strategies are attempted),
resetting to the original state uses "reset --hard" -- this can
be squelched entirely.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-12-22 15:21:55 -08:00

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#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano
#
USAGE='[-n] [--no-commit] [--squash] [-s <strategy>] [--reflog-action=<action>] [-m=<merge-message>] <commit>+'
. git-sh-setup
LF='
'
all_strategies='recur recursive octopus resolve stupid ours'
default_twohead_strategies='recursive'
default_octopus_strategies='octopus'
no_trivial_merge_strategies='ours'
use_strategies=
index_merge=t
dropsave() {
rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
"$GIT_DIR/MERGE_SAVE" || exit 1
}
savestate() {
# Stash away any local modifications.
git-diff-index -z --name-only $head |
cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
}
restorestate() {
if test -f "$GIT_DIR/MERGE_SAVE"
then
git reset --hard $head >/dev/null
cpio -iuv <"$GIT_DIR/MERGE_SAVE"
git-update-index --refresh >/dev/null
fi
}
finish_up_to_date () {
case "$squash" in
t)
echo "$1 (nothing to squash)" ;;
'')
echo "$1" ;;
esac
dropsave
}
squash_message () {
echo Squashed commit of the following:
echo
git-log --no-merges ^"$head" $remote
}
finish () {
if test '' = "$2"
then
rlogm="$rloga"
else
echo "$2"
rlogm="$rloga: $2"
fi
case "$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
;;
esac
;;
esac
case "$1" in
'')
;;
?*)
case "$no_summary" in
'')
git-diff-tree --stat --summary -M "$head" "$1"
;;
esac
;;
esac
}
merge_name () {
remote="$1"
rh=$(git-rev-parse --verify "$remote^0" 2>/dev/null) || return
bh=$(git-show-ref -s --verify "refs/heads/$remote" 2>/dev/null)
if test "$rh" = "$bh"
then
echo "$rh branch '$remote' of ."
elif truname=$(expr "$remote" : '\(.*\)~[1-9][0-9]*$') &&
git-show-ref -q --verify "refs/heads/$truname" 2>/dev/null
then
echo "$rh branch '$truname' (early part) of ."
else
echo "$rh commit '$remote'"
fi
}
case "$#" in 0) usage ;; esac
rloga= have_message=
while case "$#" in 0) break ;; esac
do
case "$1" in
-n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
--no-summa|--no-summar|--no-summary)
no_summary=t ;;
--sq|--squ|--squa|--squas|--squash)
squash=t no_commit=t ;;
--no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
no_commit=t ;;
-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
--strateg=*|--strategy=*|\
-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
case "$#,$1" in
*,*=*)
strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
1,*)
usage ;;
*)
strategy="$2"
shift ;;
esac
case " $all_strategies " in
*" $strategy "*)
use_strategies="$use_strategies$strategy " ;;
*)
die "available strategies are: $all_strategies" ;;
esac
;;
--reflog-action=*)
rloga=`expr "z$1" : 'z-[^=]*=\(.*\)'`
;;
-m=*|--m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
merge_msg=`expr "z$1" : 'z-[^=]*=\(.*\)'`
have_message=t
;;
-m|--m|--me|--mes|--mess|--messa|--messag|--message)
shift
case "$#" in
1) usage ;;
esac
merge_msg="$1"
have_message=t
;;
-*) usage ;;
*) break ;;
esac
shift
done
# This could be traditional "merge <msg> HEAD <commit>..." and the
# way we can tell it is to see if the second token is HEAD, but some
# people might have misused the interface and used a committish that
# is the same as HEAD there instead. Traditional format never would
# have "-m" so it is an additional safety measure to check for it.
if test -z "$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 $#
then
echo >&2 "Can merge only exactly one commit into empty head"
exit 1
fi
rh=$(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_name=$(for remote
do
merge_name "$remote"
done | git-fmt-merge-msg
)
merge_msg="${merge_msg:+$merge_msg$LF$LF}$merge_name"
fi
head=$(git-rev-parse --verify "$head_arg"^0) || usage
# All the rest are remote heads
test "$#" = 0 && usage ;# we need at least one remote head.
test "$rloga" = '' && rloga="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 "
done
set x $remoteheads ; shift
case "$use_strategies" in
'')
case "$#" in
1)
use_strategies="$default_twohead_strategies" ;;
*)
use_strategies="$default_octopus_strategies" ;;
esac
;;
esac
for s in $use_strategies
do
case " $s " in
*" $no_trivial_merge_strategies "*)
index_merge=f
break
;;
esac
done
case "$#" in
1)
common=$(git-merge-base --all $head "$@")
;;
*)
common=$(git-show-branch --merge-base $head "$@")
;;
esac
echo "$head" >"$GIT_DIR/ORIG_HEAD"
case "$index_merge,$#,$common,$no_commit" in
f,*)
# We've been told not to try anything clever. Skip to real merge.
;;
?,*,'',*)
# No common ancestors found. We need a real merge.
;;
?,1,"$1",*)
# If head can reach all the merge then we are up to date.
# but first the most common case of merging one remote.
finish_up_to_date "Already up-to-date."
exit 0
;;
?,1,"$head",*)
# Again the most common case of merging one remote.
echo "Updating $(git-rev-parse --short $head)..$(git-rev-parse --short $1)"
git-update-index --refresh 2>/dev/null
new_head=$(git-rev-parse --verify "$1^0") &&
git-read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
finish "$new_head" "Fast forward"
dropsave
exit 0
;;
?,1,?*"$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. See if it is really trivial.
git var GIT_COMMITTER_IDENT >/dev/null || exit
echo "Trying really trivial in-index merge..."
git-update-index --refresh 2>/dev/null
if git-read-tree --trivial -m -u -v $common $head "$1" &&
result_tree=$(git-write-tree)
then
echo "Wonderful."
result_commit=$(
echo "$merge_msg" |
git-commit-tree $result_tree -p HEAD -p "$1"
) || exit
finish "$result_commit" "In-index merge"
dropsave
exit 0
fi
echo "Nope."
;;
*)
# 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
# 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_SAVE"
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
git-merge-$strategy $common -- "$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 -o $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 '' != "$result_tree"
then
parents=$(git-show-branch --independent "$head" "$@" | sed -e 's/^/-p /')
result_commit=$(echo "$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"
echo "$merge_msg" >"$GIT_DIR/MERGE_MSG"
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"
if test -d "$GIT_DIR/rr-cache"
then
git-rerere
fi
die "Automatic merge failed; fix conflicts and then commit the result."
fi