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git-merge --squash
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Some people tend to do many little commits on a topic branch,
recording all the trials and errors, and when the topic is
reasonably cooked well, would want to record the net effect of
the series as one commit on top of the mainline, removing the
cruft from the history.  The topic is then abandoned or forked
off again from that point at the mainline.

The barebone porcelainish that comes with core git tools does
not officially support such operation, but you can fake it by
using "git pull --no-merge" when such a topic branch is not a
strict superset of the mainline, like this:

	git checkout mainline
	git pull --no-commit . that-topic-branch
	: fix conflicts if any
	rm -f .git/MERGE_HEAD
        git commit -a -m 'consolidated commit log message'
	git branch -f that-topic-branch ;# now fully merged

This however does not work when the topic branch is a fast
forward of the mainline, because normal "git pull" will never
create a merge commit in such a case, and there is nothing
special --no-commit could do to begin with.

This patch introduces a new option, --squash, to support such a
workflow officially in both fast-forward case and true merge
case.  The user-level operation would be the same in both cases:

	git checkout mainline
        git pull --squash . that-topic-branch
        : fix conflicts if any -- naturally, there would be
        : no conflict if fast forward.
	git commit -a -m  'consolidated commit log message'
	git branch -f that-topic-branch ;# now fully merged

When the current branch is already up-to-date with respect to
the other branch, there truly is nothing to do, so the new
option does not have any effect.

This was brought up in #git IRC channel recently.

Signed-off-by: Junio C Hamano <junkio@cox.net>
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Junio C Hamano committed Jun 24, 2006
1 parent 86378b3 commit 7d0c688
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8 changes: 8 additions & 0 deletions Documentation/merge-options.txt
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Expand Up @@ -6,6 +6,14 @@
not autocommit, to give the user a chance to inspect and
further tweak the merge result before committing.

--squash::
Produce the working tree and index state as if a real
merge happened, but do not actually make a commit or
move the `HEAD`, nor record `$GIT_DIR/MERGE_HEAD` to
cause the next `git commit` command to create a merge
commit. This allows you to create a single commit on
top of the current branch whose effect is the same as
merging another branch (or more in case of an octopus).

-s <strategy>, \--strategy=<strategy>::
Use the given merge strategy; can be supplied more than
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7 changes: 5 additions & 2 deletions git-commit.sh
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Expand Up @@ -566,6 +566,9 @@ then
elif test -f "$GIT_DIR/MERGE_HEAD" && test -f "$GIT_DIR/MERGE_MSG"
then
cat "$GIT_DIR/MERGE_MSG"
elif test -f "$GIT_DIR/SQUASH_MSG"
then
cat "$GIT_DIR/SQUASH_MSG"
fi | git-stripspace >"$GIT_DIR"/COMMIT_EDITMSG

case "$signoff" in
Expand Down Expand Up @@ -663,7 +666,7 @@ else
fi
if [ "$?" != "0" -a ! -f "$GIT_DIR/MERGE_HEAD" -a -z "$amend" ]
then
rm -f "$GIT_DIR/COMMIT_EDITMSG"
rm -f "$GIT_DIR/COMMIT_EDITMSG" "$GIT_DIR/SQUASH_MSG"
run_status
exit 1
fi
Expand Down Expand Up @@ -729,7 +732,7 @@ else
false
fi
ret="$?"
rm -f "$GIT_DIR/COMMIT_MSG" "$GIT_DIR/COMMIT_EDITMSG"
rm -f "$GIT_DIR/COMMIT_MSG" "$GIT_DIR/COMMIT_EDITMSG" "$GIT_DIR/SQUASH_MSG"
if test -d "$GIT_DIR/rr-cache"
then
git-rerere
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72 changes: 53 additions & 19 deletions git-merge.sh
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Expand Up @@ -3,8 +3,7 @@
# Copyright (c) 2005 Junio C Hamano
#


USAGE='[-n] [--no-commit] [-s <strategy>]... <merge-message> <head> <remote>+'
USAGE='[-n] [--no-commit] [--squash] [-s <strategy>]... <merge-message> <head> <remote>+'
. git-sh-setup

LF='
Expand Down Expand Up @@ -42,20 +41,49 @@ restorestate() {
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 () {
test '' = "$2" || echo "$2"
case "$merge_msg" in
'')
echo "No merge message -- not updating HEAD"
case "$squash" in
t)
echo "Squash commit -- not updating HEAD"
squash_message >"$GIT_DIR/SQUASH_MSG"
;;
*)
git-update-ref HEAD "$1" "$head" || exit 1
'')
case "$merge_msg" in
'')
echo "No merge message -- not updating HEAD"
;;
*)
git-update-ref HEAD "$1" "$head" || exit 1
;;
esac
;;
esac

case "$no_summary" in
case "$1" in
'')
git-diff-tree --stat --summary -M "$head" "$1"
;;
?*)
case "$no_summary" in
'')
git-diff-tree --stat --summary -M "$head" "$1"
;;
esac
;;
esac
}
Expand All @@ -66,6 +94,8 @@ do
-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=*|\
Expand Down Expand Up @@ -152,8 +182,7 @@ f,*)
?,1,"$1",*)
# If head can reach all the merge then we are up to date.
# but first the most common case of merging one remote.
echo "Already up-to-date."
dropsave
finish_up_to_date "Already up-to-date."
exit 0
;;
?,1,"$head",*)
Expand Down Expand Up @@ -205,8 +234,7 @@ f,*)
done
if test "$up_to_date" = t
then
echo "Already up-to-date. Yeeah!"
dropsave
finish_up_to_date "Already up-to-date. Yeeah!"
exit 0
fi
;;
Expand Down Expand Up @@ -310,11 +338,17 @@ case "$best_strategy" in
git-merge-$best_strategy $common -- "$head_arg" "$@"
;;
esac
for remote
do
echo $remote
done >"$GIT_DIR/MERGE_HEAD"
echo "$merge_msg" >"$GIT_DIR/MERGE_MSG"

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
Expand Down
7 changes: 5 additions & 2 deletions git-pull.sh
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Expand Up @@ -8,7 +8,7 @@ USAGE='[-n | --no-summary] [--no-commit] [-s strategy]... [<fetch-options>] <rep
LONG_USAGE='Fetch one or more remote refs and merge it/them into the current HEAD.'
. git-sh-setup

strategy_args= no_summary= no_commit=
strategy_args= no_summary= no_commit= squash=
while case "$#,$1" in 0) break ;; *,-*) ;; *) break ;; esac
do
case "$1" in
Expand All @@ -17,6 +17,8 @@ do
no_summary=-n ;;
--no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
no_commit=--no-commit ;;
--sq|--squ|--squa|--squas|--squash)
squash=--squash ;;
-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
--strateg=*|--strategy=*|\
-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
Expand Down Expand Up @@ -100,4 +102,5 @@ case "$strategy_args" in
esac

merge_name=$(git-fmt-merge-msg <"$GIT_DIR/FETCH_HEAD") || exit
git-merge $no_summary $no_commit $strategy_args "$merge_name" HEAD $merge_head
git-merge $no_summary $no_commit $squash $strategy_args \
"$merge_name" HEAD $merge_head
2 changes: 1 addition & 1 deletion git-reset.sh
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Expand Up @@ -61,4 +61,4 @@ case "$reset_type" in
;;
esac

rm -f "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/rr-cache/MERGE_RR"
rm -f "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/rr-cache/MERGE_RR" "$GIT_DIR/SQUASH_MSG"

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