git-merge --squash

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>

diff --git a/Documentation/merge-options.txt b/Documentation/merge-options.txt
index 53cc35590debbb7e4d7dfae536be19e59d038560..182cef54be5963ff0f32a24329ca195607413e29 100644 (file)
--- a/Documentation/merge-options.txt
+++ b/Documentation/merge-options.txt
@@ -6,6 +6,14 @@
        not autocommit, to give the user a chance to inspect and
        further tweak the merge result before committing.
 
        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
 
 -s <strategy>, \--strategy=<strategy>::
        Use the given merge strategy; can be supplied more than

diff --git a/git-commit.sh b/git-commit.sh
index e74fe640b8acb87bef2cc118e87d8779c79f8786..9f49651cfdce101af3ba2c1980121d9ccea8a194 100755 (executable)
--- a/git-commit.sh
+++ b/git-commit.sh
@@ -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/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 "$signoff" in
 fi | git-stripspace >"$GIT_DIR"/COMMIT_EDITMSG
 
 case "$signoff" in


@@ -663,7 +666,7 @@ else
 fi
 if [ "$?" != "0" -a ! -f "$GIT_DIR/MERGE_HEAD" -a -z "$amend" ]
 then
 fi
 if [ "$?" != "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
        run_status
        exit 1
 fi


@@ -729,7 +732,7 @@ else
        false
 fi
 ret="$?"
        false
 fi
 ret="$?"

-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 "$GIT_DIR/rr-cache"
 then
        git-rerere
 if test -d "$GIT_DIR/rr-cache"
 then
        git-rerere

diff --git a/git-merge.sh b/git-merge.sh
index da5657eb40516430d0302eea2e15bac6fa699b55..fc25f8dda01ecf4733165308d9fb1fa80dffbe0c 100755 (executable)
--- a/git-merge.sh
+++ b/git-merge.sh
@@ -3,8 +3,7 @@
 # Copyright (c) 2005 Junio C Hamano
 #
 
 # 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='
 . git-sh-setup
 
 LF='


@@ -42,20 +41,49 @@ restorestate() {
        fi
 }
 
        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"
 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
                ;;
        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
 }
                ;;
        esac
 }


@@ -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 ;;
        -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=*|\
        --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
                no_commit=t ;;
        -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\


@@ -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.
 ?,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,"$head",*)
        exit 0
        ;;
 ?,1,"$head",*)


@@ -205,8 +234,7 @@ f,*)
        done
        if test "$up_to_date" = t
        then
        done
        if test "$up_to_date" = t
        then

-               echo "Already up-to-date. Yeeah!"
-               dropsave
+               finish_up_to_date "Already up-to-date. Yeeah!"

                exit 0
        fi
        ;;
                exit 0
        fi
        ;;


@@ -310,11 +338,17 @@ case "$best_strategy" in
        git-merge-$best_strategy $common -- "$head_arg" "$@"
        ;;
 esac
        git-merge-$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
 
 if test "$merge_was_ok" = t
 then

diff --git a/git-pull.sh b/git-pull.sh
index bdd3939923bb905d561eb3ca88bda729cc93660d..aa8c2080927661cca281fca543dc5f0808f678e3 100755 (executable)
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -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
 
 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 "$1" in
 while case "$#,$1" in 0) break ;; *,-*) ;; *) break ;; esac
 do
        case "$1" in


@@ -17,6 +17,8 @@ do
                no_summary=-n ;;
        --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
                no_commit=--no-commit ;;
                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)
        -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
                --strateg=*|--strategy=*|\
        -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)


@@ -100,4 +102,5 @@ case "$strategy_args" in
 esac
 
 merge_name=$(git-fmt-merge-msg <"$GIT_DIR/FETCH_HEAD") || exit
 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

diff --git a/git-reset.sh b/git-reset.sh
index 296f3b779b5889e4f9e69f994587d70503e8b25e..46451d0d64bdff2c0061d100c8d3b3bd38c21454 100755 (executable)
--- a/git-reset.sh
+++ b/git-reset.sh
@@ -61,4 +61,4 @@ case "$reset_type" in
        ;;
 esac
 
        ;;
 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"