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pull: allow pull to preserve merges when rebasing
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If a user is working on master, and has merged in their feature branch, but now
has to "git pull" because master moved, with pull.rebase their feature branch
will be flattened into master.

This is because "git pull" currently does not know about rebase's preserve
merges flag, which would avoid this behavior, as it would instead replay just
the merge commit of the feature branch onto the new master, and not replay each
individual commit in the feature branch.

Add a --rebase=preserve option, which will pass along --preserve-merges to
rebase.

Also add 'preserve' to the allowed values for the pull.rebase config setting.

Signed-off-by: Stephen Haberman <stephen@exigencecorp.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Stephen Haberman authored and Junio C Hamano committed Sep 4, 2013
1 parent 96cb27a commit 66713ef
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8 changes: 8 additions & 0 deletions Documentation/config.txt
Original file line number Diff line number Diff line change
Expand Up @@ -765,6 +765,10 @@ branch.<name>.rebase::
instead of merging the default branch from the default remote when
"git pull" is run. See "pull.rebase" for doing this in a non
branch-specific manner.
+
When preserve, also pass `--preserve-merges` along to 'git rebase'
so that locally committed merge commits will not be flattened
by running 'git pull'.
+
*NOTE*: this is a possibly dangerous operation; do *not* use
it unless you understand the implications (see linkgit:git-rebase[1]
Expand Down Expand Up @@ -1825,6 +1829,10 @@ pull.rebase::
of merging the default branch from the default remote when "git
pull" is run. See "branch.<name>.rebase" for setting this on a
per-branch basis.
+
When preserve, also pass `--preserve-merges` along to 'git rebase'
so that locally committed merge commits will not be flattened
by running 'git pull'.
+
*NOTE*: this is a possibly dangerous operation; do *not* use
it unless you understand the implications (see linkgit:git-rebase[1]
Expand Down
18 changes: 12 additions & 6 deletions Documentation/git-pull.txt
Original file line number Diff line number Diff line change
Expand Up @@ -102,12 +102,18 @@ include::merge-options.txt[]
:git-pull: 1

-r::
--rebase::
Rebase the current branch on top of the upstream branch after
fetching. If there is a remote-tracking branch corresponding to
the upstream branch and the upstream branch was rebased since last
fetched, the rebase uses that information to avoid rebasing
non-local changes.
--rebase[=false|true|preserve]::
When true, rebase the current branch on top of the upstream
branch after fetching. If there is a remote-tracking branch
corresponding to the upstream branch and the upstream branch
was rebased since last fetched, the rebase uses that information
to avoid rebasing non-local changes.
+
When preserve, also rebase the current branch on top of the upstream
branch, but pass `--preserve-merges` along to `git rebase` so that
locally created merge commits will not be flattened.
+
When false, merge the current branch into the upstream branch.
+
See `pull.rebase`, `branch.<name>.rebase` and `branch.autosetuprebase` in
linkgit:git-config[1] if you want to make `git pull` always use
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31 changes: 26 additions & 5 deletions git-pull.sh
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@
#
# Fetch one or more remote refs and merge it/them into the current HEAD.

USAGE='[-n | --no-stat] [--[no-]commit] [--[no-]squash] [--[no-]ff] [-s strategy]... [<fetch-options>] <repo> <head>...'
USAGE='[-n | --no-stat] [--[no-]commit] [--[no-]squash] [--[no-]ff] [--[no-]rebase|--rebase=preserve] [-s strategy]... [<fetch-options>] <repo> <head>...'
LONG_USAGE='Fetch one or more remote refs and integrate it/them with the current HEAD.'
SUBDIRECTORY_OK=Yes
OPTIONS_SPEC=
Expand Down Expand Up @@ -38,15 +38,19 @@ Please, commit your changes before you can merge.")"
test -z "$(git ls-files -u)" || die_conflict
test -f "$GIT_DIR/MERGE_HEAD" && die_merge

bool_or_string_config () {
git config --bool "$1" 2>/dev/null || git config "$1"
}

strategy_args= diffstat= no_commit= squash= no_ff= ff_only=
log_arg= verbosity= progress= recurse_submodules= verify_signatures=
merge_args= edit=
merge_args= edit= rebase_args=
curr_branch=$(git symbolic-ref -q HEAD)
curr_branch_short="${curr_branch#refs/heads/}"
rebase=$(git config --bool branch.$curr_branch_short.rebase)
rebase=$(bool_or_string_config branch.$curr_branch_short.rebase)
if test -z "$rebase"
then
rebase=$(git config --bool pull.rebase)
rebase=$(bool_or_string_config pull.rebase)
fi
dry_run=
while :
Expand Down Expand Up @@ -110,6 +114,9 @@ do
esac
merge_args="$merge_args$xx "
;;
-r=*|--r=*|--re=*|--reb=*|--reba=*|--rebas=*|--rebase=*)
rebase="${1#*=}"
;;
-r|--r|--re|--reb|--reba|--rebas|--rebase)
rebase=true
;;
Expand Down Expand Up @@ -145,6 +152,20 @@ do
shift
done

case "$rebase" in
preserve)
rebase=true
rebase_args=--preserve-merges
;;
true|false|'')
;;
*)
echo "Invalid value for --rebase, should be true, false, or preserve"
usage
exit 1
;;
esac

error_on_no_merge_candidates () {
exec >&2
for opt
Expand Down Expand Up @@ -292,7 +313,7 @@ fi
merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit
case "$rebase" in
true)
eval="git-rebase $diffstat $strategy_args $merge_args $verbosity"
eval="git-rebase $diffstat $strategy_args $merge_args $rebase_args $verbosity"
eval="$eval --onto $merge_head ${oldremoteref:-$merge_head}"
;;
*)
Expand Down
89 changes: 89 additions & 0 deletions t/t5520-pull.sh
Original file line number Diff line number Diff line change
Expand Up @@ -148,6 +148,95 @@ test_expect_success 'branch.to-rebase.rebase should override pull.rebase' '
test new = $(git show HEAD:file2)
'

# add a feature branch, keep-merge, that is merged into master, so the
# test can try preserving the merge commit (or not) with various
# --rebase flags/pull.rebase settings.
test_expect_success 'preserve merge setup' '
git reset --hard before-rebase &&
git checkout -b keep-merge second^ &&
test_commit file3 &&
git checkout to-rebase &&
git merge keep-merge &&
git tag before-preserve-rebase
'

test_expect_success 'pull.rebase=false create a new merge commit' '
git reset --hard before-preserve-rebase &&
test_config pull.rebase false &&
git pull . copy &&
test $(git rev-parse HEAD^1) = $(git rev-parse before-preserve-rebase) &&
test $(git rev-parse HEAD^2) = $(git rev-parse copy) &&
test file3 = $(git show HEAD:file3.t)
'

test_expect_success 'pull.rebase=true flattens keep-merge' '
git reset --hard before-preserve-rebase &&
test_config pull.rebase true &&
git pull . copy &&
test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
test file3 = $(git show HEAD:file3.t)
'

test_expect_success 'pull.rebase=1 is treated as true and flattens keep-merge' '
git reset --hard before-preserve-rebase &&
test_config pull.rebase 1 &&
git pull . copy &&
test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
test file3 = $(git show HEAD:file3.t)
'

test_expect_success 'pull.rebase=preserve rebases and merges keep-merge' '
git reset --hard before-preserve-rebase &&
test_config pull.rebase preserve &&
git pull . copy &&
test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
test $(git rev-parse HEAD^2) = $(git rev-parse keep-merge)
'

test_expect_success 'pull.rebase=invalid fails' '
git reset --hard before-preserve-rebase &&
test_config pull.rebase invalid &&
! git pull . copy
'

test_expect_success '--rebase=false create a new merge commit' '
git reset --hard before-preserve-rebase &&
test_config pull.rebase true &&
git pull --rebase=false . copy &&
test $(git rev-parse HEAD^1) = $(git rev-parse before-preserve-rebase) &&
test $(git rev-parse HEAD^2) = $(git rev-parse copy) &&
test file3 = $(git show HEAD:file3.t)
'

test_expect_success '--rebase=true rebases and flattens keep-merge' '
git reset --hard before-preserve-rebase &&
test_config pull.rebase preserve &&
git pull --rebase=true . copy &&
test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
test file3 = $(git show HEAD:file3.t)
'

test_expect_success '--rebase=preserve rebases and merges keep-merge' '
git reset --hard before-preserve-rebase &&
test_config pull.rebase true &&
git pull --rebase=preserve . copy &&
test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
test $(git rev-parse HEAD^2) = $(git rev-parse keep-merge)
'

test_expect_success '--rebase=invalid fails' '
git reset --hard before-preserve-rebase &&
! git pull --rebase=invalid . copy
'

test_expect_success '--rebase overrides pull.rebase=preserve and flattens keep-merge' '
git reset --hard before-preserve-rebase &&
test_config pull.rebase preserve &&
git pull --rebase . copy &&
test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
test file3 = $(git show HEAD:file3.t)
'

test_expect_success '--rebase with rebased upstream' '
git remote add -f me . &&
Expand Down

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