[PATCH v6 5/7] pull: add merge-ff-only option

From

Felipe Contreras <felipe.contreras@gmail.com>

Date

May 2, 2014, 00:00 UTC

Message-ID

<1398988808-29678-6-git-send-email-felipe.contreras@gmail.com>

In-Reply-To

<1398988808-29678-1-git-send-email-felipe.contreras@gmail.com>

Later on this mode can be enabled by default.

For the full discussion you can read:

http://thread.gmane.org/gmane.comp.version-control.git/225146/focus=225305

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
---
 Documentation/config.txt |  7 +++++--
 git-pull.sh              | 15 ++++++++++++++-
 t/t5520-pull.sh          | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index c028aeb..b391ec1 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1886,8 +1886,11 @@ pretty.<name>::
 pull.mode::
 	When "git pull" is run, this determines if it would either merge or
 	rebase the fetched branch. The possible values are 'merge',
-	'rebase', and 'rebase-preserve'. See "branch.<name>.pullmode" for doing
-	this in a non branch-specific manner.
+	'rebase', 'ff-only,' and 'rebase-preserve'.
+	If 'ff-only' is specified, the merge will only succeed if it's
+	fast-forward.
+	See "branch.<name>.pullmode" for doing this in a non branch-specific
+	manner.
 +
 	When 'rebase-preserve', also pass `--preserve-merges` along to
 	'git rebase' so that locally committed merge commits will not be
diff --git a/git-pull.sh b/git-pull.sh
index e7e52ec..2446417 100755
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -57,7 +57,7 @@ then
 	mode=$(git config pull.mode)
 fi
 case "$mode" in
-merge|rebase|'')
+merge|rebase|ff-only|'')
 	;;
 rebase-preserve)
 	mode="rebase"
@@ -78,6 +78,7 @@ then
 		rebase=$(bool_or_string_config pull.rebase)
 	fi
 fi
+test -z "$mode" && mode=merge
 dry_run=
 while :
 do
@@ -313,6 +314,18 @@ case "$merge_head" in
 		die "$(gettext "Cannot rebase onto multiple branches")"
 	fi
 	;;
+*)
+	# check if a non-fast-foward merge would be needed
+	merge_head=${merge_head% }
+	if test "$mode" = 'ff-only' && test -z "$no_ff$ff_only${squash#--no-squash}" &&
+		test -n "$orig_head" &&
+		! git merge-base --is-ancestor "$orig_head" "$merge_head" &&
+		! git merge-base --is-ancestor "$merge_head" "$orig_head"
+	then
+		die "$(gettext "The pull was not fast-forward, please either merge or rebase.
+If unsure, run 'git pull --merge'.")"
+	fi
+	;;
 esac
 
 # Pulling into unborn branch: a shorthand for branching off
diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index 01ad17a..a548c1b 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -365,4 +365,40 @@ test_expect_success 'git pull --rebase against local branch' '
 	test file = "$(cat file2)"
 '
 
+test_expect_success 'git pull fast-forward (ff-only)' '
+	test_when_finished "git checkout master && git branch -D other test" &&
+	test_config pull.mode ff-only &&
+	git checkout -b other master &&
+	>new &&
+	git add new &&
+	git commit -m new &&
+	git checkout -b test -t other &&
+	git reset --hard master &&
+	git pull
+'
+
+test_expect_success 'git pull non-fast-forward (ff-only)' '
+	test_when_finished "git checkout master && git branch -D other test" &&
+	test_config pull.mode ff-only &&
+	git checkout -b other master^ &&
+	>new &&
+	git add new &&
+	git commit -m new &&
+	git checkout -b test -t other &&
+	git reset --hard master &&
+	test_must_fail git pull
+'
+
+test_expect_success 'git pull non-fast-forward with merge (ff-only)' '
+	test_when_finished "git checkout master && git branch -D other test" &&
+	test_config pull.mode ff-only &&
+	git checkout -b other master^ &&
+	>new &&
+	git add new &&
+	git commit -m new &&
+	git checkout -b test -t other &&
+	git reset --hard master &&
+	git pull --merge
+'
+
 test_done

-- 
1.9.2+fc1.19.g85b6256