[PATCH v4 4/7] pull: add merge-ff-only option

From

Felipe Contreras <felipe.contreras@gmail.com>

Date

Oct 12, 2013, 07:01 UTC

Message-ID

<1381561322-20059-1-git-send-email-felipe.contreras@gmail.com>

Later on this mode can be enabled by default (e.g. in v2.0).

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 |  8 +++++---
 git-pull.sh              | 13 +++++++++++++
 t/t5520-pull.sh          | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 9489a59..13635e0 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1822,9 +1822,11 @@ 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' and
-	'rebase'. See "branch.<name>.pullmode" for doing this in a non
-	branch-specific manner.
+	rebase the fetched branch. The possible values are 'merge',
+	'rebase', and 'merge-ff-only'. If 'merge-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.
 +
 *NOTE*: this is a possibly dangerous operation; do *not* use
 it unless you understand the implications (see linkgit:git-rebase[1]
diff --git a/git-pull.sh b/git-pull.sh
index fbb8a9b..6e6b887 100755
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -62,6 +62,7 @@ then
 		echo "Please use pull.mode and branch.<name>.pullmode instead."
 	fi
 fi
+test -z "$mode" && mode=merge
 dry_run=
 while :
 do
@@ -282,6 +283,18 @@ case "$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 "$mode" = merge-ff-only -a -z "$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 978a3c1..798ae2f 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -310,4 +310,40 @@ test_expect_success 'branch.to-rebase.pullmode should override pull.mode' '
 	test new = $(git show HEAD:file2)
 '
 
+test_expect_success 'git pull fast-forward' '
+	test_when_finished "git checkout master && git branch -D other test" &&
+	test_config pull.mode merge-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' '
+	test_when_finished "git checkout master && git branch -D other test" &&
+	test_config pull.mode merge-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 (merge)' '
+	test_when_finished "git checkout master && git branch -D other test" &&
+	test_config pull.mode merge-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

-- 
1.8.4-fc