[PATCH 6/6] pull: add merge-ff-only option

From

Felipe Contreras <felipe.contreras@gmail.com>

Date

Sep 2, 2013, 22:17 UTC

Message-ID

<1378160278-14872-7-git-send-email-felipe.contreras@gmail.com>

In-Reply-To

<1378160278-14872-1-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 +++++---
 builtin/merge.c          |  9 ++++++++-
 git-pull.sh              |  7 +++++++
 t/t5520-pull.sh          | 36 ++++++++++++++++++++++++++++++++++++
 4 files changed, 56 insertions(+), 4 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/builtin/merge.c b/builtin/merge.c
index da9fc08..97b4205 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1437,8 +1437,15 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		}
 	}
 
-	if (fast_forward == FF_ONLY)
+	if (fast_forward == FF_ONLY) {
+		const char *msg = getenv("GIT_MERGE_FF_ONLY_HELP");
+		if (msg) {
+			fprintf(stderr, "%s\n", msg);
+			ret = 1;
+			goto done;
+		}
 		die(_("Not possible to fast-forward, aborting."));
+	}
 
 	/* We are going to make a new commit. */
 	git_committer_info(IDENT_STRICT);
diff --git a/git-pull.sh b/git-pull.sh
index fbb8a9b..a9cf7ac 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
@@ -307,6 +308,12 @@ then
 	fi
 fi
 
+if test "$mode" = merge-ff-only -a -z "$no_ff$ff_only${squash#--no-squash}"
+then
+	ff_only=--ff-only
+	export GIT_MERGE_FF_ONLY_HELP="The pull was not fast-forward, please either merge or rebase."
+fi
+
 merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit
 case "$mode" in
 rebase)
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

-- 
1.8.4-338-gefd7fa6