[PATCH v5 6/6] pull: only allow ff merges by default

@@ -23,6 +23,7 @@ More precisely, 'git pull' runs 'git fetch' with the given
 parameters and calls 'git merge' to merge the retrieved branch
 heads into the current branch.
 With `--rebase`, it runs 'git rebase' instead of 'git merge'.
+With `--merge`, it forces the merge, even if it's non-fast forward.
 
 <repository> should be the name of a remote repository as
 passed to linkgit:git-fetch[1].  <refspec> can name an

@@ -41,11 +42,28 @@ Assume the following history exists and the current branch is
 ------------
 	  A---B---C master on origin
 	 /
+    D---E master
+------------
+
+Then `git pull` will merge in a fast-foward way up to the new master.
+
+------------
+    D---E---A---B---C master, origin/master
+------------
+
+However, a non-fast-foward case looks very different.
+
+------------
+	  A---B---C origin/master
+	 /
     D---E---F---G master
 	^
 	origin/master in your repository
 ------------
 
+By default `git pull` will fail on these situations, however, most likely
+you would want to force a merge, which you can do with `git pull --merge`.
+
 Then "`git pull`" will fetch and replay the changes from the remote
 `master` branch since it diverged from the local `master` (i.e., `E`)
 until its current commit (`C`) on top of `master` and record the

@@ -83,7 +83,7 @@ then
 		warn "$(gettext "Please use pull.mode and branch.<name>.pullmode instead.")"
 	fi
 fi
-test -z "$mode" && mode=merge
+test -z "$mode" && mode=merge-ff-only
 dry_run=
 while :
 do

@@ -64,7 +64,7 @@ test_expect_success setup '
 	export GIT_AUTHOR_DATE GIT_COMMITTER_DATE &&
 
 	git checkout master &&
-	git pull -s ours . side &&
+	git pull --merge -s ours . side &&
 
 	GIT_AUTHOR_DATE="2006-06-26 00:05:00 +0000" &&
 	GIT_COMMITTER_DATE="2006-06-26 00:05:00 +0000" &&

@@ -259,7 +259,7 @@ test_expect_success 'clone shallow object count' '
 test_expect_success 'pull in shallow repo with missing merge base' '
 	(
 		cd shallow &&
-		test_must_fail git pull --depth 4 .. A
+		test_must_fail git pull --merge --depth 4 .. A
 	)
 '
 

@@ -25,7 +25,7 @@ test_expect_success setup '
 test_expect_success pull '
 (
 	cd cloned &&
-	git pull --log &&
+	git pull --merge --log &&
 	git log -2 &&
 	git cat-file commit HEAD >result &&
 	grep Dollar result

@@ -94,7 +94,7 @@ cd "$base_dir"
 
 test_expect_success 'pulling changes from origin' \
 'cd C &&
-git pull origin'
+git pull --merge origin'
 
 cd "$base_dir"
 

@@ -109,7 +109,7 @@ cd "$base_dir"
 
 test_expect_success 'pulling changes from origin' \
 'cd D &&
-git pull origin'
+git pull --merge origin'
 
 cd "$base_dir"
 

@@ -100,7 +100,7 @@ git checkout master'
 test_expect_success 'pull renaming branch into unrenaming one' \
 '
 	git show-branch &&
-	test_expect_code 1 git pull . white &&
+	test_expect_code 1 git pull --merge . white &&
 	git ls-files -s &&
 	git ls-files -u B >b.stages &&
 	test_line_count = 3 b.stages &&

@@ -118,7 +118,7 @@ test_expect_success 'pull renaming branch into another renaming one' \
 	rm -f B &&
 	git reset --hard &&
 	git checkout red &&
-	test_expect_code 1 git pull . white &&
+	test_expect_code 1 git pull --merge . white &&
 	git ls-files -u B >b.stages &&
 	test_line_count = 3 b.stages &&
 	git ls-files -s N >n.stages &&

@@ -134,7 +134,7 @@ test_expect_success 'pull unrenaming branch into renaming one' \
 '
 	git reset --hard &&
 	git show-branch &&
-	test_expect_code 1 git pull . master &&
+	test_expect_code 1 git pull --merge . master &&
 	git ls-files -u B >b.stages &&
 	test_line_count = 3 b.stages &&
 	git ls-files -s N >n.stages &&

@@ -150,7 +150,7 @@ test_expect_success 'pull conflicting renames' \
 '
 	git reset --hard &&
 	git show-branch &&
-	test_expect_code 1 git pull . blue &&
+	test_expect_code 1 git pull --merge . blue &&
 	git ls-files -u A >a.stages &&
 	test_line_count = 1 a.stages &&
 	git ls-files -u B >b.stages &&

@@ -170,7 +170,7 @@ test_expect_success 'interference with untracked working tree file' '
 	git reset --hard &&
 	git show-branch &&
 	echo >A this file should not matter &&
-	test_expect_code 1 git pull . white &&
+	test_expect_code 1 git pull --merge . white &&
 	test_path_is_file A
 '
 

@@ -180,7 +180,7 @@ test_expect_success 'interference with untracked working tree file' '
 	git show-branch &&
 	rm -f A &&
 	echo >A this file should not matter &&
-	test_expect_code 1 git pull . red &&
+	test_expect_code 1 git pull --merge . red &&
 	test_path_is_file A
 '
 

@@ -190,7 +190,7 @@ test_expect_success 'interference with untracked working tree file' '
 	git checkout -f master &&
 	git tag -f anchor &&
 	git show-branch &&
-	git pull . yellow &&
+	git pull --merge . yellow &&
 	test_path_is_missing M &&
 	git reset --hard anchor
 '

@@ -203,7 +203,7 @@ test_expect_success 'updated working tree file should prevent the merge' '
 	git show-branch &&
 	echo >>M one line addition &&
 	cat M >M.saved &&
-	test_expect_code 128 git pull . yellow &&
+	test_expect_code 128 git pull --merge . yellow &&
 	test_cmp M M.saved &&
 	rm -f M.saved
 '

@@ -217,7 +217,7 @@ test_expect_success 'updated working tree file should prevent the merge' '
 	echo >>M one line addition &&
 	cat M >M.saved &&
 	git update-index M &&
-	test_expect_code 128 git pull . yellow &&
+	test_expect_code 128 git pull --merge . yellow &&
 	test_cmp M M.saved &&
 	rm -f M.saved
 '

@@ -229,7 +229,7 @@ test_expect_success 'interference with untracked working tree file' '
 	git tag -f anchor &&
 	git show-branch &&
 	echo >M this file should not matter &&
-	git pull . master &&
+	git pull --merge . master &&
 	test_path_is_file M &&
 	! {
 		git ls-files -s |

@@ -172,7 +172,7 @@ test_expect_success 'up-to-date merge without common ancestor' '
 	test_tick &&
 	(
 		cd repo1 &&
-		git pull ../repo2 master
+		git pull --merge ../repo2 master
 	)
 '
 

@@ -69,7 +69,7 @@ test_expect_success 'merge update' '
 	git checkout -b master2 &&
 	git commit -m "update git-gui" &&
 	cd ../git &&
-	git pull -s subtree gui master2 &&
+	git pull --merge -s subtree gui master2 &&
 	git ls-files -s >actual &&
 	(
 		echo "100644 $o3 0	git-gui/git-gui.sh"

@@ -98,7 +98,7 @@ test_expect_success 'initial ambiguous subtree' '
 test_expect_success 'merge using explicit' '
 	cd ../git &&
 	git reset --hard master2 &&
-	git pull -Xsubtree=git-gui gui master2 &&
+	git pull --merge -Xsubtree=git-gui gui master2 &&
 	git ls-files -s >actual &&
 	(
 		echo "100644 $o3 0	git-gui/git-gui.sh"

@@ -111,7 +111,7 @@ test_expect_success 'merge using explicit' '
 test_expect_success 'merge2 using explicit' '
 	cd ../git &&
 	git reset --hard master2 &&
-	git pull -Xsubtree=git-gui2 gui master2 &&
+	git pull --merge -Xsubtree=git-gui2 gui master2 &&
 	git ls-files -s >actual &&
 	(
 		echo "100644 $o1 0	git-gui/git-gui.sh"

@@ -66,11 +66,11 @@ test_expect_success 'binary file with -Xours/-Xtheirs' '
 '
 
 test_expect_success 'pull passes -X to underlying merge' '
-	git reset --hard master && git pull -s recursive -Xours . side &&
-	git reset --hard master && git pull -s recursive -X ours . side &&
-	git reset --hard master && git pull -s recursive -Xtheirs . side &&
-	git reset --hard master && git pull -s recursive -X theirs . side &&
-	git reset --hard master && test_must_fail git pull -s recursive -X bork . side
+	git reset --hard master && git pull -m -s recursive -Xours . side &&
+	git reset --hard master && git pull -m -s recursive -X ours . side &&
+	git reset --hard master && git pull -m -s recursive -Xtheirs . side &&
+	git reset --hard master && git pull -m -s recursive -X theirs . side &&
+	git reset --hard master && test_must_fail git pull -m -s recursive -X bork . side
 '
 
 test_done