Re: [RFC/PATCH Second draft] Fast forward strategies allow, never, and only

["Sverre Hvammen Johansen" <hvammen@gmail.com>]

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I have attached four patches to this email (to avoid line-wrapping
issues if someone needs them for testing).  They are also posted
inlined for comments.

On Sat, Mar 22, 2008 at 11:49 AM, Junio C Hamano <gitster@pobox.com> wrote:
>  In a series of patches, restructuring without changing
>  semantics should come first to make existing logic cleaner and later
>  enhancements on top of it easier to follow.

The patch series consists of the following four patches:

   0001-Introduce-ff-fast-forward-option.patch
   0002-Restructuring-git-merge.sh.patch
   0003-Head-reduction-before-selecting-merge-strategy.patch
   0004-Introduce-fast-forward-option-only.patch

The first and the last one is trivial.  Head reduction is more
complicated.   I have split this one in two as you suggested except
that the one for restructuring does not come as the first on in this
series of patches.

-- 
Sverre Hvammen Johansen

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From 89fbd87b93017d8a65afd6fd27796c0e8f204c22 Mon Sep 17 00:00:00 2001
From: Sverre Hvammen Johansen <hvammen@gmail.com>
Date: Sun, 23 Mar 2008 19:15:52 -0800
Subject: [PATCH 1/4] Introduce -ff=<fast forward option>

--ff now takes an argument allowing --ff to be written
as --ff=allow and -no-ff to be written as --ff=never.
This change allow other fast forward options to be
introduced later.

See the documentation for a further explanation of these options.

Signed-off-by: Sverre Hvammen Johansen <hvammen@gmail.com>
---
 Documentation/fast-forward-options.txt |   44 +++
 Documentation/git-merge.txt            |    6 +-
 Documentation/git-pull.txt             |    2 +
 Documentation/merge-options.txt        |    9 +-
 git-merge.sh                           |   47 ++-
 git-pull.sh                            |    4 +-
 t/t7601-merge-ff-options.sh            |  639 ++++++++++++++++++++++++++++++++
 7 files changed, 728 insertions(+), 23 deletions(-)
 create mode 100644 Documentation/fast-forward-options.txt
 create mode 100755 t/t7601-merge-ff-options.sh

diff --git a/Documentation/fast-forward-options.txt b/Documentation/fast-forward-options.txt
new file mode 100644
index 0000000..95d0e6f
--- /dev/null
+++ b/Documentation/fast-forward-options.txt
@@ -0,0 +1,44 @@
+FAST FORWARD OPTIONS
+--------------------
+
+allow::
+
+	Do not generate a merge commit if the merge resolves as a
+	fast-forward, only update the branch pointer.  This option is
+	equivalent of '--ff' without any argument.  This is the
+	default behavior.
+
+never::
+	Generate a merge commit even if the merge resolves as a
+	fast-forward.  This option is equivalent of '--no-ff'.
+
+If your workflow is always to branch from the special branch
+("master") when working on a topic and merge that back to "master", if
+you happen to have worked only on a single topic and the "master" was
+never advanced during the time you worked on that topic, merging the
+topic back to "master" will result in a fast-forward.  When you look
+back that history, you will not be able to tell where the topic
+started and ended by following the ancestry chain of the "master"
+branch.
+
+Using "never fast forward" policy on such a special branch will be a
+way to make sure that all commits on the first-parent ancestry of that
+special branch will be merges from something else.  From the history
+you can determine where the topic started and ended.
+
+The following shows two branches forked off from "master".  The branch
+"master" have merged in changes from branch "topicA" twice and
+"topicB" once:
+
+------------
+         o---o---o---o---o  topicA
+        /     \           \
+    ---*-------*-------*---*  master
+      /         \     /
+                 o---o  topicB
+------------
+
+The first merge of topicA or the only merge of topicB would have
+resulted in a fast forward without '--ff=never'.  Topic A consist of
+those commits that can be reached from master^2 without passing
+through any of the first-parent ancestries of master.
diff --git a/Documentation/git-merge.txt b/Documentation/git-merge.txt
index c136b10..2af33d8 100644
--- a/Documentation/git-merge.txt
+++ b/Documentation/git-merge.txt
@@ -9,7 +9,8 @@ git-merge - Join two or more development histories together
 SYNOPSIS
 --------
 [verse]
-'git-merge' [-n] [--summary] [--no-commit] [--squash] [-s <strategy>]...
+'git-merge' [-n] [--summary] [--no-commit] [--squash]
+	[-s <strategy>]... [--ff[=<fast forward option>]]
 	[-m <msg>] <remote> <remote>...
 'git-merge' <msg> HEAD <remote>...
 
@@ -37,6 +38,9 @@ include::merge-options.txt[]
 	least one <remote>.  Specifying more than one <remote>
 	obviously means you are trying an Octopus.
 
+
+include::fast-forward-options.txt[]
+
 include::merge-strategies.txt[]
 
 
diff --git a/Documentation/git-pull.txt b/Documentation/git-pull.txt
index 3405ca0..e4e013c 100644
--- a/Documentation/git-pull.txt
+++ b/Documentation/git-pull.txt
@@ -52,6 +52,8 @@ include::pull-fetch-param.txt[]
 
 include::urls-remotes.txt[]
 
+include::fast-forward-options.txt[]
+
 include::merge-strategies.txt[]
 
 DEFAULT BEHAVIOUR
diff --git a/Documentation/merge-options.txt b/Documentation/merge-options.txt
index 9f1fc82..cf4881b 100644
--- a/Documentation/merge-options.txt
+++ b/Documentation/merge-options.txt
@@ -29,12 +29,11 @@
 
 --no-ff::
 	Generate a merge commit even if the merge resolved as a
-	fast-forward.
+	fast-forward.  --no-ff is an alias for --ff=never.
 
---ff::
-	Do not generate a merge commit if the merge resolved as
-	a fast-forward, only update the branch pointer. This is
-	the default behavior of git-merge.
+--ff[=<fast forward option>]::
+	Select fast forward option.  --ff without any argument
+	is an alias for --ff=allow which is the default behavior.
 
 -s <strategy>, \--strategy=<strategy>::
 	Use the given merge strategy; can be supplied more than
diff --git a/git-merge.sh b/git-merge.sh
index 7dbbb1d..17f40f2 100755
--- a/git-merge.sh
+++ b/git-merge.sh
@@ -12,7 +12,7 @@ summary              show a diffstat at the end of the merge
 n,no-summary         don't show a diffstat at the end of the merge
 squash               create a single commit instead of doing a merge
 commit               perform a commit if the merge sucesses (default)
-ff                   allow fast forward (default)
+ff?                  fast forward options
 s,strategy=          merge strategy to use
 m,message=           message to be used for the merge commit (if any)
 "
@@ -35,7 +35,7 @@ no_fast_forward_strategies='subtree ours'
 no_trivial_strategies='recursive recur subtree ours'
 use_strategies=
 
-allow_fast_forward=t
+fast_forward=allow
 allow_trivial_merge=t
 squash= no_commit=
 
@@ -153,8 +153,6 @@ parse_config () {
 		--summary)
 			show_diffstat=t ;;
 		--squash)
-			test "$allow_fast_forward" = t ||
-				die "You cannot combine --squash with --no-ff."
 			squash=t no_commit=t ;;
 		--no-squash)
 			squash= no_commit= ;;
@@ -163,11 +161,26 @@ parse_config () {
 		--no-commit)
 			no_commit=t ;;
 		--ff)
-			allow_fast_forward=t ;;
+			case "$2" in
+			allow|never)
+				fast_forward=$2; shift ;;
+			-*)
+				fast_forward=allow ;;
+			*)
+				die "Available fast-forward options are: allow and newer" ;;
+			esac
+			;;
+		--ff=*)
+			fast_forward=${1#--ff=}
+			case "$fast_forward" in
+			allow|never) 
+				;;
+			*)
+				die "Available fast-forward options are: allow and newer" ;;
+			esac
+			;;
 		--no-ff)
-			test "$squash" != t ||
-				die "You cannot combine --squash with --no-ff."
-			allow_fast_forward=f ;;
+			fast_forward=never ;;
 		-s|--strategy)
 			shift
 			case " $all_strategies " in
@@ -189,6 +202,8 @@ parse_config () {
 		esac
 		shift
 	done
+	test "$fast_forward" = allow -o "$squash" = "" ||
+		die "You cannot combine --squash with --ff=never"
 	args_left=$#
 }
 
@@ -308,7 +323,7 @@ do
 	do
 		case " $s " in
 		*" $ss "*)
-			allow_fast_forward=f
+			fast_forward=never
 			break
 			;;
 		esac
@@ -334,17 +349,17 @@ case "$#" in
 esac
 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 
-case "$allow_fast_forward,$#,$common,$no_commit" in
-?,*,'',*)
+case "$fast_forward,$#,$common,$no_commit" in
+*,*,'',*)
 	# No common ancestors found. We need a real merge.
 	;;
-?,1,"$1",*)
+*,1,"$1",*)
 	# If head can reach all the merge then we are up to date.
 	# but first the most common case of merging one remote.
 	finish_up_to_date "Already up-to-date."
 	exit 0
 	;;
-t,1,"$head",*)
+allow,1,"$head",*)
 	# Again the most common case of merging one remote.
 	echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
 	git update-index --refresh 2>/dev/null
@@ -359,11 +374,11 @@ t,1,"$head",*)
 	dropsave
 	exit 0
 	;;
-?,1,?*"$LF"?*,*)
+*,1,?*"$LF"?*,*)
 	# We are not doing octopus and not fast forward.  Need a
 	# real merge.
 	;;
-?,1,*,)
+*,1,*,)
 	# We are not doing octopus, not fast forward, and have only
 	# one common.
 	git update-index --refresh 2>/dev/null
@@ -481,7 +496,7 @@ done
 # auto resolved the merge cleanly.
 if test '' != "$result_tree"
 then
-    if test "$allow_fast_forward" = "t"
+    if test $fast_forward = allow
     then
         parents=$(git show-branch --independent "$head" "$@")
     else
diff --git a/git-pull.sh b/git-pull.sh
index 3ce32b5..2d7293a 100755
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -4,7 +4,7 @@
 #
 # Fetch one or more remote refs and merge it/them into the current HEAD.
 
-USAGE='[-n | --no-summary] [--[no-]commit] [--[no-]squash] [--[no-]ff] [-s strategy]... [<fetch-options>] <repo> <head>...'
+USAGE='[-n | --no-summary] [--[no-]commit] [--[no-]squash] [--ff=<ff-strategy>] [-s strategy]... [<fetch-options>] <repo> <head>...'
 LONG_USAGE='Fetch one or more remote refs and merge it/them into the current HEAD.'
 SUBDIRECTORY_OK=Yes
 OPTIONS_SPEC=
@@ -41,6 +41,8 @@ do
 		no_ff=--ff ;;
 	--no-ff)
 		no_ff=--no-ff ;;
+	--ff=allow|--ff=never)
+		no_ff=$1 ;;
 	-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
 		--strateg=*|--strategy=*|\
 	-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
diff --git a/t/t7601-merge-ff-options.sh b/t/t7601-merge-ff-options.sh
new file mode 100755
index 0000000..636e71e
--- /dev/null
+++ b/t/t7601-merge-ff-options.sh
@@ -0,0 +1,639 @@
+#!/bin/sh
+#
+# Copyright (c) 2008 Sverre Hvammen Johansen, based on t7600 by Lars Hjemli
+#
+
+test_description='git-merge
+
+Testing basic merge operations/option parsing.'
+
+. ./test-lib.sh
+
+cat >file <<EOF
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
+12
+EOF
+
+cat >file.1 <<EOF
+1 X
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
+12
+EOF
+
+cat >file.5 <<EOF
+1
+2
+3
+4
+5 X
+6
+7
+8
+9
+10
+11
+12
+EOF
+
+cat >file.9 <<EOF
+1
+2
+3
+4
+5
+6
+7
+8
+9 X
+10
+11
+12
+EOF
+
+cat  >result.0 <<EOF
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
+12
+EOF
+
+cat  >result.1 <<EOF
+1 X
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
+12
+EOF
+
+cat >result.1-5 <<EOF
+1 X
+2
+3
+4
+5 X
+6
+7
+8
+9
+10
+11
+12
+EOF
+
+cat >result.9 <<EOF
+1
+2
+3
+4
+5
+6
+7
+8
+9 X
+10
+11
+12
+EOF
+
+cat >result.1-5-9 <<EOF
+1 X
+2
+3
+4
+5 X
+6
+7
+8
+9 X
+10
+11
+12
+EOF
+
+cat >result.1-5-9-13 <<EOF
+1 X
+2
+3
+4
+5 X
+6
+7
+8
+9 X
+10
+11
+12
+13 x
+EOF
+
+cat >result.1-5-13 <<EOF
+1 X
+2
+3
+4
+5 X
+6
+7
+8
+9
+10
+11
+12
+13 x
+EOF
+
+cat >result.5-13 <<EOF
+1
+2
+3
+4
+5 X
+6
+7
+8
+9
+10
+11
+12
+13 x
+EOF
+
+cat >result.1-13 <<EOF
+1 X
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
+12
+13 x
+EOF
+
+cat >extend <<EOF
+13 x
+EOF
+
+
+create_merge_msgs() {
+	echo "Merge commit 'c2'" >msg.1-5 &&
+	echo "Merge commit 'c2'; commit 'c3'" >msg.1-5-9 &&
+	echo "Squashed commit of the following:" >squash.1 &&
+	echo >>squash.1 &&
+	git log --no-merges ^HEAD c1 >>squash.1 &&
+	echo "Squashed commit of the following:" >squash.1-5 &&
+	echo >>squash.1-5 &&
+	git log --no-merges ^HEAD c2 >>squash.1-5 &&
+	echo "Squashed commit of the following:" >squash.1-5-9 &&
+	echo >>squash.1-5-9 &&
+	git log --no-merges ^HEAD c2 c3 >>squash.1-5-9
+}
+
+verify_diff() {
+	if ! diff -u "$1" "$2"
+	then
+		echo "$3"
+		false
+	fi
+}
+
+verify_merge() {
+	verify_diff "$2" "$1" "[OOPS] bad merge result" &&
+	if test $(git ls-files -u | wc -l) -gt 0
+	then
+		echo "[OOPS] unmerged files"
+		false
+	fi &&
+	if ! git diff --exit-code
+	then
+		echo "[OOPS] working tree != index"
+		false
+	fi &&
+	if test -n "$3"
+	then
+		git show -s --pretty=format:%s HEAD >msg.act &&
+		verify_diff "$3" msg.act "[OOPS] bad merge message"
+	fi
+}
+
+verify_head() {
+	if test "$1" != "$(git rev-parse HEAD)"
+	then
+		echo "[OOPS] HEAD != $1"
+		false
+	fi
+}
+
+verify_parents() {
+	i=1
+	while test $# -gt 0
+	do
+		if test "$1" != "$(git rev-parse HEAD^$i)"
+		then
+			echo "[OOPS] HEAD^$i != $1"
+			return 1
+		fi
+		i=$(expr $i + 1)
+		shift
+	done
+}
+
+verify_mergeheads() {
+	i=1
+	if ! test -f .git/MERGE_HEAD
+	then
+		echo "[OOPS] MERGE_HEAD is missing"
+		false
+	fi &&
+	while test $# -gt 0
+	do
+		head=$(head -n $i .git/MERGE_HEAD | tail -n 1)
+		if test "$1" != "$head"
+		then
+			echo "[OOPS] MERGE_HEAD $i != $1"
+			return 1
+		fi
+		i=$(expr $i + 1)
+		shift
+	done
+}
+
+verify_no_mergehead() {
+	if test -f .git/MERGE_HEAD
+	then
+		echo "[OOPS] MERGE_HEAD exists"
+		false
+	fi
+}
+
+
+test_expect_success 'setup' '
+	git add file &&
+	test_tick &&
+	git commit -m "commit 0" &&
+	git tag c0 &&
+	c0=$(git rev-parse HEAD) &&
+
+	cp file.1 file &&
+	git add file &&
+	test_tick &&
+	git commit -m "commit 1" &&
+	git tag c1 &&
+	c1=$(git rev-parse HEAD) &&
+	test_tick &&
+
+	git reset --hard "$c0" &&
+	cp file.5 file &&
+	git add file &&
+	git commit -m "commit 2" &&
+	test_tick &&
+	git tag c2 &&
+	c2=$(git rev-parse HEAD) &&
+
+	git reset --hard "$c0" &&
+	cp file.9 file &&
+	git add file &&
+	test_tick &&
+	git commit -m "commit 3" &&
+	git tag c3 &&
+	c3=$(git rev-parse HEAD) &&
+	test_tick &&
+
+	git reset --hard "$c1" &&
+	cat extend >>file &&
+	git add file &&
+	git commit -m "commit 4" &&
+	git tag x1 &&
+	x1=$(git rev-parse HEAD) &&
+	test_tick &&
+
+	git reset --hard "$c1" &&
+	git merge "$c2" &&
+	git tag x0 &&
+	x0=$(git rev-parse HEAD) &&
+	test_tick &&
+
+	git reset --hard "$c2" &&
+	cat extend >>file &&
+	git add file &&
+	git commit -m "commit 5" &&
+	git tag x2 &&
+	x2=$(git rev-parse HEAD) &&
+	test_tick &&
+
+	git reset --hard "$x1" &&
+	git merge "$x0" &&
+	git tag y1 &&
+	y1=$(git rev-parse HEAD) &&
+	test_tick &&
+
+	git reset --hard "$x0" &&
+	git merge "$x2" &&
+	git tag y2 &&
+	y2=$(git rev-parse HEAD) &&
+	test_tick &&
+
+	git reset --hard "$y1" &&
+	git merge "$y2" &&
+	git tag y3 &&
+	y3=$(git rev-parse HEAD) &&
+	test_tick &&
+	git reset --hard "$c0" &&
+	create_merge_msgs &&
+
+	git reset --hard x1 &&
+	git clone .git clone &&
+	git config remote.clone.url clone &&
+	git config remote.clone.fetch "+refs/heads/*:refs/remotes/clone/*" &&
+
+	(mkdir new && cd new && git init && cp ../file.9 file2 && git add file2 && test_tick && git commit -m "commit new") &&
+	git config remote.new.url new &&
+	git config remote.new.fetch "+refs/heads/*:refs/remotes/new/*"
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c0 with c1 and c2' '
+	git reset --hard c0 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c1 c2 &&
+	verify_merge file result.1-5 &&
+	verify_parents $c1 $c2
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with c0, c2, c0, and c1' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c0 c2 c0 c1 &&
+	verify_merge file result.1-5 &&
+	verify_parents $c1 $c2
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge y2 with x0, c3, and c0' '
+	git reset --hard y2 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge x0 c3 c0 &&
+	verify_merge file result.1-5-9-13 &&
+	verify_parents $y2 $c3
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge x0 with y2, c3, and c0' '
+	git reset --hard x0 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge y2 c3 c0 &&
+	verify_merge file result.1-5-9-13 &&
+	verify_parents $y2 $c3
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with c2 and x1' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c2 x1 &&
+	verify_merge file result.1-5-13 &&
+	verify_parents $c2 $x1
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge x0 with c1 (--squash combined with --ff=allow)' '
+	git reset --hard x0 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c1 --squash --ff=allow &&
+	verify_merge file result.1-5 &&
+	verify_head $x0
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with c2 (--squash combined with --ff=allow)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c2 --squash --ff=allow &&
+	verify_merge file result.1-5 &&
+	verify_head $c1 &&
+	git commit &&
+	verify_parents $c1
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with x0 (--no-commit combined with --ff=allow)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge x0 --no-commit --ff=allow &&
+	verify_merge file result.1-5 &&
+	verify_parents $c1
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge x0 with c1 (--no-commit combined with --ff=allow)' '
+	git reset --hard x0 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c1 --no-commit --ff=allow &&
+	verify_merge file result.1-5 &&
+	verify_head $x0
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with c2 (--no-commit combined with --ff=allow)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c2 --no-commit --ff=allow &&
+	verify_merge file result.1-5 &&
+	verify_head $c1 &&
+	git commit &&
+	verify_parents $c1
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with x1 (pull --ff=allow)' '
+	git reset --hard c1 &&
+	test_tick &&
+	git pull --ff=allow clone refs/heads/master &&
+	verify_merge file result.1-13 &&
+	verify_head $x1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge x2 with x1 (pull --ff=allow)' '
+	git reset --hard x2 &&
+	test_tick &&
+	git pull --ff=allow clone refs/heads/master &&
+	verify_merge file result.1-5-13 &&
+	verify_parents $x2 $x1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with new repository (pull --ff=allow)' '
+	git reset --hard c1 &&
+	test_tick &&
+	git pull --ff=allow new refs/heads/master &&
+	verify_merge file result.1 &&
+	verify_merge file2 result.9
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge x0 with c1 (--squash combined with --ff=never)' '
+	git reset --hard x0 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	test_must_fail git merge c1 --squash --ff=never &&
+	verify_merge file result.1-5 &&
+	verify_head $x0
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with c2 (--squash combined with --ff=never)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	test_must_fail git merge c2 --squash --ff=never &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with x0 (--no-commit combined with --ff=never)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge x0 --no-commit --ff=never &&
+	verify_merge file result.1-5 &&
+	verify_head $c1 &&
+	git commit &&
+	verify_parents $c1
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge x0 with c1 (--no-commit combined with --ff=never)' '
+	git reset --hard x0 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c1 --no-commit --ff=never &&
+	verify_merge file result.1-5 &&
+	verify_head $x0
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with c2 (--no-commit combined with --ff=never)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c2 --no-commit --ff=never &&
+	verify_merge file result.1-5 &&
+	verify_head $c1 &&
+	git commit &&
+	verify_parents $c1
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with x1 (pull --ff=never)' '
+	git reset --hard c1 &&
+	test_tick &&
+	git pull --ff=never clone refs/heads/master &&
+	verify_merge file result.1-13 &&
+	verify_parents $c1 $x1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge x2 with x1 (pull --ff=never)' '
+	git reset --hard x2 &&
+	test_tick &&
+	git pull --ff=never clone refs/heads/master &&
+	verify_merge file result.1-5-13 &&
+	verify_parents $x2 $x1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with new repository (pull --ff=never)' '
+	git reset --hard c1 &&
+	test_tick &&
+	git pull --ff=never new refs/heads/master &&
+	verify_merge file result.1 &&
+	verify_merge file2 result.9
+'
+
+test_debug 'gitk --all'
+
+test_done
-- 
1.5.3.3


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From 55d0664258c1053309514b192effd33d1db4c7a0 Mon Sep 17 00:00:00 2001
From: Sverre Hvammen Johansen <hvammen@gmail.com>
Date: Sun, 23 Mar 2008 23:19:37 -0800
Subject: [PATCH 2/4] Restructuring git-merge.sh

for preparation of new feature:

   Head reduction before selecting merge strategy

Signed-off-by: Sverre Hvammen Johansen <hvammen@gmail.com>
---
 git-merge.sh |  166 ++++++++++++++++++++++++++++++----------------------------
 1 files changed, 85 insertions(+), 81 deletions(-)

diff --git a/git-merge.sh b/git-merge.sh
index 17f40f2..2acd2cc 100755
--- a/git-merge.sh
+++ b/git-merge.sh
@@ -207,6 +207,29 @@ parse_config () {
 	args_left=$#
 }
 
+# Find real parents
+# Set the following variables as followd:
+#   real_parents: The parents specified on the command line
+#   common:       All common ancestors or not_queried
+#   ff_head:      Fast forward of head
+find_real_parents () {
+	real_parents=$(git rev-parse "$@")
+	real_parents=${real_parents#$LF}
+	if test $# = 1
+	then
+		common=$(git merge-base --all $head "$@")
+		if test "$common" = $head
+		then
+			ff_head=$1
+		else
+			ff_head=$head
+		fi
+	else
+		common=not_queried
+		ff_head=$head
+	fi
+}
+
 test $# != 0 || usage
 
 have_message=
@@ -294,24 +317,26 @@ do
 done
 set x $remoteheads ; shift
 
+find_real_parents "$@"
+
 case "$use_strategies" in
 '')
-	case "$#" in
-	1)
-		var="`git config --get pull.twohead`"
+	case "$real_parents" in
+	?*"$LF"?*)
+		var="`git config --get pull.octopus`"
 		if test -n "$var"
 		then
 			use_strategies="$var"
 		else
-			use_strategies="$default_twohead_strategies"
+			use_strategies="$default_octopus_strategies"
 		fi ;;
 	*)
-		var="`git config --get pull.octopus`"
+		var="`git config --get pull.twohead`"
 		if test -n "$var"
 		then
 			use_strategies="$var"
 		else
-			use_strategies="$default_octopus_strategies"
+			use_strategies="$default_twohead_strategies"
 		fi ;;
 	esac
 	;;
@@ -339,87 +364,66 @@ do
 	done
 done
 
-case "$#" in
-1)
-	common=$(git merge-base --all $head "$@")
-	;;
-*)
-	common=$(git show-branch --merge-base $head "$@")
-	;;
-esac
 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 
-case "$fast_forward,$#,$common,$no_commit" in
-*,*,'',*)
-	# No common ancestors found. We need a real merge.
-	;;
-*,1,"$1",*)
-	# If head can reach all the merge then we are up to date.
-	# but first the most common case of merging one remote.
-	finish_up_to_date "Already up-to-date."
-	exit 0
-	;;
-allow,1,"$head",*)
-	# Again the most common case of merging one remote.
-	echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
-	git update-index --refresh 2>/dev/null
-	msg="Fast forward"
-	if test -n "$have_message"
+if true
+then
+	if test $head = $ff_head -a "$common" = "$real_parents"
 	then
-		msg="$msg (no commit created; -m option ignored)"
-	fi
-	new_head=$(git rev-parse --verify "$1^0") &&
-	git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
-	finish "$new_head" "$msg" || exit
-	dropsave
-	exit 0
-	;;
-*,1,?*"$LF"?*,*)
-	# We are not doing octopus and not fast forward.  Need a
-	# real merge.
-	;;
-*,1,*,)
-	# We are not doing octopus, not fast forward, and have only
-	# one common.
-	git update-index --refresh 2>/dev/null
-	case "$allow_trivial_merge" in
-	t)
-		# See if it is really trivial.
-		git var GIT_COMMITTER_IDENT >/dev/null || exit
-		echo "Trying really trivial in-index merge..."
-		if git read-tree --trivial -m -u -v $common $head "$1" &&
-		   result_tree=$(git write-tree)
-		then
-			echo "Wonderful."
-			result_commit=$(
-				printf '%s\n' "$merge_msg" |
-				git commit-tree $result_tree -p HEAD -p "$1"
-			) || exit
-			finish "$result_commit" "In-index merge"
-			dropsave
-			exit 0
-		fi
-		echo "Nope."
-	esac
-	;;
-*)
-	# An octopus.  If we can reach all the remote we are up to date.
-	up_to_date=t
-	for remote
-	do
-		common_one=$(git merge-base --all $head $remote)
-		if test "$common_one" != "$remote"
+		finish_up_to_date "Already up-to-date."
+		exit 0
+	elif test $fast_forward != never -a $ff_head = "$real_parents"
+	then
+		echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $ff_head)"
+		git update-index --refresh 2>/dev/null
+		msg="Fast forward"
+		if test -n "$have_message"
 		then
-			up_to_date=f
-			break
+			msg="$msg (no commit created; -m option ignored)"
 		fi
-	done
-	if test "$up_to_date" = t
-	then
-		finish_up_to_date "Already up-to-date. Yeeah!"
+		new_head=$(git rev-parse --verify "$ff_head^0") &&
+		git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
+		finish "$new_head" "$msg" || exit
+		dropsave
 		exit 0
 	fi
+fi
+
+case "$real_parents" in
+?*"$LF"?*)
+	# We have more than one parent
+	common=$(git show-branch --merge-base $head $real_parents)
 	;;
+*)
+	# We have exactly one parent
+	test "$common" != not_queried || common=$(git merge-base --all $head $real_parents)
+	case "$common" in
+	?*"$LF"?*)
+		# We are not doing octopus and not fast forward.  Need a
+		# real merge.
+		;;
+	*)
+		git update-index --refresh 2>/dev/null
+		if test "$allow_trivial_merge" = t
+		then
+			# See if it is really trivial.
+			git var GIT_COMMITTER_IDENT >/dev/null || exit
+			echo "Trying really trivial in-index merge..."
+			if git read-tree --trivial -m -u -v $common $head $real_parents &&
+				result_tree=$(git write-tree)
+			then
+				echo "Wonderful."
+				result_commit=$(
+					printf '%s\n' "$merge_msg" |
+					git commit-tree $result_tree -p HEAD -p $real_parents
+				) || exit
+				finish "$result_commit" "In-index merge"
+				dropsave
+				exit 0
+			fi
+			echo "Nope."
+		fi ;;
+	esac ;;
 esac
 
 # We are going to make a new commit.
@@ -460,7 +464,7 @@ do
     # Remember which strategy left the state in the working tree
     wt_strategy=$strategy
 
-    git-merge-$strategy $common -- "$head_arg" "$@"
+    git-merge-$strategy $common -- "$head_arg" $real_parents
     exit=$?
     if test "$no_commit" = t && test "$exit" = 0
     then
@@ -530,7 +534,7 @@ case "$best_strategy" in
 	echo "Rewinding the tree to pristine..."
 	restorestate
 	echo "Using the $best_strategy to prepare resolving by hand."
-	git-merge-$best_strategy $common -- "$head_arg" "$@"
+	git-merge-$best_strategy $common -- "$head_arg" $real_parents
 	;;
 esac
 
-- 
1.5.3.3


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From 2227b803ecfd47b2d5586ec923cb887f017f3b67 Mon Sep 17 00:00:00 2001
From: Sverre Hvammen Johansen <hvammen@gmail.com>
Date: Sun, 23 Mar 2008 23:23:52 -0800
Subject: [PATCH 3/4] Head reduction before selecting merge strategy

See the documentation for an explanation of this feature.

Signed-off-by: Sverre Hvammen Johansen <hvammen@gmail.com>
---
 Documentation/git-merge.txt |   43 +++++++++++++++++++++++-
 git-merge.sh                |   76 +++++++++++++++++++++++++++++--------------
 2 files changed, 93 insertions(+), 26 deletions(-)

diff --git a/Documentation/git-merge.txt b/Documentation/git-merge.txt
index 2af33d8..e94d26b 100644
--- a/Documentation/git-merge.txt
+++ b/Documentation/git-merge.txt
@@ -36,7 +36,7 @@ include::merge-options.txt[]
 <remote>::
 	Other branch head merged into our branch.  You need at
 	least one <remote>.  Specifying more than one <remote>
-	obviously means you are trying an Octopus.
+	usually means you are trying an Octopus.
 
 
 include::fast-forward-options.txt[]
@@ -133,6 +133,47 @@ merge (which is typically a fraction of the whole tree), you can
 have local modifications in your working tree as long as they do
 not overlap with what the merge updates.
 
+If more than one commit are specified for the merge, git will try to
+reduce the number of commits (real parents) by eliminating commits
+than can be reached from other commits.  The commit message will
+reflect the actual commits specified but the merge strategy will be
+selected based on the real parents, but always including `HEAD`.  The
+real parents (only including `HEAD` if it is real) are the parents
+recorded in the merge commit object.
+
+The following shows master and three topic branches.  topicB is based
+on topicA, topicA is previously branched off from master, and topicC
+is based on the current `HEAD` of master:
+
+------------
+                    o---o---o  topicB
+                   /
+          o---o---o  topicA
+         /
+    o---o---o---o---o---o  master
+                         \
+                          o---o  topicC
+------------
+
+A merger of master with topicA, topicB, and topicC will select the
+merge strategy based on the three branches master, topicB, and topicC
+(topicA is eliminated since it can be reached from topicB).  topicB
+and topicC are the only real parents and are therefore the only
+parents recorded in the merge commit object:
+
+------------
+         % git checkout master
+         % git merge topicA topicB topicC
+
+                    o---o---o  topicB
+                   /         \
+          o---o---o  topicA   \
+         /                     \
+    o---o---o---o---o---o       o  master
+                         \     /
+                          o---o  topicC
+------------
+
 When there are conflicts, these things happen:
 
 1. `HEAD` stays the same.
diff --git a/git-merge.sh b/git-merge.sh
index 2acd2cc..5398606 100755
--- a/git-merge.sh
+++ b/git-merge.sh
@@ -209,24 +209,41 @@ parse_config () {
 
 # Find real parents
 # Set the following variables as followd:
-#   real_parents: The parents specified on the command line
+#   real_parents: The real parents except fast forward of head
 #   common:       All common ancestors or not_queried
 #   ff_head:      Fast forward of head
 find_real_parents () {
-	real_parents=$(git rev-parse "$@")
-	real_parents=${real_parents#$LF}
-	if test $# = 1
+	if test $fast_forward = never
 	then
-		common=$(git merge-base --all $head "$@")
-		if test "$common" = $head
+		real_parents=$(git rev-parse "$@")
+		ff_head=$head
+		common=not_queried
+	else
+		if test $# = 1
 		then
-			ff_head=$1
+			common=$(git merge-base --all $head "$1")
+			if test "$common" = $head
+			then
+				real_parents=
+				ff_head=$1
+			elif test "$common" = "$1"
+			then
+				real_parents=
+				ff_head=$head
+			else
+				real_parents=$1
+				ff_head=$head
+			    
+			fi
 		else
-			ff_head=$head
+			real_parents=$(git show-branch --independent $head "$@")
+			# Here we may actually lie about which bransh is ff of head.
+			# This will preserve the order the user gave.
+			ff_head=${real_parents%%$LF*}
+			real_parents=${real_parents#$ff_head}
+			real_parents=${real_parents#$LF}
+			common=not_queried
 		fi
-	else
-		common=not_queried
-		ff_head=$head
 	fi
 }
 
@@ -319,6 +336,12 @@ set x $remoteheads ; shift
 
 find_real_parents "$@"
 
+if test -n "$real_parents"
+then
+	test $head = $ff_head ||
+		real_parents="$ff_head$LF$real_parents"
+fi
+
 case "$use_strategies" in
 '')
 	case "$real_parents" in
@@ -366,13 +389,13 @@ done
 
 echo "$head" >"$GIT_DIR/ORIG_HEAD"
 
-if true
+if test -z "$real_parents"
 then
-	if test $head = $ff_head -a "$common" = "$real_parents"
+	if test $head = $ff_head
 	then
 		finish_up_to_date "Already up-to-date."
 		exit 0
-	elif test $fast_forward != never -a $ff_head = "$real_parents"
+	elif test $fast_forward != never
 	then
 		echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $ff_head)"
 		git update-index --refresh 2>/dev/null
@@ -386,6 +409,14 @@ then
 		finish "$new_head" "$msg" || exit
 		dropsave
 		exit 0
+	else
+		real_parents="$ff_head"
+		ff_head=$head
+	fi
+else
+	if test $head != $ff_head -a $fast_forward = never
+	then
+		real_parents="$ff_head$LF$real_parents"
 	fi
 fi
 
@@ -500,17 +531,12 @@ done
 # auto resolved the merge cleanly.
 if test '' != "$result_tree"
 then
-    if test $fast_forward = allow
-    then
-        parents=$(git show-branch --independent "$head" "$@")
-    else
-        parents=$(git rev-parse "$head" "$@")
-    fi
-    parents=$(echo "$parents" | sed -e 's/^/-p /')
-    result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
-    finish "$result_commit" "Merge made by $wt_strategy."
-    dropsave
-    exit 0
+	test $head = $ff_head && real_parents="$head$LF$real_parents"
+	parents=$(echo "$real_parents" | sed -e 's/^/-p /')
+	result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
+	finish "$result_commit" "Merge made by $wt_strategy."
+	dropsave
+	exit 0
 fi
 
 # Pick the result from the best strategy and have the user fix it up.
-- 
1.5.3.3


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From df159d4275d25a57898b757489f3d675e715efa3 Mon Sep 17 00:00:00 2001
From: Sverre Hvammen Johansen <hvammen@gmail.com>
Date: Sun, 23 Mar 2008 19:02:39 -0800
Subject: [PATCH 4/4] Introduce fast forward option only

This feature is needed for git integration with accurev.
See the documentation for an explanation of this feature.

Signed-off-by: Sverre Hvammen Johansen <hvammen@gmail.com>
---
 Documentation/fast-forward-options.txt |    9 ++
 git-merge.sh                           |   12 +-
 git-pull.sh                            |    2 +-
 t/t7601-merge-ff-options.sh            |  214 ++++++++++++++++++++++++++++++++
 4 files changed, 231 insertions(+), 6 deletions(-)

diff --git a/Documentation/fast-forward-options.txt b/Documentation/fast-forward-options.txt
index 95d0e6f..4445b0e 100644
--- a/Documentation/fast-forward-options.txt
+++ b/Documentation/fast-forward-options.txt
@@ -12,6 +12,10 @@ never::
 	Generate a merge commit even if the merge resolves as a
 	fast-forward.  This option is equivalent of '--no-ff'.
 
+only::
+	Only allow a fast-forward.  The merge will fail unless HEAD is
+	up to date or the merge resolves as a fast-forward.
+
 If your workflow is always to branch from the special branch
 ("master") when working on a topic and merge that back to "master", if
 you happen to have worked only on a single topic and the "master" was
@@ -42,3 +46,8 @@ The first merge of topicA or the only merge of topicB would have
 resulted in a fast forward without '--ff=never'.  Topic A consist of
 those commits that can be reached from master^2 without passing
 through any of the first-parent ancestries of master.
+
+However, if the workflow require that the branch you are merging with
+is based on the current HEAD you can use "only fast forward" policy to
+enforce fast forward or a failure.  The last merge of topicA in
+the example above would have failed with '--ff=only'.
diff --git a/git-merge.sh b/git-merge.sh
index 5398606..b6c428f 100755
--- a/git-merge.sh
+++ b/git-merge.sh
@@ -162,21 +162,21 @@ parse_config () {
 			no_commit=t ;;
 		--ff)
 			case "$2" in
-			allow|never)
+			allow|never|only)
 				fast_forward=$2; shift ;;
 			-*)
 				fast_forward=allow ;;
 			*)
-				die "Available fast-forward options are: allow and newer" ;;
+				die "Available fast-forward options are: allow, newer, and only" ;;
 			esac
 			;;
 		--ff=*)
 			fast_forward=${1#--ff=}
 			case "$fast_forward" in
-			allow|never) 
+			allow|never|only) 
 				;;
 			*)
-				die "Available fast-forward options are: allow and newer" ;;
+				die "Available fast-forward options are: allow, newer, and only" ;;
 			esac
 			;;
 		--no-ff)
@@ -203,7 +203,7 @@ parse_config () {
 		shift
 	done
 	test "$fast_forward" = allow -o "$squash" = "" ||
-		die "You cannot combine --squash with --ff=never"
+		die "You cannot combine --squash with --ff=never or --ff=only."
 	args_left=$#
 }
 
@@ -338,6 +338,8 @@ find_real_parents "$@"
 
 if test -n "$real_parents"
 then
+	test $fast_forward = only &&
+		die "--ff=only can not handle more than one real parent"
 	test $head = $ff_head ||
 		real_parents="$ff_head$LF$real_parents"
 fi
diff --git a/git-pull.sh b/git-pull.sh
index 2d7293a..5bc84a6 100755
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -41,7 +41,7 @@ do
 		no_ff=--ff ;;
 	--no-ff)
 		no_ff=--no-ff ;;
-	--ff=allow|--ff=never)
+	--ff=allow|--ff=only|--ff=never)
 		no_ff=$1 ;;
 	-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
 		--strateg=*|--strategy=*|\
diff --git a/t/t7601-merge-ff-options.sh b/t/t7601-merge-ff-options.sh
index 636e71e..ca4cc67 100755
--- a/t/t7601-merge-ff-options.sh
+++ b/t/t7601-merge-ff-options.sh
@@ -636,4 +636,218 @@ test_expect_success 'merge c1 with new repository (pull --ff=never)' '
 
 test_debug 'gitk --all'
 
+test_expect_success 'merge c0 with c1 (--ff=only overrides --no-ff)' '
+	git reset --hard c0 &&
+	git config branch.master.mergeoptions "--no-ff" &&
+	git merge --ff=only c1 &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c0 with c1 (--ff=only in config)' '
+	git reset --hard c0 &&
+	git config branch.master.mergeoptions "--ff=only" &&
+	git merge c1 &&
+	test_tick &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with c0 (--ff=only in config)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "--ff=only" &&
+	git merge c0 &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with c2 (--ff=only in config)' '
+	git reset --hard c1 &&
+	test_tick &&
+	git config branch.master.mergeoptions "--ff=only" &&
+	test_must_fail git merge c2 &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c0 with c1 (--ff=only)' '
+	git reset --hard c0 &&
+	test_tick &&
+	git merge --ff=only c1 &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with c0 (--ff=only)' '
+	git reset --hard c1 &&
+	test_tick &&
+	git merge --ff=only c0 &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c0 with c1 and c2 (--ff=only)' '
+	git reset --hard c0 &&
+	test_must_fail git merge --ff=only c1 c2 &&
+	verify_merge file result.0 &&
+	verify_head $c0
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with c0 (--ff=only)' '
+	git reset --hard c1 &&
+	test_tick &&
+	git merge --ff=only c0 &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with c2 (--ff=only overrides --no-ff)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "--no-ff" &&
+	test_tick &&
+	test_must_fail git merge c2 --ff=only &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c0 with c1 (--no-ff overrides --ff=only)' '
+	git reset --hard c0 &&
+	git config branch.master.mergeoptions "--ff=only" &&
+	test_tick &&
+	git merge --no-ff c1 &&
+	verify_merge file result.1 &&
+	verify_parents $c0 $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with c2 (--ff owerrides --ff=only)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "--ff=only" &&
+	test_tick &&
+	git merge --ff c2 &&
+	verify_merge file result.1-5 &&
+	verify_parents $c1 $c2
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with x0 (--squash combined with --ff=only)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	test_must_fail git merge x0 --squash --ff=only &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge x0 with c1 (--squash combined with --ff=only)' '
+	git reset --hard x0 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	test_must_fail git merge c1 --squash --ff=only &&
+	verify_merge file result.1-5 &&
+	verify_head $x0
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with c2 (--squash combined with --ff=only)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	test_must_fail git merge c2 --squash --ff=only &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge c1 with x0 (--no-commit combined with --ff=only)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge x0 --no-commit --ff=only &&
+	verify_merge file result.1-5 &&
+	verify_head $x0
+'
+
+test_debug 'gitk --all'
+
+
+test_expect_success 'merge x0 with c1 (--no-commit combined with --ff=only)' '
+	git reset --hard x0 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	git merge c1 --no-commit --ff=only &&
+	verify_merge file result.1-5 &&
+	verify_head $x0
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with c2 (--no-commit combined with --ff=only)' '
+	git reset --hard c1 &&
+	git config branch.master.mergeoptions "" &&
+	test_tick &&
+	test_must_fail git merge c2 --no-commit --ff=only &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with x1 (pull --ff=only)' '
+	git reset --hard c1 &&
+	test_tick &&
+	git pull --ff=only clone refs/heads/master &&
+	verify_merge file result.1-13 &&
+	verify_head $x1
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge x2 with x1 (pull --ff=only)' '
+	git reset --hard x2 &&
+	test_tick &&
+	test_must_fail git pull --ff=only clone refs/heads/master &&
+	verify_merge file result.5-13 &&
+	verify_head $x2
+'
+
+test_debug 'gitk --all'
+
+test_expect_success 'merge c1 with new repository (pull --ff=only)' '
+	git reset --hard c1 &&
+	test_tick &&
+	test_must_fail git pull --ff=only new refs/heads/master &&
+	verify_merge file result.1 &&
+	verify_head $c1
+'
+
+test_debug 'gitk --all'
+
 test_done
-- 
1.5.3.3