Merge branch 'jc/merge'

"git merge FETCH_HEAD" learned that the previous "git fetch" could
be to create an Octopus merge, i.e. recording multiple branches
that are not marked as "not-for-merge"; this allows us to lose an
old style invocation "git merge <msg> HEAD $commits..." in the
implementation of "git pull" script; the old style syntax can now
be deprecated.

* jc/merge:
  merge: deprecate 'git merge <message> HEAD <commit>' syntax
  merge: handle FETCH_HEAD internally
  merge: decide if we auto-generate the message early in collect_parents()
  merge: make collect_parents() auto-generate the merge message
  merge: extract prepare_merge_message() logic out
  merge: narrow scope of merge_names
  merge: split reduce_parents() out of collect_parents()
  merge: clarify collect_parents() logic
  merge: small leakfix and code simplification
  merge: do not check argc to determine number of remote heads
  merge: clarify "pulling into void" special case
  t5520: test pulling an octopus into an unborn branch
  t5520: style fixes
  merge: simplify code flow
  merge: test the top-level merge driver

6 files changed, 157 insertions, 22 deletions

diff --git a/t/t3033-merge-toplevel.sh b/t/t3033-merge-toplevel.sh
new file mode 100755
index 0000000000..46aadc410b
--- /dev/null
+++ b/t/t3033-merge-toplevel.sh
@@ -0,0 +1,136 @@
+#!/bin/sh
+
+test_description='"git merge" top-level frontend'
+
+. ./test-lib.sh
+
+t3033_reset () {
+	git checkout -B master two &&
+	git branch -f left three &&
+	git branch -f right four
+}
+
+test_expect_success setup '
+	test_commit one &&
+	git branch left &&
+	git branch right &&
+	test_commit two &&
+	git checkout left &&
+	test_commit three &&
+	git checkout right &&
+	test_commit four &&
+	git checkout master
+'
+
+# Local branches
+
+test_expect_success 'merge an octopus into void' '
+	t3033_reset &&
+	git checkout --orphan test &&
+	git rm -fr . &&
+	test_must_fail git merge left right &&
+	test_must_fail git rev-parse --verify HEAD &&
+	git diff --quiet &&
+	test_must_fail git rev-parse HEAD
+'
+
+test_expect_success 'merge an octopus, fast-forward (ff)' '
+	t3033_reset &&
+	git reset --hard one &&
+	git merge left right &&
+	# one is ancestor of three (left) and four (right)
+	test_must_fail git rev-parse --verify HEAD^3 &&
+	git rev-parse HEAD^1 HEAD^2 | sort >actual &&
+	git rev-parse three four | sort >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'merge octopus, non-fast-forward (ff)' '
+	t3033_reset &&
+	git reset --hard one &&
+	git merge --no-ff left right &&
+	# one is ancestor of three (left) and four (right)
+	test_must_fail git rev-parse --verify HEAD^4 &&
+	git rev-parse HEAD^1 HEAD^2 HEAD^3 | sort >actual &&
+	git rev-parse one three four | sort >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'merge octopus, fast-forward (does not ff)' '
+	t3033_reset &&
+	git merge left right &&
+	# two (master) is not an ancestor of three (left) and four (right)
+	test_must_fail git rev-parse --verify HEAD^4 &&
+	git rev-parse HEAD^1 HEAD^2 HEAD^3 | sort >actual &&
+	git rev-parse two three four | sort >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'merge octopus, non-fast-forward' '
+	t3033_reset &&
+	git merge --no-ff left right &&
+	test_must_fail git rev-parse --verify HEAD^4 &&
+	git rev-parse HEAD^1 HEAD^2 HEAD^3 | sort >actual &&
+	git rev-parse two three four | sort >expect &&
+	test_cmp expect actual
+'
+
+# The same set with FETCH_HEAD
+
+test_expect_success 'merge FETCH_HEAD octopus into void' '
+	t3033_reset &&
+	git checkout --orphan test &&
+	git rm -fr . &&
+	git fetch . left right &&
+	test_must_fail git merge FETCH_HEAD &&
+	test_must_fail git rev-parse --verify HEAD &&
+	git diff --quiet &&
+	test_must_fail git rev-parse HEAD
+'
+
+test_expect_success 'merge FETCH_HEAD octopus fast-forward (ff)' '
+	t3033_reset &&
+	git reset --hard one &&
+	git fetch . left right &&
+	git merge FETCH_HEAD &&
+	# one is ancestor of three (left) and four (right)
+	test_must_fail git rev-parse --verify HEAD^3 &&
+	git rev-parse HEAD^1 HEAD^2 | sort >actual &&
+	git rev-parse three four | sort >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'merge FETCH_HEAD octopus non-fast-forward (ff)' '
+	t3033_reset &&
+	git reset --hard one &&
+	git fetch . left right &&
+	git merge --no-ff FETCH_HEAD &&
+	# one is ancestor of three (left) and four (right)
+	test_must_fail git rev-parse --verify HEAD^4 &&
+	git rev-parse HEAD^1 HEAD^2 HEAD^3 | sort >actual &&
+	git rev-parse one three four | sort >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'merge FETCH_HEAD octopus fast-forward (does not ff)' '
+	t3033_reset &&
+	git fetch . left right &&
+	git merge FETCH_HEAD &&
+	# two (master) is not an ancestor of three (left) and four (right)
+	test_must_fail git rev-parse --verify HEAD^4 &&
+	git rev-parse HEAD^1 HEAD^2 HEAD^3 | sort >actual &&
+	git rev-parse two three four | sort >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'merge FETCH_HEAD octopus non-fast-forward' '
+	t3033_reset &&
+	git fetch . left right &&
+	git merge --no-ff FETCH_HEAD &&
+	test_must_fail git rev-parse --verify HEAD^4 &&
+	git rev-parse HEAD^1 HEAD^2 HEAD^3 | sort >actual &&
+	git rev-parse two three four | sort >expect &&
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t3402-rebase-merge.sh b/t/t3402-rebase-merge.sh
index 5a27ec9b5e..8f64505e4f 100755
--- a/t/t3402-rebase-merge.sh
+++ b/t/t3402-rebase-merge.sh
@@ -47,7 +47,7 @@ test_expect_success setup '
 '
 
 test_expect_success 'reference merge' '
-	git merge -s recursive "reference merge" HEAD master
+	git merge -s recursive -m "reference merge" master
 '
 
 PRE_REBASE=$(git rev-parse test-rebase)
diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index 227d293350..7efd45bc27 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -9,36 +9,27 @@ modify () {
 	mv "$2.x" "$2"
 }
 
-D=`pwd`
-
 test_expect_success setup '
-
 	echo file >file &&
 	git add file &&
 	git commit -a -m original
-
 '
 
 test_expect_success 'pulling into void' '
-	mkdir cloned &&
-	cd cloned &&
-	git init &&
-	git pull ..
-'
-
-cd "$D"
-
-test_expect_success 'checking the results' '
+	git init cloned &&
+	(
+		cd cloned &&
+		git pull ..
+	) &&
 	test -f file &&
 	test -f cloned/file &&
 	test_cmp file cloned/file
 '
 
 test_expect_success 'pulling into void using master:master' '
-	mkdir cloned-uho &&
+	git init cloned-uho &&
 	(
 		cd cloned-uho &&
-		git init &&
 		git pull .. master:master
 	) &&
 	test -f file &&
@@ -71,7 +62,6 @@ test_expect_success 'pulling into void does not overwrite staged files' '
 	)
 '
 
-
 test_expect_success 'pulling into void does not remove new staged files' '
 	git init cloned-staged-new &&
 	(
@@ -86,6 +76,15 @@ test_expect_success 'pulling into void does not remove new staged files' '
 	)
 '
 
+test_expect_success 'pulling into void must not create an octopus' '
+	git init cloned-octopus &&
+	(
+		cd cloned-octopus &&
+		test_must_fail git pull .. master master &&
+		! test -f file
+	)
+'
+
 test_expect_success 'test . as a remote' '
 
 	git branch copy master &&
diff --git a/t/t6020-merge-df.sh b/t/t6020-merge-df.sh
index 27c3d73961..2af1beec5f 100755
--- a/t/t6020-merge-df.sh
+++ b/t/t6020-merge-df.sh
@@ -24,7 +24,7 @@ test_expect_success 'prepare repository' '
 '
 
 test_expect_success 'Merge with d/f conflicts' '
-	test_expect_code 1 git merge "merge msg" B master
+	test_expect_code 1 git merge -m "merge msg" master
 '
 
 test_expect_success 'F/D conflict' '
diff --git a/t/t6021-merge-criss-cross.sh b/t/t6021-merge-criss-cross.sh
index d15b313d4b..213deecab1 100755
--- a/t/t6021-merge-criss-cross.sh
+++ b/t/t6021-merge-criss-cross.sh
@@ -48,7 +48,7 @@ echo "1
 " > file &&
 git commit -m "C3" file &&
 git branch C3 &&
-git merge "pre E3 merge" B A &&
+git merge -m "pre E3 merge" A &&
 echo "1
 2
 3 changed in E3, branch B. New file size
@@ -61,7 +61,7 @@ echo "1
 " > file &&
 git commit -m "E3" file &&
 git checkout A &&
-git merge "pre D8 merge" A C3 &&
+git merge -m "pre D8 merge" C3 &&
 echo "1
 2
 3 changed in C3, branch B
@@ -73,7 +73,7 @@ echo "1
 9" > file &&
 git commit -m D8 file'
 
-test_expect_success 'Criss-cross merge' 'git merge "final merge" A B'
+test_expect_success 'Criss-cross merge' 'git merge -m "final merge" B'
 
 cat > file-expect <<EOF
 1
diff --git a/t/t9402-git-cvsserver-refs.sh b/t/t9402-git-cvsserver-refs.sh
index 1e266effff..d00df08731 100755
--- a/t/t9402-git-cvsserver-refs.sh
+++ b/t/t9402-git-cvsserver-refs.sh
@@ -496,7 +496,7 @@ test_expect_success 'check [cvswork3] diff' '
 '
 
 test_expect_success 'merge early [cvswork3] b3 with b1' '
-	( cd gitwork3 && git merge "message" HEAD b1 ) &&
+	( cd gitwork3 && git merge -m "message" b1 ) &&
 	git fetch gitwork3 b3:b3 &&
 	git tag v3merged b3 &&
 	git push --tags gitcvs.git b3:b3