#!/bin/sh

test_description='recursive merge corner cases involving criss-cross merges'

. ./test-lib.sh

#
#  L1  L2
#   o---o
#  / \ / \
# o   X   ?
#  \ / \ /
#   o---o
#  R1  R2
#

test_expect_success 'setup basic criss-cross + rename with no modifications' '
	test_create_repo basic-rename &&
	(
		cd basic-rename &&

		ten="0 1 2 3 4 5 6 7 8 9" &&
		for i in $ten
		do
			echo line $i in a sample file
		done >one &&
		for i in $ten
		do
			echo line $i in another sample file
		done >two &&
		git add one two &&
		test_tick && git commit -m initial &&

		git branch L1 &&
		git checkout -b R1 &&
		git mv one three &&
		test_tick && git commit -m R1 &&

		git checkout L1 &&
		git mv two three &&
		test_tick && git commit -m L1 &&

		git checkout L1^0 &&
		test_tick && git merge -s ours R1 &&
		git tag L2 &&

		git checkout R1^0 &&
		test_tick && git merge -s ours L1 &&
		git tag R2
	)
'

test_expect_success 'merge simple rename+criss-cross with no modifications' '
	(
		cd basic-rename &&

		git reset --hard &&
		git checkout L2^0 &&

		test_must_fail git merge -s recursive R2^0 &&

		git ls-files -s >out &&
		test_line_count = 2 out &&
		git ls-files -u >out &&
		test_line_count = 2 out &&
		git ls-files -o >out &&
		test_line_count = 3 out &&

		git rev-parse >expect       \
			L2:three   R2:three \
			L2:three   R2:three &&
		git rev-parse   >actual     \
			:2:three   :3:three &&
		git hash-object >>actual    \
			three~HEAD three~R2^0 &&
		test_cmp expect actual
	)
'

#
# Same as before, but modify L1 slightly:
#
#  L1m L2
#   o---o
#  / \ / \
# o   X   ?
#  \ / \ /
#   o---o
#  R1  R2
#

test_expect_success 'setup criss-cross + rename merges with basic modification' '
	test_create_repo rename-modify &&
	(
		cd rename-modify &&

		ten="0 1 2 3 4 5 6 7 8 9" &&
		for i in $ten
		do
			echo line $i in a sample file
		done >one &&
		for i in $ten
		do
			echo line $i in another sample file
		done >two &&
		git add one two &&
		test_tick && git commit -m initial &&

		git branch L1 &&
		git checkout -b R1 &&
		git mv one three &&
		echo more >>two &&
		git add two &&
		test_tick && git commit -m R1 &&

		git checkout L1 &&
		git mv two three &&
		test_tick && git commit -m L1 &&

		git checkout L1^0 &&
		test_tick && git merge -s ours R1 &&
		git tag L2 &&

		git checkout R1^0 &&
		test_tick && git merge -s ours L1 &&
		git tag R2
	)
'

test_expect_success 'merge criss-cross + rename merges with basic modification' '
	(
		cd rename-modify &&

		git checkout L2^0 &&

		test_must_fail git merge -s recursive R2^0 &&

		git ls-files -s >out &&
		test_line_count = 2 out &&
		git ls-files -u >out &&
		test_line_count = 2 out &&
		git ls-files -o >out &&
		test_line_count = 3 out &&

		git rev-parse >expect       \
			L2:three   R2:three \
			L2:three   R2:three &&
		git rev-parse   >actual     \
			:2:three   :3:three &&
		git hash-object >>actual    \
			three~HEAD three~R2^0 &&
		test_cmp expect actual
	)
'

#
# For the next test, we start with three commits in two lines of development
# which setup a rename/add conflict:
#   Commit A: File 'a' exists
#   Commit B: Rename 'a' -> 'new_a'
#   Commit C: Modify 'a', create different 'new_a'
# Later, two different people merge and resolve differently:
#   Commit D: Merge B & C, ignoring separately created 'new_a'
#   Commit E: Merge B & C making use of some piece of secondary 'new_a'
# Finally, someone goes to merge D & E.  Does git detect the conflict?
#
#      B   D
#      o---o
#     / \ / \
#  A o   X   ? F
#     \ / \ /
#      o---o
#      C   E
#

test_expect_success 'setup differently handled merges of rename/add conflict' '
	test_create_repo rename-add &&
	(
		cd rename-add &&

		printf "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n" >a &&
		git add a &&
		test_tick && git commit -m A &&

		git branch B &&
		git checkout -b C &&
		echo 10 >>a &&
		echo "other content" >>new_a &&
		git add a new_a &&
		test_tick && git commit -m C &&

		git checkout B &&
		git mv a new_a &&
		test_tick && git commit -m B &&

		git checkout B^0 &&
		test_must_fail git merge C &&
		git clean -f &&
		test_tick && git commit -m D &&
		git tag D &&

		git checkout C^0 &&
		test_must_fail git merge B &&
		rm new_a~HEAD new_a &&
		printf "Incorrectly merged content" >>new_a &&
		git add -u &&
		test_tick && git commit -m E &&
		git tag E
	)
'

test_expect_success 'git detects differently handled merges conflict' '
	(
		cd rename-add &&

		git checkout D^0 &&

		test_must_fail git merge -s recursive E^0 &&

		git ls-files -s >out &&
		test_line_count = 3 out &&
		git ls-files -u >out &&
		test_line_count = 3 out &&
		git ls-files -o >out &&
		test_line_count = 1 out &&

		git rev-parse >expect       \
			D:new_a  E:new_a &&
		git rev-parse   >actual     \
			:2:new_a :3:new_a &&
		test_cmp expect actual &&

		git cat-file -p B:new_a >ours &&
		git cat-file -p C:new_a >theirs &&
		>empty &&
		test_must_fail git merge-file \
			-L "Temporary merge branch 2" \
			-L "" \
			-L "Temporary merge branch 1" \
			ours empty theirs &&
		sed -e "s/^\([<=>]\)/\1\1\1/" ours >expect &&
		git cat-file -p :1:new_a >actual &&
		test_cmp expect actual
	)
'

#
# criss-cross + modify/delete:
#
#      B   D
#      o---o
#     / \ / \
#  A o   X   ? F
#     \ / \ /
#      o---o
#      C   E
#
#   Commit A: file with contents 'A\n'
#   Commit B: file with contents 'B\n'
#   Commit C: file not present
#   Commit D: file with contents 'B\n'
#   Commit E: file not present
#
# Merging commits D & E should result in modify/delete conflict.

test_expect_success 'setup criss-cross + modify/delete resolved differently' '
	test_create_repo modify-delete &&
	(
		cd modify-delete &&

		echo A >file &&
		git add file &&
		test_tick &&
		git commit -m A &&

		git branch B &&
		git checkout -b C &&
		git rm file &&
		test_tick &&
		git commit -m C &&

		git checkout B &&
		echo B >file &&
		git add file &&
		test_tick &&
		git commit -m B &&

		git checkout B^0 &&
		test_must_fail git merge C &&
		echo B >file &&
		git add file &&
		test_tick &&
		git commit -m D &&
		git tag D &&

		git checkout C^0 &&
		test_must_fail git merge B &&
		git rm file &&
		test_tick &&
		git commit -m E &&
		git tag E
	)
'

test_expect_success 'git detects conflict merging criss-cross+modify/delete' '
	(
		cd modify-delete &&

		git checkout D^0 &&

		test_must_fail git merge -s recursive E^0 &&

		git ls-files -s >out &&
		test_line_count = 2 out &&
		git ls-files -u >out &&
		test_line_count = 2 out &&

		git rev-parse >expect       \
			master:file  B:file &&
		git rev-parse   >actual      \
			:1:file      :2:file &&
		test_cmp expect actual
	)
'

test_expect_success 'git detects conflict merging criss-cross+modify/delete, reverse direction' '
	(
		cd modify-delete &&

		git reset --hard &&
		git checkout E^0 &&

		test_must_fail git merge -s recursive D^0 &&

		git ls-files -s >out &&
		test_line_count = 2 out &&
		git ls-files -u >out &&
		test_line_count = 2 out &&

		git rev-parse >expect       \
			master:file  B:file &&
		git rev-parse   >actual      \
			:1:file      :3:file &&
		test_cmp expect actual
	)
'

#
# criss-cross + d/f conflict via add/add:
#   Commit A: Neither file 'a' nor directory 'a/' exists.
#   Commit B: Introduce 'a'
#   Commit C: Introduce 'a/file'
#   Commit D: Merge B & C, keeping 'a' and deleting 'a/'
#
# Two different later cases:
#   Commit E1: Merge B & C, deleting 'a' but keeping 'a/file'
#   Commit E2: Merge B & C, deleting 'a' but keeping a slightly modified 'a/file'
#
#      B   D
#      o---o
#     / \ / \
#  A o   X   ? F
#     \ / \ /
#      o---o
#      C   E1 or E2
#
# Merging D & E1 requires we first create a virtual merge base X from
# merging A & B in memory.  Now, if X could keep both 'a' and 'a/file' in
# the index, then the merge of D & E1 could be resolved cleanly with both
# 'a' and 'a/file' removed.  Since git does not currently allow creating
# such a tree, the best we can do is have X contain both 'a~<unique>' and
# 'a/file' resulting in the merge of D and E1 having a rename/delete
# conflict for 'a'.  (Although this merge appears to be unsolvable with git
# currently, git could do a lot better than it currently does with these
# d/f conflicts, which is the purpose of this test.)
#
# Merge of D & E2 has similar issues for path 'a', but should always result
# in a modify/delete conflict for path 'a/file'.
#
# We run each merge in both directions, to check for directional issues
# with D/F conflict handling.
#

test_expect_success 'setup differently handled merges of directory/file conflict' '
	test_create_repo directory-file &&
	(
		cd directory-file &&

		>ignore-me &&
		git add ignore-me &&
		test_tick &&
		git commit -m A &&
		git tag A &&

		git branch B &&
		git checkout -b C &&
		mkdir a &&
		echo 10 >a/file &&
		git add a/file &&
		test_tick &&
		git commit -m C &&

		git checkout B &&
		echo 5 >a &&
		git add a &&
		test_tick &&
		git commit -m B &&

		git checkout B^0 &&
		test_must_fail git merge C &&
		git clean -f &&
		rm -rf a/ &&
		echo 5 >a &&
		git add a &&
		test_tick &&
		git commit -m D &&
		git tag D &&

		git checkout C^0 &&
		test_must_fail git merge B &&
		git clean -f &&
		git rm --cached a &&
		echo 10 >a/file &&
		git add a/file &&
		test_tick &&
		git commit -m E1 &&
		git tag E1 &&

		git checkout C^0 &&
		test_must_fail git merge B &&
		git clean -f &&
		git rm --cached a &&
		printf "10\n11\n" >a/file &&
		git add a/file &&
		test_tick &&
		git commit -m E2 &&
		git tag E2
	)
'

test_expect_success 'merge of D & E1 fails but has appropriate contents' '
	test_when_finished "git -C directory-file reset --hard" &&
	test_when_finished "git -C directory-file clean -fdqx" &&
	(
		cd directory-file &&

		git checkout D^0 &&

		test_must_fail git merge -s recursive E1^0 &&

		git ls-files -s >out &&
		test_line_count = 2 out &&
		git ls-files -u >out &&
		test_line_count = 1 out &&
		git ls-files -o >out &&
		test_line_count = 1 out &&

		git rev-parse >expect    \
			A:ignore-me  B:a &&
		git rev-parse   >actual   \
			:0:ignore-me :2:a &&
		test_cmp expect actual
	)
'

test_expect_success 'merge of E1 & D fails but has appropriate contents' '
	test_when_finished "git -C directory-file reset --hard" &&
	test_when_finished "git -C directory-file clean -fdqx" &&
	(
		cd directory-file &&

		git checkout E1^0 &&

		test_must_fail git merge -s recursive D^0 &&

		git ls-files -s >out &&
		test_line_count = 2 out &&
		git ls-files -u >out &&
		test_line_count = 1 out &&
		git ls-files -o >out &&
		test_line_count = 1 out &&

		git rev-parse >expect    \
			A:ignore-me  B:a &&
		git rev-parse   >actual   \
			:0:ignore-me :3:a &&
		test_cmp expect actual
	)
'

test_expect_success 'merge of D & E2 fails but has appropriate contents' '
	test_when_finished "git -C directory-file reset --hard" &&
	test_when_finished "git -C directory-file clean -fdqx" &&
	(
		cd directory-file &&

		git checkout D^0 &&

		test_must_fail git merge -s recursive E2^0 &&

		git ls-files -s >out &&
		test_line_count = 4 out &&
		git ls-files -u >out &&
		test_line_count = 3 out &&
		git ls-files -o >out &&
		test_line_count = 2 out &&

		git rev-parse >expect    \
			B:a   E2:a/file  C:a/file   A:ignore-me &&
		git rev-parse   >actual   \
			:2:a  :3:a/file  :1:a/file  :0:ignore-me &&
		test_cmp expect actual &&

		test_path_is_file a~HEAD
	)
'

test_expect_success 'merge of E2 & D fails but has appropriate contents' '
	test_when_finished "git -C directory-file reset --hard" &&
	test_when_finished "git -C directory-file clean -fdqx" &&
	(
		cd directory-file &&

		git checkout E2^0 &&

		test_must_fail git merge -s recursive D^0 &&

		git ls-files -s >out &&
		test_line_count = 4 out &&
		git ls-files -u >out &&
		test_line_count = 3 out &&
		git ls-files -o >out &&
		test_line_count = 2 out &&

		git rev-parse >expect    \
			B:a   E2:a/file  C:a/file   A:ignore-me &&
		git rev-parse   >actual   \
			:3:a  :2:a/file  :1:a/file  :0:ignore-me &&
		test_cmp expect actual &&

		test_path_is_file a~D^0
	)
'

#
# criss-cross with rename/rename(1to2)/modify followed by
# rename/rename(2to1)/modify:
#
#      B   D
#      o---o
#     / \ / \
#  A o   X   ? F
#     \ / \ /
#      o---o
#      C   E
#
#   Commit A: new file: a
#   Commit B: rename a->b, modifying by adding a line
#   Commit C: rename a->c
#   Commit D: merge B&C, resolving conflict by keeping contents in newname
#   Commit E: merge B&C, resolving conflict similar to D but adding another line
#
# There is a conflict merging B & C, but one of filename not of file
# content.  Whoever created D and E chose specific resolutions for that
# conflict resolution.  Now, since: (1) there is no content conflict
# merging B & C, (2) D does not modify that merged content further, and (3)
# both D & E resolve the name conflict in the same way, the modification to
# newname in E should not cause any conflicts when it is merged with D.
# (Note that this can be accomplished by having the virtual merge base have
# the merged contents of b and c stored in a file named a, which seems like
# the most logical choice anyway.)
#
# Comment from Junio: I do not necessarily agree with the choice "a", but
# it feels sound to say "B and C do not agree what the final pathname
# should be, but we know this content was derived from the common A:a so we
# use one path whose name is arbitrary in the virtual merge base X between
# D and E" and then further let the rename detection to notice that that
# arbitrary path gets renamed between X-D to "newname" and X-E also to
# "newname" to resolve it as both sides renaming it to the same new
# name. It is akin to what we do at the content level, i.e. "B and C do not
# agree what the final contents should be, so we leave the conflict marker
# but that may cancel out at the final merge stage".

test_expect_success 'setup rename/rename(1to2)/modify followed by what looks like rename/rename(2to1)/modify' '
	test_create_repo rename-squared-squared &&
	(
		cd rename-squared-squared &&

		printf "1\n2\n3\n4\n5\n6\n" >a &&
		git add a &&
		git commit -m A &&
		git tag A &&

		git checkout -b B A &&
		git mv a b &&
		echo 7 >>b &&
		git add -u &&
		git commit -m B &&

		git checkout -b C A &&
		git mv a c &&
		git commit -m C &&

		git checkout -q B^0 &&
		git merge --no-commit -s ours C^0 &&
		git mv b newname &&
		git commit -m "Merge commit C^0 into HEAD" &&
		git tag D &&

		git checkout -q C^0 &&
		git merge --no-commit -s ours B^0 &&
		git mv c newname &&
		printf "7\n8\n" >>newname &&
		git add -u &&
		git commit -m "Merge commit B^0 into HEAD" &&
		git tag E
	)
'

test_expect_success 'handle rename/rename(1to2)/modify followed by what looks like rename/rename(2to1)/modify' '
	(
		cd rename-squared-squared &&

		git checkout D^0 &&

		git merge -s recursive E^0 &&

		git ls-files -s >out &&
		test_line_count = 1 out &&
		git ls-files -u >out &&
		test_line_count = 0 out &&
		git ls-files -o >out &&
		test_line_count = 1 out &&

		test $(git rev-parse HEAD:newname) = $(git rev-parse E:newname)
	)
'

#
# criss-cross with rename/rename(1to2)/add-source + resolvable modify/modify:
#
#      B   D
#      o---o
#     / \ / \
#  A o   X   ? F
#     \ / \ /
#      o---o
#      C   E
#
#   Commit A: new file: a
#   Commit B: rename a->b
#   Commit C: rename a->c, add different a
#   Commit D: merge B&C, keeping b&c and (new) a modified at beginning
#   Commit E: merge B&C, keeping b&c and (new) a modified at end
#
# Merging commits D & E should result in no conflict; doing so correctly
# requires getting the virtual merge base (from merging B&C) right, handling
# renaming carefully (both in the virtual merge base and later), and getting
# content merge handled.

test_expect_success 'setup criss-cross + rename/rename/add-source + modify/modify' '
	test_create_repo rename-rename-add-source &&
	(
		cd rename-rename-add-source &&

		printf "lots\nof\nwords\nand\ncontent\n" >a &&
		git add a &&
		git commit -m A &&
		git tag A &&

		git checkout -b B A &&
		git mv a b &&
		git commit -m B &&

		git checkout -b C A &&
		git mv a c &&
		printf "2\n3\n4\n5\n6\n7\n" >a &&
		git add a &&
		git commit -m C &&

		git checkout B^0 &&
		git merge --no-commit -s ours C^0 &&
		git checkout C -- a c &&
		mv a old_a &&
		echo 1 >a &&
		cat old_a >>a &&
		rm old_a &&
		git add -u &&
		git commit -m "Merge commit C^0 into HEAD" &&
		git tag D &&

		git checkout C^0 &&
		git merge --no-commit -s ours B^0 &&
		git checkout B -- b &&
		echo 8 >>a &&
		git add -u &&
		git commit -m "Merge commit B^0 into HEAD" &&
		git tag E
	)
'

test_expect_failure 'detect rename/rename/add-source for virtual merge-base' '
	(
		cd rename-rename-add-source &&

		git checkout D^0 &&

		git merge -s recursive E^0 &&

		git ls-files -s >out &&
		test_line_count = 3 out &&
		git ls-files -u >out &&
		test_line_count = 0 out &&
		git ls-files -o >out &&
		test_line_count = 1 out &&

		printf "1\n2\n3\n4\n5\n6\n7\n8\n" >correct &&
		git rev-parse >expect \
			A:a   A:a     \
			correct       &&
		git rev-parse   >actual  \
			:0:b  :0:c       &&
		git hash-object >>actual \
			a                &&
		test_cmp expect actual
	)
'

#
# criss-cross with rename/rename(1to2)/add-dest + simple modify:
#
#      B   D
#      o---o
#     / \ / \
#  A o   X   ? F
#     \ / \ /
#      o---o
#      C   E
#
#   Commit A: new file: a
#   Commit B: rename a->b, add c
#   Commit C: rename a->c
#   Commit D: merge B&C, keeping A:a and B:c
#   Commit E: merge B&C, keeping A:a and slightly modified c from B
#
# Merging commits D & E should result in no conflict.  The virtual merge
# base of B & C needs to not delete B:c for that to work, though...

test_expect_success 'setup criss-cross+rename/rename/add-dest + simple modify' '
	test_create_repo rename-rename-add-dest &&
	(
		cd rename-rename-add-dest &&

		>a &&
		git add a &&
		git commit -m A &&
		git tag A &&

		git checkout -b B A &&
		git mv a b &&
		printf "1\n2\n3\n4\n5\n6\n7\n" >c &&
		git add c &&
		git commit -m B &&

		git checkout -b C A &&
		git mv a c &&
		git commit -m C &&

		git checkout B^0 &&
		git merge --no-commit -s ours C^0 &&
		git mv b a &&
		git commit -m "D is like B but renames b back to a" &&
		git tag D &&

		git checkout B^0 &&
		git merge --no-commit -s ours C^0 &&
		git mv b a &&
		echo 8 >>c &&
		git add c &&
		git commit -m "E like D but has mod in c" &&
		git tag E
	)
'

test_expect_success 'virtual merge base handles rename/rename(1to2)/add-dest' '
	(
		cd rename-rename-add-dest &&

		git checkout D^0 &&

		git merge -s recursive E^0 &&

		git ls-files -s >out &&
		test_line_count = 2 out &&
		git ls-files -u >out &&
		test_line_count = 0 out &&
		git ls-files -o >out &&
		test_line_count = 1 out &&

		git rev-parse >expect \
			A:a   E:c     &&
		git rev-parse   >actual \
			:0:a  :0:c      &&
		test_cmp expect actual
	)
'

test_done