Merge branch 'jc/rerere-multi'

"git rerere" can encounter two or more files with the same conflict
signature that have to be resolved in different ways, but there was
no way to record these separate resolutions.

* jc/rerere-multi:
  rerere: adjust 'forget' to multi-variant world order
  rerere: split code to call ll_merge() further
  rerere: move code related to "forget" together
  rerere: gc and clear
  rerere: do use multiple variants
  t4200: rerere a merge with two identical conflicts
  rerere: allow multiple variants to exist
  rerere: delay the recording of preimage
  rerere: handle leftover rr-cache/$ID directory and postimage files
  rerere: scan $GIT_DIR/rr-cache/$ID when instantiating a rerere_id
  rerere: split conflict ID further

1 files changed, 169 insertions, 1 deletions

diff --git a/t/t4200-rerere.sh b/t/t4200-rerere.sh
index ed9c91e25b..1a080e7823 100755
--- a/t/t4200-rerere.sh
+++ b/t/t4200-rerere.sh
@@ -184,12 +184,27 @@ test_expect_success 'rerere updates postimage timestamp' '
 '
 
 test_expect_success 'rerere clear' '
-	rm $rr/postimage &&
+	mv $rr/postimage .git/post-saved &&
 	echo "$sha1	a1" | perl -pe "y/\012/\000/" >.git/MERGE_RR &&
 	git rerere clear &&
 	! test -d $rr
 '
 
+test_expect_success 'leftover directory' '
+	git reset --hard &&
+	mkdir -p $rr &&
+	test_must_fail git merge first &&
+	test -f $rr/preimage
+'
+
+test_expect_success 'missing preimage' '
+	git reset --hard &&
+	mkdir -p $rr &&
+	cp .git/post-saved $rr/postimage &&
+	test_must_fail git merge first &&
+	test -f $rr/preimage
+'
+
 test_expect_success 'set up for garbage collection tests' '
 	mkdir -p $rr &&
 	echo Hello >$rr/preimage &&
@@ -391,4 +406,157 @@ test_expect_success 'rerere -h' '
 	test_i18ngrep [Uu]sage help
 '
 
+concat_insert () {
+	last=$1
+	shift
+	cat early && printf "%s\n" "$@" && cat late "$last"
+}
+
+count_pre_post () {
+	find .git/rr-cache/ -type f -name "preimage*" >actual &&
+	test_line_count = "$1" actual &&
+	find .git/rr-cache/ -type f -name "postimage*" >actual &&
+	test_line_count = "$2" actual
+}
+
+test_expect_success 'rerere gc' '
+	find .git/rr-cache -type f >original &&
+	xargs test-chmtime -172800 <original &&
+
+	git -c gc.rerereresolved=5 -c gc.rerereunresolved=5 rerere gc &&
+	find .git/rr-cache -type f >actual &&
+	test_cmp original actual &&
+
+	git -c gc.rerereresolved=5 -c gc.rerereunresolved=0 rerere gc &&
+	find .git/rr-cache -type f >actual &&
+	test_cmp original actual &&
+
+	git -c gc.rerereresolved=0 -c gc.rerereunresolved=0 rerere gc &&
+	find .git/rr-cache -type f >actual &&
+	>expect &&
+	test_cmp expect actual
+'
+
+merge_conflict_resolve () {
+	git reset --hard &&
+	test_must_fail git merge six.1 &&
+	# Resolution is to replace 7 with 6.1 and 6.2 (i.e. take both)
+	concat_insert short 6.1 6.2 >file1 &&
+	concat_insert long 6.1 6.2 >file2
+}
+
+test_expect_success 'multiple identical conflicts' '
+	git reset --hard &&
+
+	test_seq 1 6 >early &&
+	>late &&
+	test_seq 11 15 >short &&
+	test_seq 111 120 >long &&
+	concat_insert short >file1 &&
+	concat_insert long >file2 &&
+	git add file1 file2 &&
+	git commit -m base &&
+	git tag base &&
+	git checkout -b six.1 &&
+	concat_insert short 6.1 >file1 &&
+	concat_insert long 6.1 >file2 &&
+	git add file1 file2 &&
+	git commit -m 6.1 &&
+	git checkout -b six.2 HEAD^ &&
+	concat_insert short 6.2 >file1 &&
+	concat_insert long 6.2 >file2 &&
+	git add file1 file2 &&
+	git commit -m 6.2 &&
+
+	# At this point, six.1 and six.2
+	# - derive from common ancestor that has two files
+	#   1...6 7 11..15 (file1) and 1...6 7 111..120 (file2)
+	# - six.1 replaces these 7s with 6.1
+	# - six.2 replaces these 7s with 6.2
+
+	merge_conflict_resolve &&
+
+	# Check that rerere knows that file1 and file2 have conflicts
+
+	printf "%s\n" file1 file2 >expect &&
+	git ls-files -u | sed -e "s/^.*	//" | sort -u >actual &&
+	test_cmp expect actual &&
+
+	git rerere status | sort >actual &&
+	test_cmp expect actual &&
+
+	git rerere remaining >actual &&
+	test_cmp expect actual &&
+
+	count_pre_post 2 0 &&
+
+	# Pretend that the conflicts were made quite some time ago
+	find .git/rr-cache/ -type f | xargs test-chmtime -172800 &&
+
+	# Unresolved entries have not expired yet
+	git -c gc.rerereresolved=5 -c gc.rerereunresolved=5 rerere gc &&
+	count_pre_post 2 0 &&
+
+	# Unresolved entries have expired
+	git -c gc.rerereresolved=5 -c gc.rerereunresolved=1 rerere gc &&
+	count_pre_post 0 0 &&
+
+	# Recreate the conflicted state
+	merge_conflict_resolve &&
+	count_pre_post 2 0 &&
+
+	# Clear it
+	git rerere clear &&
+	count_pre_post 0 0 &&
+
+	# Recreate the conflicted state
+	merge_conflict_resolve &&
+	count_pre_post 2 0 &&
+
+	# We resolved file1 and file2
+	git rerere &&
+	>expect &&
+	git rerere remaining >actual &&
+	test_cmp expect actual &&
+
+	# We must have recorded both of them
+	count_pre_post 2 2 &&
+
+	# Now we should be able to resolve them both
+	git reset --hard &&
+	test_must_fail git merge six.1 &&
+	git rerere &&
+
+	>expect &&
+	git rerere remaining >actual &&
+	test_cmp expect actual &&
+
+	concat_insert short 6.1 6.2 >file1.expect &&
+	concat_insert long 6.1 6.2 >file2.expect &&
+	test_cmp file1.expect file1 &&
+	test_cmp file2.expect file2 &&
+
+	# Forget resolution for file2
+	git rerere forget file2 &&
+	echo file2 >expect &&
+	git rerere status >actual &&
+	test_cmp expect actual &&
+	count_pre_post 2 1 &&
+
+	# file2 already has correct resolution, so record it again
+	git rerere &&
+
+	# Pretend that the resolutions are old again
+	find .git/rr-cache/ -type f | xargs test-chmtime -172800 &&
+
+	# Resolved entries have not expired yet
+	git -c gc.rerereresolved=5 -c gc.rerereunresolved=5 rerere gc &&
+
+	count_pre_post 2 2 &&
+
+	# Resolved entries have expired
+	git -c gc.rerereresolved=1 -c gc.rerereunresolved=5 rerere gc &&
+	count_pre_post 0 0
+'
+
 test_done