[PATCH v3 00/33] Add directory rename detection to git

[PATCH v3 00/33] Add directory rename detection to git

[Elijah Newren]

This patchset introduces directory rename detection to merge-recursive; I'm
resubmitting just a few hours after my PATCHv2 because I didn't know about
the DEVELOPER=1 flag previously, and my code had a number of
warnings/errors.  I would have just submitted fixup/squash patches, but
when I checked, there sadly they cause merge conflicts when rebasing

See https://public-inbox.org/git/20171110190550.27059-1-newren@gmail.com/
for the first series, design considerations, etc, and
https://public-inbox.org/git/20171120220209.15111-1-newren@gmail.com/ for
v2.

Changes since the last series:
  * Fixed various compilation errors with make DEVELOPER=1.

Elijah Newren (33):
  Tighten and correct a few testcases for merging and cherry-picking
  merge-recursive: fix logic ordering issue
  merge-recursive: add explanation for src_entry and dst_entry
  directory rename detection: basic testcases
  directory rename detection: directory splitting testcases
  directory rename detection: testcases to avoid taking detection too
    far
  directory rename detection: partially renamed directory
    testcase/discussion
  directory rename detection: files/directories in the way of some
    renames
  directory rename detection: testcases checking which side did the
    rename
  directory rename detection: more involved edge/corner testcases
  directory rename detection: testcases exploring possibly suboptimal
    merges
  directory rename detection: miscellaneous testcases to complete
    coverage
  directory rename detection: tests for handling overwriting untracked
    files
  directory rename detection: tests for handling overwriting dirty files
  merge-recursive: move the get_renames() function
  merge-recursive: introduce new functions to handle rename logic
  merge-recursive: fix leaks of allocated renames and diff_filepairs
  merge-recursive: make !o->detect_rename codepath more obvious
  merge-recursive: split out code for determining diff_filepairs
  merge-recursive: add a new hashmap for storing directory renames
  merge-recursive: add get_directory_renames()
  merge-recursive: check for directory level conflicts
  merge-recursive: add a new hashmap for storing file collisions
  merge-recursive: add computation of collisions due to dir rename &
    merging
  merge-recursive: check for file level conflicts then get new name
  merge-recursive: when comparing files, don't include trees
  merge-recursive: apply necessary modifications for directory renames
  merge-recursive: avoid clobbering untracked files with directory
    renames
  merge-recursive: fix overwriting dirty files involved in renames
  merge-recursive: fix remaining directory rename + dirty overwrite
    cases
  directory rename detection: new testcases showcasing a pair of bugs
  merge-recursive: avoid spurious rename/rename conflict from dir
    renames
  merge-recursive: ensure we write updates for directory-renamed file

 merge-recursive.c                   | 1243 +++++++++++-
 merge-recursive.h                   |   17 +
 t/t3501-revert-cherry-pick.sh       |    5 +-
 t/t6043-merge-rename-directories.sh | 3821 +++++++++++++++++++++++++++++++++++
 t/t7607-merge-overwrite.sh          |    7 +-
 unpack-trees.c                      |    4 +-
 unpack-trees.h                      |    4 +
 7 files changed, 4985 insertions(+), 116 deletions(-)
 create mode 100755 t/t6043-merge-rename-directories.sh

-- 
2.15.0.309.g62ce55426d

[PATCH v3 01/33] Tighten and correct a few testcases for merging and cherry-picking

[Elijah Newren]

t3501 had a testcase originally added in 05f2dfb965 (cherry-pick:
demonstrate a segmentation fault, 2016-11-26) to ensure cherry-pick
wouldn't segfault when working with a dirty file involved in a rename.
While the segfault was fixed, there was another problem this test
demonstrated: namely, that git would overwrite a dirty file involved in a
rename.  Further, the test encoded a "successful merge" and overwriting of
this file as correct behavior.  Modify the test so that it would still
catch the segfault, but to require the correct behavior.  Mark it as
test_expect_failure for now too, since this second bug is not yet fixed.

t7607 had a test added in 30fd3a5425 (merge overwrites unstaged changes in
renamed file, 2012-04-15) specific to looking for a merge overwriting a
dirty file involved in a rename, but it too actually encoded what I would
term incorrect behavior: it expected the merge to succeed.  Fix that, and
add a few more checks to make sure that the merge really does produce the
expected results.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t3501-revert-cherry-pick.sh | 7 +++++--
 t/t7607-merge-overwrite.sh    | 5 ++++-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/t/t3501-revert-cherry-pick.sh b/t/t3501-revert-cherry-pick.sh
index 4f2a263b63..783bdbf59d 100755
--- a/t/t3501-revert-cherry-pick.sh
+++ b/t/t3501-revert-cherry-pick.sh
@@ -141,7 +141,7 @@ test_expect_success 'cherry-pick "-" works with arguments' '
 	test_cmp expect actual
 '
 
-test_expect_success 'cherry-pick works with dirty renamed file' '
+test_expect_failure 'cherry-pick works with dirty renamed file' '
 	test_commit to-rename &&
 	git checkout -b unrelated &&
 	test_commit unrelated &&
@@ -150,7 +150,10 @@ test_expect_success 'cherry-pick works with dirty renamed file' '
 	test_tick &&
 	git commit -m renamed &&
 	echo modified >renamed &&
-	git cherry-pick refs/heads/unrelated
+	test_must_fail git cherry-pick refs/heads/unrelated >out &&
+	test_i18ngrep "Refusing to lose dirty file at renamed" out &&
+	test $(git rev-parse :0:renamed) = $(git rev-parse HEAD^:to-rename.t) &&
+	grep -q "^modified$" renamed
 '
 
 test_done
diff --git a/t/t7607-merge-overwrite.sh b/t/t7607-merge-overwrite.sh
index 9444d6a9b9..00617dadf8 100755
--- a/t/t7607-merge-overwrite.sh
+++ b/t/t7607-merge-overwrite.sh
@@ -97,7 +97,10 @@ test_expect_failure 'will not overwrite unstaged changes in renamed file' '
 	git mv c1.c other.c &&
 	git commit -m rename &&
 	cp important other.c &&
-	git merge c1a &&
+	test_must_fail git merge c1a >out &&
+	test_i18ngrep "Refusing to lose dirty file at other.c" out &&
+	test -f other.c~HEAD &&
+	test $(git hash-object other.c~HEAD) = $(git rev-parse c1a:c1.c) &&
 	test_cmp important other.c
 '
 
-- 
2.15.0.309.g62ce55426d

[PATCH v3 02/33] merge-recursive: fix logic ordering issue

[Elijah Newren]

merge_trees() did a variety of work, including:
  * Calling get_unmerged() to get unmerged entries
  * Calling record_df_conflict_files() with all unmerged entries to
    do some work to ensure we could handle D/F conflicts correctly
  * Calling get_renames() to check for renames.

An easily overlooked issue is that get_renames() can create more
unmerged entries and add them to the list, which have the possibility of
being involved in D/F conflicts.  So the call to
record_df_conflict_files() should really be moved after all the rename
detection.  I didn't come up with any testcases demonstrating any bugs
with the old ordering, but I suspect there were some for both normal
renames and for directory renames.  Fix the ordering.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index b48b15a6fd..944f938ec8 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1981,10 +1981,10 @@ int merge_trees(struct merge_options *o,
 		get_files_dirs(o, merge);
 
 		entries = get_unmerged();
-		record_df_conflict_files(o, entries);
 		re_head  = get_renames(o, head, common, head, merge, entries);
 		re_merge = get_renames(o, merge, common, head, merge, entries);
 		clean = process_renames(o, re_head, re_merge);
+		record_df_conflict_files(o, entries);
 		if (clean < 0)
 			goto cleanup;
 		for (i = entries->nr-1; 0 <= i; i--) {
-- 
2.15.0.309.g62ce55426d

[PATCH v3 03/33] merge-recursive: add explanation for src_entry and dst_entry

[Elijah Newren]

If I have to walk through the debugger and inspect the values found in
here in order to figure out their meaning, despite having known these
things inside and out some years back, then they probably need a comment
for the casual reader to explain their purpose.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/merge-recursive.c b/merge-recursive.c
index 944f938ec8..c530880333 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -513,6 +513,25 @@ static void record_df_conflict_files(struct merge_options *o,
 
 struct rename {
 	struct diff_filepair *pair;
+	/*
+	 * Purpose of src_entry and dst_entry:
+	 *
+	 * If 'before' is renamed to 'after' then src_entry will contain
+	 * the versions of 'before' from the merge_base, HEAD, and MERGE in
+	 * stages 1, 2, and 3; dst_entry will contain the respective
+	 * versions of 'after' in corresponding locations.  Thus, we have a
+	 * total of six modes and oids, though some will be null.  (Stage 0
+	 * is ignored; we're interested in handling conflicts.)
+	 *
+	 * Since we don't turn on break-rewrites by default, neither
+	 * src_entry nor dst_entry can have all three of their stages have
+	 * non-null oids, meaning at most four of the six will be non-null.
+	 * Also, since this is a rename, both src_entry and dst_entry will
+	 * have at least one non-null oid, meaning at least two will be
+	 * non-null.  Of the six oids, a typical rename will have three be
+	 * non-null.  Only two implies a rename/delete, and four implies a
+	 * rename/add.
+	 */
 	struct stage_data *src_entry;
 	struct stage_data *dst_entry;
 	unsigned processed:1;
-- 
2.15.0.309.g62ce55426d

[PATCH v3 04/33] directory rename detection: basic testcases

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 430 ++++++++++++++++++++++++++++++++++++
 1 file changed, 430 insertions(+)
 create mode 100755 t/t6043-merge-rename-directories.sh

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
new file mode 100755
index 0000000000..d8ead7c56b
--- /dev/null
+++ b/t/t6043-merge-rename-directories.sh
@@ -0,0 +1,430 @@
+#!/bin/sh
+
+test_description="recursive merge with directory renames"
+# includes checking of many corner cases, with a similar methodology to:
+#   t6042: corner cases with renames but not criss-cross merges
+#   t6036: corner cases with both renames and criss-cross merges
+#
+# The setup for all of them, pictorially, is:
+#
+#      A
+#      o
+#     / \
+#  O o   ?
+#     \ /
+#      o
+#      B
+#
+# To help make it easier to follow the flow of tests, they have been
+# divided into sections and each test will start with a quick explanation
+# of what commits O, A, and B contain.
+#
+# Notation:
+#    z/{b,c}   means  files z/b and z/c both exist
+#    x/d_1     means  file x/d exists with content d1.  (Purpose of the
+#                     underscore notation is to differentiate different
+#                     files that might be renamed into each other's paths.)
+
+. ./test-lib.sh
+
+
+###########################################################################
+# SECTION 1: Basic cases we should be able to handle
+###########################################################################
+
+# Testcase 1a, Basic directory rename.
+#   Commit O: z/{b,c}
+#   Commit A: y/{b,c}
+#   Commit B: z/{b,c,d,e/f}
+#   Expected: y/{b,c,d,e/f}
+
+test_expect_success '1a-setup: Simple directory rename detection' '
+	test_create_repo 1a &&
+	(
+		cd 1a &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo d >z/d &&
+		mkdir z/e &&
+		echo f >z/e/f &&
+		git add z/d z/e/f &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '1a-check: Simple directory rename detection' '
+	(
+		cd 1a &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/d HEAD:y/e/f &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/d B:z/e/f &&
+		test_cmp expect actual &&
+		test "$(git hash-object y/d)" = $(git rev-parse B:z/d) &&
+		test_must_fail git rev-parse HEAD:z/d &&
+		test_must_fail git rev-parse HEAD:z/e/f &&
+		test ! -d z/d &&
+		test ! -d z/e/f
+	)
+'
+
+# Testcase 1b, Merge a directory with another
+#   Commit O: z/{b,c},   y/d
+#   Commit A: z/{b,c,e}, y/d
+#   Commit B: y/{b,c,d}
+#   Expected: y/{b,c,d,e}
+
+test_expect_success '1b-setup: Merge a directory with another' '
+	test_create_repo 1b &&
+	(
+		cd 1b &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir y &&
+		echo d >y/d &&
+		git add z y &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		echo e >z/e &&
+		git add z/e &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv z/b y &&
+		git mv z/c y &&
+		rmdir z &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '1b-check: Merge a directory with another' '
+	(
+		cd 1b &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/d HEAD:y/e &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:y/d A:z/e &&
+		test_cmp expect actual &&
+		test_must_fail git rev-parse HEAD:z/e
+	)
+'
+
+# Testcase 1c, Transitive renaming
+#   (Related to testcases 3a and 6d -- when should a transitive rename apply?)
+#   (Related to testcases 9c and 9d -- can transitivity repeat?)
+#   Commit O: z/{b,c},   x/d
+#   Commit A: y/{b,c},   x/d
+#   Commit B: z/{b,c,d}
+#   Expected: y/{b,c,d}  (because x/d -> z/d -> y/d)
+
+test_expect_success '1c-setup: Transitive renaming' '
+	test_create_repo 1c &&
+	(
+		cd 1c &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir x &&
+		echo d >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/d z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '1c-check: Transitive renaming' '
+	(
+		cd 1c &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:x/d &&
+		test_cmp expect actual &&
+		test_must_fail git rev-parse HEAD:x/d &&
+		test_must_fail git rev-parse HEAD:z/d &&
+		test ! -f z/d
+	)
+'
+
+# Testcase 1d, Directory renames (merging two directories into one new one)
+#              cause a rename/rename(2to1) conflict
+#   (Related to testcases 1c and 7b)
+#   Commit O. z/{b,c},        y/{d,e}
+#   Commit A. x/{b,c},        y/{d,e,m,wham_1}
+#   Commit B. z/{b,c,n,wham_2}, x/{d,e}
+#   Expected: x/{b,c,d,e,m,n}, CONFLICT:(y/wham_1 & z/wham_2 -> x/wham)
+#   Note: y/m & z/n should definitely move into x.  By the same token, both
+#         y/wham_1 & z/wham_2 should too...giving us a conflict.
+
+test_expect_success '1d-setup: Directory renames cause a rename/rename(2to1) conflict' '
+	test_create_repo 1d &&
+	(
+		cd 1d &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir y &&
+		echo d >y/d &&
+		echo e >y/e &&
+		git add z y &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z x &&
+		echo m >y/m &&
+		echo wham1 >y/wham &&
+		git add y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv y x &&
+		echo n >z/n &&
+		echo wham2 >z/wham &&
+		git add z &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '1d-check: Directory renames cause a rename/rename(2to1) conflict' '
+	(
+		cd 1d &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/rename)" out &&
+
+		test 8 -eq $(git ls-files -s | wc -l) &&
+		test 2 -eq $(git ls-files -u | wc -l) &&
+		test 3 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:x/b :0:x/c :0:x/d :0:x/e :0:x/m :0:x/n &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:y/d O:y/e A:y/m B:z/n &&
+		test_cmp expect actual &&
+
+		test_must_fail git rev-parse :0:x/wham &&
+		git rev-parse >actual \
+			:2:x/wham :3:x/wham &&
+		git rev-parse >expect \
+			A:y/wham B:z/wham &&
+		test_cmp expect actual &&
+
+		test ! -f x/wham &&
+		test -f x/wham~HEAD &&
+		test -f x/wham~B^0 &&
+
+		git hash-object >actual \
+			x/wham~HEAD x/wham~B^0 &&
+		git rev-parse >expect \
+			A:y/wham B:z/wham &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 1e, Renamed directory, with all filenames being renamed too
+#   Commit O: z/{oldb,oldc}
+#   Commit A: y/{newb,newc}
+#   Commit B: z/{oldb,oldc,d}
+#   Expected: y/{newb,newc,d}
+
+test_expect_success '1e-setup: Renamed directory, with all files being renamed too' '
+	test_create_repo 1e &&
+	(
+		cd 1e &&
+
+		mkdir z &&
+		echo b >z/oldb &&
+		echo c >z/oldc &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		mkdir y &&
+		git mv z/oldb y/newb &&
+		git mv z/oldc y/newc &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo d >z/d &&
+		git add z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '1e-check: Renamed directory, with all files being renamed too' '
+	(
+		cd 1e &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/newb HEAD:y/newc HEAD:y/d &&
+		git rev-parse >expect \
+			O:z/oldb O:z/oldc B:z/d &&
+		test_cmp expect actual &&
+		test_must_fail git rev-parse HEAD:z/d
+	)
+'
+
+# Testcase 1f, Split a directory into two other directories
+#   (Related to testcases 3a, all of section 2, and all of section 4)
+#   Commit O: z/{b,c,d,e,f}
+#   Commit A: z/{b,c,d,e,f,g}
+#   Commit B: y/{b,c}, x/{d,e,f}
+#   Expected: y/{b,c}, x/{d,e,f,g}
+
+test_expect_success '1f-setup: Split a directory into two other directories' '
+	test_create_repo 1f &&
+	(
+		cd 1f &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		echo d >z/d &&
+		echo e >z/e &&
+		echo f >z/f &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		echo g >z/g &&
+		git add z/g &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		mkdir y &&
+		mkdir x &&
+		git mv z/b y/ &&
+		git mv z/c y/ &&
+		git mv z/d x/ &&
+		git mv z/e x/ &&
+		git mv z/f x/ &&
+		rmdir z &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '1f-check: Split a directory into two other directories' '
+	(
+		cd 1f &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 6 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:x/d HEAD:x/e HEAD:x/f HEAD:x/g &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:z/d O:z/e O:z/f A:z/g &&
+		test_cmp expect actual &&
+		test ! -f z/g &&
+		test_must_fail git rev-parse HEAD:z/g
+	)
+'
+
+###########################################################################
+# Rules suggested by testcases in section 1:
+#
+#   We should still detect the directory rename even if it wasn't just
+#   the directory renamed, but the files within it. (see 1b)
+#
+#   If renames split a directory into two or more others, the directory
+#   with the most renames, "wins" (see 1c).  However, see the testcases
+#   in section 2, plus testcases 3a and 4a.
+###########################################################################
+
+test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 05/33] directory rename detection: directory splitting testcases

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 137 ++++++++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index d8ead7c56b..335aa1c145 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -427,4 +427,141 @@ test_expect_failure '1f-check: Split a directory into two other directories' '
 #   in section 2, plus testcases 3a and 4a.
 ###########################################################################
 
+
+###########################################################################
+# SECTION 2: Split into multiple directories, with equal number of paths
+#
+# Explore the splitting-a-directory rules a bit; what happens in the
+# edge cases?
+#
+# Note that there is a closely related case of a directory not being
+# split on either side of history, but being renamed differently on
+# each side.  See testcase 8e for that.
+###########################################################################
+
+# Testcase 2a, Directory split into two on one side, with equal numbers of paths
+#   Commit O: z/{b,c}
+#   Commit A: y/b, w/c
+#   Commit B: z/{b,c,d}
+#   Expected: y/b, w/c, z/d, with warning about z/ -> (y/ vs. w/) conflict
+test_expect_success '2a-setup: Directory split into two on one side, with equal numbers of paths' '
+	test_create_repo 2a &&
+	(
+		cd 2a &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		mkdir y &&
+		mkdir w &&
+		git mv z/b y/ &&
+		git mv z/c w/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo d >z/d &&
+		git add z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '2a-check: Directory split into two on one side, with equal numbers of paths' '
+	(
+		cd 2a &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:w/c :0:z/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/d &&
+		test_cmp expect actual &&
+		test_i18ngrep "CONFLICT.*directory rename split" out
+	)
+'
+
+# Testcase 2b, Directory split into two on one side, with equal numbers of paths
+#   Commit O: z/{b,c}
+#   Commit A: y/b, w/c
+#   Commit B: z/{b,c}, x/d
+#   Expected: y/b, w/c, x/d; No warning about z/ -> (y/ vs. w/) conflict
+test_expect_success '2b-setup: Directory split into two on one side, with equal numbers of paths' '
+	test_create_repo 2b &&
+	(
+		cd 2b &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		mkdir y &&
+		mkdir w &&
+		git mv z/b y/ &&
+		git mv z/c w/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		mkdir x &&
+		echo d >x/d &&
+		git add x/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '2b-check: Directory split into two on one side, with equal numbers of paths' '
+	(
+		cd 2b &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 >out &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:w/c :0:x/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:x/d &&
+		test_cmp expect actual &&
+		! test_i18ngrep "CONFLICT.*directory rename split" out
+	)
+'
+
+###########################################################################
+# Rules suggested by section 2:
+#
+#   None; the rule was already covered in section 1.  These testcases are
+#   here just to make sure the conflict resolution and necessary warning
+#   messages are handled correctly.
+###########################################################################
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 06/33] directory rename detection: testcases to avoid taking detection too far

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 150 ++++++++++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 335aa1c145..0ccabed4a2 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -564,4 +564,154 @@ test_expect_success '2b-check: Directory split into two on one side, with equal
 #   messages are handled correctly.
 ###########################################################################
 
+
+###########################################################################
+# SECTION 3: Path in question is the source path for some rename already
+#
+# Combining cases from Section 1 and trying to handle them could lead to
+# directory renaming detection being over-applied.  So, this section
+# provides some good testcases to check that the implementation doesn't go
+# too far.
+###########################################################################
+
+# Testcase 3a, Avoid implicit rename if involved as source on other side
+#   (Related to testcases 1c and 1f)
+#   Commit O: z/{b,c,d}
+#   Commit A: z/{b,c,d} (no change)
+#   Commit B: y/{b,c}, x/d
+#   Expected: y/{b,c}, x/d
+test_expect_success '3a-setup: Avoid implicit rename if involved as source on other side' '
+	test_create_repo 3a &&
+	(
+		cd 3a &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		echo d >z/d &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		test_tick &&
+		git commit --allow-empty -m "A" &&
+
+		git checkout B &&
+		mkdir y &&
+		mkdir x &&
+		git mv z/b y/ &&
+		git mv z/c y/ &&
+		git mv z/d x/ &&
+		rmdir z &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '3a-check: Avoid implicit rename if involved as source on other side' '
+	(
+		cd 3a &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:x/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:z/d &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 3b, Avoid implicit rename if involved as source on other side
+#   (Related to testcases 5c and 7c, also kind of 1e and 1f)
+#   Commit O: z/{b,c,d}
+#   Commit A: y/{b,c}, x/d
+#   Commit B: z/{b,c}, w/d
+#   Expected: y/{b,c}, CONFLICT:(z/d -> x/d vs. w/d)
+#   NOTE: We're particularly checking that since z/d is already involved as
+#         a source in a file rename on the same side of history, that we don't
+#         get it involved in directory rename detection.  If it were, we might
+#         end up with CONFLICT:(z/d -> y/d vs. x/d vs. w/d), i.e. a
+#         rename/rename/rename(1to3) conflict, which is just weird.
+test_expect_success '3b-setup: Avoid implicit rename if involved as source on current side' '
+	test_create_repo 3b &&
+	(
+		cd 3b &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		echo d >z/d &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		mkdir y &&
+		mkdir x &&
+		git mv z/b y/ &&
+		git mv z/c y/ &&
+		git mv z/d x/ &&
+		rmdir z &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		mkdir w &&
+		git mv z/d w/ &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '3b-check: Avoid implicit rename if involved as source on current side' '
+	(
+		cd 3b &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+
+		test 5 -eq $(git ls-files -s | wc -l) &&
+		test 3 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :1:z/d :2:x/d :3:w/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:z/d O:z/d O:z/d &&
+		test_cmp expect actual &&
+
+		test ! -f z/d &&
+		git hash-object >actual \
+			x/d w/d &&
+		git rev-parse >expect \
+			O:z/d O:z/d &&
+		test_cmp expect actual &&
+
+		test_i18ngrep CONFLICT.*rename/rename.*z/d.*x/d.*w/d out &&
+	! test_i18ngrep CONFLICT.*rename/rename.*y/d
+	)
+'
+
+###########################################################################
+# Rules suggested by section 3:
+#
+#   Avoid directory-rename-detection for a path, if that path is the source
+#   of a rename on either side of a merge.
+###########################################################################
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 07/33] directory rename detection: partially renamed directory testcase/discussion

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 104 ++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 0ccabed4a2..1dcf010aa6 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -714,4 +714,108 @@ test_expect_success '3b-check: Avoid implicit rename if involved as source on cu
 #   of a rename on either side of a merge.
 ###########################################################################
 
+
+###########################################################################
+# SECTION 4: Partially renamed directory; still exists on both sides of merge
+#
+# What if we were to attempt to do directory rename detection when someone
+# "mostly" moved a directory but still left some files around, or,
+# equivalently, fully renamed a directory in one commmit and then recreated
+# that directory in a later commit adding some new files and then tried to
+# merge?
+#
+# It's hard to divine user intent in these cases, because you can make an
+# argument that, depending on the intermediate history of the side being
+# merged, that some users will want files in that directory to
+# automatically be detected and renamed, while users with a different
+# intermediate history wouldn't want that rename to happen.
+#
+# I think that it is best to simply not have directory rename detection
+# apply to such cases.  My reasoning for this is four-fold: (1) it's
+# easiest for users in general to figure out what happened if we don't
+# apply directory rename detection in any such case, (2) it's an easy rule
+# to explain ["We don't do directory rename detection if the directory
+# still exists on both sides of the merge"], (3) we can get some hairy
+# edge/corner cases that would be really confusing and possibly not even
+# representable in the index if we were to even try, and [related to 3] (4)
+# attempting to resolve this issue of divining user intent by examining
+# intermediate history goes against the spirit of three-way merges and is a
+# path towards crazy corner cases that are far more complex than what we're
+# already dealing with.
+#
+# This section contains a test for this partially-renamed-directory case.
+###########################################################################
+
+# Testcase 4a, Directory split, with original directory still present
+#   (Related to testcase 1f)
+#   Commit O: z/{b,c,d,e}
+#   Commit A: y/{b,c,d}, z/e
+#   Commit B: z/{b,c,d,e,f}
+#   Expected: y/{b,c,d}, z/{e,f}
+#   NOTE: Even though most files from z moved to y, we don't want f to follow.
+
+test_expect_success '4a-setup: Directory split, with original directory still present' '
+	test_create_repo 4a &&
+	(
+		cd 4a &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		echo d >z/d &&
+		echo e >z/e &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		mkdir y &&
+		git mv z/b y/ &&
+		git mv z/c y/ &&
+		git mv z/d y/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo f >z/f &&
+		git add z/f &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '4a-check: Directory split, with original directory still present' '
+	(
+		cd 4a &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 5 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 0 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/d HEAD:z/e HEAD:z/f &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:z/d O:z/e B:z/f &&
+		test_cmp expect actual
+	)
+'
+
+###########################################################################
+# Rules suggested by section 4:
+#
+#   Directory-rename-detection should be turned off for any directories (as
+#   a source for renames) that exist on both sides of the merge.  (The "as
+#   a source for renames" clarification is due to cases like 1c where
+#   the target directory exists on both sides and we do want the rename
+#   detection.)  But, sadly, see testcase 8b.
+###########################################################################
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 08/33] directory rename detection: files/directories in the way of some renames

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 320 ++++++++++++++++++++++++++++++++++++
 1 file changed, 320 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 1dcf010aa6..29b2af7f19 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -818,4 +818,324 @@ test_expect_success '4a-check: Directory split, with original directory still pr
 #   detection.)  But, sadly, see testcase 8b.
 ###########################################################################
 
+
+###########################################################################
+# SECTION 5: Files/directories in the way of subset of to-be-renamed paths
+#
+# Implicitly renaming files due to a detected directory rename could run
+# into problems if there are files or directories in the way of the paths
+# we want to rename.  Explore such cases in this section.
+###########################################################################
+
+# Testcase 5a, Merge directories, other side adds files to original and target
+#   Commit O: z/{b,c},       y/d
+#   Commit A: z/{b,c,e_1,f}, y/{d,e_2}
+#   Commit B: y/{b,c,d}
+#   Expected: z/e_1, y/{b,c,d,e_2,f} + CONFLICT warning
+#   NOTE: While directory rename detection is active here causing z/f to
+#         become y/f, we did not apply this for z/e_1 because that would
+#         give us an add/add conflict for y/e_1 vs y/e_2.  This problem with
+#         this add/add, is that both versions of y/e are from the same side
+#         of history, giving us no way to represent this conflict in the
+#         index.
+
+test_expect_success '5a-setup: Merge directories, other side adds files to original and target' '
+	test_create_repo 5a &&
+	(
+		cd 5a &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir y &&
+		echo d >y/d &&
+		git add z y &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		echo e1 >z/e &&
+		echo f >z/f &&
+		echo e2 >y/e &&
+		git add z/e z/f y/e &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv z/b y/ &&
+		git mv z/c y/ &&
+		rmdir z &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '5a-check: Merge directories, other side adds files to original and target' '
+	(
+		cd 5a &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+
+		test 6 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :0:y/d :0:y/e :0:z/e &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:y/d A:y/e A:z/e &&
+		test_cmp expect actual &&
+
+		test $(git rev-parse :0:y/f) = $(git rev-parse A:z/f) &&
+
+		test_i18ngrep "CONFLICT.*implicit dir rename" out
+	)
+'
+
+# Testcase 5b, Rename/delete in order to get add/add/add conflict
+#   (Related to testcase 8d; these may appear slightly inconsistent to users;
+#    Also related to testcases 7d and 7e)
+#   Commit O: z/{b,c,d_1}
+#   Commit A: y/{b,c,d_2}
+#   Commit B: z/{b,c,d_1,e}, y/d_3
+#   Expected: y/{b,c,e}, CONFLICT(add/add: y/d_2 vs. y/d_3)
+#   NOTE: If z/d_1 in commit B were to be involved in dir rename detection, as
+#         we normaly would since z/ is being renamed to y/, then this would be
+#         a rename/delete (z/d_1 -> y/d_1 vs. deleted) AND an add/add/add
+#         conflict of y/d_1 vs. y/d_2 vs. y/d_3.  Add/add/add is not
+#         representable in the index, so the existence of y/d_3 needs to
+#         cause us to bail on directory rename detection for that path, falling
+#         back to git behavior without the directory rename detection.
+
+test_expect_success '5b-setup: Rename/delete in order to get add/add/add conflict' '
+	test_create_repo 5b &&
+	(
+		cd 5b &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		echo d1 >z/d &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git rm z/d &&
+		git mv z y &&
+		echo d2 >y/d &&
+		git add y/d &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		mkdir y &&
+		echo d3 >y/d &&
+		echo e >z/e &&
+		git add y/d z/e &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '5b-check: Rename/delete in order to get add/add/add conflict' '
+	(
+		cd 5b &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (add/add).* y/d" out &&
+
+		test 5 -eq $(git ls-files -s | wc -l) &&
+		test 2 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :0:y/e :2:y/d :3:y/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/e A:y/d B:y/d &&
+		test_cmp expect actual &&
+
+		test_must_fail git rev-parse :1:y/d &&
+		test -f y/d
+	)
+'
+
+# Testcase 5c, Transitive rename would cause rename/rename/rename/add/add/add
+#   (Directory rename detection would result in transitive rename vs.
+#    rename/rename(1to2) and turn it into a rename/rename(1to3).  Further,
+#    rename paths conflict with separate adds on the other side)
+#   (Related to testcases 3b and 7c)
+#   Commit O: z/{b,c}, x/d_1
+#   Commit A: y/{b,c,d_2}, w/d_1
+#   Commit B: z/{b,c,d_1,e}, w/d_3, y/d_4
+#   Expected: A mess, but only a rename/rename(1to2)/add/add mess.  Use the
+#             presence of y/d_4 in B to avoid doing transitive rename of
+#             x/d_1 -> z/d_1 -> y/d_1, so that the only paths we have at
+#             y/d are y/d_2 and y/d_4.  We still do the move from z/e to y/e,
+#             though, because it doesn't have anything in the way.
+
+test_expect_success '5c-setup: Transitive rename would cause rename/rename/rename/add/add/add' '
+	test_create_repo 5c &&
+	(
+		cd 5c &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir x &&
+		echo d1 >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		echo d2 >y/d &&
+		git add y/d &&
+		git mv x w &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/d z/ &&
+		mkdir w &&
+		mkdir y &&
+		echo d3 >w/d &&
+		echo d4 >y/d &&
+		echo e >z/e &&
+		git add w/ y/ z/e &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '5c-check: Transitive rename would cause rename/rename/rename/add/add/add' '
+	(
+		cd 5c &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/rename).*x/d.*w/d.*z/d" out &&
+		test_i18ngrep "CONFLICT (add/add).* y/d" out &&
+
+		test 9 -eq $(git ls-files -s | wc -l) &&
+		test 6 -eq $(git ls-files -u | wc -l) &&
+		test 3 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :0:y/e &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/e &&
+		test_cmp expect actual &&
+
+		test_must_fail git rev-parse :1:y/d &&
+		git rev-parse >actual \
+			:2:w/d :3:w/d :1:x/d :2:y/d :3:y/d :3:z/d &&
+		git rev-parse >expect \
+			O:x/d B:w/d O:x/d A:y/d B:y/d O:x/d &&
+		test_cmp expect actual &&
+
+		git hash-object >actual \
+			w/d~HEAD w/d~B^0 &&
+		git rev-parse >expect \
+			O:x/d B:w/d &&
+		test_cmp expect actual &&
+		test ! -f x/d &&
+		test -f y/d &&
+		grep -q "<<<<" y/d &&  # conflict markers should be present
+		test $(git hash-object z/d) = $(git rev-parse O:x/d)
+	)
+'
+
+# Testcase 5d, Directory/file/file conflict due to directory rename
+#   Commit O: z/{b,c}
+#   Commit A: y/{b,c,d_1}
+#   Commit B: z/{b,c,d_2,f}, y/d/e
+#   Expected: y/{b,c,d/e,f}, z/d_2, CONFLICT(file/directory), y/d_1~HEAD
+#   Note: The fact that y/d/ exists in B makes us bail on directory rename
+#         detection for z/d_2, but that doesn't prevent us from applying the
+#         directory rename detection for z/f -> y/f.
+
+test_expect_success '5d-setup: Directory/file/file conflict due to directory rename' '
+	test_create_repo 5d &&
+	(
+		cd 5d &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		echo d1 >y/d &&
+		git add y/d &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		mkdir -p y/d &&
+		echo e >y/d/e &&
+		echo d2 >z/d &&
+		echo f >z/f &&
+		git add y/d/e z/d z/f &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '5d-check: Directory/file/file conflict due to directory rename' '
+	(
+		cd 5d &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (file/directory).*y/d" out &&
+
+		test 6 -eq $(git ls-files -s | wc -l) &&
+		test 1 -eq $(git ls-files -u | wc -l) &&
+		test 2 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :0:z/d :0:y/f :2:y/d :0:y/d/e &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/d B:z/f A:y/d B:y/d/e &&
+		test_cmp expect actual &&
+
+		test $(git hash-object y/d~HEAD) = $(git rev-parse A:y/d)
+	)
+'
+
+###########################################################################
+# Rules suggested by section 5:
+#
+#   If a subset of to-be-renamed files have a file or directory in the way,
+#   "turn off" the directory rename for those specific sub-paths, falling
+#   back to old handling.  But, sadly, see testcases 8a and 8b.
+###########################################################################
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 09/33] directory rename detection: testcases checking which side did the rename

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 321 ++++++++++++++++++++++++++++++++++++
 1 file changed, 321 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 29b2af7f19..5db2986de8 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -1138,4 +1138,325 @@ test_expect_failure '5d-check: Directory/file/file conflict due to directory ren
 #   back to old handling.  But, sadly, see testcases 8a and 8b.
 ###########################################################################
 
+
+###########################################################################
+# SECTION 6: Same side of the merge was the one that did the rename
+#
+# It may sound obvious that you only want to apply implicit directory
+# renames to directories if the _other_ side of history did the renaming.
+# If you did make an implementation that didn't explicitly enforce this
+# rule, the majority of cases that would fall under this section would
+# also be solved by following the rules from the above sections.  But
+# there are still a few that stick out, so this section covers them just
+# to make sure we also get them right.
+###########################################################################
+
+# Testcase 6a, Tricky rename/delete
+#   Commit O: z/{b,c,d}
+#   Commit A: z/b
+#   Commit B: y/{b,c}, z/d
+#   Expected: y/b, CONFLICT(rename/delete, z/c -> y/c vs. NULL)
+#   Note: We're just checking here that the rename of z/b and z/c to put
+#         them under y/ doesn't accidentally catch z/d and make it look like
+#         it is also involved in a rename/delete conflict.
+
+test_expect_success '6a-setup: Tricky rename/delete' '
+	test_create_repo 6a &&
+	(
+		cd 6a &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		echo d >z/d &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git rm z/c &&
+		git rm z/d &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		mkdir y &&
+		git mv z/b y/ &&
+		git mv z/c y/ &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '6a-check: Tricky rename/delete' '
+	(
+		cd 6a &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/delete).*z/c.*y/c" out &&
+
+		test 2 -eq $(git ls-files -s | wc -l) &&
+		test 1 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :3:y/c &&
+		git rev-parse >expect \
+			O:z/b O:z/c &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 6b, Same rename done on both sides
+#   (Related to testcases 6c and 8e)
+#   Commit O: z/{b,c}
+#   Commit A: y/{b,c}
+#   Commit B: y/{b,c}, z/d
+#   Expected: y/{b,c}, z/d
+#   Note: If we did directory rename detection here, we'd move z/d into y/,
+#         but B did that rename and still decided to put the file into z/,
+#         so we probably shouldn't apply directory rename detection for it.
+
+test_expect_success '6b-setup: Same rename done on both sides' '
+	test_create_repo 6b &&
+	(
+		cd 6b &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv z y &&
+		mkdir z &&
+		echo d >z/d &&
+		git add z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '6b-check: Same rename done on both sides' '
+	(
+		cd 6b &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 0 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:z/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/d &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 6c, Rename only done on same side
+#   (Related to testcases 6b and 8e)
+#   Commit O: z/{b,c}
+#   Commit A: z/{b,c} (no change)
+#   Commit B: y/{b,c}, z/d
+#   Expected: y/{b,c}, z/d
+#   NOTE: Seems obvious, but just checking that the implementation doesn't
+#         "accidentally detect a rename" and give us y/{b,c,d}.
+
+test_expect_success '6c-setup: Rename only done on same side' '
+	test_create_repo 6c &&
+	(
+		cd 6c &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		test_tick &&
+		git commit --allow-empty -m "A" &&
+
+		git checkout B &&
+		git mv z y &&
+		mkdir z &&
+		echo d >z/d &&
+		git add z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '6c-check: Rename only done on same side' '
+	(
+		cd 6c &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 0 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:z/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/d &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 6d, We don't always want transitive renaming
+#   (Related to testcase 1c)
+#   Commit O: z/{b,c}, x/d
+#   Commit A: z/{b,c}, x/d (no change)
+#   Commit B: y/{b,c}, z/d
+#   Expected: y/{b,c}, z/d
+#   NOTE: Again, this seems obvious but just checking that the implementation
+#         doesn't "accidentally detect a rename" and give us y/{b,c,d}.
+
+test_expect_success '6d-setup: We do not always want transitive renaming' '
+	test_create_repo 6d &&
+	(
+		cd 6d &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir x &&
+		echo d >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		test_tick &&
+		git commit --allow-empty -m "A" &&
+
+		git checkout B &&
+		git mv z y &&
+		git mv x z &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '6d-check: We do not always want transitive renaming' '
+	(
+		cd 6d &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 0 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:z/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:x/d &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 6e, Add/add from one-side
+#   Commit O: z/{b,c}
+#   Commit A: z/{b,c} (no change)
+#   Commit B: y/{b,c,d_1}, z/d_2
+#   Expected: y/{b,c,d_1}, z/d_2
+#   NOTE: Again, this seems obvious but just checking that the implementation
+#         doesn't "accidentally detect a rename" and give us y/{b,c} +
+#         add/add conflict on y/d_1 vs y/d_2.
+
+test_expect_success '6e-setup: Add/add from one side' '
+	test_create_repo 6e &&
+	(
+		cd 6e &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		test_tick &&
+		git commit --allow-empty -m "A" &&
+
+		git checkout B &&
+		git mv z y &&
+		echo d1 > y/d &&
+		mkdir z &&
+		echo d2 > z/d &&
+		git add y/d z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '6e-check: Add/add from one side' '
+	(
+		cd 6e &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 0 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/d HEAD:z/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:y/d B:z/d &&
+		test_cmp expect actual
+	)
+'
+
+###########################################################################
+# Rules suggested by section 6:
+#
+#   Only apply implicit directory renames to directories if the other
+#   side of history is the one doing the renaming.
+###########################################################################
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 10/33] directory rename detection: more involved edge/corner testcases

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 381 ++++++++++++++++++++++++++++++++++++
 1 file changed, 381 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 5db2986de8..2c57a02c6d 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -1459,4 +1459,385 @@ test_expect_success '6e-check: Add/add from one side' '
 #   side of history is the one doing the renaming.
 ###########################################################################
 
+
+###########################################################################
+# SECTION 7: More involved Edge/Corner cases
+#
+# The ruleset we have generated in the above sections seems to provide
+# well-defined merges.  But can we find edge/corner cases that either (a)
+# are harder for users to understand, or (b) have a resolution that is
+# non-intuitive or suboptimal?
+#
+# The testcases in this section dive into cases that I've tried to craft in
+# a way to find some that might be surprising to users or difficult for
+# them to understand (the next section will look at non-intuitive or
+# suboptimal merge results).  Some of the testcases are similar to ones
+# from past sections, but have been simplified to try to highlight error
+# messages using a "modified" path (due to the directory rename).  Are
+# users okay with these?
+#
+# In my opinion, testcases that are difficult to understand from this
+# section is due to difficulty in the testcase rather than the directory
+# renaming (similar to how t6042 and t6036 have difficult resolutions due
+# to the problem setup itself being complex).  And I don't think the
+# error messages are a problem.
+#
+# On the other hand, the testcases in section 8 worry me slightly more...
+###########################################################################
+
+# Testcase 7a, rename-dir vs. rename-dir (NOT split evenly) PLUS add-other-file
+#   Commit O: z/{b,c}
+#   Commit A: y/{b,c}
+#   Commit B: w/b, x/c, z/d
+#   Expected: y/d, CONFLICT(rename/rename for both z/b and z/c)
+#   NOTE: There's a rename of z/ here, y/ has more renames, so z/d -> y/d.
+
+test_expect_success '7a-setup: rename-dir vs. rename-dir (NOT split evenly) PLUS add-other-file' '
+	test_create_repo 7a &&
+	(
+		cd 7a &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		mkdir w &&
+		mkdir x &&
+		git mv z/b w/ &&
+		git mv z/c x/ &&
+		echo d > z/d &&
+		git add z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '7a-check: rename-dir vs. rename-dir (NOT split evenly) PLUS add-other-file' '
+	(
+		cd 7a &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/rename).*z/b.*y/b.*w/b" out &&
+		test_i18ngrep "CONFLICT (rename/rename).*z/c.*y/c.*x/c" out &&
+
+		test 7 -eq $(git ls-files -s | wc -l) &&
+		test 6 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		test $(git rev-parse :0:y/d) = $(git rev-parse B:z/d) &&
+
+		git rev-parse >actual \
+			:1:z/b :2:y/b :3:w/b :1:z/c :2:y/c :3:x/c &&
+		git rev-parse >expect \
+			O:z/b O:z/b O:z/b O:z/c O:z/c O:z/c &&
+		test_cmp expect actual &&
+
+		git hash-object >actual \
+			y/b w/b y/c x/c &&
+		git rev-parse >expect \
+			O:z/b O:z/b O:z/c O:z/c &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 7b, rename/rename(2to1), but only due to transitive rename
+#   (Related to testcase 1d)
+#   Commit O: z/{b,c},     x/d_1, w/d_2
+#   Commit A: y/{b,c,d_2}, x/d_1
+#   Commit B: z/{b,c,d_1},        w/d_2
+#   Expected: y/{b,c}, CONFLICT(rename/rename(2to1): x/d_1, w/d_2 -> y_d)
+
+test_expect_success '7b-setup: rename/rename(2to1), but only due to transitive rename' '
+	test_create_repo 7b &&
+	(
+		cd 7b &&
+
+		mkdir z &&
+		mkdir x &&
+		mkdir w &&
+		echo b >z/b &&
+		echo c >z/c &&
+		echo d1 > x/d &&
+		echo d2 > w/d &&
+		git add z x w &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		git mv w/d y/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/d z/ &&
+		rmdir x &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '7b-check: rename/rename(2to1), but only due to transitive rename' '
+	(
+		cd 7b &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/rename)" out &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+		test 2 -eq $(git ls-files -u | wc -l) &&
+		test 3 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :2:y/d :3:y/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:w/d O:x/d &&
+		test_cmp expect actual &&
+
+		test ! -f y/d &&
+		test -f y/d~HEAD &&
+		test -f y/d~B^0 &&
+
+		git hash-object >actual \
+			y/d~HEAD y/d~B^0 &&
+		git rev-parse >expect \
+			O:w/d O:x/d &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 7c, rename/rename(1to...2or3); transitive rename may add complexity
+#   (Related to testcases 3b and 5c)
+#   Commit O: z/{b,c}, x/d
+#   Commit A: y/{b,c}, w/d
+#   Commit B: z/{b,c,d}
+#   Expected: y/{b,c}, CONFLICT(x/d -> w/d vs. y/d)
+#   NOTE: z/ was renamed to y/ so we do want to report
+#         neither CONFLICT(x/d -> w/d vs. z/d)
+#         nor CONFLiCT x/d -> w/d vs. y/d vs. z/d)
+
+test_expect_success '7c-setup: rename/rename(1to...2or3); transitive rename may add complexity' '
+	test_create_repo 7c &&
+	(
+		cd 7c &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir x &&
+		echo d >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		git mv x w &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/d z/ &&
+		rmdir x &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '7c-check: rename/rename(1to...2or3); transitive rename may add complexity' '
+	(
+		cd 7c &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/rename).*x/d.*w/d.*y/d" out &&
+
+		test 5 -eq $(git ls-files -s | wc -l) &&
+		test 3 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :1:x/d :2:w/d :3:y/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:x/d O:x/d O:x/d &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 7d, transitive rename involved in rename/delete; how is it reported?
+#   (Related somewhat to testcases 5b and 8d)
+#   Commit O: z/{b,c}, x/d
+#   Commit A: y/{b,c}
+#   Commit B: z/{b,c,d}
+#   Expected: y/{b,c}, CONFLICT(delete x/d vs rename to y/d)
+#   NOTE: z->y so NOT CONFLICT(delete x/d vs rename to z/d)
+
+test_expect_success '7d-setup: transitive rename involved in rename/delete; how is it reported?' '
+	test_create_repo 7d &&
+	(
+		cd 7d &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir x &&
+		echo d >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		git rm -rf x &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/d z/ &&
+		rmdir x &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '7d-check: transitive rename involved in rename/delete; how is it reported?' '
+	(
+		cd 7d &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/delete).*x/d.*y/d" out &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 1 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :3:y/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:x/d &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 7e, transitive rename in rename/delete AND dirs in the way
+#   (Very similar to 'both rename source and destination involved in D/F conflict' from t6022-merge-rename.sh)
+#   (Also related to testcases 9c and 9d)
+#   Commit O: z/{b,c},     x/d_1
+#   Commit A: y/{b,c,d/g}, x/d/f
+#   Commit B: z/{b,c,d_1}
+#   Expected: rename/delete(x/d_1->y/d_1 vs. None) + D/F conflict on y/d
+#             y/{b,c,d/g}, y/d_1~B^0, x/d/f
+
+#   NOTE: The main path of interest here is d_1 and where it ends up, but
+#         this is actually a case that has two potential directory renames
+#         involved and D/F conflict(s), so it makes sense to walk through
+#         each step.
+#
+#         Commit A renames z/ -> y/.  Thus everything that B adds to z/
+#         should be instead moved to y/.  This gives us the D/F conflict on
+#         y/d because x/d_1 -> z/d_1 -> y/d_1 conflicts with y/d/g.
+#
+#         Further, commit B renames x/ -> z/, thus everything A adds to x/
+#         should instead be moved to z/...BUT we removed z/ and renamed it
+#         to y/, so maybe everything should move not from x/ to z/, but
+#         from x/ to z/ to y/.  Doing so might make sense from the logic so
+#         far, but note that commit A had both an x/ and a y/; it did the
+#         renaming of z/ to y/ and created x/d/f and it clearly made these
+#         things separate, so it doesn't make much sense to push these
+#         together.  Doing so is what I'd call a doubly transitive rename;
+#         see testcases 9c and 9d for further discussion of this issue and
+#         how it's resolved.
+
+test_expect_success '7e-setup: transitive rename in rename/delete AND dirs in the way' '
+	test_create_repo 7e &&
+	(
+		cd 7e &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir x &&
+		echo d1 >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		git rm x/d &&
+		mkdir -p x/d &&
+		mkdir -p y/d &&
+		echo f >x/d/f &&
+		echo g >y/d/g &&
+		git add x/d/f y/d/g &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/d z/ &&
+		rmdir x &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '7e-check: transitive rename in rename/delete AND dirs in the way' '
+	(
+		cd 7e &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/delete).*x/d.*y/d" out &&
+
+		test 5 -eq $(git ls-files -s | wc -l) &&
+		test 1 -eq $(git ls-files -u | wc -l) &&
+		test 2 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:x/d/f :0:y/d/g :0:y/b :0:y/c :3:y/d &&
+		git rev-parse >expect \
+			A:x/d/f A:y/d/g O:z/b O:z/c O:x/d &&
+		test_cmp expect actual &&
+
+		test $(git hash-object y/d~B^0) = $(git rev-parse O:x/d)
+	)
+'
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 11/33] directory rename detection: testcases exploring possibly suboptimal merges

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 392 ++++++++++++++++++++++++++++++++++++
 1 file changed, 392 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 2c57a02c6d..b153468a5c 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -1840,4 +1840,396 @@ test_expect_failure '7e-check: transitive rename in rename/delete AND dirs in th
 	)
 '
 
+###########################################################################
+# SECTION 8: Suboptimal merges
+#
+# As alluded to in the last section, the ruleset we have built up for
+# detecting directory renames unfortunately has some special cases where it
+# results in slightly suboptimal or non-intuitive behavior.  This section
+# explores these cases.
+#
+# To be fair, we already had non-intuitive or suboptimal behavior for most
+# of these cases in git before introducing implicit directory rename
+# detection, but it'd be nice if there was a modified ruleset out there
+# that handled these cases a bit better.
+###########################################################################
+
+# Testcase 8a, Dual-directory rename, one into the others' way
+#   Commit O. x/{a,b},   y/{c,d}
+#   Commit A. x/{a,b,e}, y/{c,d,f}
+#   Commit B. y/{a,b},   z/{c,d}
+#
+# Possible Resolutions:
+#   w/o dir-rename detection: y/{a,b,f},   z/{c,d},   x/e
+#   Currently expected:       y/{a,b,e,f}, z/{c,d}
+#   Optimal:                  y/{a,b,e},   z/{c,d,f}
+#
+# Note: Both x and y got renamed and it'd be nice to detect both, and we do
+# better with directory rename detection than git did previously, but the
+# simple rule from section 5 prevents me from handling this as optimally as
+# we potentially could.
+
+test_expect_success '8a-setup: Dual-directory rename, one into the others way' '
+	test_create_repo 8a &&
+	(
+		cd 8a &&
+
+		mkdir x &&
+		mkdir y &&
+		echo a >x/a &&
+		echo b >x/b &&
+		echo c >y/c &&
+		echo d >y/d &&
+		git add x y &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		echo e >x/e &&
+		echo f >y/f &&
+		git add x/e y/f &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv y z &&
+		git mv x y &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '8a-check: Dual-directory rename, one into the others way' '
+	(
+		cd 8a &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 6 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 0 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/a HEAD:y/b HEAD:y/e HEAD:y/f HEAD:z/c HEAD:z/d &&
+		git rev-parse >expect \
+			O:x/a O:x/b A:x/e A:y/f O:y/c O:y/d &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 8b, Dual-directory rename, one into the others' way, with conflicting filenames
+#   Commit O. x/{a_1,b_1},     y/{a_2,b_2}
+#   Commit A. x/{a_1,b_1,e_1}, y/{a_2,b_2,e_2}
+#   Commit B. y/{a_1,b_1},     z/{a_2,b_2}
+#
+#   w/o dir-rename detection: y/{a_1,b_1,e_2}, z/{a_2,b_2}, x/e_1
+#   Currently expected:       <same>
+#   Scary:                    y/{a_1,b_1},     z/{a_2,b_2}, CONFLICT(add/add, e_1 vs. e_2)
+#   Optimal:                  y/{a_1,b_1,e_1}, z/{a_2,b_2,e_2}
+#
+# Note: Very similar to 8a, except instead of 'e' and 'f' in directories x and
+# y, both are named 'e'.  Without directory rename detection, neither file
+# moves directories.  Implement directory rename detection suboptimally, and
+# you get an add/add conflict, but both files were added in commit A, so this
+# is an add/add conflict where one side of history added both files --
+# something we can't represent in the index.  Obviously, we'd prefer the last
+# resolution, but our previous rules are too coarse to allow it.  Using both
+# the rules from section 4 and section 5 save us from the Scary resolution,
+# making us fall back to pre-directory-rename-detection behavior for both
+# e_1 and e_2.
+
+test_expect_success '8b-setup: Dual-directory rename, one into the others way, with conflicting filenames' '
+	test_create_repo 8b &&
+	(
+		cd 8b &&
+
+		mkdir x &&
+		mkdir y &&
+		echo a1 >x/a &&
+		echo b1 >x/b &&
+		echo a2 >y/a &&
+		echo b2 >y/b &&
+		git add x y &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		echo e1 >x/e &&
+		echo e2 >y/e &&
+		git add x/e y/e &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv y z &&
+		git mv x y &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '8b-check: Dual-directory rename, one into the others way, with conflicting filenames' '
+	(
+		cd 8b &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 6 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 0 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/a HEAD:y/b HEAD:z/a HEAD:z/b HEAD:x/e HEAD:y/e &&
+		git rev-parse >expect \
+			O:x/a O:x/b O:y/a O:y/b A:x/e A:y/e &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 8c, rename+modify/delete
+#   (Related to testcases 5b and 8d)
+#   Commit O: z/{b,c,d}
+#   Commit A: y/{b,c}
+#   Commit B: z/{b,c,d_modified,e}
+#   Expected: y/{b,c,e}, CONFLICT(rename+modify/delete: x/d -> y/d or deleted)
+#
+#   Note: This testcase doesn't present any concerns for me...until you
+#         compare it with testcases 5b and 8d.  See notes in 8d for more
+#         details.
+
+test_expect_success '8c-setup: rename+modify/delete' '
+	test_create_repo 8c &&
+	(
+		cd 8c &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		test_seq 1 10 >z/d &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git rm z/d &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo 11 >z/d &&
+		test_chmod +x z/d &&
+		echo e >z/e &&
+		git add z/d z/e &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '8c-check: rename+modify/delete' '
+	(
+		cd 8c &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (rename/delete).* z/d.*y/d" out &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+		test 1 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/b :0:y/c :0:y/e :3:y/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/e B:z/d &&
+		test_cmp expect actual &&
+
+		test_must_fail git rev-parse :1:y/d &&
+		test_must_fail git rev-parse :2:y/d &&
+		git ls-files -s y/d | grep ^100755 &&
+		test -f y/d
+	)
+'
+
+# Testcase 8d, rename/delete...or not?
+#   (Related to testcase 5b; these may appear slightly inconsistent to users;
+#    Also related to testcases 7d and 7e)
+#   Commit O: z/{b,c,d}
+#   Commit A: y/{b,c}
+#   Commit B: z/{b,c,d,e}
+#   Expected: y/{b,c,e}
+#
+#   Note: It would also be somewhat reasonable to resolve this as
+#             y/{b,c,e}, CONFLICT(rename/delete: x/d -> y/d or deleted)
+#   The logic being that the only difference between this testcase and 8c
+#   is that there is no modification to d.  That suggests that instead of a
+#   rename/modify vs. delete conflict, we should just have a rename/delete
+#   conflict, otherwise we are being inconsistent.
+#
+#   However...as far as consistency goes, we didn't report a conflict for
+#   path d_1 in testcase 5b due to a different file being in the way.  So,
+#   we seem to be forced to have cases where users can change things
+#   slightly and get what they may perceive as inconsistent results.  It
+#   would be nice to avoid that, but I'm not sure I see how.
+#
+#   In this case, I'm leaning towards: commit A was the one that deleted z/d
+#   and it did the rename of z to y, so the two "conflicts" (rename vs.
+#   delete) are both coming from commit A, which is illogical.  Conflicts
+#   during merging are supposed to be about opposite sides doing things
+#   differently.
+
+test_expect_success '8d-setup: rename/delete...or not?' '
+	test_create_repo 8d &&
+	(
+		cd 8d &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		test_seq 1 10 >z/d &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git rm z/d &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo e >z/e &&
+		git add z/e &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '8d-check: rename/delete...or not?' '
+	(
+		cd 8d &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/e &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/e &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 8e, Both sides rename, one side adds to original directory
+#   Commit O: z/{b,c}
+#   Commit A: y/{b,c}
+#   Commit B: w/{b,c}, z/d
+#
+# Possible Resolutions:
+#   Previous git: z/d, CONFLICT(z/b -> y/b vs. w/b), CONFLICT(z/c -> y/c vs. w/c)
+#   Expected:     y/d, CONFLICT(z/b -> y/b vs. w/b), CONFLICT(z/c -> y/c vs. w/c)
+#   Preferred:    ??
+#
+# Notes: In commit A, directory z got renamed to y.  In commit B, directory z
+#        did NOT get renamed; the directory is still present; instead it is
+#        considered to have just renamed a subset of paths in directory z
+#        elsewhere.  Therefore, the directory rename done in commit A to z/
+#        applies to z/d and maps it to y/d.
+#
+#        It's possible that users would get confused about this, but what
+#        should we do instead?  Silently leaving at z/d seems just as bad or
+#        maybe even worse.  Perhaps we could print a big warning about z/d
+#        and how we're moving to y/d in this case, but when I started thinking
+#        about the ramifications of doing that, I didn't know how to rule out
+#        that opening other weird edge and corner cases so I just punted.
+
+test_expect_success '8e-setup: Both sides rename, one side adds to original directory' '
+	test_create_repo 8e &&
+	(
+		cd 8e &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv z w &&
+		mkdir z &&
+		echo d >z/d &&
+		git add z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '8e-check: Both sides rename, one side adds to original directory' '
+	(
+		cd 8e &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+
+		test 7 -eq $(git ls-files -s | wc -l) &&
+		test 6 -eq $(git ls-files -u | wc -l) &&
+		test 2 -eq $(git ls-files -o | wc -l) &&
+
+		test $(git rev-parse :0:y/d) = $(git rev-parse B:z/d) &&
+
+		git rev-parse >actual \
+			:1:z/b :2:y/b :3:w/b :1:z/c :2:y/c :3:w/c &&
+		git rev-parse >expect \
+			O:z/b O:z/b O:z/b O:z/c O:z/c O:z/c &&
+		test_cmp expect actual &&
+
+		git hash-object >actual \
+			y/b w/b y/c w/c &&
+		git rev-parse >expect \
+			O:z/b O:z/b O:z/c O:z/c &&
+		test_cmp expect actual &&
+
+		test ! -f z/b &&
+		test ! -f z/c &&
+
+		test_i18ngrep CONFLICT.*rename/rename.*z/c.*y/c.*w/c out &&
+		test_i18ngrep CONFLICT.*rename/rename.*z/b.*y/b.*w/b out
+	)
+'
+
 test_done
-- 
2.15.0.309.g62ce55426d

Re: [PATCH v3 11/33] directory rename detection: testcases exploring possibly suboptimal merges

[Stefan Beller]

> +# Note: Both x and y got renamed and it'd be nice to detect both, and we do
> +# better with directory rename detection than git did previously, but the
> +# simple rule from section 5 prevents me from handling this as optimally as
> +# we potentially could.

...previously...

> +# Testcase 8e, Both sides rename, one side adds to original directory
> +#   Commit O: z/{b,c}
> +#   Commit A: y/{b,c}
> +#   Commit B: w/{b,c}, z/d
> +#
> +# Possible Resolutions:
> +#   Previous git: z/d, CONFLICT(z/b -> y/b vs. w/b), CONFLICT(z/c -> y/c vs. w/c)

"Previous git" may be hard to understand when reviewing this code in 2 years.
The future proof term is "git without dir rename detection" or such.
(This is only a small nit, which on its own doesn't require a reroll;
I'll keep reading.)

[PATCH v3 12/33] directory rename detection: miscellaneous testcases to complete coverage

[Elijah Newren]

I came up with the testcases in the first eight sections before coding up
the implementation.  The testcases in this section were mostly ones I
thought of while coding/debugging, and which I was too lazy to insert
into the previous sections because I didn't want to re-label with all the
testcase references.  :-)

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 536 +++++++++++++++++++++++++++++++++++-
 1 file changed, 535 insertions(+), 1 deletion(-)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index b153468a5c..9e00a26c69 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -295,6 +295,7 @@ test_expect_failure '1d-check: Directory renames cause a rename/rename(2to1) con
 '
 
 # Testcase 1e, Renamed directory, with all filenames being renamed too
+#   (Related to testcases 9f & 9g)
 #   Commit O: z/{oldb,oldc}
 #   Commit A: y/{newb,newc}
 #   Commit B: z/{oldb,oldc,d}
@@ -575,7 +576,7 @@ test_expect_success '2b-check: Directory split into two on one side, with equal
 ###########################################################################
 
 # Testcase 3a, Avoid implicit rename if involved as source on other side
-#   (Related to testcases 1c and 1f)
+#   (Related to testcases 1c, 1f, and 9h)
 #   Commit O: z/{b,c,d}
 #   Commit A: z/{b,c,d} (no change)
 #   Commit B: y/{b,c}, x/d
@@ -2232,4 +2233,537 @@ test_expect_failure '8e-check: Both sides rename, one side adds to original dire
 	)
 '
 
+###########################################################################
+# SECTION 9: Other testcases
+#
+# This section consists of miscellaneous testcases I thought of during
+# the implementation which round out the testing.
+###########################################################################
+
+# Testcase 9a, Inner renamed directory within outer renamed directory
+#   (Related to testcase 1f)
+#   Commit O: z/{b,c,d/{e,f,g}}
+#   Commit A: y/{b,c}, x/w/{e,f,g}
+#   Commit B: z/{b,c,d/{e,f,g,h},i}
+#   Expected: y/{b,c,i}, x/w/{e,f,g,h}
+#   NOTE: The only reason this one is interesting is because when a directory
+#         is split into multiple other directories, we determine by the weight
+#         of which one had the most paths going to it.  A naive implementation
+#         of that could take the new file in commit B at z/i to x/w/i or x/i.
+
+test_expect_success '9a-setup: Inner renamed directory within outer renamed directory' '
+	test_create_repo 9a &&
+	(
+		cd 9a &&
+
+		mkdir -p z/d &&
+		echo b >z/b &&
+		echo c >z/c &&
+		echo e >z/d/e &&
+		echo f >z/d/f &&
+		echo g >z/d/g &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		mkdir x &&
+		git mv z/d x/w &&
+		git mv z y &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo h >z/d/h &&
+		echo i >z/i &&
+		git add z &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '9a-check: Inner renamed directory within outer renamed directory' '
+	(
+		cd 9a &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 7 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 0 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/i &&
+		git rev-parse >expect \
+			O:z/b O:z/c B:z/i &&
+		test_cmp expect actual &&
+
+		git rev-parse >actual \
+			HEAD:x/w/e HEAD:x/w/f HEAD:x/w/g HEAD:x/w/h &&
+		git rev-parse >expect \
+			O:z/d/e O:z/d/f O:z/d/g B:z/d/h &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 9b, Transitive rename with content merge
+#   (Related to testcase 1c)
+#   Commit O: z/{b,c},   x/d_1
+#   Commit A: y/{b,c},   x/d_2
+#   Commit B: z/{b,c,d_3}
+#   Expected: y/{b,c,d_merged}
+
+test_expect_success '9b-setup: Transitive rename with content merge' '
+	test_create_repo 9b &&
+	(
+		cd 9b &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir x &&
+		test_seq 1 10 >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		test_seq 1 11 >x/d &&
+		git add x/d &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		test_seq 0 10 >x/d &&
+		git mv x/d z/d &&
+		git add z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '9b-check: Transitive rename with content merge' '
+	(
+		cd 9b &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+
+		test_seq 0 11 >expected &&
+		git add expected &&
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c :0:expected &&
+		test_cmp expect actual &&
+		test_must_fail git rev-parse HEAD:x/d &&
+		test_must_fail git rev-parse HEAD:z/d &&
+		test ! -f z/d &&
+
+		test $(git rev-parse HEAD:y/d) != $(git rev-parse O:x/d) &&
+		test $(git rev-parse HEAD:y/d) != $(git rev-parse A:x/d) &&
+		test $(git rev-parse HEAD:y/d) != $(git rev-parse B:z/d) &&
+		test_cmp expected y/d
+	)
+'
+
+# Testcase 9c, Doubly transitive rename?
+#   (Related to testcase 1c, 7e, and 9d)
+#   Commit O: z/{b,c},     x/{d,e},    w/f
+#   Commit A: y/{b,c},     x/{d,e,f,g}
+#   Commit B: z/{b,c,d,e},             w/f
+#   Expected: y/{b,c,d,e}, x/{f,g}
+#
+#   NOTE: x/f and x/g may be slightly confusing here.  The rename from w/f to
+#         x/f is clear.  Let's look beyond that.  Here's the logic:
+#            Commit B renamed x/ -> z/
+#            Commit A renamed z/ -> y/
+#         So, we could possibly further rename x/f to z/f to y/f, a doubly
+#         transient rename.  However, where does it end?  We can chain these
+#         indefinitely (see testcase 9d).  What if there is a D/F conflict
+#         at z/f/ or y/f/?  Or just another file conflict at one of those
+#         paths?  In the case of an N-long chain of transient renamings,
+#         where do we "abort" the rename at?  Can the user make sense of
+#         the resulting conflict and resolve it?
+#
+#         To avoid this confusion I use the simple rule that if the other side
+#         of history did a directory rename to a path that your side renamed
+#         away, then ignore that particular rename from the other side of
+#         history for any implicit directory renames.
+
+test_expect_success '9c-setup: Doubly transitive rename?' '
+	test_create_repo 9c &&
+	(
+		cd 9c &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		mkdir x &&
+		echo d >x/d &&
+		echo e >x/e &&
+		mkdir w &&
+		echo f >w/f &&
+		git add z x w &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z y &&
+		git mv w/f x/ &&
+		echo g >x/g &&
+		git add x/g &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/d z/d &&
+		git mv x/e z/e &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '9c-check: Doubly transitive rename?' '
+	(
+		cd 9c &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 >out &&
+		test_i18ngrep "WARNING: Avoiding applying x -> z rename to x/f" out &&
+
+		test 6 -eq $(git ls-files -s | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:y/d HEAD:y/e HEAD:x/f HEAD:x/g &&
+		git rev-parse >expect \
+			O:z/b O:z/c O:x/d O:x/e O:w/f A:x/g &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 9d, N-fold transitive rename?
+#   (Related to testcase 9c...and 1c and 7e)
+#   Commit O: z/a, y/b, x/c, w/d, v/e, u/f
+#   Commit A:  y/{a,b},  w/{c,d},  u/{e,f}
+#   Commit B: z/{a,t}, x/{b,c}, v/{d,e}, u/f
+#   Expected: <see NOTE first>
+#
+#   NOTE: z/ -> y/ (in commit A)
+#         y/ -> x/ (in commit B)
+#         x/ -> w/ (in commit A)
+#         w/ -> v/ (in commit B)
+#         v/ -> u/ (in commit A)
+#         So, if we add a file to z, say z/t, where should it end up?  In u?
+#         What if there's another file or directory named 't' in one of the
+#         intervening directories and/or in u itself?  Also, shouldn't the
+#         same logic that places 't' in u/ also move ALL other files to u/?
+#         What if there are file or directory conflicts in any of them?  If
+#         we attempted to do N-way (N-fold? N-ary? N-uple?) transitive renames
+#         like this, would the user have any hope of understanding any
+#         conflicts or how their working tree ended up?  I think not, so I'm
+#         ruling out N-ary transitive renames for N>1.
+#
+#   Therefore our expected result is:
+#     z/t, y/a, x/b, w/c, u/d, u/e, u/f
+#   The reason that v/d DOES get transitively renamed to u/d is that u/ isn't
+#   renamed somewhere.  A slightly sub-optimal result, but it uses fairly
+#   simple rules that are consistent with what we need for all the other
+#   testcases and simplifies things for the user.
+
+test_expect_success '9d-setup: N-way transitive rename?' '
+	test_create_repo 9d &&
+	(
+		cd 9d &&
+
+		mkdir z y x w v u &&
+		echo a >z/a &&
+		echo b >y/b &&
+		echo c >x/c &&
+		echo d >w/d &&
+		echo e >v/e &&
+		echo f >u/f &&
+		git add z y x w v u &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z/a y/ &&
+		git mv x/c w/ &&
+		git mv v/e u/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo t >z/t &&
+		git mv y/b x/ &&
+		git mv w/d v/ &&
+		git add z/t &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '9d-check: N-way transitive rename?' '
+	(
+		cd 9d &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 >out &&
+		test_i18ngrep "WARNING: Avoiding applying z -> y rename to z/t" out &&
+		test_i18ngrep "WARNING: Avoiding applying y -> x rename to y/a" out &&
+		test_i18ngrep "WARNING: Avoiding applying x -> w rename to x/b" out &&
+		test_i18ngrep "WARNING: Avoiding applying w -> v rename to w/c" out &&
+
+		test 7 -eq $(git ls-files -s | wc -l) &&
+		test 1 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:z/t HEAD:y/a HEAD:x/b HEAD:w/c HEAD:u/d HEAD:u/e HEAD:u/f &&
+		git rev-parse >expect \
+			B:z/t O:z/a O:y/b O:x/c O:w/d O:v/e A:u/f &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 9e, N-to-1 whammo
+#   (Related to testcase 9c...and 1c and 7e)
+#   Commit O: dir1/{a,b}, dir2/{d,e}, dir3/{g,h}, dirN/{j,k}
+#   Commit A: dir1/{a,b,c,yo}, dir2/{d,e,f,yo}, dir3/{g,h,i,yo}, dirN/{j,k,l,yo}
+#   Commit B: combined/{a,b,d,e,g,h,j,k}
+#   Expected: combined/{a,b,c,d,e,f,g,h,i,j,k,l}, CONFLICT(Nto1) warnings,
+#             dir1/yo, dir2/yo, dir3/yo, dirN/yo
+
+test_expect_success '9e-setup: N-to-1 whammo' '
+	test_create_repo 9e &&
+	(
+		cd 9e &&
+
+		mkdir dir1 dir2 dir3 dirN &&
+		echo a >dir1/a &&
+		echo b >dir1/b &&
+		echo d >dir2/d &&
+		echo e >dir2/e &&
+		echo g >dir3/g &&
+		echo h >dir3/h &&
+		echo j >dirN/j &&
+		echo k >dirN/k &&
+		git add dir* &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		echo c  >dir1/c &&
+		echo yo >dir1/yo &&
+		echo f  >dir2/f &&
+		echo yo >dir2/yo &&
+		echo i  >dir3/i &&
+		echo yo >dir3/yo &&
+		echo l  >dirN/l &&
+		echo yo >dirN/yo &&
+		git add dir* &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv dir1 combined &&
+		git mv dir2/* combined/ &&
+		git mv dir3/* combined/ &&
+		git mv dirN/* combined/ &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '9e-check: N-to-1 whammo' '
+	(
+		cd 9e &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 >out &&
+		test_i18ngrep "CONFLICT (implicit dir rename): Cannot map more than one path to combined/yo" out >error_line &&
+		grep -q dir1/yo error_line &&
+		grep -q dir2/yo error_line &&
+		grep -q dir3/yo error_line &&
+		grep -q dirN/yo error_line &&
+
+		test 16 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 2 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:combined/a :0:combined/b :0:combined/c \
+			:0:combined/d :0:combined/e :0:combined/f \
+			:0:combined/g :0:combined/h :0:combined/i \
+			:0:combined/j :0:combined/k :0:combined/l &&
+		git rev-parse >expect \
+			O:dir1/a O:dir1/b A:dir1/c \
+			O:dir2/d O:dir2/e A:dir2/f \
+			O:dir3/g O:dir3/h A:dir3/i \
+			O:dirN/j O:dirN/k A:dirN/l &&
+		test_cmp expect actual &&
+
+		git rev-parse >actual \
+			:0:dir1/yo :0:dir2/yo :0:dir3/yo :0:dirN/yo &&
+		git rev-parse >expect \
+			A:dir1/yo A:dir2/yo A:dir3/yo A:dirN/yo &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 9f, Renamed directory that only contained immediate subdirs
+#   (Related to testcases 1e & 9g)
+#   Commit O: goal/{a,b}/$more_files
+#   Commit A: priority/{a,b}/$more_files
+#   Commit B: goal/{a,b}/$more_files, goal/c
+#   Expected: priority/{a,b}/$more_files, priority/c
+
+test_expect_success '9f-setup: Renamed directory that only contained immediate subdirs' '
+	test_create_repo 9f &&
+	(
+		cd 9f &&
+
+		mkdir -p goal/a &&
+		mkdir -p goal/b &&
+		echo foo >goal/a/foo &&
+		echo bar >goal/b/bar &&
+		echo baz >goal/b/baz &&
+		git add goal &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv goal/ priority &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo c >goal/c &&
+		git add goal/c &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '9f-check: Renamed directory that only contained immediate subdirs' '
+	(
+		cd 9f &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:priority/a/foo HEAD:priority/b/bar HEAD:priority/b/baz HEAD:priority/c &&
+		git rev-parse >expect \
+			O:goal/a/foo O:goal/b/bar O:goal/b/baz B:goal/c &&
+		test_cmp expect actual &&
+		test_must_fail git rev-parse HEAD:goal/c
+	)
+'
+
+# Testcase 9g, Renamed directory that only contained immediate subdirs, immediate subdirs renamed
+#   (Related to testcases 1e & 9f)
+#   Commit O: goal/{a,b}/$more_files
+#   Commit A: priority/{alpha,bravo}/$more_files
+#   Commit B: goal/{a,b}/$more_files, goal/c
+#   Expected: priority/{alpha,bravo}/$more_files, priority/c
+
+test_expect_success '9g-setup: Renamed directory that only contained immediate subdirs, immediate subdirs renamed' '
+	test_create_repo 9g &&
+	(
+		cd 9g &&
+
+		mkdir -p goal/a &&
+		mkdir -p goal/b &&
+		echo foo >goal/a/foo &&
+		echo bar >goal/b/bar &&
+		echo baz >goal/b/baz &&
+		git add goal &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		mkdir priority &&
+		git mv goal/a/ priority/alpha &&
+		git mv goal/b/ priority/beta &&
+		rmdir goal/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo c >goal/c &&
+		git add goal/c &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '9g-check: Renamed directory that only contained immediate subdirs, immediate subdirs renamed' '
+	(
+		cd 9g &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:priority/alpha/foo HEAD:priority/beta/bar HEAD:priority/beta/baz HEAD:priority/c &&
+		git rev-parse >expect \
+			O:goal/a/foo O:goal/b/bar O:goal/b/baz B:goal/c &&
+		test_cmp expect actual &&
+		test_must_fail git rev-parse HEAD:goal/c
+	)
+'
+
+###########################################################################
+# Rules suggested by section 9:
+#
+#   If the other side of history did a directory rename to a path that your
+#   side renamed away, then ignore that particular rename from the other
+#   side of history for any implicit directory renames.
+###########################################################################
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 13/33] directory rename detection: tests for handling overwriting untracked files

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 337 ++++++++++++++++++++++++++++++++++++
 1 file changed, 337 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 9e00a26c69..7408c788fc 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -2766,4 +2766,341 @@ test_expect_failure '9g-check: Renamed directory that only contained immediate s
 #   side of history for any implicit directory renames.
 ###########################################################################
 
+###########################################################################
+# SECTION 10: Handling untracked files
+#
+# unpack_trees(), upon which the recursive merge algorithm is based, aborts
+# the operation if untracked or dirty files would be deleted or overwritten
+# by the merge.  Unfortunately, unpack_trees() does not understand renames,
+# and if it doesn't abort, then it muddies up the working directory before
+# we even get to the point of detecting renames, so we need some special
+# handling, at least in the case of directory renames.
+###########################################################################
+
+# Testcase 10a, Overwrite untracked: normal rename/delete
+#   Commit O: z/{b,c_1}
+#   Commit A: z/b + untracked z/c + untracked z/d
+#   Commit B: z/{b,d_1}
+#   Expected: Aborted Merge +
+#       ERROR_MSG(untracked working tree files would be overwritten by merge)
+
+test_expect_success '10a-setup: Overwrite untracked with normal rename/delete' '
+	test_create_repo 10a &&
+	(
+		cd 10a &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git rm z/c &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv z/c z/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '10a-check: Overwrite untracked with normal rename/delete' '
+	(
+		cd 10a &&
+
+		git checkout A^0 &&
+		echo very >z/c &&
+		echo important >z/d &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "The following untracked working tree files would be overwritten by merge" err &&
+
+		test 1 -eq $(git ls-files -s | wc -l) &&
+		test 4 -eq $(git ls-files -o | wc -l) &&
+
+		test "very" = "$(cat z/c)" &&
+		test "important" = "$(cat z/d)" &&
+		test $(git rev-parse HEAD:z/b) = $(git rev-parse O:z/b)
+	)
+'
+
+# Testcase 10b, Overwrite untracked: dir rename + delete
+#   Commit O: z/{b,c_1}
+#   Commit A: y/b + untracked y/{c,d,e}
+#   Commit B: z/{b,d_1,e}
+#   Expected: Failed Merge; y/b + untracked y/c + untracked y/d on disk +
+#             z/c_1 -> z/d_1 rename recorded at stage 3 for y/d +
+#       ERROR_MSG(refusing to lose untracked file at 'y/d')
+
+test_expect_success '10b-setup: Overwrite untracked with dir rename + delete' '
+	test_create_repo 10b &&
+	(
+		cd 10b &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git rm z/c &&
+		git mv z/ y/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv z/c z/d &&
+		echo e >z/e &&
+		git add z/e &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '10b-check: Overwrite untracked with dir rename + delete' '
+	(
+		cd 10b &&
+
+		git checkout A^0 &&
+		echo very >y/c &&
+		echo important >y/d &&
+		echo contents >y/e &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "CONFLICT (rename/delete).*Version B^0 of y/d left in tree at y/d~B^0" out &&
+		test_i18ngrep "Error: Refusing to lose untracked file at y/e; writing to y/e~B^0 instead" out &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 2 -eq $(git ls-files -u | wc -l) &&
+		test 5 -eq $(git ls-files -o | wc -l) &&
+
+		test $(git rev-parse :0:y/b) = $(git rev-parse O:z/b) &&
+		test "very" = "$(cat y/c)" &&
+
+		test "important" = "$(cat y/d)" &&
+		test "important" != "$(git rev-parse :3:y/d)" &&
+		test $(git rev-parse :3:y/d) = $(git rev-parse O:z/c) &&
+
+		test "contents" = "$(cat y/e)" &&
+		test "contents" != "$(git rev-parse :3:y/e)" &&
+		test $(git rev-parse :3:y/e) = $(git rev-parse B:z/e)
+	)
+'
+
+# Testcase 10c, Overwrite untracked: dir rename/rename(1to2)
+#   Commit O: z/{a,b}, x/{c,d}
+#   Commit A: y/{a,b}, w/c, x/d + different untracked y/c
+#   Commit B: z/{a,b,c}, x/d
+#   Expected: Failed Merge; y/{a,b} + x/d + untracked y/c +
+#             CONFLICT(rename/rename) x/c -> w/c vs y/c +
+#             y/c~B^0 +
+#             ERROR_MSG(Refusing to lose untracked file at y/c)
+
+test_expect_success '10c-setup: Overwrite untracked with dir rename/rename(1to2)' '
+	test_create_repo 10c &&
+	(
+		cd 10c &&
+
+		mkdir z x &&
+		echo a >z/a &&
+		echo b >z/b &&
+		echo c >x/c &&
+		echo d >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		mkdir w &&
+		git mv x/c w/c &&
+		git mv z/ y/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/c z/ &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '10c-check: Overwrite untracked with dir rename/rename(1to2)' '
+	(
+		cd 10c &&
+
+		git checkout A^0 &&
+		echo important >y/c &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "CONFLICT (rename/rename)" out &&
+		test_i18ngrep "Refusing to lose untracked file at y/c; adding as y/c~B^0 instead" out &&
+
+		test 6 -eq $(git ls-files -s | wc -l) &&
+		test 3 -eq $(git ls-files -u | wc -l) &&
+		test 3 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/a :0:y/b :0:x/d :1:x/c :2:w/c :3:y/c &&
+		git rev-parse >expect \
+			O:z/a O:z/b O:x/d O:x/c O:x/c O:x/c &&
+		test_cmp expect actual &&
+
+		test "important" = "$(cat y/c)" &&
+		test "important" != "$(git rev-parse :3:y/c)" &&
+		test $(git hash-object y/c~B^0) = $(git rev-parse O:x/c)
+	)
+'
+
+# Testcase 10d, Delete untracked w/ dir rename/rename(2to1)
+#   Commit O: z/{a,b,c_1},        x/{d,e,f_2}
+#   Commit A: y/{a,b},            x/{d,e,f_2,wham_1} + untracked y/wham
+#   Commit B: z/{a,b,c_1,wham_2}, y/{d,e}
+#   Expected: Failed Merge; y/{a,b,d,e} + untracked y/{wham,wham~B^0,wham~HEAD}+
+#             CONFLICT(rename/rename) z/c_1 vs x/f_2 -> y/wham
+#             ERROR_MSG(Refusing to lose untracked file at y/wham)
+
+test_expect_success '10d-setup: Delete untracked with dir rename/rename(2to1)' '
+	test_create_repo 10d &&
+	(
+		cd 10d &&
+
+		mkdir z x &&
+		echo a >z/a &&
+		echo b >z/b &&
+		echo c >z/c &&
+		echo d >x/d &&
+		echo e >x/e &&
+		echo f >x/f &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z/c x/wham &&
+		git mv z/ y/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/f z/wham &&
+		git mv x/ y/ &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '10d-check: Delete untracked with dir rename/rename(2to1)' '
+	(
+		cd 10d &&
+
+		git checkout A^0 &&
+		echo important >y/wham &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "CONFLICT (rename/rename)" out &&
+		test_i18ngrep "Refusing to lose untracked file at y/wham" out &&
+
+		test 6 -eq $(git ls-files -s | wc -l) &&
+		test 2 -eq $(git ls-files -u | wc -l) &&
+		test 4 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/a :0:y/b :0:y/d :0:y/e :2:y/wham :3:y/wham &&
+		git rev-parse >expect \
+			O:z/a O:z/b O:x/d O:x/e O:z/c O:x/f &&
+		test_cmp expect actual &&
+
+		test_must_fail git rev-parse :1:y/wham &&
+
+		test "important" = "$(cat y/wham)" &&
+		git hash-object >actual \
+			y/wham~B^0 y/wham~HEAD &&
+		git rev-parse >expect \
+			O:x/f O:z/c &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 10e, Does git complain about untracked file that's not in the way?
+#   Commit O: z/{a,b}
+#   Commit A: y/{a,b} + untracked z/c
+#   Commit B: z/{a,b,c}
+#   Expected: y/{a,b,c} + untracked z/c
+
+test_expect_success '10e-setup: Does git complain about untracked file that is not really in the way?' '
+	test_create_repo 10e &&
+	(
+		cd 10e &&
+
+		mkdir z &&
+		echo a >z/a &&
+		echo b >z/b &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z/ y/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo c >z/c &&
+		git add z/c &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '10e-check: Does git complain about untracked file that is not really in the way?' '
+	(
+		cd 10e &&
+
+		git checkout A^0 &&
+		mkdir z &&
+		echo random >z/c &&
+
+		git merge -s recursive B^0 >out 2>err &&
+	! test_i18ngrep "following untracked working tree files would be overwritten by merge" err &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 3 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:y/a :0:y/b :0:y/c &&
+		git rev-parse >expect \
+			O:z/a O:z/b B:z/c &&
+		test_cmp expect actual &&
+
+		test "random" = "$(cat z/c)"
+	)
+'
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 14/33] directory rename detection: tests for handling overwriting dirty files

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 436 ++++++++++++++++++++++++++++++++++++
 1 file changed, 436 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 7408c788fc..88243651f7 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -3103,4 +3103,440 @@ test_expect_failure '10e-check: Does git complain about untracked file that is n
 	)
 '
 
+###########################################################################
+# SECTION 11: Handling dirty (not up-to-date) files
+#
+# unpack_trees(), upon which the recursive merge algorithm is based, aborts
+# the operation if untracked or dirty files would be deleted or overwritten
+# by the merge.  Unfortunately, unpack_trees() does not understand renames,
+# and if it doesn't abort, then it muddies up the working directory before
+# we even get to the point of detecting renames, so we need some special
+# handling.  This was true even of normal renames, but there are additional
+# codepaths that need special handling with directory renames.  Add
+# testcases for both renamed-by-directory-rename-detection and standard
+# rename cases.
+###########################################################################
+
+# Testcase 11a, Avoid losing dirty contents with simple rename
+#   Commit O: z/{a,b_v1},
+#   Commit A: z/{a,c_v1}, and z/c_v1 has uncommitted mods
+#   Commit B: z/{a,b_v2}
+#   Expected: ERROR_MSG(Refusing to lose dirty file at z/c) +
+#             z/a, staged version of z/c has sha1sum matching B:z/b_v2,
+#             z/c~HEAD with contents of B:z/b_v2,
+#             z/c with uncommitted mods on top of A:z/c_v1
+
+test_expect_success '11a-setup: Avoid losing dirty contents with simple rename' '
+	test_create_repo 11a &&
+	(
+		cd 11a &&
+
+		mkdir z &&
+		echo a >z/a &&
+		test_seq 1 10 >z/b &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z/b z/c &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo 11 >>z/b &&
+		git add z/b &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '11a-check: Avoid losing dirty contents with simple rename' '
+	(
+		cd 11a &&
+
+		git checkout A^0 &&
+		echo stuff >>z/c &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "Refusing to lose dirty file at z/c" out &&
+
+		test_seq 1 10 >expected &&
+		echo stuff >>expected &&
+
+		test 2 -eq $(git ls-files -s | wc -l) &&
+		test 1 -eq $(git ls-files -u | wc -l) &&
+		test 4 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:z/a :2:z/c &&
+		git rev-parse >expect \
+			O:z/a B:z/b &&
+		test_cmp expect actual &&
+
+		test "$(git hash-object z/c~HEAD)" = $(git rev-parse B:z/b) &&
+		test_cmp expected z/c
+	)
+'
+
+# Testcase 11b, Avoid losing dirty file involved in directory rename
+#   Commit O: z/a,         x/{b,c_v1}
+#   Commit A: z/{a,c_v1},  x/b,       and z/c_v1 has uncommitted mods
+#   Commit B: y/a,         x/{b,c_v2}
+#   Expected: y/{a,c_v2}, x/b, z/c_v1 with uncommitted mods untracked,
+#             ERROR_MSG(Refusing to lose dirty file at z/c)
+
+
+test_expect_success '11b-setup: Avoid losing dirty file involved in directory rename' '
+	test_create_repo 11b &&
+	(
+		cd 11b &&
+
+		mkdir z x &&
+		echo a >z/a &&
+		echo b >x/b &&
+		test_seq 1 10 >x/c &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv x/c z/c &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv z y &&
+		echo 11 >>x/c &&
+		git add x/c &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '11b-check: Avoid losing dirty file involved in directory rename' '
+	(
+		cd 11b &&
+
+		git checkout A^0 &&
+		echo stuff >>z/c &&
+
+		git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "Refusing to lose dirty file at z/c" out &&
+
+		grep -q stuff */* &&
+		test_seq 1 10 >expected &&
+		echo stuff >>expected &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 0 -eq $(git ls-files -m | wc -l) &&
+		test 4 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:x/b :0:y/a :0:y/c &&
+		git rev-parse >expect \
+			O:x/b O:z/a B:x/c &&
+		test_cmp expect actual &&
+
+		test "$(git hash-object y/c)" = $(git rev-parse B:x/c) &&
+		test_cmp expected z/c
+	)
+'
+
+# Testcase 11c, Avoid losing not-up-to-date with rename + D/F conflict
+#   Commit O: y/a,         x/{b,c_v1}
+#   Commit A: y/{a,c_v1},  x/b,       and y/c_v1 has uncommitted mods
+#   Commit B: y/{a,c/d},   x/{b,c_v2}
+#   Expected: Abort_msg("following files would be overwritten by merge") +
+#             y/c left untouched (still has uncommitted mods)
+
+test_expect_success '11c-setup: Avoid losing not-uptodate with rename + D/F conflict' '
+	test_create_repo 11c &&
+	(
+		cd 11c &&
+
+		mkdir y x &&
+		echo a >y/a &&
+		echo b >x/b &&
+		test_seq 1 10 >x/c &&
+		git add y x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv x/c y/c &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		mkdir y/c &&
+		echo d >y/c/d &&
+		echo 11 >>x/c &&
+		git add x/c y/c/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '11c-check: Avoid losing not-uptodate with rename + D/F conflict' '
+	(
+		cd 11c &&
+
+		git checkout A^0 &&
+		echo stuff >>y/c &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "following files would be overwritten by merge" err &&
+
+		grep -q stuff */* &&
+		test_seq 1 10 >expected &&
+		echo stuff >>expected &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+		test 0 -eq $(git ls-files -u | wc -l) &&
+		test 1 -eq $(git ls-files -m | wc -l) &&
+		test 3 -eq $(git ls-files -o | wc -l) &&
+
+		test $(git rev-parse HEAD) = $(git rev-parse A) &&
+		test_cmp expected y/c
+	)
+'
+
+# Testcase 11d, Avoid losing not-up-to-date with rename + D/F conflict
+#   Commit O: z/a,         x/{b,c_v1}
+#   Commit A: z/{a,c_v1},  x/b,       and z/c_v1 has uncommitted mods
+#   Commit B: y/{a,c/d},   x/{b,c_v2}
+#   Expected: D/F: y/c_v2 vs y/c/d) +
+#             Warning_Msg("Refusing to lose dirty file at z/c) +
+#             y/{a,c~HEAD,c/d}, x/b, now-untracked z/c_v1 with uncommitted mods
+
+test_expect_success '11d-setup: Avoid losing not-uptodate with rename + D/F conflict' '
+	test_create_repo 11d &&
+	(
+		cd 11d &&
+
+		mkdir z x &&
+		echo a >z/a &&
+		echo b >x/b &&
+		test_seq 1 10 >x/c &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv x/c z/c &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv z y &&
+		mkdir y/c &&
+		echo d >y/c/d &&
+		echo 11 >>x/c &&
+		git add x/c y/c/d &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '11d-check: Avoid losing not-uptodate with rename + D/F conflict' '
+	(
+		cd 11d &&
+
+		git checkout A^0 &&
+		echo stuff >>z/c &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "Refusing to lose dirty file at z/c" out &&
+
+		grep -q stuff */* &&
+		test_seq 1 10 >expected &&
+		echo stuff >>expected &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+		test 1 -eq $(git ls-files -u | wc -l) &&
+		test 5 -eq $(git ls-files -o | wc -l) &&
+
+		git rev-parse >actual \
+			:0:x/b :0:y/a :0:y/c/d :3:y/c &&
+		git rev-parse >expect \
+			O:x/b O:z/a B:y/c/d B:x/c &&
+		test_cmp expect actual &&
+
+		test "$(git hash-object y/c~HEAD)" = $(git rev-parse B:x/c) &&
+		test_cmp expected z/c
+	)
+'
+
+# Testcase 11e, Avoid deleting not-up-to-date with dir rename/rename(1to2)/add
+#   Commit O: z/{a,b},      x/{c_1,d}
+#   Commit A: y/{a,b,c_2},  x/d, w/c_1, and y/c_2 has uncommitted mods
+#   Commit B: z/{a,b,c_1},  x/d
+#   Expected: Failed Merge; y/{a,b} + x/d +
+#             CONFLICT(rename/rename) x/c_1 -> w/c_1 vs y/c_1 +
+#             ERROR_MSG(Refusing to lose dirty file at y/c)
+#             y/c~B^0 has O:x/c_1 contents
+#             y/c~HEAD has A:y/c_2 contents
+#             y/c has dirty file from before merge
+
+test_expect_success '11e-setup: Avoid deleting not-uptodate with dir rename/rename(1to2)/add' '
+	test_create_repo 11e &&
+	(
+		cd 11e &&
+
+		mkdir z x &&
+		echo a >z/a &&
+		echo b >z/b &&
+		echo c >x/c &&
+		echo d >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z/ y/ &&
+		echo different >y/c &&
+		mkdir w &&
+		git mv x/c w/ &&
+		git add y/c &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/c z/ &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '11e-check: Avoid deleting not-uptodate with dir rename/rename(1to2)/add' '
+	(
+		cd 11e &&
+
+		git checkout A^0 &&
+		echo mods >>y/c &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "CONFLICT (rename/rename)" out &&
+		test_i18ngrep "Refusing to lose dirty file at y/c" out &&
+
+		test 7 -eq $(git ls-files -s | wc -l) &&
+		test 4 -eq $(git ls-files -u | wc -l) &&
+		test 4 -eq $(git ls-files -o | wc -l) &&
+
+		echo different >expected &&
+		echo mods >>expected &&
+
+		git rev-parse >actual \
+			:0:y/a :0:y/b :0:x/d :1:x/c :2:w/c :2:y/c :3:y/c &&
+		git rev-parse >expect \
+			O:z/a O:z/b O:x/d O:x/c O:x/c A:y/c O:x/c &&
+		test_cmp expect actual &&
+
+		git hash-object >actual \
+			y/c~B^0 y/c~HEAD &&
+		git rev-parse >expect \
+			O:x/c A:y/c &&
+		test_cmp expect actual &&
+
+		test_cmp expected y/c
+	)
+'
+
+# Testcase 11f, Avoid deleting not-up-to-date w/ dir rename/rename(2to1)
+#   Commit O: z/{a,b},        x/{c_1,d_2}
+#   Commit A: y/{a,b,wham_1}, x/d_2, except y/wham has uncommitted mods
+#   Commit B: z/{a,b,wham_2}, x/c_1
+#   Expected: Failed Merge; y/{a,b} + untracked y/{wham~B^0,wham~B^HEAD} +
+#             y/wham with dirty changes from before merge +
+#             CONFLICT(rename/rename) x/c vs x/d -> y/wham
+#             ERROR_MSG(Refusing to lose dirty file at y/wham)
+
+test_expect_success '11f-setup: Avoid deleting not-uptodate with dir rename/rename(2to1)' '
+	test_create_repo 11f &&
+	(
+		cd 11f &&
+
+		mkdir z x &&
+		echo a >z/a &&
+		echo b >z/b &&
+		test_seq 1 10 >x/c &&
+		echo d >x/d &&
+		git add z x &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv z/ y/ &&
+		git mv x/c y/wham &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv x/d z/wham &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '11f-check: Avoid deleting not-uptodate with dir rename/rename(2to1)' '
+	(
+		cd 11f &&
+
+		git checkout A^0 &&
+		echo important >>y/wham &&
+
+		test_must_fail git merge -s recursive B^0 >out 2>err &&
+		test_i18ngrep "CONFLICT (rename/rename)" out &&
+		test_i18ngrep "Refusing to lose dirty file at y/wham" out &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+		test 2 -eq $(git ls-files -u | wc -l) &&
+		test 4 -eq $(git ls-files -o | wc -l) &&
+
+		test_seq 1 10 >expected &&
+		echo important >>expected &&
+
+		git rev-parse >actual \
+			:0:y/a :0:y/b :2:y/wham :3:y/wham &&
+		git rev-parse >expect \
+			O:z/a O:z/b O:x/c O:x/d &&
+		test_cmp expect actual &&
+
+		test_must_fail git rev-parse :1:y/wham &&
+
+		test_cmp expected y/wham &&
+		git hash-object >actual \
+			y/wham~B^0 y/wham~HEAD &&
+		git rev-parse >expect \
+			O:x/d O:x/c &&
+		test_cmp expect actual
+	)
+'
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 15/33] merge-recursive: move the get_renames() function

[Elijah Newren]

I want to re-use some other functions in the file without moving those
other functions or dealing with a handful of annoying split function
declarations and definitions.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 139 +++++++++++++++++++++++++++---------------------------
 1 file changed, 70 insertions(+), 69 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index c530880333..91bc354bec 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -537,75 +537,6 @@ struct rename {
 	unsigned processed:1;
 };
 
-/*
- * Get information of all renames which occurred between 'o_tree' and
- * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
- * 'b_tree') to be able to associate the correct cache entries with
- * the rename information. 'tree' is always equal to either a_tree or b_tree.
- */
-static struct string_list *get_renames(struct merge_options *o,
-				       struct tree *tree,
-				       struct tree *o_tree,
-				       struct tree *a_tree,
-				       struct tree *b_tree,
-				       struct string_list *entries)
-{
-	int i;
-	struct string_list *renames;
-	struct diff_options opts;
-
-	renames = xcalloc(1, sizeof(struct string_list));
-	if (!o->detect_rename)
-		return renames;
-
-	diff_setup(&opts);
-	opts.flags.recursive = 1;
-	opts.flags.rename_empty = 0;
-	opts.detect_rename = DIFF_DETECT_RENAME;
-	opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
-			    o->diff_rename_limit >= 0 ? o->diff_rename_limit :
-			    1000;
-	opts.rename_score = o->rename_score;
-	opts.show_rename_progress = o->show_rename_progress;
-	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
-	diff_setup_done(&opts);
-	diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
-	diffcore_std(&opts);
-	if (opts.needed_rename_limit > o->needed_rename_limit)
-		o->needed_rename_limit = opts.needed_rename_limit;
-	for (i = 0; i < diff_queued_diff.nr; ++i) {
-		struct string_list_item *item;
-		struct rename *re;
-		struct diff_filepair *pair = diff_queued_diff.queue[i];
-		if (pair->status != 'R') {
-			diff_free_filepair(pair);
-			continue;
-		}
-		re = xmalloc(sizeof(*re));
-		re->processed = 0;
-		re->pair = pair;
-		item = string_list_lookup(entries, re->pair->one->path);
-		if (!item)
-			re->src_entry = insert_stage_data(re->pair->one->path,
-					o_tree, a_tree, b_tree, entries);
-		else
-			re->src_entry = item->util;
-
-		item = string_list_lookup(entries, re->pair->two->path);
-		if (!item)
-			re->dst_entry = insert_stage_data(re->pair->two->path,
-					o_tree, a_tree, b_tree, entries);
-		else
-			re->dst_entry = item->util;
-		item = string_list_insert(renames, pair->one->path);
-		item->util = re;
-	}
-	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
-	diff_queued_diff.nr = 0;
-	diff_flush(&opts);
-	return renames;
-}
-
 static int update_stages(struct merge_options *opt, const char *path,
 			 const struct diff_filespec *o,
 			 const struct diff_filespec *a,
@@ -1380,6 +1311,76 @@ static int conflict_rename_rename_2to1(struct merge_options *o,
 	return ret;
 }
 
+/*
+ * Get information of all renames which occurred between 'o_tree' and
+ * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
+ * 'b_tree') to be able to associate the correct cache entries with
+ * the rename information. 'tree' is always equal to either a_tree or b_tree.
+ */
+static struct string_list *get_renames(struct merge_options *o,
+				       struct tree *tree,
+				       struct tree *o_tree,
+				       struct tree *a_tree,
+				       struct tree *b_tree,
+				       struct string_list *entries)
+{
+	int i;
+	struct string_list *renames;
+	struct diff_options opts;
+
+	renames = xcalloc(1, sizeof(struct string_list));
+	if (!o->detect_rename)
+		return renames;
+
+	diff_setup(&opts);
+	opts.flags.recursive = 1;
+	opts.flags.rename_empty = 0;
+	opts.detect_rename = DIFF_DETECT_RENAME;
+	opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
+			    o->diff_rename_limit >= 0 ? o->diff_rename_limit :
+			    1000;
+	opts.rename_score = o->rename_score;
+	opts.show_rename_progress = o->show_rename_progress;
+	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
+	diff_setup_done(&opts);
+	diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
+	diffcore_std(&opts);
+	if (opts.needed_rename_limit > o->needed_rename_limit)
+		o->needed_rename_limit = opts.needed_rename_limit;
+	for (i = 0; i < diff_queued_diff.nr; ++i) {
+		struct string_list_item *item;
+		struct rename *re;
+		struct diff_filepair *pair = diff_queued_diff.queue[i];
+
+		if (pair->status != 'R') {
+			diff_free_filepair(pair);
+			continue;
+		}
+		re = xmalloc(sizeof(*re));
+		re->processed = 0;
+		re->pair = pair;
+		item = string_list_lookup(entries, re->pair->one->path);
+		if (!item)
+			re->src_entry = insert_stage_data(re->pair->one->path,
+					o_tree, a_tree, b_tree, entries);
+		else
+			re->src_entry = item->util;
+
+		item = string_list_lookup(entries, re->pair->two->path);
+		if (!item)
+			re->dst_entry = insert_stage_data(re->pair->two->path,
+					o_tree, a_tree, b_tree, entries);
+		else
+			re->dst_entry = item->util;
+		item = string_list_insert(renames, pair->one->path);
+		item->util = re;
+	}
+	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
+	diff_queued_diff.nr = 0;
+	diff_flush(&opts);
+	return renames;
+}
+
 static int process_renames(struct merge_options *o,
 			   struct string_list *a_renames,
 			   struct string_list *b_renames)
-- 
2.15.0.309.g62ce55426d

[PATCH v3 16/33] merge-recursive: introduce new functions to handle rename logic

[Elijah Newren]

The amount of logic in merge_trees() relative to renames was just a few
lines, but split it out into new handle_renames() and cleanup_renames()
functions to prepare for additional logic to be added to each.  No code or
logic changes, just a new place to put stuff for when the rename detection
gains additional checks.

Note that process_renames() records pointers to various information (such
as diff_filepairs) into rename_conflict_info structs.  Even though the
rename string_lists are not directly used once handle_renames() completes,
we should not immediately free the lists at the end of that function
because they store the information referenced in the rename_conflict_info,
which is used later in process_entry().  Thus the reason for a separate
cleanup_renames().

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 43 +++++++++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 91bc354bec..4249caad4d 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1636,6 +1636,32 @@ static int process_renames(struct merge_options *o,
 	return clean_merge;
 }
 
+struct rename_info {
+	struct string_list *head_renames;
+	struct string_list *merge_renames;
+};
+
+static int handle_renames(struct merge_options *o,
+			  struct tree *common,
+			  struct tree *head,
+			  struct tree *merge,
+			  struct string_list *entries,
+			  struct rename_info *ri)
+{
+	ri->head_renames  = get_renames(o, head, common, head, merge, entries);
+	ri->merge_renames = get_renames(o, merge, common, head, merge, entries);
+	return process_renames(o, ri->head_renames, ri->merge_renames);
+}
+
+static void cleanup_renames(struct rename_info *re_info)
+{
+	string_list_clear(re_info->head_renames, 0);
+	string_list_clear(re_info->merge_renames, 0);
+
+	free(re_info->head_renames);
+	free(re_info->merge_renames);
+}
+
 static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
 {
 	return (is_null_oid(oid) || mode == 0) ? NULL: (struct object_id *)oid;
@@ -1987,7 +2013,8 @@ int merge_trees(struct merge_options *o,
 	}
 
 	if (unmerged_cache()) {
-		struct string_list *entries, *re_head, *re_merge;
+		struct string_list *entries;
+		struct rename_info re_info;
 		int i;
 		/*
 		 * Only need the hashmap while processing entries, so
@@ -2001,9 +2028,8 @@ int merge_trees(struct merge_options *o,
 		get_files_dirs(o, merge);
 
 		entries = get_unmerged();
-		re_head  = get_renames(o, head, common, head, merge, entries);
-		re_merge = get_renames(o, merge, common, head, merge, entries);
-		clean = process_renames(o, re_head, re_merge);
+		clean = handle_renames(o, common, head, merge, entries,
+				       &re_info);
 		record_df_conflict_files(o, entries);
 		if (clean < 0)
 			goto cleanup;
@@ -2028,16 +2054,13 @@ int merge_trees(struct merge_options *o,
 		}
 
 cleanup:
-		string_list_clear(re_merge, 0);
-		string_list_clear(re_head, 0);
+		cleanup_renames(&re_info);
+
 		string_list_clear(entries, 1);
+		free(entries);
 
 		hashmap_free(&o->current_file_dir_set, 1);
 
-		free(re_merge);
-		free(re_head);
-		free(entries);
-
 		if (clean < 0)
 			return clean;
 	}
-- 
2.15.0.309.g62ce55426d

[PATCH v3 17/33] merge-recursive: fix leaks of allocated renames and diff_filepairs

[Elijah Newren]

get_renames() has always zero'ed out diff_queued_diff.nr while only
manually free'ing diff_filepairs that did not correspond to renames.
Further, it allocated struct renames that were tucked away in the
return string_list.  Make sure all of these are deallocated when we
are done with them.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 4249caad4d..db8590ab1a 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1653,13 +1653,23 @@ static int handle_renames(struct merge_options *o,
 	return process_renames(o, ri->head_renames, ri->merge_renames);
 }
 
-static void cleanup_renames(struct rename_info *re_info)
+static void cleanup_rename(struct string_list *rename)
 {
-	string_list_clear(re_info->head_renames, 0);
-	string_list_clear(re_info->merge_renames, 0);
+	const struct rename *re;
+	int i;
 
-	free(re_info->head_renames);
-	free(re_info->merge_renames);
+	for (i = 0; i < rename->nr; i++) {
+		re = rename->items[i].util;
+		diff_free_filepair(re->pair);
+	}
+	string_list_clear(rename, 1);
+	free(rename);
+}
+
+static void cleanup_renames(struct rename_info *re_info)
+{
+	cleanup_rename(re_info->head_renames);
+	cleanup_rename(re_info->merge_renames);
 }
 
 static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
-- 
2.15.0.309.g62ce55426d

[PATCH v3 18/33] merge-recursive: make !o->detect_rename codepath more obvious

[Elijah Newren]

Previously, if !o->detect_rename then get_renames() would return an
empty string_list, and then process_renames() would have nothing to
iterate over.  It seems more straightforward to simply avoid calling
either function in that case.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index db8590ab1a..7f975f3f52 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1329,8 +1329,6 @@ static struct string_list *get_renames(struct merge_options *o,
 	struct diff_options opts;
 
 	renames = xcalloc(1, sizeof(struct string_list));
-	if (!o->detect_rename)
-		return renames;
 
 	diff_setup(&opts);
 	opts.flags.recursive = 1;
@@ -1648,6 +1646,12 @@ static int handle_renames(struct merge_options *o,
 			  struct string_list *entries,
 			  struct rename_info *ri)
 {
+	ri->head_renames = NULL;
+	ri->merge_renames = NULL;
+
+	if (!o->detect_rename)
+		return 1;
+
 	ri->head_renames  = get_renames(o, head, common, head, merge, entries);
 	ri->merge_renames = get_renames(o, merge, common, head, merge, entries);
 	return process_renames(o, ri->head_renames, ri->merge_renames);
@@ -1658,6 +1662,9 @@ static void cleanup_rename(struct string_list *rename)
 	const struct rename *re;
 	int i;
 
+	if (rename == NULL)
+		return;
+
 	for (i = 0; i < rename->nr; i++) {
 		re = rename->items[i].util;
 		diff_free_filepair(re->pair);
-- 
2.15.0.309.g62ce55426d

[PATCH v3 19/33] merge-recursive: split out code for determining diff_filepairs

[Elijah Newren]

Create a new function, get_diffpairs() to compute the diff_filepairs
between two trees.  While these are currently only used in
get_renames(), I want them to be available to some new functions.  No
actual logic changes yet.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 86 +++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 64 insertions(+), 22 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 7f975f3f52..26cae6bdfd 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1312,24 +1312,15 @@ static int conflict_rename_rename_2to1(struct merge_options *o,
 }
 
 /*
- * Get information of all renames which occurred between 'o_tree' and
- * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
- * 'b_tree') to be able to associate the correct cache entries with
- * the rename information. 'tree' is always equal to either a_tree or b_tree.
+ * Get the diff_filepairs changed between o_tree and tree.
  */
-static struct string_list *get_renames(struct merge_options *o,
-				       struct tree *tree,
-				       struct tree *o_tree,
-				       struct tree *a_tree,
-				       struct tree *b_tree,
-				       struct string_list *entries)
+static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
+					       struct tree *o_tree,
+					       struct tree *tree)
 {
-	int i;
-	struct string_list *renames;
+	struct diff_queue_struct *ret;
 	struct diff_options opts;
 
-	renames = xcalloc(1, sizeof(struct string_list));
-
 	diff_setup(&opts);
 	opts.flags.recursive = 1;
 	opts.flags.rename_empty = 0;
@@ -1345,10 +1336,43 @@ static struct string_list *get_renames(struct merge_options *o,
 	diffcore_std(&opts);
 	if (opts.needed_rename_limit > o->needed_rename_limit)
 		o->needed_rename_limit = opts.needed_rename_limit;
-	for (i = 0; i < diff_queued_diff.nr; ++i) {
+
+	ret = malloc(sizeof(struct diff_queue_struct));
+	ret->queue = diff_queued_diff.queue;
+	ret->nr = diff_queued_diff.nr;
+	/* Ignore diff_queued_diff.alloc; we won't be changing size at all */
+
+	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
+	diff_queued_diff.nr = 0;
+	diff_queued_diff.queue = NULL;
+	diff_flush(&opts);
+	return ret;
+}
+
+/*
+ * Get information of all renames which occurred in 'pairs', making use of
+ * any implicit directory renames inferred from the other side of history.
+ * We need the three trees in the merge ('o_tree', 'a_tree' and 'b_tree')
+ * to be able to associate the correct cache entries with the rename
+ * information; tree is always equal to either a_tree or b_tree.
+ */
+static struct string_list *get_renames(struct merge_options *o,
+				       struct diff_queue_struct *pairs,
+				       struct tree *tree,
+				       struct tree *o_tree,
+				       struct tree *a_tree,
+				       struct tree *b_tree,
+				       struct string_list *entries)
+{
+	int i;
+	struct string_list *renames;
+
+	renames = xcalloc(1, sizeof(struct string_list));
+
+	for (i = 0; i < pairs->nr; ++i) {
 		struct string_list_item *item;
 		struct rename *re;
-		struct diff_filepair *pair = diff_queued_diff.queue[i];
+		struct diff_filepair *pair = pairs->queue[i];
 
 		if (pair->status != 'R') {
 			diff_free_filepair(pair);
@@ -1373,9 +1397,6 @@ static struct string_list *get_renames(struct merge_options *o,
 		item = string_list_insert(renames, pair->one->path);
 		item->util = re;
 	}
-	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
-	diff_queued_diff.nr = 0;
-	diff_flush(&opts);
 	return renames;
 }
 
@@ -1646,15 +1667,36 @@ static int handle_renames(struct merge_options *o,
 			  struct string_list *entries,
 			  struct rename_info *ri)
 {
+	struct diff_queue_struct *head_pairs, *merge_pairs;
+	int clean;
+
 	ri->head_renames = NULL;
 	ri->merge_renames = NULL;
 
 	if (!o->detect_rename)
 		return 1;
 
-	ri->head_renames  = get_renames(o, head, common, head, merge, entries);
-	ri->merge_renames = get_renames(o, merge, common, head, merge, entries);
-	return process_renames(o, ri->head_renames, ri->merge_renames);
+	head_pairs = get_diffpairs(o, common, head);
+	merge_pairs = get_diffpairs(o, common, merge);
+
+	ri->head_renames  = get_renames(o, head_pairs, head,
+					 common, head, merge, entries);
+	ri->merge_renames = get_renames(o, merge_pairs, merge,
+					 common, head, merge, entries);
+	clean = process_renames(o, ri->head_renames, ri->merge_renames);
+
+	/*
+	 * Some cleanup is deferred until cleanup_renames() because the
+	 * data structures are still needed and referenced in
+	 * process_entry().  But there are a few things we can free now.
+	 */
+
+	free(head_pairs->queue);
+	free(head_pairs);
+	free(merge_pairs->queue);
+	free(merge_pairs);
+
+	return clean;
 }
 
 static void cleanup_rename(struct string_list *rename)
-- 
2.15.0.309.g62ce55426d

[PATCH v3 20/33] merge-recursive: add a new hashmap for storing directory renames

[Elijah Newren]

This just adds dir_rename_entry and the associated functions; code using
these will be added in subsequent commits.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 35 +++++++++++++++++++++++++++++++++++
 merge-recursive.h |  8 ++++++++
 2 files changed, 43 insertions(+)

diff --git a/merge-recursive.c b/merge-recursive.c
index 26cae6bdfd..2f4f85314a 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -49,6 +49,41 @@ static unsigned int path_hash(const char *path)
 	return ignore_case ? strihash(path) : strhash(path);
 }
 
+static struct dir_rename_entry *dir_rename_find_entry(struct hashmap *hashmap,
+						      char *dir)
+{
+	struct dir_rename_entry key;
+
+	if (dir == NULL)
+		return NULL;
+	hashmap_entry_init(&key, strhash(dir));
+	key.dir = dir;
+	return hashmap_get(hashmap, &key, NULL);
+}
+
+static int dir_rename_cmp(void *unused_cmp_data,
+			  const struct dir_rename_entry *e1,
+			  const struct dir_rename_entry *e2,
+			  const void *unused_keydata)
+{
+	return strcmp(e1->dir, e2->dir);
+}
+
+static void dir_rename_init(struct hashmap *map)
+{
+	hashmap_init(map, (hashmap_cmp_fn) dir_rename_cmp, NULL, 0);
+}
+
+static void dir_rename_entry_init(struct dir_rename_entry *entry,
+				  char *directory)
+{
+	hashmap_entry_init(entry, strhash(directory));
+	entry->dir = directory;
+	entry->non_unique_new_dir = 0;
+	entry->new_dir = NULL;
+	string_list_init(&entry->possible_new_dirs, 0);
+}
+
 static void flush_output(struct merge_options *o)
 {
 	if (o->buffer_output < 2 && o->obuf.len) {
diff --git a/merge-recursive.h b/merge-recursive.h
index 80d69d1401..a024949739 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -29,6 +29,14 @@ struct merge_options {
 	struct string_list df_conflict_file_set;
 };
 
+struct dir_rename_entry {
+	struct hashmap_entry ent; /* must be the first member! */
+	char *dir;
+	unsigned non_unique_new_dir:1;
+	char *new_dir;
+	struct string_list possible_new_dirs;
+};
+
 /* merge_trees() but with recursive ancestor consolidation */
 int merge_recursive(struct merge_options *o,
 		    struct commit *h1,
-- 
2.15.0.309.g62ce55426d

[PATCH v3 21/33] merge-recursive: add get_directory_renames()

[Elijah Newren]

This populates a list of directory renames for us.  The list of
directory renames is not yet used, but will be in subsequent commits.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 152 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)

diff --git a/merge-recursive.c b/merge-recursive.c
index 2f4f85314a..6a0a6d4366 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1384,6 +1384,132 @@ static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
 	return ret;
 }
 
+static void get_renamed_dir_portion(const char *old_path, const char *new_path,
+				    char **old_dir, char **new_dir)
+{
+	char *end_of_old, *end_of_new;
+	int old_len, new_len;
+
+	*old_dir = NULL;
+	*new_dir = NULL;
+
+	/* For
+	 *    "a/b/c/d/foo.c" -> "a/b/something-else/d/foo.c"
+	 * the "d/foo.c" part is the same, we just want to know that
+	 *    "a/b/c" was renamed to "a/b/something-else"
+	 * so, for this example, this function returns "a/b/c" in
+	 * *old_dir and "a/b/something-else" in *new_dir.
+	 *
+	 * Also, if the basename of the file changed, we don't care.  We
+	 * want to know which portion of the directory, if any, changed.
+	 */
+	end_of_old = strrchr(old_path, '/');
+	end_of_new = strrchr(new_path, '/');
+
+	if (end_of_old == NULL || end_of_new == NULL)
+		return;
+	while (*--end_of_new == *--end_of_old &&
+	       end_of_old != old_path &&
+	       end_of_new != new_path)
+		; /* Do nothing; all in the while loop */
+	/*
+	 * We've found the first non-matching character in the directory
+	 * paths.  That means the current directory we were comparing
+	 * represents the rename.  Move end_of_old and end_of_new back
+	 * to the full directory name.
+	 */
+	if (*end_of_old == '/')
+		end_of_old++;
+	if (*end_of_old != '/')
+		end_of_new++;
+	end_of_old = strchr(end_of_old, '/');
+	end_of_new = strchr(end_of_new, '/');
+
+	/*
+	 * It may have been the case that old_path and new_path were the same
+	 * directory all along.  Don't claim a rename if they're the same.
+	 */
+	old_len = end_of_old - old_path;
+	new_len = end_of_new - new_path;
+
+	if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
+		*old_dir = strndup(old_path, old_len);
+		*new_dir = strndup(new_path, new_len);
+	}
+}
+
+static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
+					     struct tree *tree)
+{
+	struct hashmap *dir_renames;
+	struct hashmap_iter iter;
+	struct dir_rename_entry *entry;
+	int i;
+
+	dir_renames = malloc(sizeof(struct hashmap));
+	dir_rename_init(dir_renames);
+	for (i = 0; i < pairs->nr; ++i) {
+		struct string_list_item *item;
+		int *count;
+		struct diff_filepair *pair = pairs->queue[i];
+		char *old_dir, *new_dir;
+
+		get_renamed_dir_portion(pair->one->path, pair->two->path,
+					&old_dir,        &new_dir);
+		if (!old_dir)
+			/* Directory didn't change at all; ignore this one. */
+			continue;
+
+		entry = dir_rename_find_entry(dir_renames, old_dir);
+		if (!entry) {
+			entry = xmalloc(sizeof(struct dir_rename_entry));
+			dir_rename_entry_init(entry, old_dir);
+			hashmap_put(dir_renames, entry);
+		} else {
+			free(old_dir);
+		}
+		item = string_list_lookup(&entry->possible_new_dirs, new_dir);
+		if (!item) {
+			item = string_list_insert(&entry->possible_new_dirs,
+						  new_dir);
+			item->util = xcalloc(1, sizeof(int));
+		} else {
+			free(new_dir);
+		}
+		count = item->util;
+		*count += 1;
+	}
+
+	hashmap_iter_init(dir_renames, &iter);
+	while ((entry = hashmap_iter_next(&iter))) {
+		int max = 0;
+		int bad_max = 0;
+		char *best = NULL;
+
+		for (i = 0; i < entry->possible_new_dirs.nr; i++) {
+			int *count = entry->possible_new_dirs.items[i].util;
+
+			if (*count == max)
+				bad_max = max;
+			else if (*count > max) {
+				max = *count;
+				best = entry->possible_new_dirs.items[i].string;
+			}
+		}
+		if (bad_max == max)
+			entry->non_unique_new_dir = 1;
+		else
+			entry->new_dir = strdup(best);
+		/* Strings were strndup'ed before inserting into string-list,
+		 * so ask string_list to remove the entries for us.
+		 */
+		entry->possible_new_dirs.strdup_strings = 1;
+		string_list_clear(&entry->possible_new_dirs, 1);
+	}
+
+	return dir_renames;
+}
+
 /*
  * Get information of all renames which occurred in 'pairs', making use of
  * any implicit directory renames inferred from the other side of history.
@@ -1703,6 +1829,9 @@ static int handle_renames(struct merge_options *o,
 			  struct rename_info *ri)
 {
 	struct diff_queue_struct *head_pairs, *merge_pairs;
+	struct hashmap *dir_re_head, *dir_re_merge;
+	struct hashmap_iter iter;
+	struct dir_rename_entry *e;
 	int clean;
 
 	ri->head_renames = NULL;
@@ -1714,6 +1843,9 @@ static int handle_renames(struct merge_options *o,
 	head_pairs = get_diffpairs(o, common, head);
 	merge_pairs = get_diffpairs(o, common, merge);
 
+	dir_re_head = get_directory_renames(head_pairs, head);
+	dir_re_merge = get_directory_renames(merge_pairs, merge);
+
 	ri->head_renames  = get_renames(o, head_pairs, head,
 					 common, head, merge, entries);
 	ri->merge_renames = get_renames(o, merge_pairs, merge,
@@ -1726,6 +1858,26 @@ static int handle_renames(struct merge_options *o,
 	 * process_entry().  But there are a few things we can free now.
 	 */
 
+	hashmap_iter_init(dir_re_head, &iter);
+	while ((e = hashmap_iter_next(&iter))) {
+		free(e->dir);
+		if (e->new_dir)
+			free(e->new_dir);
+		/* possible_new_dirs already cleared in get_directory_renames */
+	}
+	hashmap_free(dir_re_head, 1);
+	free(dir_re_head);
+
+	hashmap_iter_init(dir_re_merge, &iter);
+	while ((e = hashmap_iter_next(&iter))) {
+		free(e->dir);
+		if (e->new_dir)
+			free(e->new_dir);
+		/* possible_new_dirs already cleared in get_directory_renames */
+	}
+	hashmap_free(dir_re_merge, 1);
+	free(dir_re_merge);
+
 	free(head_pairs->queue);
 	free(head_pairs);
 	free(merge_pairs->queue);
-- 
2.15.0.309.g62ce55426d

Re: [PATCH v3 21/33] merge-recursive: add get_directory_renames()

[Johannes Schindelin]

Hi Elijah,

On Tue, 21 Nov 2017, Elijah Newren wrote:

> diff --git a/merge-recursive.c b/merge-recursive.c
> index 2f4f85314a..6a0a6d4366 100644
> --- a/merge-recursive.c
> +++ b/merge-recursive.c
> @@ -1384,6 +1384,132 @@ static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
>  	return ret;
>  }
>  
> +static void get_renamed_dir_portion(const char *old_path, const char *new_path,
> +				    char **old_dir, char **new_dir)
> +{
> +	char *end_of_old, *end_of_new;
> +	int old_len, new_len;
> +
> +	*old_dir = NULL;
> +	*new_dir = NULL;
> +
> +	/* For
> +	 *    "a/b/c/d/foo.c" -> "a/b/something-else/d/foo.c"
> +	 * the "d/foo.c" part is the same, we just want to know that
> +	 *    "a/b/c" was renamed to "a/b/something-else"
> +	 * so, for this example, this function returns "a/b/c" in
> +	 * *old_dir and "a/b/something-else" in *new_dir.
> +	 *
> +	 * Also, if the basename of the file changed, we don't care.  We
> +	 * want to know which portion of the directory, if any, changed.
> +	 */
> +	end_of_old = strrchr(old_path, '/');
> +	end_of_new = strrchr(new_path, '/');
> +
> +	if (end_of_old == NULL || end_of_new == NULL)
> +		return;
> +	while (*--end_of_new == *--end_of_old &&
> +	       end_of_old != old_path &&
> +	       end_of_new != new_path)
> +		; /* Do nothing; all in the while loop */
> +	/*
> +	 * We've found the first non-matching character in the directory
> +	 * paths.  That means the current directory we were comparing
> +	 * represents the rename.  Move end_of_old and end_of_new back
> +	 * to the full directory name.
> +	 */
> +	if (*end_of_old == '/')
> +		end_of_old++;
> +	if (*end_of_old != '/')
> +		end_of_new++;
> +	end_of_old = strchr(end_of_old, '/');
> +	end_of_new = strchr(end_of_new, '/');
> +
> +	/*
> +	 * It may have been the case that old_path and new_path were the same
> +	 * directory all along.  Don't claim a rename if they're the same.
> +	 */
> +	old_len = end_of_old - old_path;
> +	new_len = end_of_new - new_path;
> +
> +	if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
> +		*old_dir = strndup(old_path, old_len);
> +		*new_dir = strndup(new_path, new_len);

These two callers of strndup() are the only ones in Git's code base now.
It is also causing a compile error on Windows.

Any reason you did not use xstrndup() here?

Ciao,
Dscho

Re: [PATCH v3 21/33] merge-recursive: add get_directory_renames()

[Elijah Newren]

On Sat, Nov 25, 2017 at 4:52 PM, Johannes Schindelin
<Johannes.Schindelin@gmx.de> wrote:
> On Tue, 21 Nov 2017, Elijah Newren wrote:
>
>> diff --git a/merge-recursive.c b/merge-recursive.c
<snip>
>> +     if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
>> +             *old_dir = strndup(old_path, old_len);
>> +             *new_dir = strndup(new_path, new_len);
>
> These two callers of strndup() are the only ones in Git's code base now.
> It is also causing a compile error on Windows.
>
> Any reason you did not use xstrndup() here?
>
> Ciao,
> Dscho

Nope, was just unaware.  I'll go ahead and switch them over for my
next roll of the series.  Sorry for the pain.

[PATCH v3 22/33] merge-recursive: check for directory level conflicts

[Elijah Newren]

Before trying to apply directory renames to paths within the given
directories, we want to make sure that there aren't conflicts at the
directory level.  There will be additional checks at the individual
file level too, which will be added later.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)

diff --git a/merge-recursive.c b/merge-recursive.c
index 6a0a6d4366..c235b27c55 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1384,6 +1384,15 @@ static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
 	return ret;
 }
 
+static int tree_has_path(struct tree *tree, const char *path)
+{
+	unsigned char hashy[20];
+	unsigned int mode_o;
+
+	return !get_tree_entry(tree->object.oid.hash, path,
+			       hashy, &mode_o);
+}
+
 static void get_renamed_dir_portion(const char *old_path, const char *new_path,
 				    char **old_dir, char **new_dir)
 {
@@ -1438,6 +1447,105 @@ static void get_renamed_dir_portion(const char *old_path, const char *new_path,
 	}
 }
 
+/*
+ * There are a couple things we want to do at the directory level:
+ *   1. Check for both sides renaming to the same thing, in order to avoid
+ *      implicit renaming of files that should be left in place.  (See
+ *      testcase 6b in t6043 for details.)
+ *   2. Prune directory renames if there are still files left in the
+ *      the original directory.  These represent a partial directory rename,
+ *      i.e. a rename where only some of the files within the directory
+ *      were renamed elsewhere.  (Technically, this could be done earlier
+ *      in get_directory_renames(), except that would prevent us from
+ *      doing the previous check and thus failing testcase 6b.)
+ *   3. Check for rename/rename(1to2) conflicts (at the directory level).
+ *      In the future, we could potentially record this info as well and
+ *      omit reporting rename/rename(1to2) conflicts for each path within
+ *      the affected directories, thus cleaning up the merge output.
+ *   NOTE: We do NOT check for rename/rename(2to1) conflicts at the
+ *         directory level, because merging directories is fine.  If it
+ *         causes conflicts for files within those merged directories, then
+ *         that should be detected at the individual path level.
+ */
+static void handle_directory_level_conflicts(struct merge_options *o,
+					     struct hashmap *dir_re_head,
+					     struct tree *head,
+					     struct hashmap *dir_re_merge,
+					     struct tree *merge)
+{
+	struct hashmap_iter iter;
+	struct dir_rename_entry *head_ent;
+	struct dir_rename_entry *merge_ent;
+	int i;
+
+	struct string_list remove_from_head = STRING_LIST_INIT_NODUP;
+	struct string_list remove_from_merge = STRING_LIST_INIT_NODUP;
+
+	hashmap_iter_init(dir_re_head, &iter);
+	while ((head_ent = hashmap_iter_next(&iter))) {
+		merge_ent = dir_rename_find_entry(dir_re_merge, head_ent->dir);
+		if (merge_ent &&
+		    !head_ent->non_unique_new_dir &&
+		    !merge_ent->non_unique_new_dir &&
+		    !strcmp(head_ent->new_dir, merge_ent->new_dir)) {
+			/* 1. Renamed identically; remove it from both sides */
+			string_list_append(&remove_from_head,
+					   head_ent->dir)->util = head_ent;
+			free(head_ent->new_dir);
+			string_list_append(&remove_from_merge,
+					   merge_ent->dir)->util = merge_ent;
+			free(merge_ent->new_dir);
+		} else if (tree_has_path(head, head_ent->dir)) {
+			/* 2. This wasn't a directory rename after all */
+			string_list_append(&remove_from_head,
+					   head_ent->dir)->util = head_ent;
+			free(head_ent->new_dir);
+		}
+	}
+
+	hashmap_iter_init(dir_re_merge, &iter);
+	while ((merge_ent = hashmap_iter_next(&iter))) {
+		head_ent = dir_rename_find_entry(dir_re_head, merge_ent->dir);
+		if (tree_has_path(merge, merge_ent->dir)) {
+			/* 2. This wasn't a directory rename after all */
+			string_list_append(&remove_from_merge,
+					   merge_ent->dir)->util = merge_ent;
+		} else if (head_ent &&
+			   !head_ent->non_unique_new_dir &&
+			   !merge_ent->non_unique_new_dir) {
+			/* 3. rename/rename(1to2) */
+			/* We can assume it's not rename/rename(1to1) because
+			 * that was case (1), already checked above.  So we
+			 * know that head_ent->new_dir and merge_ent->new_dir
+			 * are different strings.
+			 */
+			output(o, 1, _("CONFLICT (rename/rename): "
+				       "Rename directory %s->%s in %s. "
+				       "Rename directory %s->%s in %s"),
+			       head_ent->dir, head_ent->new_dir, o->branch1,
+			       head_ent->dir, merge_ent->new_dir, o->branch2);
+			string_list_append(&remove_from_head,
+					   head_ent->dir)->util = head_ent;
+			free(head_ent->new_dir);
+			string_list_append(&remove_from_merge,
+					   merge_ent->dir)->util = merge_ent;
+			free(merge_ent->new_dir);
+		}
+	}
+
+	for (i = 0; i < remove_from_head.nr; i++) {
+		head_ent = remove_from_head.items[i].util;
+		hashmap_remove(dir_re_head, head_ent, NULL);
+	}
+	for (i = 0; i < remove_from_merge.nr; i++) {
+		merge_ent = remove_from_merge.items[i].util;
+		hashmap_remove(dir_re_merge, merge_ent, NULL);
+	}
+
+	string_list_clear(&remove_from_head, 0);
+	string_list_clear(&remove_from_merge, 0);
+}
+
 static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
 					     struct tree *tree)
 {
@@ -1846,6 +1954,10 @@ static int handle_renames(struct merge_options *o,
 	dir_re_head = get_directory_renames(head_pairs, head);
 	dir_re_merge = get_directory_renames(merge_pairs, merge);
 
+	handle_directory_level_conflicts(o,
+					 dir_re_head, head,
+					 dir_re_merge, merge);
+
 	ri->head_renames  = get_renames(o, head_pairs, head,
 					 common, head, merge, entries);
 	ri->merge_renames = get_renames(o, merge_pairs, merge,
-- 
2.15.0.309.g62ce55426d

Re: [PATCH v3 22/33] merge-recursive: check for directory level conflicts

[Stefan Beller]

> +                       /* We can assume it's not rename/rename(1to1) because
> +                        * that was case (1), already checked above.  So we
> +                        * know that head_ent->new_dir and merge_ent->new_dir
> +                        * are different strings.
> +                        */

micro nit:

/* we prefer comments like this */

/*
 * or like this
 */

/* but not
 * like this.
 */

[PATCH v3 23/33] merge-recursive: add a new hashmap for storing file collisions

[Elijah Newren]

Directory renames with the ability to merge directories opens up the
possibility of add/add/add/.../add conflicts, if each of the N
directories being merged into one target directory all had a file with
the same name.  We need a way to check for and report on such
collisions; this hashmap will be used for this purpose.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 23 +++++++++++++++++++++++
 merge-recursive.h |  7 +++++++
 2 files changed, 30 insertions(+)

diff --git a/merge-recursive.c b/merge-recursive.c
index c235b27c55..1fa3eb6fb5 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -84,6 +84,29 @@ static void dir_rename_entry_init(struct dir_rename_entry *entry,
 	string_list_init(&entry->possible_new_dirs, 0);
 }
 
+static struct collision_entry *collision_find_entry(struct hashmap *hashmap,
+						    char *target_file)
+{
+	struct collision_entry key;
+
+	hashmap_entry_init(&key, strhash(target_file));
+	key.target_file = target_file;
+	return hashmap_get(hashmap, &key, NULL);
+}
+
+static int collision_cmp(void *unused_cmp_data,
+			 const struct collision_entry *e1,
+			 const struct collision_entry *e2,
+			 const void *unused_keydata)
+{
+	return strcmp(e1->target_file, e2->target_file);
+}
+
+static void collision_init(struct hashmap *map)
+{
+	hashmap_init(map, (hashmap_cmp_fn) collision_cmp, NULL, 0);
+}
+
 static void flush_output(struct merge_options *o)
 {
 	if (o->buffer_output < 2 && o->obuf.len) {
diff --git a/merge-recursive.h b/merge-recursive.h
index a024949739..e02c1e1243 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -37,6 +37,13 @@ struct dir_rename_entry {
 	struct string_list possible_new_dirs;
 };
 
+struct collision_entry {
+	struct hashmap_entry ent; /* must be the first member! */
+	char *target_file;
+	struct string_list source_files;
+	unsigned reported_already:1;
+};
+
 /* merge_trees() but with recursive ancestor consolidation */
 int merge_recursive(struct merge_options *o,
 		    struct commit *h1,
-- 
2.15.0.309.g62ce55426d

[PATCH v3 24/33] merge-recursive: add computation of collisions due to dir rename & merging

[Elijah Newren]

directory renaming and merging can cause one or more files to be moved to
where an existing file is, or to cause several files to all be moved to
the same (otherwise vacant) location.  Add checking and reporting for such
cases, falling back to no-directory-rename handling for such paths.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 121 insertions(+), 3 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 1fa3eb6fb5..b8c7d6dce3 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1416,6 +1416,32 @@ static int tree_has_path(struct tree *tree, const char *path)
 			       hashy, &mode_o);
 }
 
+/*
+ * Return a new string that replaces the beginning portion (which matches
+ * entry->dir), with entry->new_dir.  In perl-speak:
+ *   new_path_name = (old_path =~ s/entry->dir/entry->new_dir/);
+ * NOTE:
+ *   Caller must ensure that old_path starts with entry->dir + '/'.
+ */
+static char *apply_dir_rename(struct dir_rename_entry *entry,
+			      const char *old_path)
+{
+	char *new_path;
+	int entrylen, oldlen, newlen;
+
+	if (entry->non_unique_new_dir)
+		return NULL;
+
+	entrylen = strlen(entry->new_dir);
+	oldlen = strlen(entry->dir);
+	newlen = entrylen + (strlen(old_path) - oldlen) + 1;
+	new_path = malloc(newlen);
+	strcpy(new_path, entry->new_dir);
+	strcpy(&new_path[entrylen], &old_path[oldlen]);
+
+	return new_path;
+}
+
 static void get_renamed_dir_portion(const char *old_path, const char *new_path,
 				    char **old_dir, char **new_dir)
 {
@@ -1641,6 +1667,84 @@ static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
 	return dir_renames;
 }
 
+static struct dir_rename_entry *check_dir_renamed(const char *path,
+						  struct hashmap *dir_renames)
+{
+	char temp[PATH_MAX];
+	char *end;
+	struct dir_rename_entry *entry;
+
+	strcpy(temp, path);
+	while ((end = strrchr(temp, '/'))) {
+		*end = '\0';
+		entry = dir_rename_find_entry(dir_renames, temp);
+		if (entry)
+			return entry;
+	}
+	return NULL;
+}
+
+static void compute_collisions(struct hashmap *collisions,
+			       struct hashmap *dir_renames,
+			       struct diff_queue_struct *pairs)
+{
+	int i;
+
+	/*
+	 * Multiple files can be mapped to the same path due to directory
+	 * renames done by the other side of history.  Since that other
+	 * side of history could have merged multiple directories into one,
+	 * if our side of history added the same file basename to each of
+	 * those directories, then all N of them would get implicitly
+	 * renamed by the directory rename detection into the same path,
+	 * and we'd get an add/add/.../add conflict, and all those adds
+	 * from *this* side of history.  This is not representable in the
+	 * index, and users aren't going to easily be able to make sense of
+	 * it.  So we need to provide a good warning about what's
+	 * happening, and fall back to no-directory-rename detection
+	 * behavior for those paths.
+	 *
+	 * See testcases 9e and all of section 5 from t6043 for examples.
+	 */
+	collision_init(collisions);
+
+	for (i = 0; i < pairs->nr; ++i) {
+		struct dir_rename_entry *dir_rename_ent;
+		struct collision_entry *collision_ent;
+		char *new_path;
+		struct diff_filepair *pair = pairs->queue[i];
+
+		if (pair->status == 'D')
+			continue;
+		dir_rename_ent = check_dir_renamed(pair->two->path,
+						   dir_renames);
+		if (!dir_rename_ent)
+			continue;
+
+		new_path = apply_dir_rename(dir_rename_ent, pair->two->path);
+		if (!new_path)
+			/*
+			 * dir_rename_ent->non_unique_new_path is true, which
+			 * means there is no directory rename for us to use,
+			 * which means it won't cause us any additional
+			 * collisions.
+			 */
+			continue;
+		collision_ent = collision_find_entry(collisions, new_path);
+		if (!collision_ent) {
+			collision_ent = xcalloc(1,
+						sizeof(struct collision_entry));
+			hashmap_entry_init(collision_ent, strhash(new_path));
+			hashmap_put(collisions, collision_ent);
+			collision_ent->target_file = new_path;
+		} else {
+			free(new_path);
+		}
+		string_list_insert(&collision_ent->source_files,
+				   pair->two->path);
+	}
+}
+
 /*
  * Get information of all renames which occurred in 'pairs', making use of
  * any implicit directory renames inferred from the other side of history.
@@ -1650,6 +1754,7 @@ static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
  */
 static struct string_list *get_renames(struct merge_options *o,
 				       struct diff_queue_struct *pairs,
+				       struct hashmap *dir_renames,
 				       struct tree *tree,
 				       struct tree *o_tree,
 				       struct tree *a_tree,
@@ -1657,8 +1762,12 @@ static struct string_list *get_renames(struct merge_options *o,
 				       struct string_list *entries)
 {
 	int i;
+	struct hashmap collisions;
+	struct hashmap_iter iter;
+	struct collision_entry *e;
 	struct string_list *renames;
 
+	compute_collisions(&collisions, dir_renames, pairs);
 	renames = xcalloc(1, sizeof(struct string_list));
 
 	for (i = 0; i < pairs->nr; ++i) {
@@ -1689,6 +1798,13 @@ static struct string_list *get_renames(struct merge_options *o,
 		item = string_list_insert(renames, pair->one->path);
 		item->util = re;
 	}
+
+	hashmap_iter_init(&collisions, &iter);
+	while ((e = hashmap_iter_next(&iter))) {
+		free(e->target_file);
+		string_list_clear(&e->source_files, 0);
+	}
+	hashmap_free(&collisions, 1);
 	return renames;
 }
 
@@ -1981,9 +2097,11 @@ static int handle_renames(struct merge_options *o,
 					 dir_re_head, head,
 					 dir_re_merge, merge);
 
-	ri->head_renames  = get_renames(o, head_pairs, head,
-					 common, head, merge, entries);
-	ri->merge_renames = get_renames(o, merge_pairs, merge,
+	ri->head_renames  = get_renames(o, head_pairs,
+					dir_re_merge, head,
+					common, head, merge, entries);
+	ri->merge_renames = get_renames(o, merge_pairs,
+					dir_re_head, merge,
 					 common, head, merge, entries);
 	clean = process_renames(o, ri->head_renames, ri->merge_renames);
 
-- 
2.15.0.309.g62ce55426d

[PATCH v3 25/33] merge-recursive: check for file level conflicts then get new name

[Elijah Newren]

Before trying to apply directory renames to paths within the given
directories, we want to make sure that there aren't conflicts at the
file level either.  If there aren't any, then get the new name from
any directory renames.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c                   | 192 ++++++++++++++++++++++++++++++++++--
 t/t6043-merge-rename-directories.sh |   2 +-
 2 files changed, 185 insertions(+), 9 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index b8c7d6dce3..5bc207b819 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1496,6 +1496,109 @@ static void get_renamed_dir_portion(const char *old_path, const char *new_path,
 	}
 }
 
+/*
+ * Write:
+ *   element1, element2, element3, ..., elementN
+ * to str.  If only one element, just write "element1" to str.
+ */
+static void comma_separated_list(char *str, struct string_list *slist)
+{
+	int i;
+
+	for (i = 0; i < slist->nr; i++) {
+		str += sprintf(str, "%s", slist->items[i].string);
+		if (i < slist->nr-1)
+			str += sprintf(str, ", ");
+	}
+}
+
+/*
+ * See if there is a directory rename for path, and if there are any file
+ * level conflicts for the renamed location.  If there is a rename and
+ * there are no conflicts, return the new name.  Otherwise, return NULL.
+ */
+static char *handle_path_level_conflicts(struct merge_options *o,
+					 const char *path,
+					 struct dir_rename_entry *entry,
+					 struct hashmap *collisions,
+					 struct tree *tree)
+{
+	char *new_path = NULL;
+	struct collision_entry *collision_ent;
+	int clean = 1;
+	char *collision_paths;
+
+	/*
+	 * entry has the mapping of old directory name to new directory name
+	 * that we want to apply to path.
+	 */
+	new_path = apply_dir_rename(entry, path);
+
+	if (!new_path) {
+		/* This should only happen when entry->non_unique_new_dir set */
+		if (!entry->non_unique_new_dir)
+			BUG("entry->non_unqiue_dir not set and !new_path");
+		output(o, 1, _("CONFLICT (directory rename split): "
+			       "Unclear where to place %s because directory "
+			       "%s was renamed to multiple other directories, "
+			       "with no destination getting a majority of the "
+			       "files."),
+		       path, entry->dir);
+		clean = 0;
+		return NULL;
+	}
+
+	/*
+	 * The caller needs to have ensured that it has pre-populated
+	 * collisions with all paths that map to new_path.  Do a quick check
+	 * to ensure that's the case.
+	 */
+	collision_ent = collision_find_entry(collisions, new_path);
+	if (collision_ent == NULL)
+		BUG("collision_ent is NULL");
+
+	/*
+	 * Check for one-sided add/add/.../add conflicts, i.e.
+	 * where implicit renames from the other side doing
+	 * directory rename(s) can affect this side of history
+	 * to put multiple paths into the same location.  Warn
+	 * and bail on directory renames for such paths.
+	 */
+	collision_paths = malloc((PATH_MAX+2) * collision_ent->source_files.nr);
+
+	if (collision_ent->reported_already) {
+		clean = 0;
+	} else if (tree_has_path(tree, new_path)) {
+		collision_ent->reported_already = 1;
+		comma_separated_list(collision_paths,
+				     &collision_ent->source_files);
+		output(o, 1, _("CONFLICT (implicit dir rename): Existing "
+			       "file/dir at %s in the way of implicit "
+			       "directory rename(s) putting the following "
+			       "path(s) there: %s."),
+		       new_path, collision_paths);
+		clean = 0;
+	} else if (collision_ent->source_files.nr > 1) {
+		collision_ent->reported_already = 1;
+		comma_separated_list(collision_paths,
+				     &collision_ent->source_files);
+		output(o, 1, _("CONFLICT (implicit dir rename): Cannot map "
+			       "more than one path to %s; implicit directory "
+			       "renames tried to put these paths there: %s"),
+		       new_path, collision_paths);
+		clean = 0;
+	}
+
+	/* Free memory we no longer need */
+	free(collision_paths);
+	if (!clean && new_path) {
+		free(new_path);
+		return NULL;
+	}
+
+	return new_path;
+}
+
 /*
  * There are a couple things we want to do at the directory level:
  *   1. Check for both sides renaming to the same thing, in order to avoid
@@ -1745,6 +1848,59 @@ static void compute_collisions(struct hashmap *collisions,
 	}
 }
 
+static char *check_for_directory_rename(struct merge_options *o,
+					const char *path,
+					struct tree *tree,
+					struct hashmap *dir_renames,
+					struct hashmap *dir_rename_exclusions,
+					struct hashmap *collisions,
+					int *clean_merge)
+{
+	char *new_path = NULL;
+	struct dir_rename_entry *entry = check_dir_renamed(path, dir_renames);
+	struct dir_rename_entry *oentry = NULL;
+
+	if (!entry)
+		return new_path;
+
+	/*
+	 * This next part is a little weird.  We do not want to do an
+	 * implicit rename into a directory we renamed on our side, because
+	 * that will result in a spurious rename/rename(1to2) conflict.  An
+	 * example:
+	 *   Base commit: dumbdir/afile, otherdir/bfile
+	 *   Side 1:      smrtdir/afile, otherdir/bfile
+	 *   Side 2:      dumbdir/afile, dumbdir/bfile
+	 * Here, while working on Side 1, we could notice that otherdir was
+	 * renamed/merged to dumbdir, and change the diff_filepair for
+	 * otherdir/bfile into a rename into dumbdir/bfile.  However, Side
+	 * 2 will notice the rename from dumbdir to smrtdir, and do the
+	 * transitive rename to move it from dumbdir/bfile to
+	 * smrtdir/bfile.  That gives us bfile in dumbdir vs being in
+	 * smrtdir, a rename/rename(1to2) conflict.  We really just want
+	 * the file to end up in smrtdir.  And the way to achieve that is
+	 * to not let Side1 do the rename to dumbdir, since we know that is
+	 * the source of one of our directory renames.
+	 *
+	 * That's why oentry and dir_rename_exclusions is here.
+	 *
+	 * As it turns out, this also prevents N-way transient rename
+	 * confusion; See testcases 9c and 9d of t6043.
+	 */
+	oentry = dir_rename_find_entry(dir_rename_exclusions, entry->new_dir);
+	if (oentry) {
+		output(o, 1, _("WARNING: Avoiding applying %s -> %s rename "
+			       "to %s, because %s itself was renamed."),
+		       entry->dir, entry->new_dir, path, entry->new_dir);
+	} else {
+		new_path = handle_path_level_conflicts(o, path, entry,
+						       collisions, tree);
+		*clean_merge &= (new_path != NULL);
+	}
+
+	return new_path;
+}
+
 /*
  * Get information of all renames which occurred in 'pairs', making use of
  * any implicit directory renames inferred from the other side of history.
@@ -1755,11 +1911,13 @@ static void compute_collisions(struct hashmap *collisions,
 static struct string_list *get_renames(struct merge_options *o,
 				       struct diff_queue_struct *pairs,
 				       struct hashmap *dir_renames,
+				       struct hashmap *dir_rename_exclusions,
 				       struct tree *tree,
 				       struct tree *o_tree,
 				       struct tree *a_tree,
 				       struct tree *b_tree,
-				       struct string_list *entries)
+				       struct string_list *entries,
+				       int *clean_merge)
 {
 	int i;
 	struct hashmap collisions;
@@ -1774,11 +1932,22 @@ static struct string_list *get_renames(struct merge_options *o,
 		struct string_list_item *item;
 		struct rename *re;
 		struct diff_filepair *pair = pairs->queue[i];
+		char *new_path; /* non-NULL only with directory renames */
 
-		if (pair->status != 'R') {
+		if (pair->status == 'D') {
+			diff_free_filepair(pair);
+			continue;
+		}
+		new_path = check_for_directory_rename(o, pair->two->path, tree,
+						      dir_renames,
+						      dir_rename_exclusions,
+						      &collisions,
+						      clean_merge);
+		if (pair->status != 'R' && !new_path) {
 			diff_free_filepair(pair);
 			continue;
 		}
+
 		re = xmalloc(sizeof(*re));
 		re->processed = 0;
 		re->pair = pair;
@@ -2079,7 +2248,7 @@ static int handle_renames(struct merge_options *o,
 	struct hashmap *dir_re_head, *dir_re_merge;
 	struct hashmap_iter iter;
 	struct dir_rename_entry *e;
-	int clean;
+	int clean = 1;
 
 	ri->head_renames = NULL;
 	ri->merge_renames = NULL;
@@ -2098,13 +2267,20 @@ static int handle_renames(struct merge_options *o,
 					 dir_re_merge, merge);
 
 	ri->head_renames  = get_renames(o, head_pairs,
-					dir_re_merge, head,
-					common, head, merge, entries);
+					dir_re_merge, dir_re_head, head,
+					common, head, merge, entries,
+					&clean);
+	if (clean < 0)
+		goto cleanup;
 	ri->merge_renames = get_renames(o, merge_pairs,
-					dir_re_head, merge,
-					 common, head, merge, entries);
-	clean = process_renames(o, ri->head_renames, ri->merge_renames);
+					dir_re_head, dir_re_merge, merge,
+					common, head, merge, entries,
+					&clean);
+	if (clean < 0)
+		goto cleanup;
+	clean &= process_renames(o, ri->head_renames, ri->merge_renames);
 
+cleanup:
 	/*
 	 * Some cleanup is deferred until cleanup_renames() because the
 	 * data structures are still needed and referenced in
diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 88243651f7..a45425f4d7 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -477,7 +477,7 @@ test_expect_success '2a-setup: Directory split into two on one side, with equal
 	)
 '
 
-test_expect_failure '2a-check: Directory split into two on one side, with equal numbers of paths' '
+test_expect_success '2a-check: Directory split into two on one side, with equal numbers of paths' '
 	(
 		cd 2a &&
 
-- 
2.15.0.309.g62ce55426d

Re: [PATCH v3 25/33] merge-recursive: check for file level conflicts then get new name

[Stefan Beller]

On Tue, Nov 21, 2017 at 12:00 AM, Elijah Newren <newren@gmail.com> wrote:
> Before trying to apply directory renames to paths within the given
> directories, we want to make sure that there aren't conflicts at the
> file level either.  If there aren't any, then get the new name from
> any directory renames.
>
> Signed-off-by: Elijah Newren <newren@gmail.com>
> ---
>  merge-recursive.c                   | 192 ++++++++++++++++++++++++++++++++++--
>  t/t6043-merge-rename-directories.sh |   2 +-
>  2 files changed, 185 insertions(+), 9 deletions(-)
>
> diff --git a/merge-recursive.c b/merge-recursive.c
> index b8c7d6dce3..5bc207b819 100644
> --- a/merge-recursive.c
> +++ b/merge-recursive.c
> @@ -1496,6 +1496,109 @@ static void get_renamed_dir_portion(const char *old_path, const char *new_path,
>         }
>  }
>
> +/*
> + * Write:
> + *   element1, element2, element3, ..., elementN
> + * to str.  If only one element, just write "element1" to str.
> + */
> +static void comma_separated_list(char *str, struct string_list *slist)

This is quite a low level function, so I wondered if we have such functionality
already, but neither string-list.h nor strbuf.h present a drop-in replacement.
Speaking of strbufs, this might be another "big thing" to use in this series as
strbufs make using strings (and its memory management) easier in git.

This functionality could look like this (in strbuf.c):

/*
 * Adds all strings of a string list to the strbuf, separated by the
given separator.
 * For example a list of ("a", "b") with sep=";" would result in "a;b" added
 * to the strbuf.
 */
void strbuf_add_separated_string_list(struct strbuf *sb, struct
string_list *slist, const char *sep)
{
    int add_sep = 0;
    struct string_list_item *item;

    for_each_string_list_item(item, s_list) {
        if (add_sep)
            strbuf_addstr(sb, sep);
        strbuf_addstr(item->string);
        add_sep = 1;
    }
}


> +{
> +       int i;
> +
> +       for (i = 0; i < slist->nr; i++) {
> +               str += sprintf(str, "%s", slist->items[i].string);
> +               if (i < slist->nr-1)

style nit: blanks before and after '-';

> +                       str += sprintf(str, ", ");
> +       }
> +}

[PATCH v3 26/33] merge-recursive: when comparing files, don't include trees

[Elijah Newren]

get_renames() would look up stage data that already existed (populated
in get_unmerged(), taken from whatever unpack_trees() created), and if
it didn't exist, would call insert_stage_data() to create the necessary
entry for the given file.  The insert_stage_data() fallback becomes
much more important for directory rename detection, because that creates
a mechanism to have a file in the resulting merge that didn't exist on
either side of history.  However, insert_stage_data(), due to calling
get_tree_entry() loaded up trees as readily as files.  We aren't
interested in comparing trees to files; the D/F conflict handling is
done elsewhere.  This code is just concerned with what entries existed
for a given path on the different sides of the merge, so create a
get_tree_entry_if_blob() helper function and use it.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 5bc207b819..90c753cd7e 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -418,6 +418,21 @@ static void get_files_dirs(struct merge_options *o, struct tree *tree)
 	read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o);
 }
 
+static int get_tree_entry_if_blob(const unsigned char *tree,
+				  const char *path,
+				  unsigned char *hashy,
+				  unsigned int *mode_o)
+{
+	int ret;
+
+	ret = get_tree_entry(tree, path, hashy, mode_o);
+	if (S_ISDIR(*mode_o)) {
+		hashcpy(hashy, null_sha1);
+		*mode_o = 0;
+	}
+	return ret;
+}
+
 /*
  * Returns an index_entry instance which doesn't have to correspond to
  * a real cache entry in Git's index.
@@ -428,12 +443,12 @@ static struct stage_data *insert_stage_data(const char *path,
 {
 	struct string_list_item *item;
 	struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
-	get_tree_entry(o->object.oid.hash, path,
-			e->stages[1].oid.hash, &e->stages[1].mode);
-	get_tree_entry(a->object.oid.hash, path,
-			e->stages[2].oid.hash, &e->stages[2].mode);
-	get_tree_entry(b->object.oid.hash, path,
-			e->stages[3].oid.hash, &e->stages[3].mode);
+	get_tree_entry_if_blob(o->object.oid.hash, path,
+			       e->stages[1].oid.hash, &e->stages[1].mode);
+	get_tree_entry_if_blob(a->object.oid.hash, path,
+			       e->stages[2].oid.hash, &e->stages[2].mode);
+	get_tree_entry_if_blob(b->object.oid.hash, path,
+			       e->stages[3].oid.hash, &e->stages[3].mode);
 	item = string_list_insert(entries, path);
 	item->util = e;
 	return e;
-- 
2.15.0.309.g62ce55426d

[PATCH v3 27/33] merge-recursive: apply necessary modifications for directory renames

[Elijah Newren]

This commit hooks together all the directory rename logic by making the
necessary changes to the rename struct, it's dst_entry, and the
diff_filepair under consideration.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c                   | 187 +++++++++++++++++++++++++++++++++++-
 t/t6043-merge-rename-directories.sh |  50 +++++-----
 2 files changed, 211 insertions(+), 26 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 90c753cd7e..9e8f9ea3c4 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -177,6 +177,7 @@ static int oid_eq(const struct object_id *a, const struct object_id *b)
 
 enum rename_type {
 	RENAME_NORMAL = 0,
+	RENAME_DIR,
 	RENAME_DELETE,
 	RENAME_ONE_FILE_TO_ONE,
 	RENAME_ONE_FILE_TO_TWO,
@@ -607,6 +608,7 @@ struct rename {
 	 */
 	struct stage_data *src_entry;
 	struct stage_data *dst_entry;
+	unsigned add_turned_into_rename:1;
 	unsigned processed:1;
 };
 
@@ -641,6 +643,27 @@ static int update_stages(struct merge_options *opt, const char *path,
 	return 0;
 }
 
+static int update_stages_for_stage_data(struct merge_options *opt,
+					const char *path,
+					const struct stage_data *stage_data)
+{
+	struct diff_filespec o, a, b;
+
+	o.mode = stage_data->stages[1].mode;
+	oidcpy(&o.oid, &stage_data->stages[1].oid);
+
+	a.mode = stage_data->stages[2].mode;
+	oidcpy(&a.oid, &stage_data->stages[2].oid);
+
+	b.mode = stage_data->stages[3].mode;
+	oidcpy(&b.oid, &stage_data->stages[3].oid);
+
+	return update_stages(opt, path,
+			     is_null_sha1(o.oid.hash) ? NULL : &o,
+			     is_null_sha1(a.oid.hash) ? NULL : &a,
+			     is_null_sha1(b.oid.hash) ? NULL : &b);
+}
+
 static void update_entry(struct stage_data *entry,
 			 struct diff_filespec *o,
 			 struct diff_filespec *a,
@@ -1108,6 +1131,18 @@ static int merge_file_one(struct merge_options *o,
 	return merge_file_1(o, &one, &a, &b, branch1, branch2, mfi);
 }
 
+static int conflict_rename_dir(struct merge_options *o,
+			       struct diff_filepair *pair,
+			       const char *rename_branch,
+			       const char *other_branch)
+{
+	const struct diff_filespec *dest = pair->two;
+
+	if (update_file(o, 1, &dest->oid, dest->mode, dest->path))
+		return -1;
+	return 0;
+}
+
 static int handle_change_delete(struct merge_options *o,
 				 const char *path, const char *old_path,
 				 const struct object_id *o_oid, int o_mode,
@@ -1377,6 +1412,24 @@ static int conflict_rename_rename_2to1(struct merge_options *o,
 		if (!ret)
 			ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
 					  new_path2);
+		/*
+		 * unpack_trees() actually populates the index for us for
+		 * "normal" rename/rename(2to1) situtations so that the
+		 * correct entries are at the higher stages, which would
+		 * make the call below to update_stages_for_stage_data
+		 * unnecessary.  However, if either of the renames came
+		 * from a directory rename, then unpack_trees() will not
+		 * have gotten the right data loaded into the index, so we
+		 * need to do so now.  (While it'd be tempting to move this
+		 * call to update_stages_for_stage_data() to
+		 * apply_directory_rename_modifications(), that would break
+		 * our intermediate calls to would_lose_untracked() since
+		 * those rely on the current in-memory index.  See also the
+		 * big "NOTE" in update_stages()).
+		 */
+		if (update_stages_for_stage_data(o, path, ci->dst_entry1))
+			ret = -1;
+
 		free(new_path2);
 		free(new_path1);
 	}
@@ -1916,6 +1969,111 @@ static char *check_for_directory_rename(struct merge_options *o,
 	return new_path;
 }
 
+static void apply_directory_rename_modifications(struct merge_options *o,
+						 struct diff_filepair *pair,
+						 char *new_path,
+						 struct rename *re,
+						 struct tree *tree,
+						 struct tree *o_tree,
+						 struct tree *a_tree,
+						 struct tree *b_tree,
+						 struct string_list *entries,
+						 int *clean)
+{
+	struct string_list_item *item;
+	int stage = (tree == a_tree ? 2 : 3);
+
+	/*
+	 * In all cases where we can do directory rename detection,
+	 * unpack_trees() will have read pair->two->path into the
+	 * index and the working copy.  We need to remove it so that
+	 * we can instead place it at new_path.  It is guaranteed to
+	 * not be untracked (unpack_trees() would have errored out
+	 * saying the file would have been overwritten), but it might
+	 * be dirty, though.
+	 */
+	remove_file(o, 1, pair->two->path, 0 /* no_wd */);
+
+	/* Find or create a new re->dst_entry */
+	item = string_list_lookup(entries, new_path);
+	if (item) {
+		/*
+		 * Since we're renaming on this side of history, and it's
+		 * due to a directory rename on the other side of history
+		 * (which we only allow when the directory in question no
+		 * longer exists on the other side of history), the
+		 * original entry for re->dst_entry is no longer
+		 * necessary...
+		 */
+		re->dst_entry->processed = 1;
+
+		/*
+		 * ...because we'll be using this new one.
+		 */
+		re->dst_entry = item->util;
+	} else {
+		/*
+		 * re->dst_entry is for the before-dir-rename path, and we
+		 * need it to hold information for the after-dir-rename
+		 * path.  Before creating a new entry, we need to mark the
+		 * old one as unnecessary (...unless it is shared by
+		 * src_entry, i.e. this didn't use to be a rename, in which
+		 * case we can just allow the normal processing to happen
+		 * for it).
+		 */
+		if (pair->status == 'R')
+			re->dst_entry->processed = 1;
+
+		re->dst_entry = insert_stage_data(new_path,
+						  o_tree, a_tree, b_tree,
+						  entries);
+		item = string_list_insert(entries, new_path);
+		item->util = re->dst_entry;
+	}
+
+	/*
+	 * Update the stage_data with the information about the path we are
+	 * moving into place.  That slot will be empty and available for us
+	 * to write to because of the collision checks in
+	 * handle_path_level_conflicts().  In other words,
+	 * re->dst_entry->stages[stage].oid will be the null_oid, so it's
+	 * open for us to write to.
+	 *
+	 * It may be tempting to actually update the index at this point as
+	 * well, using update_stages_for_stage_data(), but as per the big
+	 * "NOTE" in update_stages(), doing so will modify the current
+	 * in-memory index which will break calls to would_lose_untracked()
+	 * that we need to make.  Instead, we need to just make sure that
+	 * the various conflict_rename_*() functions update the index
+	 * explicitly rather than relying on unpack_trees() to have done it.
+	 */
+	get_tree_entry(tree->object.oid.hash,
+		       pair->two->path,
+		       re->dst_entry->stages[stage].oid.hash,
+		       &re->dst_entry->stages[stage].mode);
+
+	/* Update pair status */
+	if (pair->status == 'A') {
+		/*
+		 * Recording rename information for this add makes it look
+		 * like a rename/delete conflict.  Make sure we can
+		 * correctly handle this as an add that was moved to a new
+		 * directory instead of reporting a rename/delete conflict.
+		 */
+		re->add_turned_into_rename = 1;
+	}
+	/*
+	 * We don't actually look at pair->status again, but it seems
+	 * pedagogically correct to adjust it.
+	 */
+	pair->status = 'R';
+
+	/*
+	 * Finally, record the new location.
+	 */
+	pair->two->path = new_path;
+}
+
 /*
  * Get information of all renames which occurred in 'pairs', making use of
  * any implicit directory renames inferred from the other side of history.
@@ -1965,6 +2123,7 @@ static struct string_list *get_renames(struct merge_options *o,
 
 		re = xmalloc(sizeof(*re));
 		re->processed = 0;
+		re->add_turned_into_rename = 0;
 		re->pair = pair;
 		item = string_list_lookup(entries, re->pair->one->path);
 		if (!item)
@@ -1981,6 +2140,12 @@ static struct string_list *get_renames(struct merge_options *o,
 			re->dst_entry = item->util;
 		item = string_list_insert(renames, pair->one->path);
 		item->util = re;
+		if (new_path)
+			apply_directory_rename_modifications(o, pair, new_path,
+							     re, tree, o_tree,
+							     a_tree, b_tree,
+							     entries,
+							     clean_merge);
 	}
 
 	hashmap_iter_init(&collisions, &iter);
@@ -2150,7 +2315,19 @@ static int process_renames(struct merge_options *o,
 			dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
 			try_merge = 0;
 
-			if (oid_eq(&src_other.oid, &null_oid)) {
+			if (oid_eq(&src_other.oid, &null_oid) &&
+			    ren1->add_turned_into_rename) {
+				setup_rename_conflict_info(RENAME_DIR,
+							   ren1->pair,
+							   NULL,
+							   branch1,
+							   branch2,
+							   ren1->dst_entry,
+							   NULL,
+							   o,
+							   NULL,
+							   NULL);
+			} else if (oid_eq(&src_other.oid, &null_oid)) {
 				setup_rename_conflict_info(RENAME_DELETE,
 							   ren1->pair,
 							   NULL,
@@ -2573,6 +2750,14 @@ static int process_entry(struct merge_options *o,
 						    o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
 						    conflict_info);
 			break;
+		case RENAME_DIR:
+			clean_merge = 1;
+			if (conflict_rename_dir(o,
+						conflict_info->pair1,
+						conflict_info->branch1,
+						conflict_info->branch2))
+				clean_merge = -1;
+			break;
 		case RENAME_DELETE:
 			clean_merge = 0;
 			if (conflict_rename_delete(o,
diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index a45425f4d7..6efe7a45ec 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -69,7 +69,7 @@ test_expect_success '1a-setup: Simple directory rename detection' '
 	)
 '
 
-test_expect_failure '1a-check: Simple directory rename detection' '
+test_expect_success '1a-check: Simple directory rename detection' '
 	(
 		cd 1a &&
 
@@ -131,7 +131,7 @@ test_expect_success '1b-setup: Merge a directory with another' '
 	)
 '
 
-test_expect_failure '1b-check: Merge a directory with another' '
+test_expect_success '1b-check: Merge a directory with another' '
 	(
 		cd 1b &&
 
@@ -188,7 +188,7 @@ test_expect_success '1c-setup: Transitive renaming' '
 	)
 '
 
-test_expect_failure '1c-check: Transitive renaming' '
+test_expect_success '1c-check: Transitive renaming' '
 	(
 		cd 1c &&
 
@@ -256,7 +256,7 @@ test_expect_success '1d-setup: Directory renames cause a rename/rename(2to1) con
 	)
 '
 
-test_expect_failure '1d-check: Directory renames cause a rename/rename(2to1) conflict' '
+test_expect_success '1d-check: Directory renames cause a rename/rename(2to1) conflict' '
 	(
 		cd 1d &&
 
@@ -332,7 +332,7 @@ test_expect_success '1e-setup: Renamed directory, with all files being renamed t
 	)
 '
 
-test_expect_failure '1e-check: Renamed directory, with all files being renamed too' '
+test_expect_success '1e-check: Renamed directory, with all files being renamed too' '
 	(
 		cd 1e &&
 
@@ -397,7 +397,7 @@ test_expect_success '1f-setup: Split a directory into two other directories' '
 	)
 '
 
-test_expect_failure '1f-check: Split a directory into two other directories' '
+test_expect_success '1f-check: Split a directory into two other directories' '
 	(
 		cd 1f &&
 
@@ -875,7 +875,7 @@ test_expect_success '5a-setup: Merge directories, other side adds files to origi
 	)
 '
 
-test_expect_failure '5a-check: Merge directories, other side adds files to original and target' '
+test_expect_success '5a-check: Merge directories, other side adds files to original and target' '
 	(
 		cd 5a &&
 
@@ -949,7 +949,7 @@ test_expect_success '5b-setup: Rename/delete in order to get add/add/add conflic
 	)
 '
 
-test_expect_failure '5b-check: Rename/delete in order to get add/add/add conflict' '
+test_expect_success '5b-check: Rename/delete in order to get add/add/add conflict' '
 	(
 		cd 5b &&
 
@@ -1026,7 +1026,7 @@ test_expect_success '5c-setup: Transitive rename would cause rename/rename/renam
 	)
 '
 
-test_expect_failure '5c-check: Transitive rename would cause rename/rename/rename/add/add/add' '
+test_expect_success '5c-check: Transitive rename would cause rename/rename/rename/add/add/add' '
 	(
 		cd 5c &&
 
@@ -1108,7 +1108,7 @@ test_expect_success '5d-setup: Directory/file/file conflict due to directory ren
 	)
 '
 
-test_expect_failure '5d-check: Directory/file/file conflict due to directory rename' '
+test_expect_success '5d-check: Directory/file/file conflict due to directory rename' '
 	(
 		cd 5d &&
 
@@ -1526,7 +1526,7 @@ test_expect_success '7a-setup: rename-dir vs. rename-dir (NOT split evenly) PLUS
 	)
 '
 
-test_expect_failure '7a-check: rename-dir vs. rename-dir (NOT split evenly) PLUS add-other-file' '
+test_expect_success '7a-check: rename-dir vs. rename-dir (NOT split evenly) PLUS add-other-file' '
 	(
 		cd 7a &&
 
@@ -1597,7 +1597,7 @@ test_expect_success '7b-setup: rename/rename(2to1), but only due to transitive r
 	)
 '
 
-test_expect_failure '7b-check: rename/rename(2to1), but only due to transitive rename' '
+test_expect_success '7b-check: rename/rename(2to1), but only due to transitive rename' '
 	(
 		cd 7b &&
 
@@ -1670,7 +1670,7 @@ test_expect_success '7c-setup: rename/rename(1to...2or3); transitive rename may
 	)
 '
 
-test_expect_failure '7c-check: rename/rename(1to...2or3); transitive rename may add complexity' '
+test_expect_success '7c-check: rename/rename(1to...2or3); transitive rename may add complexity' '
 	(
 		cd 7c &&
 
@@ -1731,7 +1731,7 @@ test_expect_success '7d-setup: transitive rename involved in rename/delete; how
 	)
 '
 
-test_expect_failure '7d-check: transitive rename involved in rename/delete; how is it reported?' '
+test_expect_success '7d-check: transitive rename involved in rename/delete; how is it reported?' '
 	(
 		cd 7d &&
 
@@ -1818,7 +1818,7 @@ test_expect_success '7e-setup: transitive rename in rename/delete AND dirs in th
 	)
 '
 
-test_expect_failure '7e-check: transitive rename in rename/delete AND dirs in the way' '
+test_expect_success '7e-check: transitive rename in rename/delete AND dirs in the way' '
 	(
 		cd 7e &&
 
@@ -1904,7 +1904,7 @@ test_expect_success '8a-setup: Dual-directory rename, one into the others way' '
 	)
 '
 
-test_expect_failure '8a-check: Dual-directory rename, one into the others way' '
+test_expect_success '8a-check: Dual-directory rename, one into the others way' '
 	(
 		cd 8a &&
 
@@ -2043,7 +2043,7 @@ test_expect_success '8c-setup: rename+modify/delete' '
 	)
 '
 
-test_expect_failure '8c-check: rename+modify/delete' '
+test_expect_success '8c-check: rename+modify/delete' '
 	(
 		cd 8c &&
 
@@ -2127,7 +2127,7 @@ test_expect_success '8d-setup: rename/delete...or not?' '
 	)
 '
 
-test_expect_failure '8d-check: rename/delete...or not?' '
+test_expect_success '8d-check: rename/delete...or not?' '
 	(
 		cd 8d &&
 
@@ -2199,7 +2199,7 @@ test_expect_success '8e-setup: Both sides rename, one side adds to original dire
 	)
 '
 
-test_expect_failure '8e-check: Both sides rename, one side adds to original directory' '
+test_expect_success '8e-check: Both sides rename, one side adds to original directory' '
 	(
 		cd 8e &&
 
@@ -2286,7 +2286,7 @@ test_expect_success '9a-setup: Inner renamed directory within outer renamed dire
 	)
 '
 
-test_expect_failure '9a-check: Inner renamed directory within outer renamed directory' '
+test_expect_success '9a-check: Inner renamed directory within outer renamed directory' '
 	(
 		cd 9a &&
 
@@ -2353,7 +2353,7 @@ test_expect_success '9b-setup: Transitive rename with content merge' '
 	)
 '
 
-test_expect_failure '9b-check: Transitive rename with content merge' '
+test_expect_success '9b-check: Transitive rename with content merge' '
 	(
 		cd 9b &&
 
@@ -2442,7 +2442,7 @@ test_expect_success '9c-setup: Doubly transitive rename?' '
 	)
 '
 
-test_expect_failure '9c-check: Doubly transitive rename?' '
+test_expect_success '9c-check: Doubly transitive rename?' '
 	(
 		cd 9c &&
 
@@ -2528,7 +2528,7 @@ test_expect_success '9d-setup: N-way transitive rename?' '
 	)
 '
 
-test_expect_failure '9d-check: N-way transitive rename?' '
+test_expect_success '9d-check: N-way transitive rename?' '
 	(
 		cd 9d &&
 
@@ -2604,7 +2604,7 @@ test_expect_success '9e-setup: N-to-1 whammo' '
 	)
 '
 
-test_expect_failure '9e-check: N-to-1 whammo' '
+test_expect_success '9e-check: N-to-1 whammo' '
 	(
 		cd 9e &&
 
@@ -2679,7 +2679,7 @@ test_expect_success '9f-setup: Renamed directory that only contained immediate s
 	)
 '
 
-test_expect_failure '9f-check: Renamed directory that only contained immediate subdirs' '
+test_expect_success '9f-check: Renamed directory that only contained immediate subdirs' '
 	(
 		cd 9f &&
 
-- 
2.15.0.309.g62ce55426d

[PATCH v3 28/33] merge-recursive: avoid clobbering untracked files with directory renames

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c                   | 42 +++++++++++++++++++++++++++++++++++--
 t/t6043-merge-rename-directories.sh |  6 +++---
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 9e8f9ea3c4..cf2f087fcd 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1138,6 +1138,26 @@ static int conflict_rename_dir(struct merge_options *o,
 {
 	const struct diff_filespec *dest = pair->two;
 
+	if (!o->call_depth && would_lose_untracked(dest->path)) {
+		char *alt_path = unique_path(o, dest->path, rename_branch);
+
+		output(o, 1, _("Error: Refusing to lose untracked file at %s; "
+			       "writing to %s instead."),
+		       dest->path, alt_path);
+		/*
+		 * Write the file in worktree at alt_path, but not in the
+		 * index.  Instead, write to dest->path for the index but
+		 * only at the higher appropriate stage.
+		 */
+		if (update_file(o, 0, &dest->oid, dest->mode, alt_path))
+			return -1;
+		free(alt_path);
+		return update_stages(o, dest->path, NULL,
+				     rename_branch == o->branch1 ? dest : NULL,
+				     rename_branch == o->branch1 ? NULL : dest);
+	}
+
+	/* Update dest->path both in index and in worktree */
 	if (update_file(o, 1, &dest->oid, dest->mode, dest->path))
 		return -1;
 	return 0;
@@ -1156,7 +1176,8 @@ static int handle_change_delete(struct merge_options *o,
 	const char *update_path = path;
 	int ret = 0;
 
-	if (dir_in_way(path, !o->call_depth, 0)) {
+	if (dir_in_way(path, !o->call_depth, 0) ||
+	    (!o->call_depth && would_lose_untracked(path))) {
 		update_path = alt_path = unique_path(o, path, change_branch);
 	}
 
@@ -1282,6 +1303,12 @@ static int handle_file(struct merge_options *o,
 			dst_name = unique_path(o, rename->path, cur_branch);
 			output(o, 1, _("%s is a directory in %s adding as %s instead"),
 			       rename->path, other_branch, dst_name);
+		} else if (!o->call_depth &&
+			   would_lose_untracked(rename->path)) {
+			dst_name = unique_path(o, rename->path, cur_branch);
+			output(o, 1, _("Refusing to lose untracked file at %s; "
+				       "adding as %s instead"),
+			       rename->path, dst_name);
 		}
 	}
 	if ((ret = update_file(o, 0, &rename->oid, rename->mode, dst_name)))
@@ -1407,7 +1434,18 @@ static int conflict_rename_rename_2to1(struct merge_options *o,
 		char *new_path2 = unique_path(o, path, ci->branch2);
 		output(o, 1, _("Renaming %s to %s and %s to %s instead"),
 		       a->path, new_path1, b->path, new_path2);
-		remove_file(o, 0, path, 0);
+		if (would_lose_untracked(path))
+			/*
+			 * Only way we get here is if both renames were from
+			 * a directory rename AND user had an untracked file
+			 * at the location where both files end up after the
+			 * two directory renames.  See testcase 10d of t6043.
+			 */
+			output(o, 1, _("Refusing to lose untracked file at "
+				       "%s, even though it's in the way."),
+			       path);
+		else
+			remove_file(o, 0, path, 0);
 		ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, new_path1);
 		if (!ret)
 			ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 6efe7a45ec..915a920e1e 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -2871,7 +2871,7 @@ test_expect_success '10b-setup: Overwrite untracked with dir rename + delete' '
 	)
 '
 
-test_expect_failure '10b-check: Overwrite untracked with dir rename + delete' '
+test_expect_success '10b-check: Overwrite untracked with dir rename + delete' '
 	(
 		cd 10b &&
 
@@ -2942,7 +2942,7 @@ test_expect_success '10c-setup: Overwrite untracked with dir rename/rename(1to2)
 	)
 '
 
-test_expect_failure '10c-check: Overwrite untracked with dir rename/rename(1to2)' '
+test_expect_success '10c-check: Overwrite untracked with dir rename/rename(1to2)' '
 	(
 		cd 10c &&
 
@@ -3011,7 +3011,7 @@ test_expect_success '10d-setup: Delete untracked with dir rename/rename(2to1)' '
 	)
 '
 
-test_expect_failure '10d-check: Delete untracked with dir rename/rename(2to1)' '
+test_expect_success '10d-check: Delete untracked with dir rename/rename(2to1)' '
 	(
 		cd 10d &&
 
-- 
2.15.0.309.g62ce55426d

[PATCH v3 29/33] merge-recursive: fix overwriting dirty files involved in renames

[Elijah Newren]

This fixes an issue that existed before my directory rename detection
patches that affects both normal renames and renames implied by
directory rename detection.  Additional codepaths that only affect
overwriting of directy files that are involved in directory rename
detection will be added in a subsequent commit.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c                   | 85 ++++++++++++++++++++++++++++---------
 merge-recursive.h                   |  2 +
 t/t3501-revert-cherry-pick.sh       |  2 +-
 t/t6043-merge-rename-directories.sh |  2 +-
 t/t7607-merge-overwrite.sh          |  2 +-
 unpack-trees.c                      |  4 +-
 unpack-trees.h                      |  4 ++
 7 files changed, 77 insertions(+), 24 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index cf2f087fcd..5b4c313b40 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -334,32 +334,37 @@ static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 	init_tree_desc(desc, tree->buffer, tree->size);
 }
 
-static int git_merge_trees(int index_only,
+static int git_merge_trees(struct merge_options *o,
 			   struct tree *common,
 			   struct tree *head,
 			   struct tree *merge)
 {
 	int rc;
 	struct tree_desc t[3];
-	struct unpack_trees_options opts;
 
-	memset(&opts, 0, sizeof(opts));
-	if (index_only)
-		opts.index_only = 1;
+	memset(&o->unpack_opts, 0, sizeof(o->unpack_opts));
+	if (o->call_depth)
+		o->unpack_opts.index_only = 1;
 	else
-		opts.update = 1;
-	opts.merge = 1;
-	opts.head_idx = 2;
-	opts.fn = threeway_merge;
-	opts.src_index = &the_index;
-	opts.dst_index = &the_index;
-	setup_unpack_trees_porcelain(&opts, "merge");
+		o->unpack_opts.update = 1;
+	o->unpack_opts.merge = 1;
+	o->unpack_opts.head_idx = 2;
+	o->unpack_opts.fn = threeway_merge;
+	o->unpack_opts.src_index = &the_index;
+	o->unpack_opts.dst_index = &the_index;
+	setup_unpack_trees_porcelain(&o->unpack_opts, "merge");
 
 	init_tree_desc_from_tree(t+0, common);
 	init_tree_desc_from_tree(t+1, head);
 	init_tree_desc_from_tree(t+2, merge);
 
-	rc = unpack_trees(3, t, &opts);
+	rc = unpack_trees(3, t, &o->unpack_opts);
+	/*
+	 * unpack_trees NULLifies src_index, but it's used in verify_uptodate,
+	 * so set to the new index which will usually have modification
+	 * timestamp info copied over.
+	 */
+	o->unpack_opts.src_index = &the_index;
 	cache_tree_free(&active_cache_tree);
 	return rc;
 }
@@ -792,6 +797,20 @@ static int would_lose_untracked(const char *path)
 	return !was_tracked(path) && file_exists(path);
 }
 
+static int was_dirty(struct merge_options *o, const char *path)
+{
+	struct cache_entry *ce;
+	int dirty = 1;
+
+	if (o->call_depth || !was_tracked(path))
+		return !dirty;
+
+	ce = cache_file_exists(path, strlen(path), ignore_case);
+	dirty = (ce->ce_stat_data.sd_mtime.sec > 0 &&
+		 verify_uptodate(ce, &o->unpack_opts) != 0);
+	return dirty;
+}
+
 static int make_room_for_path(struct merge_options *o, const char *path)
 {
 	int status, i;
@@ -2657,6 +2676,7 @@ static int handle_modify_delete(struct merge_options *o,
 
 static int merge_content(struct merge_options *o,
 			 const char *path,
+			 int file_in_way,
 			 struct object_id *o_oid, int o_mode,
 			 struct object_id *a_oid, int a_mode,
 			 struct object_id *b_oid, int b_mode,
@@ -2731,7 +2751,7 @@ static int merge_content(struct merge_options *o,
 				return -1;
 	}
 
-	if (df_conflict_remains) {
+	if (df_conflict_remains || file_in_way) {
 		char *new_path;
 		if (o->call_depth) {
 			remove_file_from_cache(path);
@@ -2765,6 +2785,30 @@ static int merge_content(struct merge_options *o,
 	return mfi.clean;
 }
 
+static int conflict_rename_normal(struct merge_options *o,
+				  const char *path,
+				  struct object_id *o_oid, unsigned int o_mode,
+				  struct object_id *a_oid, unsigned int a_mode,
+				  struct object_id *b_oid, unsigned int b_mode,
+				  struct rename_conflict_info *ci)
+{
+	int clean_merge;
+	int file_in_the_way = 0;
+
+	if (was_dirty(o, path)) {
+		file_in_the_way = 1;
+		output(o, 1, _("Refusing to lose dirty file at %s"), path);
+	}
+
+	/* Merge the content and write it out */
+	clean_merge = merge_content(o, path, file_in_the_way,
+				    o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
+				    ci);
+	if (clean_merge > 0 && file_in_the_way)
+		clean_merge = 0;
+	return clean_merge;
+}
+
 /* Per entry merge function */
 static int process_entry(struct merge_options *o,
 			 const char *path, struct stage_data *entry)
@@ -2784,9 +2828,12 @@ static int process_entry(struct merge_options *o,
 		switch (conflict_info->rename_type) {
 		case RENAME_NORMAL:
 		case RENAME_ONE_FILE_TO_ONE:
-			clean_merge = merge_content(o, path,
-						    o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
-						    conflict_info);
+			clean_merge = conflict_rename_normal(o,
+							     path,
+							     o_oid, o_mode,
+							     a_oid, a_mode,
+							     b_oid, b_mode,
+							     conflict_info);
 			break;
 		case RENAME_DIR:
 			clean_merge = 1;
@@ -2881,7 +2928,7 @@ static int process_entry(struct merge_options *o,
 	} else if (a_oid && b_oid) {
 		/* Case C: Added in both (check for same permissions) and */
 		/* case D: Modified in both, but differently. */
-		clean_merge = merge_content(o, path,
+		clean_merge = merge_content(o, path, 0 /* file_in_way */,
 					    o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
 					    NULL);
 	} else if (!o_oid && !a_oid && !b_oid) {
@@ -2915,7 +2962,7 @@ int merge_trees(struct merge_options *o,
 		return 1;
 	}
 
-	code = git_merge_trees(o->call_depth, common, head, merge);
+	code = git_merge_trees(o, common, head, merge);
 
 	if (code != 0) {
 		if (show(o, 4) || o->call_depth)
diff --git a/merge-recursive.h b/merge-recursive.h
index e02c1e1243..591b824a98 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -1,6 +1,7 @@
 #ifndef MERGE_RECURSIVE_H
 #define MERGE_RECURSIVE_H
 
+#include "unpack-trees.h"
 #include "string-list.h"
 
 struct merge_options {
@@ -27,6 +28,7 @@ struct merge_options {
 	struct strbuf obuf;
 	struct hashmap current_file_dir_set;
 	struct string_list df_conflict_file_set;
+	struct unpack_trees_options unpack_opts;
 };
 
 struct dir_rename_entry {
diff --git a/t/t3501-revert-cherry-pick.sh b/t/t3501-revert-cherry-pick.sh
index 783bdbf59d..0d89f6d0f6 100755
--- a/t/t3501-revert-cherry-pick.sh
+++ b/t/t3501-revert-cherry-pick.sh
@@ -141,7 +141,7 @@ test_expect_success 'cherry-pick "-" works with arguments' '
 	test_cmp expect actual
 '
 
-test_expect_failure 'cherry-pick works with dirty renamed file' '
+test_expect_success 'cherry-pick works with dirty renamed file' '
 	test_commit to-rename &&
 	git checkout -b unrelated &&
 	test_commit unrelated &&
diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 915a920e1e..8c2faeb342 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -3155,7 +3155,7 @@ test_expect_success '11a-setup: Avoid losing dirty contents with simple rename'
 	)
 '
 
-test_expect_failure '11a-check: Avoid losing dirty contents with simple rename' '
+test_expect_success '11a-check: Avoid losing dirty contents with simple rename' '
 	(
 		cd 11a &&
 
diff --git a/t/t7607-merge-overwrite.sh b/t/t7607-merge-overwrite.sh
index 00617dadf8..e44fb50173 100755
--- a/t/t7607-merge-overwrite.sh
+++ b/t/t7607-merge-overwrite.sh
@@ -92,7 +92,7 @@ test_expect_success 'will not overwrite removed file with staged changes' '
 	test_cmp important c1.c
 '
 
-test_expect_failure 'will not overwrite unstaged changes in renamed file' '
+test_expect_success 'will not overwrite unstaged changes in renamed file' '
 	git reset --hard c1 &&
 	git mv c1.c other.c &&
 	git commit -m rename &&
diff --git a/unpack-trees.c b/unpack-trees.c
index 25740cb593..b8146728d3 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -1484,8 +1484,8 @@ static int verify_uptodate_1(const struct cache_entry *ce,
 		add_rejected_path(o, error_type, ce->name);
 }
 
-static int verify_uptodate(const struct cache_entry *ce,
-			   struct unpack_trees_options *o)
+int verify_uptodate(const struct cache_entry *ce,
+		    struct unpack_trees_options *o)
 {
 	if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
 		return 0;
diff --git a/unpack-trees.h b/unpack-trees.h
index 6c48117b84..41178ada94 100644
--- a/unpack-trees.h
+++ b/unpack-trees.h
@@ -1,6 +1,7 @@
 #ifndef UNPACK_TREES_H
 #define UNPACK_TREES_H
 
+#include "tree-walk.h"
 #include "string-list.h"
 
 #define MAX_UNPACK_TREES 8
@@ -78,6 +79,9 @@ struct unpack_trees_options {
 extern int unpack_trees(unsigned n, struct tree_desc *t,
 		struct unpack_trees_options *options);
 
+int verify_uptodate(const struct cache_entry *ce,
+		    struct unpack_trees_options *o);
+
 int threeway_merge(const struct cache_entry * const *stages,
 		   struct unpack_trees_options *o);
 int twoway_merge(const struct cache_entry * const *src,
-- 
2.15.0.309.g62ce55426d

[PATCH v3 30/33] merge-recursive: fix remaining directory rename + dirty overwrite cases

[Elijah Newren]

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c                   | 26 +++++++++++++++++++++++---
 t/t6043-merge-rename-directories.sh |  8 ++++----
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 5b4c313b40..eaa50e6413 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1311,11 +1311,23 @@ static int handle_file(struct merge_options *o,
 
 	add = filespec_from_entry(&other, dst_entry, stage ^ 1);
 	if (add) {
+		int ren_src_was_dirty = was_dirty(o, rename->path);
 		char *add_name = unique_path(o, rename->path, other_branch);
 		if (update_file(o, 0, &add->oid, add->mode, add_name))
 			return -1;
 
-		remove_file(o, 0, rename->path, 0);
+		if (ren_src_was_dirty) {
+			output(o, 1, _("Refusing to lose dirty file at %s"),
+			       rename->path);
+		}
+		/*
+		 * Stupid double negatives in remove_file; it somehow manages
+		 * to repeatedly mess me up.  So, just for myself:
+		 *    1) update_wd iff !ren_src_was_dirty.
+		 *    2) no_wd iff !update_wd
+		 *    3) so, no_wd == !!ren_src_was_dirty == ren_src_was_dirty
+		 */
+		remove_file(o, 0, rename->path, ren_src_was_dirty);
 		dst_name = unique_path(o, rename->path, cur_branch);
 	} else {
 		if (dir_in_way(rename->path, !o->call_depth, 0)) {
@@ -1453,7 +1465,10 @@ static int conflict_rename_rename_2to1(struct merge_options *o,
 		char *new_path2 = unique_path(o, path, ci->branch2);
 		output(o, 1, _("Renaming %s to %s and %s to %s instead"),
 		       a->path, new_path1, b->path, new_path2);
-		if (would_lose_untracked(path))
+		if (was_dirty(o, path))
+			output(o, 1, _("Refusing to lose dirty file at %s"),
+			       path);
+		else if (would_lose_untracked(path))
 			/*
 			 * Only way we get here is if both renames were from
 			 * a directory rename AND user had an untracked file
@@ -2039,6 +2054,7 @@ static void apply_directory_rename_modifications(struct merge_options *o,
 {
 	struct string_list_item *item;
 	int stage = (tree == a_tree ? 2 : 3);
+	int update_wd;
 
 	/*
 	 * In all cases where we can do directory rename detection,
@@ -2049,7 +2065,11 @@ static void apply_directory_rename_modifications(struct merge_options *o,
 	 * saying the file would have been overwritten), but it might
 	 * be dirty, though.
 	 */
-	remove_file(o, 1, pair->two->path, 0 /* no_wd */);
+	update_wd = !was_dirty(o, pair->two->path);
+	if (!update_wd)
+		output(o, 1, _("Refusing to lose dirty file at %s"),
+		       pair->two->path);
+	remove_file(o, 1, pair->two->path, !update_wd);
 
 	/* Find or create a new re->dst_entry */
 	item = string_list_lookup(entries, new_path);
diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 8c2faeb342..e48d5443c5 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -3222,7 +3222,7 @@ test_expect_success '11b-setup: Avoid losing dirty file involved in directory re
 	)
 '
 
-test_expect_failure '11b-check: Avoid losing dirty file involved in directory rename' '
+test_expect_success '11b-check: Avoid losing dirty file involved in directory rename' '
 	(
 		cd 11b &&
 
@@ -3356,7 +3356,7 @@ test_expect_success '11d-setup: Avoid losing not-uptodate with rename + D/F conf
 	)
 '
 
-test_expect_failure '11d-check: Avoid losing not-uptodate with rename + D/F conflict' '
+test_expect_success '11d-check: Avoid losing not-uptodate with rename + D/F conflict' '
 	(
 		cd 11d &&
 
@@ -3430,7 +3430,7 @@ test_expect_success '11e-setup: Avoid deleting not-uptodate with dir rename/rena
 	)
 '
 
-test_expect_failure '11e-check: Avoid deleting not-uptodate with dir rename/rename(1to2)/add' '
+test_expect_success '11e-check: Avoid deleting not-uptodate with dir rename/rename(1to2)/add' '
 	(
 		cd 11e &&
 
@@ -3504,7 +3504,7 @@ test_expect_success '11f-setup: Avoid deleting not-uptodate with dir rename/rena
 	)
 '
 
-test_expect_failure '11f-check: Avoid deleting not-uptodate with dir rename/rename(2to1)' '
+test_expect_success '11f-check: Avoid deleting not-uptodate with dir rename/rename(2to1)' '
 	(
 		cd 11f &&
 
-- 
2.15.0.309.g62ce55426d

[PATCH v3 31/33] directory rename detection: new testcases showcasing a pair of bugs

[Elijah Newren]

Add a testcase showing spurious rename/rename(1to2) conflicts occurring
due to directory rename detection.

Also add a pair of testcases dealing with moving directory hierarchies
around that were suggested by Stefan Beller as "food for thought" during
his review of an earlier patch series, but which actually uncovered a
bug.  Round things out with a test that is a cross between the two
testcases that showed existing bugs in order to make sure we aren't
merely addressing problems in isolation but in general.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t6043-merge-rename-directories.sh | 284 ++++++++++++++++++++++++++++++++++++
 1 file changed, 284 insertions(+)

diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index e48d5443c5..224d266695 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -153,6 +153,7 @@ test_expect_success '1b-check: Merge a directory with another' '
 # Testcase 1c, Transitive renaming
 #   (Related to testcases 3a and 6d -- when should a transitive rename apply?)
 #   (Related to testcases 9c and 9d -- can transitivity repeat?)
+#   (Related to testcase 12b -- joint-transitivity?)
 #   Commit O: z/{b,c},   x/d
 #   Commit A: y/{b,c},   x/d
 #   Commit B: z/{b,c,d}
@@ -2758,6 +2759,67 @@ test_expect_failure '9g-check: Renamed directory that only contained immediate s
 	)
 '
 
+# Testcase 9h, Avoid implicit rename if involved as source on other side
+#   (Extremely closely related to testcase 3a)
+#   Commit O: z/{b,c,d_1}
+#   Commit A: z/{b,c,d_2}
+#   Commit B: y/{b,c}, x/d_1
+#   Expected: y/{b,c}, x/d_2
+#   NOTE: If we applied the z/ -> y/ rename to z/d, then we'd end up with
+#         a rename/rename(1to2) conflict (z/d -> y/d vs. x/d)
+test_expect_success '9h-setup: Avoid dir rename on merely modified path' '
+	test_create_repo 9h &&
+	(
+		cd 9h &&
+
+		mkdir z &&
+		echo b >z/b &&
+		echo c >z/c &&
+		printf "1\n2\n3\n4\n5\n6\n7\n8\nd\n" >z/d &&
+		git add z &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		test_tick &&
+		echo more >>z/d &&
+		git add z/d &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		mkdir y &&
+		mkdir x &&
+		git mv z/b y/ &&
+		git mv z/c y/ &&
+		git mv z/d x/ &&
+		rmdir z &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '9h-check: Avoid dir rename on merely modified path' '
+	(
+		cd 9h &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 3 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:y/b HEAD:y/c HEAD:x/d &&
+		git rev-parse >expect \
+			O:z/b O:z/c A:z/d &&
+		test_cmp expect actual
+	)
+'
+
 ###########################################################################
 # Rules suggested by section 9:
 #
@@ -3539,4 +3601,226 @@ test_expect_success '11f-check: Avoid deleting not-uptodate with dir rename/rena
 	)
 '
 
+###########################################################################
+# SECTION 12: Everything else
+#
+# Tests suggested by others.  Tests added after implementation completed
+# and submitted.  Grab bag.
+###########################################################################
+
+# Testcase 12a, Moving one directory hierarchy into another
+#   (Related to testcase 9a)
+#   Commit O: node1/{leaf1,leaf2}, node2/{leaf3,leaf4}
+#   Commit A: node1/{leaf1,leaf2,node2/{leaf3,leaf4}}
+#   Commit B: node1/{leaf1,leaf2,leaf5}, node2/{leaf3,leaf4,leaf6}
+#   Expected: node1/{leaf1,leaf2,leaf5,node2/{leaf3,leaf4,leaf6}}
+
+test_expect_success '12a-setup: Moving one directory hierarchy into another' '
+	test_create_repo 12a &&
+	(
+		cd 12a &&
+
+		mkdir -p node1 node2 &&
+		echo leaf1 >node1/leaf1 &&
+		echo leaf2 >node1/leaf2 &&
+		echo leaf3 >node2/leaf3 &&
+		echo leaf4 >node2/leaf4 &&
+		git add node1 node2 &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv node2/ node1/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		echo leaf5 >node1/leaf5 &&
+		echo leaf6 >node2/leaf6 &&
+		git add node1 node2 &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_success '12a-check: Moving one directory hierarchy into another' '
+	(
+		cd 12a &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 6 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:node1/leaf1 HEAD:node1/leaf2 HEAD:node1/leaf5 HEAD:node1/node2/leaf3 HEAD:node1/node2/leaf4 HEAD:node1/node2/leaf6 &&
+		git rev-parse >expect \
+			O:node1/leaf1 O:node1/leaf2 B:node1/leaf5 O:node2/leaf3 O:node2/leaf4 B:node2/leaf6 &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 12b, Moving two directory hierarchies into each other
+#   (Related to testcases 1c and 12c)
+#   Commit O: node1/{leaf1, leaf2}, node2/{leaf3, leaf4}
+#   Commit A: node1/{leaf1, leaf2, node2/{leaf3, leaf4}}
+#   Commit B: node2/{leaf3, leaf4, node1/{leaf1, leaf2}}
+#   Expected: node1/node2/node1/{leaf1, leaf2},
+#             node2/node1/node2/{leaf3, leaf4}
+#   NOTE: Without directory renames, we would expect
+#                   node2/node1/{leaf1, leaf2},
+#                   node1/node2/{leaf3, leaf4}
+#         with directory rename detection, we note that
+#             commit A renames node2/ -> node1/node2/
+#             commit B renames node1/ -> node2/node1/
+#         therefore, applying those directory renames to the initial result
+#         (making all four paths experience a transitive renaming), yields
+#         the expected result.
+#
+#         You may ask, is it weird to have two directories rename each other?
+#         To which, I can do no more than shrug my shoulders and say that
+#         even simple rules give weird results when given weird inputs.
+
+test_expect_success '12b-setup: Moving one directory hierarchy into another' '
+	test_create_repo 12b &&
+	(
+		cd 12b &&
+
+		mkdir -p node1 node2 &&
+		echo leaf1 >node1/leaf1 &&
+		echo leaf2 >node1/leaf2 &&
+		echo leaf3 >node2/leaf3 &&
+		echo leaf4 >node2/leaf4 &&
+		git add node1 node2 &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv node2/ node1/ &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv node1/ node2/ &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '12b-check: Moving one directory hierarchy into another' '
+	(
+		cd 12b &&
+
+		git checkout A^0 &&
+
+		git merge -s recursive B^0 &&
+
+		test 4 -eq $(git ls-files -s | wc -l) &&
+
+		git rev-parse >actual \
+			HEAD:node1/node2/node1/leaf1 \
+			HEAD:node1/node2/node1/leaf2 \
+			HEAD:node2/node1/node2/leaf3 \
+			HEAD:node2/node1/node2/leaf4 &&
+		git rev-parse >expect \
+			O:node1/leaf1 O:node1/leaf2 \
+			O:node2/leaf3 O:node2/leaf4 &&
+		test_cmp expect actual
+	)
+'
+
+# Testcase 12c, Moving two directory hierarchies into each other w/ content merge
+#   (Related to testcase 12b)
+#   Commit O: node1/{       leaf1_1, leaf2_1}, node2/{leaf3_1, leaf4_1}
+#   Commit A: node1/{       leaf1_2, leaf2_2,  node2/{leaf3_2, leaf4_2}}
+#   Commit B: node2/{node1/{leaf1_3, leaf2_3},        leaf3_3, leaf4_3}
+#   Expected: Content merge conflicts for each of:
+#               node1/node2/node1/{leaf1, leaf2},
+#               node2/node1/node2/{leaf3, leaf4}
+#   NOTE: This is *exactly* like 12c, except that every path is modified on
+#         each side of the merge.
+
+test_expect_success '12c-setup: Moving one directory hierarchy into another w/ content merge' '
+	test_create_repo 12c &&
+	(
+		cd 12c &&
+
+		mkdir -p node1 node2 &&
+		printf "1\n2\n3\n4\n5\n6\n7\n8\nleaf1\n" >node1/leaf1 &&
+		printf "1\n2\n3\n4\n5\n6\n7\n8\nleaf2\n" >node1/leaf2 &&
+		printf "1\n2\n3\n4\n5\n6\n7\n8\nleaf3\n" >node2/leaf3 &&
+		printf "1\n2\n3\n4\n5\n6\n7\n8\nleaf4\n" >node2/leaf4 &&
+		git add node1 node2 &&
+		test_tick &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git checkout A &&
+		git mv node2/ node1/ &&
+		for i in `git ls-files`; do echo side A >>$i; done &&
+		git add -u &&
+		test_tick &&
+		git commit -m "A" &&
+
+		git checkout B &&
+		git mv node1/ node2/ &&
+		for i in `git ls-files`; do echo side B >>$i; done &&
+		git add -u &&
+		test_tick &&
+		git commit -m "B"
+	)
+'
+
+test_expect_failure '12c-check: Moving one directory hierarchy into another w/ content merge' '
+	(
+		cd 12c &&
+
+		git checkout A^0 &&
+
+		test_must_fail git merge -s recursive B^0 &&
+
+		test 12 -eq $(git ls-files -u | wc -l) &&
+
+		git rev-parse >actual \
+			:1:node1/node2/node1/leaf1 \
+			:1:node1/node2/node1/leaf2 \
+			:1:node2/node1/node2/leaf3 \
+			:1:node2/node1/node2/leaf4 \
+			:2:node1/node2/node1/leaf1 \
+			:2:node1/node2/node1/leaf2 \
+			:2:node2/node1/node2/leaf3 \
+			:2:node2/node1/node2/leaf4 \
+			:3:node1/node2/node1/leaf1 \
+			:3:node1/node2/node1/leaf2 \
+			:3:node2/node1/node2/leaf3 \
+			:3:node2/node1/node2/leaf4 &&
+		git rev-parse >expect \
+			O:node1/leaf1 \
+			O:node1/leaf2 \
+			O:node2/leaf3 \
+			O:node2/leaf4 \
+			A:node1/leaf1 \
+			A:node1/leaf2 \
+			A:node1/node2/leaf3 \
+			A:node1/node2/leaf4 \
+			B:node2/node1/leaf1 \
+			B:node2/node1/leaf2 \
+			B:node2/leaf3 \
+			B:node2/leaf4 &&
+		test_cmp expect actual
+	)
+'
+
 test_done
-- 
2.15.0.309.g62ce55426d

[PATCH v3 32/33] merge-recursive: avoid spurious rename/rename conflict from dir renames

[Elijah Newren]

If a file on one side of history was renamed, and merely modified on the
other side, then applying a directory rename to the modified side gives us
a rename/rename(1to2) conflict.  We should only apply directory renames to
pairs representing either adds or renames.

Making this change means that a directory rename testcase that was
previously reported as a rename/delete conflict will now be reported as a
modify/delete conflict.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c                   |  4 +--
 t/t6043-merge-rename-directories.sh | 55 +++++++++++++++++--------------------
 2 files changed, 27 insertions(+), 32 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index eaa50e6413..65cc997e93 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1957,7 +1957,7 @@ static void compute_collisions(struct hashmap *collisions,
 		char *new_path;
 		struct diff_filepair *pair = pairs->queue[i];
 
-		if (pair->status == 'D')
+		if (pair->status == 'D' || pair->status == 'M')
 			continue;
 		dir_rename_ent = check_dir_renamed(pair->two->path,
 						   dir_renames);
@@ -2184,7 +2184,7 @@ static struct string_list *get_renames(struct merge_options *o,
 		struct diff_filepair *pair = pairs->queue[i];
 		char *new_path; /* non-NULL only with directory renames */
 
-		if (pair->status == 'D') {
+		if (pair->status == 'D' || pair->status == 'M') {
 			diff_free_filepair(pair);
 			continue;
 		}
diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 224d266695..119d7f5d70 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -2000,18 +2000,23 @@ test_expect_success '8b-check: Dual-directory rename, one into the others way, w
 	)
 '
 
-# Testcase 8c, rename+modify/delete
-#   (Related to testcases 5b and 8d)
+# Testcase 8c, modify/delete or rename+modify/delete?
+#   (Related to testcases 5b, 8d, and 9h)
 #   Commit O: z/{b,c,d}
 #   Commit A: y/{b,c}
 #   Commit B: z/{b,c,d_modified,e}
-#   Expected: y/{b,c,e}, CONFLICT(rename+modify/delete: x/d -> y/d or deleted)
+#   Expected: y/{b,c,e}, CONFLICT(modify/delete: on z/d)
 #
-#   Note: This testcase doesn't present any concerns for me...until you
-#         compare it with testcases 5b and 8d.  See notes in 8d for more
-#         details.
-
-test_expect_success '8c-setup: rename+modify/delete' '
+#   Note: It could easily be argued that the correct resolution here is
+#         y/{b,c,e}, CONFLICT(rename/delete: z/d -> y/d vs deleted)
+#         and that the modifed version of d should be present in y/ after
+#         the merge, just marked as conflicted.  Indeed, I previously did
+#         argue that.  But applying directory renames to the side of
+#         history where a file is merely modified results in spurious
+#         rename/rename(1to2) conflicts -- see testcase 9h.  See also
+#         notes in 8d.
+
+test_expect_success '8c-setup: modify/delete or rename+modify/delete?' '
 	test_create_repo 8c &&
 	(
 		cd 8c &&
@@ -2044,29 +2049,29 @@ test_expect_success '8c-setup: rename+modify/delete' '
 	)
 '
 
-test_expect_success '8c-check: rename+modify/delete' '
+test_expect_success '8c-check: modify/delete or rename+modify/delete' '
 	(
 		cd 8c &&
 
 		git checkout A^0 &&
 
 		test_must_fail git merge -s recursive B^0 >out &&
-		test_i18ngrep "CONFLICT (rename/delete).* z/d.*y/d" out &&
+		test_i18ngrep "CONFLICT (modify/delete).* z/d" out &&
 
-		test 4 -eq $(git ls-files -s | wc -l) &&
-		test 1 -eq $(git ls-files -u | wc -l) &&
+		test 5 -eq $(git ls-files -s | wc -l) &&
+		test 2 -eq $(git ls-files -u | wc -l) &&
 		test 1 -eq $(git ls-files -o | wc -l) &&
 
 		git rev-parse >actual \
-			:0:y/b :0:y/c :0:y/e :3:y/d &&
+			:0:y/b :0:y/c :0:y/e :1:z/d :3:z/d &&
 		git rev-parse >expect \
-			O:z/b O:z/c B:z/e B:z/d &&
+			O:z/b O:z/c B:z/e O:z/d B:z/d &&
 		test_cmp expect actual &&
 
-		test_must_fail git rev-parse :1:y/d &&
-		test_must_fail git rev-parse :2:y/d &&
-		git ls-files -s y/d | grep ^100755 &&
-		test -f y/d
+		test_must_fail git rev-parse :2:z/d &&
+		git ls-files -s z/d | grep ^100755 &&
+		test -f z/d &&
+		! test -f y/d
 	)
 '
 
@@ -2080,16 +2085,6 @@ test_expect_success '8c-check: rename+modify/delete' '
 #
 #   Note: It would also be somewhat reasonable to resolve this as
 #             y/{b,c,e}, CONFLICT(rename/delete: x/d -> y/d or deleted)
-#   The logic being that the only difference between this testcase and 8c
-#   is that there is no modification to d.  That suggests that instead of a
-#   rename/modify vs. delete conflict, we should just have a rename/delete
-#   conflict, otherwise we are being inconsistent.
-#
-#   However...as far as consistency goes, we didn't report a conflict for
-#   path d_1 in testcase 5b due to a different file being in the way.  So,
-#   we seem to be forced to have cases where users can change things
-#   slightly and get what they may perceive as inconsistent results.  It
-#   would be nice to avoid that, but I'm not sure I see how.
 #
 #   In this case, I'm leaning towards: commit A was the one that deleted z/d
 #   and it did the rename of z to y, so the two "conflicts" (rename vs.
@@ -2802,7 +2797,7 @@ test_expect_success '9h-setup: Avoid dir rename on merely modified path' '
 	)
 '
 
-test_expect_failure '9h-check: Avoid dir rename on merely modified path' '
+test_expect_success '9h-check: Avoid dir rename on merely modified path' '
 	(
 		cd 9h &&
 
@@ -3783,7 +3778,7 @@ test_expect_success '12c-setup: Moving one directory hierarchy into another w/ c
 	)
 '
 
-test_expect_failure '12c-check: Moving one directory hierarchy into another w/ content merge' '
+test_expect_success '12c-check: Moving one directory hierarchy into another w/ content merge' '
 	(
 		cd 12c &&
 
-- 
2.15.0.309.g62ce55426d

[PATCH v3 33/33] merge-recursive: ensure we write updates for directory-renamed file

[Elijah Newren]

When a file is present in HEAD before the merge and the other side of the
merge does not modify that file, we try to avoid re-writing the file and
making it stat-dirty.  However, when a file is present in HEAD before the
merge and was in a directory that was renamed by the other side of the
merge, we have to move the file to a new location and re-write it.
Update the code that checks whether we can skip the update to also work in
the presence of directory renames.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c                   | 4 +---
 t/t6043-merge-rename-directories.sh | 2 +-
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 65cc997e93..9349eb4391 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -2744,7 +2744,6 @@ static int merge_content(struct merge_options *o,
 
 	if (mfi.clean && !df_conflict_remains &&
 	    oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
-		int path_renamed_outside_HEAD;
 		output(o, 3, _("Skipped %s (merged same as existing)"), path);
 		/*
 		 * The content merge resulted in the same file contents we
@@ -2752,8 +2751,7 @@ static int merge_content(struct merge_options *o,
 		 * are recorded at the correct path (which may not be true
 		 * if the merge involves a rename).
 		 */
-		path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
-		if (!path_renamed_outside_HEAD) {
+		if (was_tracked(path)) {
 			add_cacheinfo(o, mfi.mode, &mfi.oid, path,
 				      0, (!o->call_depth), 0);
 			return mfi.clean;
diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
index 119d7f5d70..f1538087ca 100755
--- a/t/t6043-merge-rename-directories.sh
+++ b/t/t6043-merge-rename-directories.sh
@@ -3711,7 +3711,7 @@ test_expect_success '12b-setup: Moving one directory hierarchy into another' '
 	)
 '
 
-test_expect_failure '12b-check: Moving one directory hierarchy into another' '
+test_expect_success '12b-check: Moving one directory hierarchy into another' '
 	(
 		cd 12b &&
 
-- 
2.15.0.309.g62ce55426d

Re: [PATCH v3 00/33] Add directory rename detection to git

[Stefan Beller]

On Tue, Nov 21, 2017 at 12:00 AM, Elijah Newren <newren@gmail.com> wrote:
> This patchset introduces directory rename detection to merge-recursive; I'm
> resubmitting just a few hours after my PATCHv2 because I didn't know about
> the DEVELOPER=1 flag previously, and my code had a number of
> warnings/errors.  I would have just submitted fixup/squash patches, but
> when I checked, there sadly they cause merge conflicts when rebasing
>
> See https://public-inbox.org/git/20171110190550.27059-1-newren@gmail.com/
> for the first series, design considerations, etc, and
> https://public-inbox.org/git/20171120220209.15111-1-newren@gmail.com/ for
> v2.

Thanks, I'll take a look!

Protip: To make it easy for reviewers add an interdiff[1] between the different
versions of the patch series, this can be done via tbdiff[2] for example,
or in case you still have the old branch around or Junio has it queued already,
you can do a diff against that branch.

I just looked through recent cover letters and it doesn't seem to be common
(any more?), or just not suitable for the series currently in flight.

[1] for example
https://public-inbox.org/git/20171116020039.17810-1-sbeller@google.com/
[2] https://github.com/trast/tbdiff

Stefan

Re: [PATCH v3 00/33] Add directory rename detection to git

[Elijah Newren]

On Tue, Nov 21, 2017 at 4:42 PM, Stefan Beller <sbeller@google.com> wrote:
> On Tue, Nov 21, 2017 at 12:00 AM, Elijah Newren <newren@gmail.com> wrote:
>> This patchset introduces directory rename detection to merge-recursive; I'm
>> resubmitting just a few hours after my PATCHv2 because I didn't know about
>> the DEVELOPER=1 flag previously, and my code had a number of
>> warnings/errors.  I would have just submitted fixup/squash patches, but
>> when I checked, there sadly they cause merge conflicts when rebasing
>>
>> See https://public-inbox.org/git/20171110190550.27059-1-newren@gmail.com/
>> for the first series, design considerations, etc, and
>> https://public-inbox.org/git/20171120220209.15111-1-newren@gmail.com/ for
>> v2.
>
> Thanks, I'll take a look!
>
> Protip: To make it easy for reviewers add an interdiff[1] between the different
> versions of the patch series, this can be done via tbdiff[2] for example,
> or in case you still have the old branch around or Junio has it queued already,
> you can do a diff against that branch.

Thanks!

Interesting; tbdiff looks cool.  Junio hasn't queued this series yet,
but it's easy enough to reconstruct the old one.  It does weigh in
pretty heavy, and I'm slighly worried about gmail mangling all the
lines, but I'm going to give it a shot anyway.  If it's too mangled,
I'll try to repost using git-send-email.  It does weigh in at over
1600 lines, so it's not small.


$ git tbdiff --no-color v2.15.0..detect-directory-renames-v1
origin/master..detect-directory-renames
 1: 054c9c1a76 !  1: a0abcb1378 Tighten and correct a few testcases
for merging and cherry-picking
    @@ -2,18 +2,21 @@

         Tighten and correct a few testcases for merging and cherry-picking

    -    t3501 had a testcase originally added to ensure cherry-pick wouldn't
    -    segfault when working with a dirty file involved in a rename.  While
    -    the segfault was fixed, there was another problem this test
demonstrated:
    -    namely, that git would overwrite a dirty file involved in a rename.
    -    Further, the test encoded a "successful merge" and overwriting of this
    -    file as correct behavior.  Modify the test so that it would still catch
    -    the segfault, but to require the correct behavior.
    +    t3501 had a testcase originally added in 05f2dfb965 (cherry-pick:
    +    demonstrate a segmentation fault, 2016-11-26) to ensure cherry-pick
    +    wouldn't segfault when working with a dirty file involved in a rename.
    +    While the segfault was fixed, there was another problem this test
    +    demonstrated: namely, that git would overwrite a dirty file
involved in a
    +    rename.  Further, the test encoded a "successful merge" and
overwriting of
    +    this file as correct behavior.  Modify the test so that it would still
    +    catch the segfault, but to require the correct behavior.  Mark it as
    +    test_expect_failure for now too, since this second bug is not
yet fixed.

    -    t7607 had a test specific to looking for a merge overwriting
a dirty file
    -    involved in a rename, but it too actually encoded what I would term
    -    incorrect behavior: it expected the merge to succeed.  Fix
that, and add
    -    a few more checks to make sure that the merge really does produce the
    +    t7607 had a test added in 30fd3a5425 (merge overwrites
unstaged changes in
    +    renamed file, 2012-04-15) specific to looking for a merge overwriting a
    +    dirty file involved in a rename, but it too actually encoded
what I would
    +    term incorrect behavior: it expected the merge to succeed.
Fix that, and
    +    add a few more checks to make sure that the merge really does
produce the
         expected results.

         Signed-off-by: Elijah Newren <newren@gmail.com>
 2: 80e8d435ad !  2: e8745c4f1b merge-recursive: fix logic ordering issue
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Fix logic ordering issue
    +    merge-recursive: fix logic ordering issue

         merge_trees() did a variety of work, including:
           * Calling get_unmerged() to get unmerged entries
 3: 2714320c37 !  3: 0ae4156994 merge-recursive: add explanation for
src_entry and dst_entry
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Add explanation for src_entry and dst_entry
    +    merge-recursive: add explanation for src_entry and dst_entry

         If I have to walk through the debugger and inspect the values found in
         here in order to figure out their meaning, despite having known these
    @@ -17,17 +17,14 @@
      struct rename {
          struct diff_filepair *pair;
     +    /*
    -+     * Because I keep forgetting every few years what src_entry and
    -+     * dst_entry are and have to walk through a debugger and puzzle
    -+     * through it to remind myself...
    ++     * Purpose of src_entry and dst_entry:
     +     *
     +     * If 'before' is renamed to 'after' then src_entry will contain
     +     * the versions of 'before' from the merge_base, HEAD, and MERGE in
    -+     * stages 1, 2, and 3; dst_entry will contain the versions of
    -+     * 'after' from the merge_base, HEAD, and MERGE in stages 1, 2, and
    -+     * 3.  Thus, we have a total of six modes and oids, though some
    -+     * will be null.  (Stage 0 is ignored; we're interested in handling
    -+     * conflicts.)
    ++     * stages 1, 2, and 3; dst_entry will contain the respective
    ++     * versions of 'after' in corresponding locations.  Thus, we have a
    ++     * total of six modes and oids, though some will be null.  (Stage 0
    ++     * is ignored; we're interested in handling conflicts.)
     +     *
     +     * Since we don't turn on break-rewrites by default, neither
     +     * src_entry nor dst_entry can have all three of their stages have
 4: 990ee6d921 < --:  ------- directory rename detection: basic testcases
 5: 4d2ec7d534 < --:  ------- directory rename detection: directory
splitting testcases
 6: 407a9b04fc < --:  ------- directory rename detection: testcases to
avoid taking detection too far
--:  ------- >  4: f13686ea6a directory rename detection: basic testcases
--:  ------- >  5: 16e7dea569 directory rename detection: directory
splitting testcases
--:  ------- >  6: 51d9a5b059 directory rename detection: testcases to
avoid taking detection too far
 7: ca6b39d08d !  7: 4b39f6bea3 directory rename detection: partially
renamed directory testcase/discussion
    @@ -45,60 +45,64 @@
     +
     +# Testcase 4a, Directory split, with original directory still present
     +#   (Related to testcase 1f)
    -+#   Commit A: z/{b,c,d,e}
    -+#   Commit B: y/{b,c,d}, z/e
    -+#   Commit C: z/{b,c,d,e,f}
    ++#   Commit O: z/{b,c,d,e}
    ++#   Commit A: y/{b,c,d}, z/e
    ++#   Commit B: z/{b,c,d,e,f}
     +#   Expected: y/{b,c,d}, z/{e,f}
     +#   NOTE: Even though most files from z moved to y, we don't
want f to follow.
     +
     +test_expect_success '4a-setup: Directory split, with original
directory still present' '
    -+    git rm -rf . &&
    -+    git clean -fdqx &&
    -+    rm -rf .git &&
    -+    git init &&
    ++    test_create_repo 4a &&
    ++    (
    ++        cd 4a &&
     +
    -+    mkdir z &&
    -+    echo b >z/b &&
    -+    echo c >z/c &&
    -+    echo d >z/d &&
    -+    echo e >z/e &&
    -+    git add z &&
    -+    test_tick &&
    -+    git commit -m "A" &&
    ++        mkdir z &&
    ++        echo b >z/b &&
    ++        echo c >z/c &&
    ++        echo d >z/d &&
    ++        echo e >z/e &&
    ++        git add z &&
    ++        test_tick &&
    ++        git commit -m "O" &&
     +
    -+    git branch A &&
    -+    git branch B &&
    -+    git branch C &&
    ++        git branch O &&
    ++        git branch A &&
    ++        git branch B &&
     +
    -+    git checkout B &&
    -+    mkdir y &&
    -+    git mv z/b y/ &&
    -+    git mv z/c y/ &&
    -+    git mv z/d y/ &&
    -+    test_tick &&
    -+    git commit -m "B" &&
    ++        git checkout A &&
    ++        mkdir y &&
    ++        git mv z/b y/ &&
    ++        git mv z/c y/ &&
    ++        git mv z/d y/ &&
    ++        test_tick &&
    ++        git commit -m "A" &&
     +
    -+    git checkout C &&
    -+    echo f >z/f &&
    -+    git add z/f &&
    -+    test_tick &&
    -+    git commit -m "C"
    ++        git checkout B &&
    ++        echo f >z/f &&
    ++        git add z/f &&
    ++        test_tick &&
    ++        git commit -m "B"
    ++    )
     +'
     +
     +test_expect_success '4a-check: Directory split, with original
directory still present' '
    -+    git checkout B^0 &&
    ++    (
    ++        cd 4a &&
     +
    -+    git merge -s recursive C^0 &&
    ++        git checkout A^0 &&
     +
    -+    test 5 -eq $(git ls-files -s | wc -l) &&
    -+    test 0 -eq $(git ls-files -u | wc -l) &&
    -+    test 0 -eq $(git ls-files -o | wc -l) &&
    ++        git merge -s recursive B^0 &&
     +
    -+    test $(git rev-parse HEAD:y/b) = $(git rev-parse A:z/b) &&
    -+    test $(git rev-parse HEAD:y/c) = $(git rev-parse A:z/c) &&
    -+    test $(git rev-parse HEAD:y/d) = $(git rev-parse A:z/d) &&
    -+    test $(git rev-parse HEAD:z/e) = $(git rev-parse A:z/e) &&
    -+    test $(git rev-parse HEAD:z/f) = $(git rev-parse C:z/f)
    ++        test 5 -eq $(git ls-files -s | wc -l) &&
    ++        test 0 -eq $(git ls-files -u | wc -l) &&
    ++        test 0 -eq $(git ls-files -o | wc -l) &&
    ++
    ++        git rev-parse >actual \
    ++            HEAD:y/b HEAD:y/c HEAD:y/d HEAD:z/e HEAD:z/f &&
    ++        git rev-parse >expect \
    ++            O:z/b O:z/c O:z/d O:z/e B:z/f &&
    ++        test_cmp expect actual
    ++    )
     +'
     +
     +###########################################################################
 8: 3a338bb00e < --:  ------- directory rename detection:
files/directories in the way of some renames
 9: 6361c3e908 < --:  ------- directory rename detection: testcases
checking which side did the rename
10: 498364bafb < --:  ------- directory rename detection: more
involved edge/corner testcases
11: 5d06e25db0 < --:  ------- directory rename detection: testcases
exploring possibly suboptimal merges
12: 779e8ac363 < --:  ------- directory rename detection:
miscellaneous testcases to complete coverage
13: 93061c9a96 < --:  ------- directory rename detection: tests for
handling overwriting untracked files
14: 9c2cec2f5b < --:  ------- directory rename detection: tests for
handling overwriting dirty files
--:  ------- >  8: 0668e65864 directory rename detection:
files/directories in the way of some renames
--:  ------- >  9: fcce655243 directory rename detection: testcases
checking which side did the rename
--:  ------- > 10: 04213cc213 directory rename detection: more
involved edge/corner testcases
--:  ------- > 11: 21992300aa directory rename detection: testcases
exploring possibly suboptimal merges
--:  ------- > 12: 727238bf64 directory rename detection:
miscellaneous testcases to complete coverage
--:  ------- > 13: 44b25c31e2 directory rename detection: tests for
handling overwriting untracked files
--:  ------- > 14: fa05a0240c directory rename detection: tests for
handling overwriting dirty files
15: 54acafcb6d ! 15: 131af0e3f2 merge-recursive: move the get_renames() function
    @@ -1,10 +1,10 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Move the get_renames() function
    +    merge-recursive: move the get_renames() function

    -    I want to re-use some other functions in the file without
moving those other
    -    functions or dealing with a handful of annoying split
function declarations
    -    and definitions.
    +    I want to re-use some other functions in the file without moving those
    +    other functions or dealing with a handful of annoying split function
    +    declarations and definitions.

         Signed-off-by: Elijah Newren <newren@gmail.com>

    @@ -37,8 +37,8 @@
     -        return renames;
     -
     -    diff_setup(&opts);
    --    DIFF_OPT_SET(&opts, RECURSIVE);
    --    DIFF_OPT_CLR(&opts, RENAME_EMPTY);
    +-    opts.flags.recursive = 1;
    +-    opts.flags.rename_empty = 0;
     -    opts.detect_rename = DIFF_DETECT_RENAME;
     -    opts.rename_limit = o->merge_rename_limit >= 0 ?
o->merge_rename_limit :
     -                o->diff_rename_limit >= 0 ? o->diff_rename_limit :
    @@ -113,8 +113,8 @@
     +        return renames;
     +
     +    diff_setup(&opts);
    -+    DIFF_OPT_SET(&opts, RECURSIVE);
    -+    DIFF_OPT_CLR(&opts, RENAME_EMPTY);
    ++    opts.flags.recursive = 1;
    ++    opts.flags.rename_empty = 0;
     +    opts.detect_rename = DIFF_DETECT_RENAME;
     +    opts.rename_limit = o->merge_rename_limit >= 0 ?
o->merge_rename_limit :
     +                o->diff_rename_limit >= 0 ? o->diff_rename_limit :
    @@ -131,6 +131,7 @@
     +        struct string_list_item *item;
     +        struct rename *re;
     +        struct diff_filepair *pair = diff_queued_diff.queue[i];
    ++
     +        if (pair->status != 'R') {
     +            diff_free_filepair(pair);
     +            continue;
16: 55d0103c72 ! 16: c7d1d15bec merge-recursive: introduce new
functions to handle rename logic
    @@ -1,12 +1,20 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Introduce new functions to handle rename logic
    +    merge-recursive: introduce new functions to handle rename logic

         The amount of logic in merge_trees() relative to renames was just a few
         lines, but split it out into new handle_renames() and cleanup_renames()
    -    functions to prepare for additional logic to be added to each.  No code
    -    or logic changes, just a new place to put stuff for when the rename
    -    detection gains additional checks.
    +    functions to prepare for additional logic to be added to
each.  No code or
    +    logic changes, just a new place to put stuff for when the
rename detection
    +    gains additional checks.
    +
    +    Note that process_renames() records pointers to various
information (such
    +    as diff_filepairs) into rename_conflict_info structs.  Even though the
    +    rename string_lists are not directly used once
handle_renames() completes,
    +    we should not immediately free the lists at the end of that function
    +    because they store the information referenced in the
rename_conflict_info,
    +    which is used later in process_entry().  Thus the reason for a separate
    +    cleanup_renames().

         Signed-off-by: Elijah Newren <newren@gmail.com>

    @@ -22,20 +30,16 @@
     +    struct string_list *merge_renames;
     +};
     +
    -+static struct rename_info *handle_renames(struct merge_options *o,
    -+                      struct tree *common,
    -+                      struct tree *head,
    -+                      struct tree *merge,
    -+                      struct string_list *entries,
    -+                      int *clean)
    ++static int handle_renames(struct merge_options *o,
    ++              struct tree *common,
    ++              struct tree *head,
    ++              struct tree *merge,
    ++              struct string_list *entries,
    ++              struct rename_info *ri)
     +{
    -+    struct rename_info *rei = xcalloc(1, sizeof(struct rename_info));
    -+
    -+    rei->head_renames  = get_renames(o, head, common, head,
merge, entries);
    -+    rei->merge_renames = get_renames(o, merge, common, head,
merge, entries);
    -+    *clean = process_renames(o, rei->head_renames, rei->merge_renames);
    -+
    -+    return rei;
    ++    ri->head_renames  = get_renames(o, head, common, head,
merge, entries);
    ++    ri->merge_renames = get_renames(o, merge, common, head,
merge, entries);
    ++    return process_renames(o, ri->head_renames, ri->merge_renames);
     +}
     +
     +static void cleanup_renames(struct rename_info *re_info)
    @@ -45,8 +49,6 @@
     +
     +    free(re_info->head_renames);
     +    free(re_info->merge_renames);
    -+
    -+    free(re_info);
     +}
     +
      static struct object_id *stage_oid(const struct object_id *oid,
unsigned mode)
    @@ -58,7 +60,7 @@
          if (unmerged_cache()) {
     -        struct string_list *entries, *re_head, *re_merge;
     +        struct string_list *entries;
    -+        struct rename_info *re_info;
    ++        struct rename_info re_info;
              int i;
              /*
               * Only need the hashmap while processing entries, so
    @@ -69,7 +71,8 @@
     -        re_head  = get_renames(o, head, common, head, merge, entries);
     -        re_merge = get_renames(o, merge, common, head, merge, entries);
     -        clean = process_renames(o, re_head, re_merge);
    -+        re_info = handle_renames(o, common, head, merge, entries, &clean);
    ++        clean = handle_renames(o, common, head, merge, entries,
    ++                       &re_info);
              record_df_conflict_files(o, entries);
              if (clean < 0)
                  goto cleanup;
    @@ -79,7 +82,7 @@
      cleanup:
     -        string_list_clear(re_merge, 0);
     -        string_list_clear(re_head, 0);
    -+        cleanup_renames(re_info);
    ++        cleanup_renames(&re_info);
     +
              string_list_clear(entries, 1);
     +        free(entries);
17: 69de4f9cc8 < --:  ------- merge-recursive: Fix leaks of allocated
renames and diff_filepairs
18: ab86763c82 < --:  ------- merge-recursive: Make !o->detect_rename
codepath more obvious
--:  ------- > 17: 1ca5c22551 merge-recursive: fix leaks of allocated
renames and diff_filepairs
--:  ------- > 18: 57288cf7b1 merge-recursive: make !o->detect_rename
codepath more obvious
19: a92df27fb3 ! 19: fd6602a327 merge-recursive: split out code for
determining diff_filepairs
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Split out code for determining diff_filepairs
    +    merge-recursive: split out code for determining diff_filepairs

         Create a new function, get_diffpairs() to compute the diff_filepairs
         between two trees.  While these are currently only used in
    @@ -40,8 +40,8 @@
     -    renames = xcalloc(1, sizeof(struct string_list));
     -
          diff_setup(&opts);
    -     DIFF_OPT_SET(&opts, RECURSIVE);
    -     DIFF_OPT_CLR(&opts, RENAME_EMPTY);
    +     opts.flags.recursive = 1;
    +     opts.flags.rename_empty = 0;
     @@
          diffcore_std(&opts);
          if (opts.needed_rename_limit > o->needed_rename_limit)
    @@ -51,7 +51,7 @@
     +    ret = malloc(sizeof(struct diff_queue_struct));
     +    ret->queue = diff_queued_diff.queue;
     +    ret->nr = diff_queued_diff.nr;
    -+    // Ignore diff_queued_diff.alloc; we won't be changing the size at all
    ++    /* Ignore diff_queued_diff.alloc; we won't be changing size at all */
     +
     +    opts.output_format = DIFF_FORMAT_NO_OUTPUT;
     +    diff_queued_diff.nr = 0;
    @@ -85,9 +85,9 @@
              struct rename *re;
     -        struct diff_filepair *pair = diff_queued_diff.queue[i];
     +        struct diff_filepair *pair = pairs->queue[i];
    +
              if (pair->status != 'R') {
                  diff_free_filepair(pair);
    -             continue;
     @@
              item = string_list_insert(renames, pair->one->path);
              item->util = re;
    @@ -99,27 +99,30 @@
      }

     @@
    -                       int *clean)
    +               struct string_list *entries,
    +               struct rename_info *ri)
      {
    -     struct rename_info *rei = xcalloc(1, sizeof(struct rename_info));
     +    struct diff_queue_struct *head_pairs, *merge_pairs;
    ++    int clean;
    ++
    +     ri->head_renames = NULL;
    +     ri->merge_renames = NULL;

    -     *clean = 1;
          if (!o->detect_rename)
    -         return NULL;
    +         return 1;

    --    rei->head_renames  = get_renames(o, head, common, head,
merge, entries);
    --    rei->merge_renames = get_renames(o, merge, common, head,
merge, entries);
    +-    ri->head_renames  = get_renames(o, head, common, head,
merge, entries);
    +-    ri->merge_renames = get_renames(o, merge, common, head,
merge, entries);
    +-    return process_renames(o, ri->head_renames, ri->merge_renames);
     +    head_pairs = get_diffpairs(o, common, head);
     +    merge_pairs = get_diffpairs(o, common, merge);
     +
    -+    rei->head_renames  = get_renames(o, head_pairs, head,
    ++    ri->head_renames  = get_renames(o, head_pairs, head,
     +                     common, head, merge, entries);
    -+    rei->merge_renames = get_renames(o, merge_pairs, merge,
    ++    ri->merge_renames = get_renames(o, merge_pairs, merge,
     +                     common, head, merge, entries);
    -     *clean = process_renames(o, rei->head_renames, rei->merge_renames);
    -
    -+cleanup:
    ++    clean = process_renames(o, ri->head_renames, ri->merge_renames);
    ++
     +    /*
     +     * Some cleanup is deferred until cleanup_renames() because the
     +     * data structures are still needed and referenced in
    @@ -131,6 +134,7 @@
     +    free(merge_pairs->queue);
     +    free(merge_pairs);
     +
    -     return rei;
    ++    return clean;
      }

    + static void cleanup_rename(struct string_list *rename)
20: fe8b73c07b ! 20: 8828dd4093 merge-recursive: add a new hashmap for
storing directory renames
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Add a new hashmap for storing directory renames
    +    merge-recursive: add a new hashmap for storing directory renames

         This just adds dir_rename_entry and the associated functions;
code using
         these will be added in subsequent commits.
    @@ -14,7 +14,8 @@
          return ignore_case ? strihash(path) : strhash(path);
      }

    -+static struct dir_rename_entry *dir_rename_find_entry(struct
hashmap *hashmap, char *dir)
    ++static struct dir_rename_entry *dir_rename_find_entry(struct
hashmap *hashmap,
    ++                              char *dir)
     +{
     +    struct dir_rename_entry key;
     +
    @@ -36,6 +37,16 @@
     +static void dir_rename_init(struct hashmap *map)
     +{
     +    hashmap_init(map, (hashmap_cmp_fn) dir_rename_cmp, NULL, 0);
    ++}
    ++
    ++static void dir_rename_entry_init(struct dir_rename_entry *entry,
    ++                  char *directory)
    ++{
    ++    hashmap_entry_init(entry, strhash(directory));
    ++    entry->dir = directory;
    ++    entry->non_unique_new_dir = 0;
    ++    entry->new_dir = NULL;
    ++    string_list_init(&entry->possible_new_dirs, 0);
     +}
     +
      static void flush_output(struct merge_options *o)
21: f720f90aea ! 21: f1d3b1f7ab merge-recursive: add get_directory_renames()
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Add get_directory_renames()
    +    merge-recursive: add get_directory_renames()

         This populates a list of directory renames for us.  The list of
         directory renames is not yet used, but will be in subsequent commits.
    @@ -15,7 +15,11 @@
      }

     +static void get_renamed_dir_portion(const char *old_path, const
char *new_path,
    -+                    char **old_dir, char **new_dir) {
    ++                    char **old_dir, char **new_dir)
    ++{
    ++    char *end_of_old, *end_of_new;
    ++    int old_len, new_len;
    ++
     +    *old_dir = NULL;
     +    *new_dir = NULL;
     +
    @@ -29,14 +33,15 @@
     +     * Also, if the basename of the file changed, we don't care.  We
     +     * want to know which portion of the directory, if any, changed.
     +     */
    -+    char *end_of_old = strrchr(old_path, '/');
    -+    char *end_of_new = strrchr(new_path, '/');
    ++    end_of_old = strrchr(old_path, '/');
    ++    end_of_new = strrchr(new_path, '/');
    ++
     +    if (end_of_old == NULL || end_of_new == NULL)
     +        return;
     +    while (*--end_of_new == *--end_of_old &&
     +           end_of_old != old_path &&
     +           end_of_new != new_path)
    -+        ; // Do nothing; all in the while loop
    ++        ; /* Do nothing; all in the while loop */
     +    /*
     +     * We've found the first non-matching character in the directory
     +     * paths.  That means the current directory we were comparing
    @@ -54,8 +59,8 @@
     +     * It may have been the case that old_path and new_path were the same
     +     * directory all along.  Don't claim a rename if they're the same.
     +     */
    -+    int old_len = end_of_old - old_path;
    -+    int new_len = end_of_new - new_path;
    ++    old_len = end_of_old - old_path;
    ++    new_len = end_of_new - new_path;
     +
     +    if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
     +        *old_dir = strndup(old_path, old_len);
    @@ -64,7 +69,8 @@
     +}
     +
     +static struct hashmap *get_directory_renames(struct
diff_queue_struct *pairs,
    -+                         struct tree *tree) {
    ++                         struct tree *tree)
    ++{
     +    struct hashmap *dir_renames;
     +    struct hashmap_iter iter;
     +    struct dir_rename_entry *entry;
    @@ -76,26 +82,26 @@
     +        struct string_list_item *item;
     +        int *count;
     +        struct diff_filepair *pair = pairs->queue[i];
    ++        char *old_dir, *new_dir;
     +
    -+        char *old_dir, *new_dir;
     +        get_renamed_dir_portion(pair->one->path, pair->two->path,
     +                    &old_dir,        &new_dir);
     +        if (!old_dir)
    -+            // Directory didn't change at all; ignore this one.
    ++            /* Directory didn't change at all; ignore this one. */
     +            continue;
     +
     +        entry = dir_rename_find_entry(dir_renames, old_dir);
     +        if (!entry) {
    -+            entry = xcalloc(1, sizeof(struct dir_rename_entry));
    -+            hashmap_entry_init(entry, strhash(old_dir));
    ++            entry = xmalloc(sizeof(struct dir_rename_entry));
    ++            dir_rename_entry_init(entry, old_dir);
     +            hashmap_put(dir_renames, entry);
    -+            entry->dir = old_dir;
     +        } else {
     +            free(old_dir);
     +        }
     +        item = string_list_lookup(&entry->possible_new_dirs, new_dir);
     +        if (!item) {
    -+            item = string_list_insert(&entry->possible_new_dirs, new_dir);
    ++            item = string_list_insert(&entry->possible_new_dirs,
    ++                          new_dir);
     +            item->util = xcalloc(1, sizeof(int));
     +        } else {
     +            free(new_dir);
    @@ -109,8 +115,10 @@
     +        int max = 0;
     +        int bad_max = 0;
     +        char *best = NULL;
    ++
     +        for (i = 0; i < entry->possible_new_dirs.nr; i++) {
     +            int *count = entry->possible_new_dirs.items[i].util;
    ++
     +            if (*count == max)
     +                bad_max = max;
     +            else if (*count > max) {
    @@ -136,15 +144,15 @@
       * Get information of all renames which occurred in 'pairs', making use of
       * any implicit directory renames inferred from the other side of history.
     @@
    +               struct rename_info *ri)
      {
    -     struct rename_info *rei = xcalloc(1, sizeof(struct rename_info));
          struct diff_queue_struct *head_pairs, *merge_pairs;
     +    struct hashmap *dir_re_head, *dir_re_merge;
     +    struct hashmap_iter iter;
     +    struct dir_rename_entry *e;
    +     int clean;

    -     *clean = 1;
    -     if (!o->detect_rename)
    +     ri->head_renames = NULL;
     @@
          head_pairs = get_diffpairs(o, common, head);
          merge_pairs = get_diffpairs(o, common, merge);
    @@ -152,9 +160,9 @@
     +    dir_re_head = get_directory_renames(head_pairs, head);
     +    dir_re_merge = get_directory_renames(merge_pairs, merge);
     +
    -     rei->head_renames  = get_renames(o, head_pairs, head,
    +     ri->head_renames  = get_renames(o, head_pairs, head,
                           common, head, merge, entries);
    -     rei->merge_renames = get_renames(o, merge_pairs, merge,
    +     ri->merge_renames = get_renames(o, merge_pairs, merge,
     @@
           * process_entry().  But there are a few things we can free now.
           */
    @@ -165,7 +173,6 @@
     +        if (e->new_dir)
     +            free(e->new_dir);
     +        /* possible_new_dirs already cleared in get_directory_renames */
    -+        //string_list_clear(&e->possible_new_dirs, 1);
     +    }
     +    hashmap_free(dir_re_head, 1);
     +    free(dir_re_head);
    @@ -176,7 +183,6 @@
     +        if (e->new_dir)
     +            free(e->new_dir);
     +        /* possible_new_dirs already cleared in get_directory_renames */
    -+        //string_list_clear(&e->possible_new_dirs, 1);
     +    }
     +    hashmap_free(dir_re_merge, 1);
     +    free(dir_re_merge);
22: ad04489ad6 ! 22: ba1aa81d38 merge-recursive: check for directory
level conflicts
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Check for directory level conflicts
    +    merge-recursive: check for directory level conflicts

         Before trying to apply directory renames to paths within the given
         directories, we want to make sure that there aren't conflicts at the
    @@ -19,15 +19,15 @@
     +static int tree_has_path(struct tree *tree, const char *path)
     +{
     +    unsigned char hashy[20];
    -+    unsigned mode_o;
    ++    unsigned int mode_o;
     +
     +    return !get_tree_entry(tree->object.oid.hash, path,
     +                   hashy, &mode_o);
     +}
     +
      static void get_renamed_dir_portion(const char *old_path, const
char *new_path,
    -                     char **old_dir, char **new_dir) {
    -     *old_dir = NULL;
    +                     char **old_dir, char **new_dir)
    + {
     @@
          }
      }
    @@ -100,10 +100,10 @@
     +               !merge_ent->non_unique_new_dir) {
     +            /* 3. rename/rename(1to2) */
     +            /* We can assume it's not rename/rename(1to1) because
    -+             * that was case (1), already checked above.  But
    -+             * quickly test that assertion, just because.
    ++             * that was case (1), already checked above.  So we
    ++             * know that head_ent->new_dir and merge_ent->new_dir
    ++             * are different strings.
     +             */
    -+            assert(strcmp(head_ent->new_dir, merge_ent->new_dir));
     +            output(o, 1, _("CONFLICT (rename/rename): "
     +                       "Rename directory %s->%s in %s. "
     +                       "Rename directory %s->%s in %s"),
    @@ -132,8 +132,8 @@
     +}
     +
      static struct hashmap *get_directory_renames(struct
diff_queue_struct *pairs,
    -                          struct tree *tree) {
    -     struct hashmap *dir_renames;
    +                          struct tree *tree)
    + {
     @@
          dir_re_head = get_directory_renames(head_pairs, head);
          dir_re_merge = get_directory_renames(merge_pairs, merge);
    @@ -142,6 +142,6 @@
     +                     dir_re_head, head,
     +                     dir_re_merge, merge);
     +
    -     rei->head_renames  = get_renames(o, head_pairs, head,
    +     ri->head_renames  = get_renames(o, head_pairs, head,
                           common, head, merge, entries);
    -     rei->merge_renames = get_renames(o, merge_pairs, merge,
    +     ri->merge_renames = get_renames(o, merge_pairs, merge,
23: 83082ea5c6 ! 23: 96534fe595 merge-recursive: add a new hashmap for
storing file collisions
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Add a new hashmap for storing file collisions
    +    merge-recursive: add a new hashmap for storing file collisions

         Directory renames with the ability to merge directories opens up the
         possibility of add/add/add/.../add conflicts, if each of the N
    @@ -14,7 +14,7 @@
     --- a/merge-recursive.c
     +++ b/merge-recursive.c
     @@
    -     hashmap_init(map, (hashmap_cmp_fn) dir_rename_cmp, NULL, 0);
    +     string_list_init(&entry->possible_new_dirs, 0);
      }

     +static struct collision_entry *collision_find_entry(struct
hashmap *hashmap,
24: 02573ae17c ! 24: 66ada0e7c0 merge-recursive: add computation of
collisions due to dir rename & merging
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Add computation of collisions due to dir
rename & merging
    +    merge-recursive: add computation of collisions due to dir
rename & merging

         directory renaming and merging can cause one or more files to
be moved to
         where an existing file is, or to cause several files to all be moved to
    @@ -20,35 +20,38 @@
     + * Return a new string that replaces the beginning portion (which matches
     + * entry->dir), with entry->new_dir.  In perl-speak:
     + *   new_path_name = (old_path =~ s/entry->dir/entry->new_dir/);
    ++ * NOTE:
    ++ *   Caller must ensure that old_path starts with entry->dir + '/'.
     + */
     +static char *apply_dir_rename(struct dir_rename_entry *entry,
    -+                   const char *old_path) {
    ++                  const char *old_path)
    ++{
     +    char *new_path;
    -+    int oldlen, newlen;
    ++    int entrylen, oldlen, newlen;
     +
     +    if (entry->non_unique_new_dir)
     +        return NULL;
     +
    ++    entrylen = strlen(entry->new_dir);
     +    oldlen = strlen(entry->dir);
    -+    assert(strncmp(entry->dir, old_path, oldlen) == 0 &&
    -+           old_path[oldlen] == '/');
    -+    newlen = strlen(entry->new_dir) + (strlen(old_path) - oldlen) + 1;
    ++    newlen = entrylen + (strlen(old_path) - oldlen) + 1;
     +    new_path = malloc(newlen);
     +    strcpy(new_path, entry->new_dir);
    -+    strcpy(&new_path[strlen(new_path)], &old_path[oldlen]);
    ++    strcpy(&new_path[entrylen], &old_path[oldlen]);
     +
     +    return new_path;
     +}
     +
      static void get_renamed_dir_portion(const char *old_path, const
char *new_path,
    -                     char **old_dir, char **new_dir) {
    -     *old_dir = NULL;
    +                     char **old_dir, char **new_dir)
    + {
     @@
          return dir_renames;
      }

     +static struct dir_rename_entry *check_dir_renamed(const char *path,
    -+                          struct hashmap *dir_renames) {
    ++                          struct hashmap *dir_renames)
    ++{
     +    char temp[PATH_MAX];
     +    char *end;
     +    struct dir_rename_entry *entry;
    @@ -95,7 +98,8 @@
     +
     +        if (pair->status == 'D')
     +            continue;
    -+        dir_rename_ent = check_dir_renamed(pair->two->path, dir_renames);
    ++        dir_rename_ent = check_dir_renamed(pair->two->path,
    ++                           dir_renames);
     +        if (!dir_rename_ent)
     +            continue;
     +
    @@ -165,13 +169,14 @@
                           dir_re_head, head,
                           dir_re_merge, merge);

    --    rei->head_renames  = get_renames(o, head_pairs, head,
    -+    rei->head_renames  = get_renames(o, head_pairs,
    -+                     dir_re_merge, head,
    +-    ri->head_renames  = get_renames(o, head_pairs, head,
    +-                     common, head, merge, entries);
    +-    ri->merge_renames = get_renames(o, merge_pairs, merge,
    ++    ri->head_renames  = get_renames(o, head_pairs,
    ++                    dir_re_merge, head,
    ++                    common, head, merge, entries);
    ++    ri->merge_renames = get_renames(o, merge_pairs,
    ++                    dir_re_head, merge,
                           common, head, merge, entries);
    --    rei->merge_renames = get_renames(o, merge_pairs, merge,
    -+    rei->merge_renames = get_renames(o, merge_pairs,
    -+                     dir_re_head, merge,
    -                      common, head, merge, entries);
    -     *clean = process_renames(o, rei->head_renames, rei->merge_renames);
    +     clean = process_renames(o, ri->head_renames, ri->merge_renames);

25: 1bb7823ff5 ! 25: 0f49ea9449 merge-recursive: check for file level
conflicts then get new name
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Check for file level conflicts then get new name
    +    merge-recursive: check for file level conflicts then get new name

         Before trying to apply directory renames to paths within the given
         directories, we want to make sure that there aren't conflicts at the
    @@ -21,9 +21,11 @@
     + *   element1, element2, element3, ..., elementN
     + * to str.  If only one element, just write "element1" to str.
     + */
    -+static void comma_separated_list(char *str, struct string_list *slist) {
    ++static void comma_separated_list(char *str, struct string_list *slist)
    ++{
     +    int i;
    -+    for (i=0; i<slist->nr; i++) {
    ++
    ++    for (i = 0; i < slist->nr; i++) {
     +        str += sprintf(str, "%s", slist->items[i].string);
     +        if (i < slist->nr-1)
     +            str += sprintf(str, ", ");
    @@ -35,7 +37,7 @@
     + * level conflicts for the renamed location.  If there is a rename and
     + * there are no conflicts, return the new name.  Otherwise, return NULL.
     + */
    -+static char* handle_path_level_conflicts(struct merge_options *o,
    ++static char *handle_path_level_conflicts(struct merge_options *o,
     +                     const char *path,
     +                     struct dir_rename_entry *entry,
     +                     struct hashmap *collisions,
    @@ -44,6 +46,7 @@
     +    char *new_path = NULL;
     +    struct collision_entry *collision_ent;
     +    int clean = 1;
    ++    char *collision_paths;
     +
     +    /*
     +     * entry has the mapping of old directory name to new directory name
    @@ -53,7 +56,8 @@
     +
     +    if (!new_path) {
     +        /* This should only happen when entry->non_unique_new_dir set */
    -+        assert(entry->non_unique_new_dir);
    ++        if (!entry->non_unique_new_dir)
    ++            BUG("entry->non_unqiue_dir not set and !new_path");
     +        output(o, 1, _("CONFLICT (directory rename split): "
     +                   "Unclear where to place %s because directory "
     +                   "%s was renamed to multiple other directories, "
    @@ -68,9 +72,10 @@
     +     * The caller needs to have ensured that it has pre-populated
     +     * collisions with all paths that map to new_path.  Do a quick check
     +     * to ensure that's the case.
    -+      */
    ++     */
     +    collision_ent = collision_find_entry(collisions, new_path);
    -+    assert(collision_ent != NULL);
    ++    if (collision_ent == NULL)
    ++        BUG("collision_ent is NULL");
     +
     +    /*
     +     * Check for one-sided add/add/.../add conflicts, i.e.
    @@ -79,7 +84,8 @@
     +     * to put multiple paths into the same location.  Warn
     +     * and bail on directory renames for such paths.
     +     */
    -+    char collision_paths[(PATH_MAX+2) * collision_ent->source_files.nr];
    ++    collision_paths = malloc((PATH_MAX+2) *
collision_ent->source_files.nr);
    ++
     +    if (collision_ent->reported_already) {
     +        clean = 0;
     +    } else if (tree_has_path(tree, new_path)) {
    @@ -104,6 +110,7 @@
     +    }
     +
     +    /* Free memory we no longer need */
    ++    free(collision_paths);
     +    if (!clean && new_path) {
     +        free(new_path);
     +        return NULL;
    @@ -129,6 +136,8 @@
     +{
     +    char *new_path = NULL;
     +    struct dir_rename_entry *entry = check_dir_renamed(path, dir_renames);
    ++    struct dir_rename_entry *oentry = NULL;
    ++
     +    if (!entry)
     +        return new_path;
     +
    @@ -156,7 +165,6 @@
     +     * As it turns out, this also prevents N-way transient rename
     +     * confusion; See testcases 9c and 9d of t6043.
     +     */
    -+    struct dir_rename_entry *oentry = NULL;
     +    oentry = dir_rename_find_entry(dir_rename_exclusions, entry->new_dir);
     +    if (oentry) {
     +        output(o, 1, _("WARNING: Avoiding applying %s -> %s rename "
    @@ -193,76 +201,71 @@
              struct string_list_item *item;
              struct rename *re;
              struct diff_filepair *pair = pairs->queue[i];
    ++        char *new_path; /* non-NULL only with directory renames */
    +
     -        if (pair->status != 'R') {
    -+        char *new_path; // non-NULL only with directory renames
    -+
     +        if (pair->status == 'D') {
    -             diff_free_filepair(pair);
    -             continue;
    -         }
    ++            diff_free_filepair(pair);
    ++            continue;
    ++        }
     +        new_path = check_for_directory_rename(o, pair->two->path, tree,
     +                              dir_renames,
     +                              dir_rename_exclusions,
     +                              &collisions,
     +                              clean_merge);
     +        if (pair->status != 'R' && !new_path) {
    -+            diff_free_filepair(pair);
    -+            continue;
    -+        }
    +             diff_free_filepair(pair);
    +             continue;
    +         }
     +
              re = xmalloc(sizeof(*re));
              re->processed = 0;
              re->pair = pair;
     @@
    +     struct hashmap *dir_re_head, *dir_re_merge;
    +     struct hashmap_iter iter;
    +     struct dir_rename_entry *e;
    +-    int clean;
    ++    int clean = 1;
    +
    +     ri->head_renames = NULL;
    +     ri->merge_renames = NULL;
    +@@
                           dir_re_merge, merge);

    -     rei->head_renames  = get_renames(o, head_pairs,
    --                     dir_re_merge, head,
    +     ri->head_renames  = get_renames(o, head_pairs,
    +-                    dir_re_merge, head,
    +-                    common, head, merge, entries);
    ++                    dir_re_merge, dir_re_head, head,
    ++                    common, head, merge, entries,
    ++                    &clean);
    ++    if (clean < 0)
    ++        goto cleanup;
    +     ri->merge_renames = get_renames(o, merge_pairs,
    +-                    dir_re_head, merge,
     -                     common, head, merge, entries);
    -+                     dir_re_merge, dir_re_head, head,
    -+                     common, head, merge, entries,
    -+                     clean);
    -+    if (*clean < 0)
    +-    clean = process_renames(o, ri->head_renames, ri->merge_renames);
    ++                    dir_re_head, dir_re_merge, merge,
    ++                    common, head, merge, entries,
    ++                    &clean);
    ++    if (clean < 0)
     +        goto cleanup;
    -     rei->merge_renames = get_renames(o, merge_pairs,
    --                     dir_re_head, merge,
    --                     common, head, merge, entries);
    --    *clean = process_renames(o, rei->head_renames, rei->merge_renames);
    -+                     dir_re_head, dir_re_merge, merge,
    -+                     common, head, merge, entries,
    -+                     clean);
    -+    if (*clean < 0)
    -+        goto cleanup;
    -+    *clean &= process_renames(o, rei->head_renames, rei->merge_renames);
    -
    - cleanup:
    ++    clean &= process_renames(o, ri->head_renames, ri->merge_renames);
    +
    ++cleanup:
          /*
    -@@
    -         if (e->new_dir)
    -             free(e->new_dir);
    -         /* possible_new_dirs already cleared in get_directory_renames */
    --        //string_list_clear(&e->possible_new_dirs, 1);
    -     }
    -     hashmap_free(dir_re_head, 1);
    -     free(dir_re_head);
    -@@
    -         if (e->new_dir)
    -             free(e->new_dir);
    -         /* possible_new_dirs already cleared in get_directory_renames */
    --        //string_list_clear(&e->possible_new_dirs, 1);
    -     }
    -     hashmap_free(dir_re_merge, 1);
    -     free(dir_re_merge);
    +      * Some cleanup is deferred until cleanup_renames() because the
    +      * data structures are still needed and referenced in

     diff --git a/t/t6043-merge-rename-directories.sh
b/t/t6043-merge-rename-directories.sh
     --- a/t/t6043-merge-rename-directories.sh
     +++ b/t/t6043-merge-rename-directories.sh
     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '2a-check: Directory split into two on one
side, with equal numbers of paths' '
     +test_expect_success '2a-check: Directory split into two on one
side, with equal numbers of paths' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    +     (
    +         cd 2a &&
    +
26: c5180f2d23 ! 26: 996de01e67 merge-recursive: when comparing files,
don't include trees
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: When comparing files, don't include trees
    +    merge-recursive: when comparing files, don't include trees

         get_renames() would look up stage data that already existed (populated
         in get_unmerged(), taken from whatever unpack_trees() created), and if
    @@ -27,7 +27,7 @@
     +static int get_tree_entry_if_blob(const unsigned char *tree,
     +                  const char *path,
     +                  unsigned char *hashy,
    -+                  unsigned *mode_o)
    ++                  unsigned int *mode_o)
     +{
     +    int ret;
     +
27: f2f3bed14a ! 27: 07401ad0ff merge-recursive: apply necessary
modifications for directory renames
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Apply necessary modifications for directory renames
    +    merge-recursive: apply necessary modifications for directory renames

         This commit hooks together all the directory rename logic by making the
         necessary changes to the rename struct, it's dst_entry, and the
    @@ -36,6 +36,7 @@
     +                    const struct stage_data *stage_data)
     +{
     +    struct diff_filespec o, a, b;
    ++
     +    o.mode = stage_data->stages[1].mode;
     +    oidcpy(&o.oid, &stage_data->stages[1].oid);
     +
    @@ -154,18 +155,8 @@
     +         * case we can just allow the normal processing to happen
     +         * for it).
     +         */
    -+        if (!strcmp(pair->one->path, pair->two->path)) {
    -+            /*
    -+             * Paths should only match if this was initially a
    -+             * non-rename that is being turned into one by
    -+             * directory rename detection.
    -+             */
    -+            assert(pair->status != 'R');
    -+        } else {
    -+            assert(pair->status == 'R');
    ++        if (pair->status == 'R')
     +            re->dst_entry->processed = 1;
    -+            //string_list_remove(entries, pair->two->path, 0);
    -+        }
     +
     +        re->dst_entry = insert_stage_data(new_path,
     +                          o_tree, a_tree, b_tree,
    @@ -178,7 +169,9 @@
     +     * Update the stage_data with the information about the path we are
     +     * moving into place.  That slot will be empty and available for us
     +     * to write to because of the collision checks in
    -+     * handle_path_level_conflicts().
    ++     * handle_path_level_conflicts().  In other words,
    ++     * re->dst_entry->stages[stage].oid will be the null_oid, so it's
    ++     * open for us to write to.
     +     *
     +     * It may be tempting to actually update the index at this point as
     +     * well, using update_stages_for_stage_data(), but as per the big
    @@ -188,7 +181,6 @@
     +     * the various conflict_rename_*() functions update the index
     +     * explicitly rather than relying on unpack_trees() to have done it.
     +     */
    -+    assert(is_null_oid(&re->dst_entry->stages[stage].oid));
     +    get_tree_entry(tree->object.oid.hash,
     +               pair->two->path,
     +               re->dst_entry->stages[stage].oid.hash,
    @@ -232,11 +224,11 @@
              item = string_list_insert(renames, pair->one->path);
              item->util = re;
     +        if (new_path)
    -+              apply_directory_rename_modifications(o, pair, new_path,
    -+                                   re, tree, o_tree,
    -+                                   a_tree, b_tree,
    -+                                   entries,
    -+                                   clean_merge);
    ++            apply_directory_rename_modifications(o, pair, new_path,
    ++                                 re, tree, o_tree,
    ++                                 a_tree, b_tree,
    ++                                 entries,
    ++                                 clean_merge);
          }

          hashmap_iter_init(&collisions, &iter);
    @@ -281,227 +273,227 @@
     --- a/t/t6043-merge-rename-directories.sh
     +++ b/t/t6043-merge-rename-directories.sh
     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '1a-check: Simple directory rename detection' '
     +test_expect_success '1a-check: Simple directory rename detection' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 1a &&
    +
    +@@
    +     )
      '

     -test_expect_failure '1b-check: Merge a directory with another' '
     +test_expect_success '1b-check: Merge a directory with another' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 1b &&
    +
    +@@
    +     )
      '

     -test_expect_failure '1c-check: Transitive renaming' '
     +test_expect_success '1c-check: Transitive renaming' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 1c &&
    +
    +@@
    +     )
      '

     -test_expect_failure '1d-check: Directory renames cause a
rename/rename(2to1) conflict' '
     +test_expect_success '1d-check: Directory renames cause a
rename/rename(2to1) conflict' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 1d &&
    +
    +@@
    +     )
      '

     -test_expect_failure '1e-check: Renamed directory, with all files
being renamed too' '
     +test_expect_success '1e-check: Renamed directory, with all files
being renamed too' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 1e &&
    +
    +@@
    +     )
      '

     -test_expect_failure '1f-check: Split a directory into two other
directories' '
     +test_expect_success '1f-check: Split a directory into two other
directories' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 1f &&
    +
    +@@
    +     )
      '

     -test_expect_failure '5a-check: Merge directories, other side
adds files to original and target' '
     +test_expect_success '5a-check: Merge directories, other side
adds files to original and target' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 5a &&
    +
    +@@
    +     )
      '

     -test_expect_failure '5b-check: Rename/delete in order to get
add/add/add conflict' '
     +test_expect_success '5b-check: Rename/delete in order to get
add/add/add conflict' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 5b &&
    +
    +@@
    +     )
      '

     -test_expect_failure '5c-check: Transitive rename would cause
rename/rename/rename/add/add/add' '
     +test_expect_success '5c-check: Transitive rename would cause
rename/rename/rename/add/add/add' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 5c &&
    +
    +@@
    +     )
      '

     -test_expect_failure '5d-check: Directory/file/file conflict due
to directory rename' '
     +test_expect_success '5d-check: Directory/file/file conflict due
to directory rename' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 5d &&
    +
    +@@
    +     )
      '

     -test_expect_failure '7a-check: rename-dir vs. rename-dir (NOT
split evenly) PLUS add-other-file' '
     +test_expect_success '7a-check: rename-dir vs. rename-dir (NOT
split evenly) PLUS add-other-file' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 7a &&
    +
    +@@
    +     )
      '

     -test_expect_failure '7b-check: rename/rename(2to1), but only due
to transitive rename' '
     +test_expect_success '7b-check: rename/rename(2to1), but only due
to transitive rename' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 7b &&
    +
    +@@
    +     )
      '

     -test_expect_failure '7c-check: rename/rename(1to...2or3);
transitive rename may add complexity' '
     +test_expect_success '7c-check: rename/rename(1to...2or3);
transitive rename may add complexity' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 7c &&
    +
    +@@
    +     )
      '

     -test_expect_failure '7d-check: transitive rename involved in
rename/delete; how is it reported?' '
     +test_expect_success '7d-check: transitive rename involved in
rename/delete; how is it reported?' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 7d &&
    +
    +@@
    +     )
      '

     -test_expect_failure '7e-check: transitive rename in
rename/delete AND dirs in the way' '
     +test_expect_success '7e-check: transitive rename in
rename/delete AND dirs in the way' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 7e &&
    +
    +@@
    +     )
      '

     -test_expect_failure '8a-check: Dual-directory rename, one into
the others way' '
     +test_expect_success '8a-check: Dual-directory rename, one into
the others way' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 8a &&
    +
    +@@
    +     )
      '

     -test_expect_failure '8c-check: rename+modify/delete' '
     +test_expect_success '8c-check: rename+modify/delete' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 8c &&
    +
    +@@
    +     )
      '

     -test_expect_failure '8d-check: rename/delete...or not?' '
     +test_expect_success '8d-check: rename/delete...or not?' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 8d &&
    +
    +@@
    +     )
      '

     -test_expect_failure '8e-check: Both sides rename, one side adds
to original directory' '
     +test_expect_success '8e-check: Both sides rename, one side adds
to original directory' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out 2>err &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 8e &&
    +
    +@@
    +     )
      '

     -test_expect_failure '9a-check: Inner renamed directory within
outer renamed directory' '
     +test_expect_success '9a-check: Inner renamed directory within
outer renamed directory' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 9a &&
    +
    +@@
    +     )
      '

     -test_expect_failure '9b-check: Transitive rename with content merge' '
     +test_expect_success '9b-check: Transitive rename with content merge' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 9b &&
    +
    +@@
    +     )
      '

     -test_expect_failure '9c-check: Doubly transitive rename?' '
     +test_expect_success '9c-check: Doubly transitive rename?' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 9c &&
    +
    +@@
    +     )
      '

     -test_expect_failure '9d-check: N-way transitive rename?' '
     +test_expect_success '9d-check: N-way transitive rename?' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 9d &&
    +
    +@@
    +     )
      '

     -test_expect_failure '9e-check: N-to-1 whammo' '
     +test_expect_success '9e-check: N-to-1 whammo' '
    -     git checkout B^0 &&
    -
    -     test_must_fail git merge -s recursive C^0 >out &&
    -@@
    -     git commit -m "C"
    +     (
    +         cd 9e &&
    +
    +@@
    +     )
      '

     -test_expect_failure '9f-check: Renamed directory that only
contained immediate subdirs' '
     +test_expect_success '9f-check: Renamed directory that only
contained immediate subdirs' '
    -     git checkout B^0 &&
    -
    -     git merge -s recursive C^0 &&
    +     (
    +         cd 9f &&
    +
28: 2b31d16009 ! 28: fafa66de08 merge-recursive: avoid clobbering
untracked files with directory renames
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Avoid clobbering untracked files with
directory renames
    +    merge-recursive: avoid clobbering untracked files with
directory renames

         Signed-off-by: Elijah Newren <newren@gmail.com>

    @@ -13,6 +13,7 @@

     +    if (!o->call_depth && would_lose_untracked(dest->path)) {
     +        char *alt_path = unique_path(o, dest->path, rename_branch);
    ++
     +        output(o, 1, _("Error: Refusing to lose untracked file at %s; "
     +                   "writing to %s instead."),
     +               dest->path, alt_path);
    @@ -47,9 +48,11 @@
                  dst_name = unique_path(o, rename->path, cur_branch);
                  output(o, 1, _("%s is a directory in %s adding as %s
instead"),
                         rename->path, other_branch, dst_name);
    -+        } else if (!o->call_depth && would_lose_untracked(rename->path)) {
    ++        } else if (!o->call_depth &&
    ++               would_lose_untracked(rename->path)) {
     +            dst_name = unique_path(o, rename->path, cur_branch);
    -+            output(o, 1, _("Refusing to lose untracked file at
%s; adding as %s instead"),
    ++            output(o, 1, _("Refusing to lose untracked file at %s; "
    ++                       "adding as %s instead"),
     +                   rename->path, dst_name);
              }
          }
    @@ -79,29 +82,29 @@
     --- a/t/t6043-merge-rename-directories.sh
     +++ b/t/t6043-merge-rename-directories.sh
     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '10b-check: Overwrite untracked with dir
rename + delete' '
     +test_expect_success '10b-check: Overwrite untracked with dir
rename + delete' '
    -     git checkout B^0 &&
    -     echo very >y/c &&
    -     echo important >y/d &&
    +     (
    +         cd 10b &&
    +
     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '10c-check: Overwrite untracked with dir
rename/rename(1to2)' '
     +test_expect_success '10c-check: Overwrite untracked with dir
rename/rename(1to2)' '
    -     git checkout B^0 &&
    -     echo important >y/c &&
    +     (
    +         cd 10c &&

     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '10d-check: Delete untracked with dir
rename/rename(2to1)' '
     +test_expect_success '10d-check: Delete untracked with dir
rename/rename(2to1)' '
    -     git checkout B^0 &&
    -     echo important >y/wham &&
    +     (
    +         cd 10d &&

29: 48becdc226 ! 29: 9ab0339ebb merge-recursive: fix overwriting dirty
files involved in renames
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Fix overwriting dirty files involved in renames
    +    merge-recursive: fix overwriting dirty files involved in renames

         This fixes an issue that existed before my directory rename detection
         patches that affects both normal renames and renames implied by
    @@ -55,7 +55,12 @@

     -    rc = unpack_trees(3, t, &opts);
     +    rc = unpack_trees(3, t, &o->unpack_opts);
    -+    o->unpack_opts.src_index = &the_index; // unpack_trees
NULLifies src_index, but it's used in verify_uptodate, so set it back
    ++    /*
    ++     * unpack_trees NULLifies src_index, but it's used in verify_uptodate,
    ++     * so set to the new index which will usually have modification
    ++     * timestamp info copied over.
    ++     */
    ++    o->unpack_opts.src_index = &the_index;
          cache_tree_free(&active_cache_tree);
          return rc;
      }
    @@ -66,10 +71,10 @@
     +static int was_dirty(struct merge_options *o, const char *path)
     +{
     +    struct cache_entry *ce;
    -+
     +    int dirty = 1;
    ++
     +    if (o->call_depth || !was_tracked(path))
    -+      return !dirty;
    ++        return !dirty;
     +
     +    ce = cache_file_exists(path, strlen(path), ignore_case);
     +    dirty = (ce->ce_stat_data.sd_mtime.sec > 0 &&
    @@ -103,18 +108,17 @@

     +static int conflict_rename_normal(struct merge_options *o,
     +                  const char *path,
    -+                  struct object_id *o_oid, unsigned o_mode,
    -+                  struct object_id *a_oid, unsigned a_mode,
    -+                  struct object_id *b_oid, unsigned b_mode,
    ++                  struct object_id *o_oid, unsigned int o_mode,
    ++                  struct object_id *a_oid, unsigned int a_mode,
    ++                  struct object_id *b_oid, unsigned int b_mode,
     +                  struct rename_conflict_info *ci)
     +{
     +    int clean_merge;
     +    int file_in_the_way = 0;
     +
     +    if (was_dirty(o, path)) {
    -+            file_in_the_way = 1;
    -+            output(o, 1, _("Refusing to lose dirty file at %s"),
    -+                   path);
    ++        file_in_the_way = 1;
    ++        output(o, 1, _("Refusing to lose dirty file at %s"), path);
     +    }
     +
     +    /* Merge the content and write it out */
    @@ -201,13 +205,13 @@
     --- a/t/t6043-merge-rename-directories.sh
     +++ b/t/t6043-merge-rename-directories.sh
     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '11a-check: Avoid losing dirty contents with
simple rename' '
     +test_expect_success '11a-check: Avoid losing dirty contents with
simple rename' '
    -     git checkout B^0 &&
    -     echo stuff >>z/c &&
    +     (
    +         cd 11a &&


     diff --git a/t/t7607-merge-overwrite.sh b/t/t7607-merge-overwrite.sh
30: 2a68d42ff9 ! 30: feb4781c7a merge-recursive: fix remaining
directory rename + dirty overwrite cases
    @@ -1,6 +1,6 @@
     Author: Elijah Newren <newren@gmail.com>

    -    merge-recursive: Fix remaining directory rename + dirty overwrite cases
    +    merge-recursive: fix remaining directory rename + dirty overwrite cases

         Signed-off-by: Elijah Newren <newren@gmail.com>

    @@ -70,38 +70,38 @@
     --- a/t/t6043-merge-rename-directories.sh
     +++ b/t/t6043-merge-rename-directories.sh
     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '11b-check: Avoid losing dirty file involved
in directory rename' '
     +test_expect_success '11b-check: Avoid losing dirty file involved
in directory rename' '
    -     git checkout B^0 &&
    -     echo stuff >>z/c &&
    +     (
    +         cd 11b &&

     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '11d-check: Avoid losing not-uptodate with
rename + D/F conflict' '
     +test_expect_success '11d-check: Avoid losing not-uptodate with
rename + D/F conflict' '
    -     git checkout B^0 &&
    -     echo stuff >>z/c &&
    +     (
    +         cd 11d &&

     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '11e-check: Avoid deleting not-uptodate with
dir rename/rename(1to2)/add' '
     +test_expect_success '11e-check: Avoid deleting not-uptodate with
dir rename/rename(1to2)/add' '
    -     git checkout B^0 &&
    -     echo mods >>y/c &&
    +     (
    +         cd 11e &&

     @@
    -     git commit -m "C"
    +     )
      '

     -test_expect_failure '11f-check: Avoid deleting not-uptodate with
dir rename/rename(2to1)' '
     +test_expect_success '11f-check: Avoid deleting not-uptodate with
dir rename/rename(2to1)' '
    -     git checkout B^0 &&
    -     echo important >>y/wham &&
    +     (
    +         cd 11f &&

--:  ------- > 31: 29975384e0 directory rename detection: new
testcases showcasing a pair of bugs
--:  ------- > 32: b084ea16ac merge-recursive: avoid spurious
rename/rename conflict from dir renames
--:  ------- > 33: 62ce55426d merge-recursive: ensure we write updates
for directory-renamed file

Re: [PATCH v3 00/33] Add directory rename detection to git

[Junio C Hamano]

Elijah Newren <newren@gmail.com> writes:

> Interesting; tbdiff looks cool.  Junio hasn't queued this series yet,
> but it's easy enough to reconstruct the old one.  It does weigh in
> pretty heavy, and I'm slighly worried about gmail mangling all the
> lines, but I'm going to give it a shot anyway.  If it's too mangled,
> I'll try to repost using git-send-email.  It does weigh in at over
> 1600 lines, so it's not small.

It seems that you have installed tbdiff correctly.  The below seems
to match what I saw when I queued this round, relative to the
previous one.

What I often do when I see a new round of patches is:

    $ git checkout en/rename-directory
    $ git checkout master... ;# detach at the base of the old
    $ git am -s mbox ;# take the new 
    $ git tbdiff ..@{-1} @{-1}..

to compare the old and new.  Often (but not with this topic) earlier
parts of the topic are identical between the old and the new, so I
may rebase the new to preserve the commit timestamp of the old one
when it happens after the above sequence of commands.  For example,
if I see these in tbdiff

    1: 7893bf1720 = 1: f17207893b commit #1
    2: c291293b2e = 2: 93b2ec2912 commit #2
    3: a7d3c870a3 ! 3: 87b5e236a1 commit #3
        @@ ... @@@

then we know up to commit #2 are the same as before, so I'd do

    $ git rebase --onto c29129eb2e 93b2ec2912

by using the two commit object names on the last "=" line in the
output.  Then, running the same tbdiff again:

    $ git tbdiff ..@{-1} @{-1}..

would now show the output starting from "commit #3".

Re: [PATCH v3 00/33] Add directory rename detection to git

[Stefan Beller]

On Tue, Nov 21, 2017 at 5:12 PM, Elijah Newren <newren@gmail.com> wrote:
> On Tue, Nov 21, 2017 at 4:42 PM, Stefan Beller <sbeller@google.com> wrote:
>> On Tue, Nov 21, 2017 at 12:00 AM, Elijah Newren <newren@gmail.com> wrote:
>>> This patchset introduces directory rename detection to merge-recursive; I'm
>>> resubmitting just a few hours after my PATCHv2 because I didn't know about
>>> the DEVELOPER=1 flag previously, and my code had a number of
>>> warnings/errors.  I would have just submitted fixup/squash patches, but
>>> when I checked, there sadly they cause merge conflicts when rebasing
>>>
>>> See https://public-inbox.org/git/20171110190550.27059-1-newren@gmail.com/
>>> for the first series, design considerations, etc, and
>>> https://public-inbox.org/git/20171120220209.15111-1-newren@gmail.com/ for
>>> v2.
>>
>> Thanks, I'll take a look!
>>
>> Protip: To make it easy for reviewers add an interdiff[1] between the different
>> versions of the patch series, this can be done via tbdiff[2] for example,
>> or in case you still have the old branch around or Junio has it queued already,
>> you can do a diff against that branch.
>
> Thanks!
>
> Interesting; tbdiff looks cool.  Junio hasn't queued this series yet,
> but it's easy enough to reconstruct the old one.  It does weigh in
> pretty heavy, and I'm slighly worried about gmail mangling all the
> lines, but I'm going to give it a shot anyway.  If it's too mangled,
> I'll try to repost using git-send-email.  It does weigh in at over
> 1600 lines, so it's not small.

In my first round of review I only looked over the tests to see if I'd
find the behavior intuitive, I spared the implementation, as Junio seemed
to have reviewed a couple patches of the v1 implementation.

Now I also looked over the implementation and quite like it, though
I'd be happy if others would also have a look.

All but one comment were minor style nits, which are no big deal;
the other remark that I was musing about was whether we want to use
strbufs in the new code instead of e.g. sprintfs to extend strings.
And I'd think we would want to use them unless there are compelling
reasons not to.

Thanks,
Stefan

Re: [PATCH v3 00/33] Add directory rename detection to git

[Elijah Newren]

On Wed, Nov 22, 2017 at 11:24 AM, Stefan Beller <sbeller@google.com> wrote:
> On Tue, Nov 21, 2017 at 5:12 PM, Elijah Newren <newren@gmail.com> wrote:
>> On Tue, Nov 21, 2017 at 4:42 PM, Stefan Beller <sbeller@google.com> wrote:
>>> On Tue, Nov 21, 2017 at 12:00 AM, Elijah Newren <newren@gmail.com> wrote:

>>>> This patchset introduces directory rename detection to merge-recursive; I'm

> In my first round of review I only looked over the tests to see if I'd
> find the behavior intuitive, I spared the implementation, as Junio seemed
> to have reviewed a couple patches of the v1 implementation.
>
> Now I also looked over the implementation and quite like it, though
> I'd be happy if others would also have a look.
>
> All but one comment were minor style nits, which are no big deal;
> the other remark that I was musing about was whether we want to use
> strbufs in the new code instead of e.g. sprintfs to extend strings.
> And I'd think we would want to use them unless there are compelling
> reasons not to.

Thanks for the reviews!  I've fixed up the style issues already and
will take a look into switching over to strbuf.

Re: [PATCH v3 00/33] Add directory rename detection to git

[Adam Dinwoodie]

On Tuesday 21 November 2017 at 12:00 am -0800, Elijah Newren wrote:
> <snip>
> 
>  merge-recursive.c                   | 1243 +++++++++++-
>  merge-recursive.h                   |   17 +
>  t/t3501-revert-cherry-pick.sh       |    5 +-
>  t/t6043-merge-rename-directories.sh | 3821 +++++++++++++++++++++++++++++++++++
>  t/t7607-merge-overwrite.sh          |    7 +-
>  unpack-trees.c                      |    4 +-
>  unpack-trees.h                      |    4 +
>  7 files changed, 4985 insertions(+), 116 deletions(-)
>  create mode 100755 t/t6043-merge-rename-directories.sh

The new t6043.44 introduced in this branch is failing on my Cygwin
system.  I can't immeditely see what's causing the failure, but I've
copied the relevant verbose + shell tracing output below in the hope it
makes more sense to you:

expecting success:
        (
                cd 7b &&

                git checkout A^0 &&

                test_must_fail git merge -s recursive B^0 >out &&
                test_i18ngrep "CONFLICT (rename/rename)" out &&

                test 4 -eq $(git ls-files -s | wc -l) &&
                test 2 -eq $(git ls-files -u | wc -l) &&
                test 3 -eq $(git ls-files -o | wc -l) &&

                git rev-parse >actual \
                        :0:y/b :0:y/c :2:y/d :3:y/d &&
                git rev-parse >expect \
                        O:z/b O:z/c O:w/d O:x/d &&
                test_cmp expect actual &&

                test ! -f y/d &&
                test -f y/d~HEAD &&
                test -f y/d~B^0 &&

                git hash-object >actual \
                        y/d~HEAD y/d~B^0 &&
                git rev-parse >expect \
                        O:w/d O:x/d &&
                test_cmp expect actual
        )

++ cd 7b
++ git checkout 'A^0'
Note: checking out 'A^0'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b <new-branch-name>

HEAD is now at 0808992 A
++ test_must_fail git merge -s recursive 'B^0'
++ case "$1" in
++ _test_ok=
++ git merge -s recursive 'B^0'
++ exit_code=1
++ test 1 -eq 0
++ test_match_signal 13 1
++ test 1 = 141
++ test 1 = 269
++ return 1
++ test 1 -gt 129
++ test 1 -eq 127
++ test 1 -eq 126
++ return 0
++ test_i18ngrep 'CONFLICT (rename/rename)' out
++ test -n ''
++ test 'x!' = 'xCONFLICT (rename/rename)'
++ grep 'CONFLICT (rename/rename)' out
CONFLICT (rename/rename): Rename w/d->y/d in HEAD. Rename x/d->y/d in B^0
+++ git ls-files -s
+++ wc -l
++ test 4 -eq 4
+++ git ls-files -u
+++ wc -l
++ test 2 -eq 2
+++ git ls-files -o
+++ wc -l
++ test 3 -eq 3
++ git rev-parse :0:y/b :0:y/c :2:y/d :3:y/d
++ git rev-parse O:z/b O:z/c O:w/d O:x/d
++ test_cmp expect actual
++ diff -u expect actual
++ test '!' -f y/d
+ test_eval_ret_=1
+ want_trace
+ test t = t
+ test t = t
+ set +x
error: last command exited with $?=1
not ok 44 - 7b-check: rename/rename(2to1), but only due to transitive rename

Re: [PATCH v3 00/33] Add directory rename detection to git

[Elijah Newren]

On Thu, Nov 23, 2017 at 3:52 AM, Adam Dinwoodie <adam@dinwoodie.org> wrote:
> On Tuesday 21 November 2017 at 12:00 am -0800, Elijah Newren wrote:
>> <snip>
>>
>>  merge-recursive.c                   | 1243 +++++++++++-
>>  merge-recursive.h                   |   17 +
>>  t/t3501-revert-cherry-pick.sh       |    5 +-
>>  t/t6043-merge-rename-directories.sh | 3821 +++++++++++++++++++++++++++++++++++
>>  t/t7607-merge-overwrite.sh          |    7 +-
>>  unpack-trees.c                      |    4 +-
>>  unpack-trees.h                      |    4 +
>>  7 files changed, 4985 insertions(+), 116 deletions(-)
>>  create mode 100755 t/t6043-merge-rename-directories.sh
>
> The new t6043.44 introduced in this branch is failing on my Cygwin
> system.  I can't immeditely see what's causing the failure, but I've
> copied the relevant verbose + shell tracing output below in the hope it
> makes more sense to you:

Thanks for reporting.  Unfortunately, I have been unable to locate or
create a cygwin system on which to replicate the testing.  Valgrind is
running clean for me, and I find it interesting that the output shows
it did detect the rename/rename(2to1) conflict on y/d for you, and the
index has all the right values, but somehow the 'test ! -f y/d' line
isn't passing for you.

Out of curiosity:
  * What is in the y/ directory in that test?  (That is, the y/
directory within the 7b/ directory)
  * What are the full contents of the 'out' file?  (again, within the
7b/ directory)
  * What commit have you actually built and run with (maybe I'm trying
with something slightly different?)

Re: [PATCH v3 00/33] Add directory rename detection to git

[Elijah Newren]

On Thu, Nov 23, 2017 at 2:28 PM, Elijah Newren <newren@gmail.com> wrote:
> On Thu, Nov 23, 2017 at 3:52 AM, Adam Dinwoodie <adam@dinwoodie.org> wrote:
>> On Tuesday 21 November 2017 at 12:00 am -0800, Elijah Newren wrote:
>>> <snip>
>>>
>>>  merge-recursive.c                   | 1243 +++++++++++-
>>>  merge-recursive.h                   |   17 +
>>>  t/t3501-revert-cherry-pick.sh       |    5 +-
>>>  t/t6043-merge-rename-directories.sh | 3821 +++++++++++++++++++++++++++++++++++
>>>  t/t7607-merge-overwrite.sh          |    7 +-
>>>  unpack-trees.c                      |    4 +-
>>>  unpack-trees.h                      |    4 +
>>>  7 files changed, 4985 insertions(+), 116 deletions(-)
>>>  create mode 100755 t/t6043-merge-rename-directories.sh
>>
>> The new t6043.44 introduced in this branch is failing on my Cygwin
>> system.  I can't immeditely see what's causing the failure, but I've
>> copied the relevant verbose + shell tracing output below in the hope it
>> makes more sense to you:
>
> Thanks for reporting.  Unfortunately, I have been unable to locate or
> create a cygwin system on which to replicate the testing.  Valgrind is

Nevermind; found a system that allowed me to reproduce the problem,
even if it far more wrangling than I'd like.  I believe I have a
one-line fix, but I'm worried that attempting to fully explain it will
result in a novel-length commit message.

Re: [PATCH v3 00/33] Add directory rename detection to git

[Elijah Newren]

On Thu, Nov 23, 2017 at 9:25 PM, Elijah Newren <newren@gmail.com> wrote:
> On Thu, Nov 23, 2017 at 2:28 PM, Elijah Newren <newren@gmail.com> wrote:
>> On Thu, Nov 23, 2017 at 3:52 AM, Adam Dinwoodie <adam@dinwoodie.org> wrote:
>>> On Tuesday 21 November 2017 at 12:00 am -0800, Elijah Newren wrote:
>>>> <snip>
>>>>
>>>>  merge-recursive.c                   | 1243 +++++++++++-
>>>>  merge-recursive.h                   |   17 +
>>>>  t/t3501-revert-cherry-pick.sh       |    5 +-
>>>>  t/t6043-merge-rename-directories.sh | 3821 +++++++++++++++++++++++++++++++++++
>>>>  t/t7607-merge-overwrite.sh          |    7 +-
>>>>  unpack-trees.c                      |    4 +-
>>>>  unpack-trees.h                      |    4 +
>>>>  7 files changed, 4985 insertions(+), 116 deletions(-)
>>>>  create mode 100755 t/t6043-merge-rename-directories.sh
>>>
>>> The new t6043.44 introduced in this branch is failing on my Cygwin
>>> system.  I can't immeditely see what's causing the failure, but I've
>>> copied the relevant verbose + shell tracing output below in the hope it
>>> makes more sense to you:
>>
>> Thanks for reporting.  Unfortunately, I have been unable to locate or
>> create a cygwin system on which to replicate the testing.  Valgrind is
>
> Nevermind; found a system that allowed me to reproduce the problem,
> even if it far more wrangling than I'd like.  I believe I have a
> one-line fix, but I'm worried that attempting to fully explain it will
> result in a novel-length commit message.

This issue is addressed by the commit at
https://public-inbox.org/git/20171124195901.2581-1-newren@gmail.com/ .
I opted to make it a different series, because from my view it looks
like a separate latent bug in the ignore_case handling that was just
unearthed by a combination of events that included my series.  It's
conceivable it could have eventually been triggered some other way.
However, that commit cleanly cherry picks to any of maint, master,
next, or pu, so If Junio just wants to just include that commit on the
top of the en/rename-directory-detection series, that's fine too.

Without that commit, I get the same failure you did on cygwin.  With
that commit, I get all tests passing on cygwin for pu as of yesterday.
(Well, all tests that ran; I didn't have svn or apache or p4 or
various other things installed.  Also, there were some unexpected
passing TODOs, but I've already seen others discussing those exact
testcases on the list elsewhere.)

Hope that helps,
Elijah