[PATCH v7 0/3] Detection of directory renames

[PATCH v7 0/3] Detection of directory renames

[Yann Dirson]

Changes since v6.1:
* now using a sorted list for bulkmove_candidates, improved lookup code
* added a bit of doc
* fixed decl-after-stmt and code style issues (Junio)
* fixed signedness of i_am_not_single bitfield (sparse)
* removed useless filtering of debug messages in tests
* avoid using "git update-index" where "git mv" and friends are more readable
* added a testcase for move of a subdir, fixed the code
* more naming normalisation
* added short note in commit message about implementation
* added Thanks-to's to commit messages (hope I did not forget anyone)
* added more possible future uses to commit message
* moved list of optimisation opportunities from FIXME's to commit message,
  leaving only a handful of things as real FIXME tags (purposely kept as C99
  comments)


Yann Dirson (3):
  Introduce bulk-move detection in diffcore.
  Add testcases for the --detect-bulk-moves diffcore flag.
  [WIP] Allow hiding renames of individual files involved in a
    directory rename.

 Documentation/diff-options.txt   |    4 +
 Documentation/gitdiffcore.txt    |   12 +
 diff-lib.c                       |    6 +-
 diff.c                           |   21 ++-
 diff.h                           |    6 +
 diffcore-rename.c                |  418 ++++++++++++++++++++++++++++++++++++-
 diffcore.h                       |    2 +
 t/t4046-diff-rename-factorize.sh |  296 +++++++++++++++++++++++++++
 tree-diff.c                      |    4 +-
 9 files changed, 753 insertions(+), 16 deletions(-)
 create mode 100755 t/t4046-diff-rename-factorize.sh

-- 
1.7.2.3

[PATCH v7 1/3] Introduce bulk-move detection in diffcore.

[Yann Dirson]

This feature tries to group together files moving from and to
identical directories - the most common case being directory renames.

It is activated by the new --detect-bulk-moves diffcore
flag.

This is only the first step, adding the basic functionnality and
adding support to raw diff output (and it is not supported in
unified-diff output yet)

It is implemented as a new pass in diffcore-rename, occuring after the
file renames get detected, grouping those renames looking like a move
of a full directory into some other place.

The output of raw diff is displayed as "Rnnn a/* b/".  Those cannot be
confused with renames of files named "whatever/*" with a literal star
character, from the full-zero SHA1's.

Possible optimisations to this code include:
* avoid use of i_am_not_single by using a separate list
* use a more informative prefixcmp to avoid strcmp calls
  eg. in discard_if_outside()
* optimize for bulk insertions (avoid useless successive memmove's)

Other future developements to be made on top of this include:
* extension of unified-diff format to express this
* detect inexact bulk-moves (where some files were not moved, or were
  moved to a different place) - problem of computing a similarity score
* display as such the special case of directory move/rename
* application of such new diffs: issue a conflict, or just a warning ?
* teach git-svn (and others ?) to make use of that flag
* handle new conflict type "bulk-move/add"
* detect "directory splits" as well
* use inexact dir renames to bump score of below-threshold renames
  from/to same locations
* support other types of bluk-grouping, like prefixes (see eg. kernel
  5d1e859c), and maybe config-specified patterns
* add yours here

This patch has been improved by the following contributions:
- Jonathan Nieder: better implementation of copy_dirname()
- Jonathan Nieder: portable implementation of memrchr() in another patch
- Junio C Hamano: split individual renames hiding under control of another flag
- Junio C Hamano: coding style issues
- Ævar Arnfjörð Bjarmason: Don't use C99 comments.
- Jonathan Nieder: just too many other helpful suggestions to list them all

Thanks-to: Jonathan Nieder <jrnieder@gmail.com>
Thanks-to: Junio C Hamano <gitster@pobox.com>
Thanks-to: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Yann Dirson <ydirson@free.fr>
---
 Documentation/diff-options.txt |    4 +
 Documentation/gitdiffcore.txt  |   12 ++
 diff-lib.c                     |    6 +-
 diff.c                         |   14 ++-
 diff.h                         |    3 +
 diffcore-rename.c              |  354 ++++++++++++++++++++++++++++++++++++++--
 diffcore.h                     |    1 +
 tree-diff.c                    |    4 +-
 8 files changed, 383 insertions(+), 15 deletions(-)

diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index e954af0..2d99511 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -243,6 +243,10 @@ endif::git-log[]
 	delete/add pair to be a rename if more than 90% of the file
 	hasn't changed.
 
+--detect-bulk-moves::
+	Detect bulk move of all files of a directory into a
+	different one.
+
 -C[<n>]::
 	Detect copies as well as renames.  See also `--find-copies-harder`.
 	If `n` is specified, it has the same meaning as for `-M<n>`.
diff --git a/Documentation/gitdiffcore.txt b/Documentation/gitdiffcore.txt
index 6af29a4..edeb159 100644
--- a/Documentation/gitdiffcore.txt
+++ b/Documentation/gitdiffcore.txt
@@ -175,6 +175,18 @@ the expense of making it slower.  Without `\--find-copies-harder`,
 'git diff-{asterisk}' commands can detect copies only if the file that was
 copied happened to have been modified in the same changeset.
 
+Bulk move of all files of a directory into a different one can get
+detected using the `\--detect-bulk-moves` option.  This adds an
+additional pass on top of the results of per-file rename detection.
+They are reported with NULL SHA1 id, in addition to the file renames:
+
+------------------------------------------------
+:040000 040000 0000000... 0000000... R100	a/*	b/
+:100644 100644 0123456... 1234567... R90	a/file0	b/file3
+:100644 100644 0123456... 1234567... R100	a/file1	b/file1
+:100644 100644 0123456... 1234567... R100	a/file2	b/file2
+------------------------------------------------
+
 
 diffcore-merge-broken: For Putting "Complete Rewrites" Back Together
 --------------------------------------------------------------------
diff --git a/diff-lib.c b/diff-lib.c
index 392ce2b..5ec3ddc 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -208,7 +208,8 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 						    ce_option, &dirty_submodule);
 		if (!changed && !dirty_submodule) {
 			ce_mark_uptodate(ce);
-			if (!DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
+			if (!DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER) &&
+			    !DIFF_OPT_TST(&revs->diffopt, DETECT_BULK_MOVES))
 				continue;
 		}
 		oldmode = ce->ce_mode;
@@ -338,7 +339,8 @@ static int show_modified(struct rev_info *revs,
 
 	oldmode = old->ce_mode;
 	if (mode == oldmode && !hashcmp(sha1, old->sha1) && !dirty_submodule &&
-	    !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
+	    !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER) &&
+	    !DIFF_OPT_TST(&revs->diffopt, DETECT_BULK_MOVES))
 		return 0;
 
 	diff_change(&revs->diffopt, oldmode, mode,
diff --git a/diff.c b/diff.c
index 71efa8e..1d88281 100644
--- a/diff.c
+++ b/diff.c
@@ -3188,6 +3188,11 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		DIFF_OPT_SET(options, REVERSE_DIFF);
 	else if (!strcmp(arg, "--find-copies-harder"))
 		DIFF_OPT_SET(options, FIND_COPIES_HARDER);
+	else if (!strcmp(arg, "--detect-bulk-moves")) {
+		DIFF_OPT_SET(options, DETECT_BULK_MOVES);
+		if (!options->detect_rename)
+			options->detect_rename = DIFF_DETECT_RENAME;
+	}
 	else if (!strcmp(arg, "--follow"))
 		DIFF_OPT_SET(options, FOLLOW_RENAMES);
 	else if (!strcmp(arg, "--color"))
@@ -3466,7 +3471,14 @@ static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
 	if (p->status == DIFF_STATUS_COPIED ||
 	    p->status == DIFF_STATUS_RENAMED) {
 		const char *name_a, *name_b;
-		name_a = p->one->path;
+		if (p->is_bulkmove) {
+			/* append "*" to the first dirname */
+			char buf[PATH_MAX];
+			char *next = memccpy(buf, p->one->path, '\0', PATH_MAX);
+			next[-1] = '*'; *next = '\0';
+			name_a = buf;
+		} else
+			name_a = p->one->path;
 		name_b = p->two->path;
 		strip_prefix(opt->prefix_length, &name_a, &name_b);
 		write_name_quoted(name_a, opt->file, inter_name_termination);
diff --git a/diff.h b/diff.h
index 1fd44f5..b0d6fa6 100644
--- a/diff.h
+++ b/diff.h
@@ -78,6 +78,7 @@ typedef struct strbuf *(*diff_prefix_fn_t)(struct diff_options *opt, void *data)
 #define DIFF_OPT_IGNORE_UNTRACKED_IN_SUBMODULES (1 << 25)
 #define DIFF_OPT_IGNORE_DIRTY_SUBMODULES (1 << 26)
 #define DIFF_OPT_OVERRIDE_SUBMODULE_CONFIG (1 << 27)
+#define DIFF_OPT_DETECT_BULK_MOVES  (1 << 28)
 
 #define DIFF_OPT_TST(opts, flag)    ((opts)->flags & DIFF_OPT_##flag)
 #define DIFF_OPT_SET(opts, flag)    ((opts)->flags |= DIFF_OPT_##flag)
@@ -265,6 +266,8 @@ extern void diffcore_fix_diff_index(struct diff_options *);
 "  -C            detect copies.\n" \
 "  --find-copies-harder\n" \
 "                try unchanged files as candidate for copy detection.\n" \
+"  --detect-bulk-moves\n" \
+"                detect wholesale directory renames.\n" \
 "  -l<n>         limit rename attempts up to <n> paths.\n" \
 "  -O<file>      reorder diffs according to the <file>.\n" \
 "  -S<string>    find filepair whose only one side contains the string.\n" \
diff --git a/diffcore-rename.c b/diffcore-rename.c
index df41be5..fa2ba7c 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -11,9 +11,13 @@
 static struct diff_rename_dst {
 	struct diff_filespec *two;
 	struct diff_filepair *pair;
+	unsigned i_am_not_single:1; /* does not look for a match, only here to be looked at */
 } *rename_dst;
 static int rename_dst_nr, rename_dst_alloc;
 
+/*
+ * Do a binary search of "two" in "rename_dst", inserting it if not found.
+ */
 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
 						 int insert_ok)
 {
@@ -49,9 +53,36 @@ static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
 	rename_dst[first].two = alloc_filespec(two->path);
 	fill_filespec(rename_dst[first].two, two->sha1, two->mode);
 	rename_dst[first].pair = NULL;
+	rename_dst[first].i_am_not_single = 0;
 	return &(rename_dst[first]);
 }
 
+/*
+ * Do a binary search in "rename_dst" of any entry under "dirname".
+ */
+static struct diff_rename_dst *locate_rename_dst_dir(const char *dirname)
+{
+	int first, last;
+	int prefixlength = strlen(dirname);
+
+	first = 0;
+	last = rename_dst_nr;
+	while (last > first) {
+		int next = (last + first) >> 1;
+		struct diff_rename_dst *dst = &(rename_dst[next]);
+		int cmp = strncmp(dirname, dst->two->path, prefixlength);
+		if (!cmp)
+			return dst;
+		if (cmp < 0) {
+			last = next;
+			continue;
+		}
+		first = next+1;
+	}
+	/* not found */
+	return NULL;
+}
+
 /* Table of rename/copy src files */
 static struct diff_rename_src {
 	struct diff_filespec *one;
@@ -386,8 +417,11 @@ static int find_exact_renames(void)
 	for (i = 0; i < rename_src_nr; i++)
 		insert_file_table(&file_table, -1, i, rename_src[i].one);
 
-	for (i = 0; i < rename_dst_nr; i++)
+	for (i = 0; i < rename_dst_nr; i++) {
+		if (rename_dst[i].i_am_not_single)
+			continue;
 		insert_file_table(&file_table, 1, i, rename_dst[i].two);
+	}
 
 	/* Find the renames */
 	i = for_each_hash(&file_table, find_same_files);
@@ -414,6 +448,270 @@ static void record_if_better(struct diff_score m[], struct diff_score *o)
 		m[worst] = *o;
 }
 
+static struct diff_bulk_rename {
+	struct diff_filespec *one;
+	struct diff_filespec *two;
+	int discarded;
+} *bulkmove_candidates;
+static int bulkmove_candidates_nr, bulkmove_candidates_alloc;
+
+/*
+ * Do a binary search of "one" in "bulkmove_candidate", inserting it if not
+ * found.
+ * A good part was copy-pasted from locate_rename_dst().
+ */
+static struct diff_bulk_rename *locate_bulkmove_candidate(const char *one_path,
+							  const char *two_path)
+{
+	int first, last;
+
+	first = 0;
+	last = bulkmove_candidates_nr;
+	while (last > first) {
+		int next = (last + first) >> 1;
+		struct diff_bulk_rename *candidate = &(bulkmove_candidates[next]);
+		/* primary sort key on one_path, secondary on two_path */
+		int cmp = strcmp(one_path, candidate->one->path);
+		if (!cmp)
+			cmp = strcmp(two_path, candidate->two->path);
+		if (!cmp)
+			return candidate;
+		if (cmp < 0) {
+			last = next;
+			continue;
+		}
+		first = next+1;
+	}
+	/* not found */
+	/* insert to make it at "first" */
+	if (bulkmove_candidates_alloc <= bulkmove_candidates_nr) {
+		bulkmove_candidates_alloc = alloc_nr(bulkmove_candidates_alloc);
+		bulkmove_candidates = xrealloc(bulkmove_candidates,
+				      bulkmove_candidates_alloc * sizeof(*bulkmove_candidates));
+	}
+	bulkmove_candidates_nr++;
+	if (first < bulkmove_candidates_nr)
+		memmove(bulkmove_candidates + first + 1, bulkmove_candidates + first,
+			(bulkmove_candidates_nr - first - 1) * sizeof(*bulkmove_candidates));
+
+	bulkmove_candidates[first].one = alloc_filespec(one_path);
+	fill_filespec(bulkmove_candidates[first].one, null_sha1, S_IFDIR);
+	bulkmove_candidates[first].two = alloc_filespec(two_path);
+	fill_filespec(bulkmove_candidates[first].two, null_sha1, S_IFDIR);
+	bulkmove_candidates[first].discarded = 0;
+	return &(bulkmove_candidates[first]);
+}
+
+/*
+ * Copy dirname of src into dst, suitable to append a filename without
+ * an additional "/".
+ * Only handles relative paths since there is no absolute path in a git repo.
+ * Writes "" when there is no "/" in src.
+ * May overwrite more chars than really needed, if src ends with a "/".
+ * Supports in-place modification of src by passing dst == src.
+ */
+static const char *copy_dirname(char *dst, const char *src)
+{
+	size_t len = strlen(src);
+	const char *slash;
+	char *end;
+
+	if (len > 0 && src[len - 1] == '/')
+		/* Trailing slash.  Ignore it. */
+		len--;
+
+	slash = memrchr(src, '/', len);
+	if (!slash) {
+		*dst = '\0';
+		return dst;
+	}
+
+	end = mempcpy(dst, src, slash - src + 1);
+	*end = '\0';
+	return dst;
+}
+
+// FIXME: leaks like hell.
+/* See if the fact that one_leftover exists under one_parent_path in
+ * dst tree should disqualify one_parent_path from bulkmove eligibility.
+ * Return 1 if it disqualifies, 0 if it is OK.
+ */
+static int dispatched_to_different_dirs(const char *one_parent_path)
+{
+	/* this might be a dir split, or files added
+	 * after the bulk move, or just an isolated
+	 * rename */
+	int two_idx, j, onep_len, maybe_dir_rename;
+	struct diff_rename_dst *one_leftover =
+		one_leftover = locate_rename_dst_dir(one_parent_path);
+
+	if (!one_leftover)
+		return 0;
+
+	/* try to see if it is a file added after the bulk move */
+	two_idx = one_leftover - rename_dst;
+	onep_len = strlen(one_parent_path);
+	maybe_dir_rename = 1;
+
+	/* check no leftover file was already here before */
+	for (j = two_idx; j < rename_dst_nr; j++) {
+		if (strncmp(rename_dst[j].two->path,
+			    one_parent_path, onep_len))
+			break; /* exhausted directory in this direction */
+		fprintf(stderr, "[DBG] leftover file %s in %s\n",
+			rename_dst[j].two->path, one_parent_path);
+		if (rename_dst[j].i_am_not_single || /* those were already here */
+		    (rename_dst[j].pair &&
+		     !strncmp(rename_dst[j].pair->one->path,
+			      one_parent_path, onep_len) && /* renamed from here */
+		     strncmp(rename_dst[j].two->path,
+			     one_parent_path, onep_len))) { /* not to a subdir */
+			maybe_dir_rename = 0;
+			fprintf(stderr, "[DBG] ... tells not a bulk move\n");
+			break;
+		}
+		fprintf(stderr, "[DBG] ... not believed to prevent bulk move\n");
+	}
+	if (!maybe_dir_rename)
+		return 1;
+	/* try the other direction (dup code) */
+	for (j = two_idx-1; j >= 0; j--) {
+		if (strncmp(rename_dst[j].two->path,
+			    one_parent_path, onep_len))
+			break; /* exhausted directory in this direction */
+		fprintf(stderr, "[DBG] leftover file %s in '%s'\n",
+			rename_dst[j].two->path, one_parent_path);
+		if (rename_dst[j].i_am_not_single || /* those were already here */
+		    (rename_dst[j].pair &&
+		     !strncmp(rename_dst[j].pair->one->path,
+			      one_parent_path, onep_len) && /* renamed from here */
+		     strncmp(rename_dst[j].two->path,
+			     one_parent_path, onep_len))) { /* not to a subdir */
+			maybe_dir_rename = 0;
+			fprintf(stderr, "[DBG] ... tells not a bulk move\n");
+			break;
+		}
+		fprintf(stderr, "[DBG] ... not believed to prevent bulk move\n");
+	}
+	if (!maybe_dir_rename)
+		return 1;
+
+	/* Here we are in the case where a directory
+	 * content was completely moved, but files
+	 * were added to it afterwards.  Proceed as
+	 * for a simple bulk move. */
+	return 0;
+}
+
+/*
+ * Assumes candidate->one is a subdir of seen->one, mark 'seen' as
+ * discarded if candidate->two is outside seen->two.  Also mark
+ * 'candidate' itself as discarded if the conflict implies so.
+ *
+ * Return 1 if 'seen' was discarded
+ */
+static int discard_if_outside(struct diff_bulk_rename *candidate,
+			 struct diff_bulk_rename *seen) {
+	if (!prefixcmp(candidate->two->path, seen->two->path)) {
+		fprintf(stderr, "[DBG]  'dstpair' conforts 'seen'\n");
+		return 0;
+	} else {
+		fprintf(stderr, "[DBG] discarding %s -> %s from bulk moves (split into %s and %s)\n",
+			seen->one->path, seen->two->path,
+			candidate->two->path, seen->two->path);
+		seen->discarded = 1;
+		/* Need to discard dstpair as well, unless moving from
+		 * a strict subdir of seen->one or to a strict subdir
+		 * of seen->two */
+		if (!strcmp(seen->one->path, candidate->one->path) &&
+		    prefixcmp(seen->two->path, candidate->two->path)) {
+			fprintf(stderr, "[DBG] ... and not adding self\n");
+			candidate->discarded = 1;
+		}
+		return 1;
+	}
+}
+
+/*
+ * Check if the rename specified by "dstpair" could cause a
+ * bulk move to be detected, record it in bulkmove_candidates if yes.
+ */
+static void check_one_bulk_move(struct diff_filepair *dstpair)
+{
+	char one_parent_path[PATH_MAX], two_parent_path[PATH_MAX];
+
+	/* genuine new files (or believed to be so) */
+	if (!dstpair)
+		return;
+	/* dummy renames used by copy detection */
+	if (!strcmp(dstpair->one->path, dstpair->two->path))
+		return;
+
+	copy_dirname(one_parent_path, dstpair->one->path);
+	copy_dirname(two_parent_path, dstpair->two->path);
+
+	/* simple rename with no directory change */
+	if (!strcmp(one_parent_path, two_parent_path))
+		return;
+
+	fprintf(stderr, "[] %s -> %s ?\n", dstpair->one->path, dstpair->two->path);
+
+	/* loop up one_parent_path over successive parents */
+	// FIXME: also loop over two_parent_path prefixes
+	do {
+		struct diff_bulk_rename *seen;
+		int old_nr = bulkmove_candidates_nr;
+		struct diff_bulk_rename *candidate =
+			locate_bulkmove_candidate(one_parent_path, two_parent_path);
+		fprintf(stderr, "[[]] %s ...\n", one_parent_path);
+		if (old_nr == bulkmove_candidates_nr) {
+			fprintf(stderr, "[DBG]  already seen\n");
+			return;
+		}
+
+		/* After this commit, are there any files still under one_parent_path ?
+		 * Any file left would disqualifies this dir for bulk move.
+		 */
+		if (dispatched_to_different_dirs(one_parent_path)) {
+			// FIXME: check overlap with discard_if_outside()
+			candidate->discarded = 1;
+			return;
+		}
+
+		/* walk up for one_parent_path prefixes */
+		for (seen = candidate-1; (seen >= bulkmove_candidates) &&
+			     !prefixcmp(one_parent_path, seen->one->path); seen--) {
+			fprintf(stderr, "[DBG]  ? %s -> %s\n", seen->one->path, seen->two->path);
+			/* subdir of "seen" dest dir ? */
+			if (discard_if_outside(candidate, seen))
+				continue;
+		}
+		/* look down for other moves from one_parent_path */
+		seen = candidate + 1;
+		if (seen != bulkmove_candidates + bulkmove_candidates_nr &&
+		    !strcmp(one_parent_path, seen->one->path)) {
+			fprintf(stderr, "[DBG]  ? %s -> %s (2)\n", seen->one->path, seen->two->path);
+			/* subdir of "seen" dest dir ? */
+			if (discard_if_outside(candidate, seen))
+				continue;
+		}
+
+		/* next parent if any */
+		copy_dirname(one_parent_path, one_parent_path);
+	} while (*one_parent_path);
+}
+
+/*
+ * Take all file renames recorded so far and check if they could cause
+ * a bulk move to be detected.
+ */
+static void diffcore_bulk_moves(void)
+{
+	int i;
+	for (i = 0; i < rename_dst_nr; i++)
+		check_one_bulk_move(rename_dst[i].pair);
+}
+
 void diffcore_rename(struct diff_options *options)
 {
 	int detect_rename = options->detect_rename;
@@ -424,6 +722,7 @@ void diffcore_rename(struct diff_options *options)
 	struct diff_score *mx;
 	int i, j, rename_count;
 	int num_create, num_src, dst_cnt;
+	struct diff_bulk_rename *candidate;
 
 	if (!minimum_score)
 		minimum_score = DEFAULT_RENAME_SCORE;
@@ -438,8 +737,7 @@ void diffcore_rename(struct diff_options *options)
 				continue; /* not interested */
 			else
 				locate_rename_dst(p->two, 1);
-		}
-		else if (!DIFF_FILE_VALID(p->two)) {
+		} else if (!DIFF_FILE_VALID(p->two)) {
 			/*
 			 * If the source is a broken "delete", and
 			 * they did not really want to get broken,
@@ -450,14 +748,23 @@ void diffcore_rename(struct diff_options *options)
 			if (p->broken_pair && !p->score)
 				p->one->rename_used++;
 			register_rename_src(p->one, p->score);
-		}
-		else if (detect_rename == DIFF_DETECT_COPY) {
-			/*
-			 * Increment the "rename_used" score by
-			 * one, to indicate ourselves as a user.
-			 */
-			p->one->rename_used++;
-			register_rename_src(p->one, p->score);
+		} else {
+			if (detect_rename == DIFF_DETECT_COPY) {
+				/*
+				 * Increment the "rename_used" score by
+				 * one, to indicate ourselves as a user.
+				 */
+				p->one->rename_used++;
+				register_rename_src(p->one, p->score);
+			}
+			if (DIFF_OPT_TST(options, DETECT_BULK_MOVES)) {
+				/* similarly, bulk move detection needs to
+				 * see all files from second tree, but we don't
+				 * want them to be matched against single sources.
+				 */
+				// FIXME: check interaction with --find-copies-harder
+				locate_rename_dst(p->two, 1)->i_am_not_single = 1;
+			}
 		}
 	}
 	if (rename_dst_nr == 0 || rename_src_nr == 0)
@@ -509,6 +816,8 @@ void diffcore_rename(struct diff_options *options)
 
 		if (rename_dst[i].pair)
 			continue; /* dealt with exact match already. */
+		if (rename_dst[i].i_am_not_single)
+			continue; /* not looking for a match. */
 
 		m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 		for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
@@ -569,7 +878,30 @@ void diffcore_rename(struct diff_options *options)
 	/* At this point, we have found some renames and copies and they
 	 * are recorded in rename_dst.  The original list is still in *q.
 	 */
+
+	/* Now possibly factorize those renames and copies. */
+	if (DIFF_OPT_TST(options, DETECT_BULK_MOVES))
+		diffcore_bulk_moves();
+
 	DIFF_QUEUE_CLEAR(&outq);
+
+	/* Now turn non-discarded bulkmove_candidates into real renames */
+	for (candidate = bulkmove_candidates;
+	     candidate < bulkmove_candidates + bulkmove_candidates_nr; candidate++) {
+		struct diff_filepair* pair;
+		if (candidate->discarded)
+			continue;
+		/* visualize toplevel dir if needed */
+		if (!*candidate->one->path)
+			candidate->one->path = "./";
+		if (!*candidate->two->path)
+			candidate->two->path = "./";
+		pair = diff_queue(&outq, candidate->one, candidate->two);
+		pair->score = MAX_SCORE;
+		pair->renamed_pair = 1;
+		pair->is_bulkmove = 1;
+	}
+
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];
 		struct diff_filepair *pair_to_free = NULL;
diff --git a/diffcore.h b/diffcore.h
index b8f1fde..6dab95b 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -69,6 +69,7 @@ struct diff_filepair {
 	unsigned broken_pair : 1;
 	unsigned renamed_pair : 1;
 	unsigned is_unmerged : 1;
+	unsigned is_bulkmove : 1;
 };
 #define DIFF_PAIR_UNMERGED(p) ((p)->is_unmerged)
 
diff --git a/tree-diff.c b/tree-diff.c
index cd659c6..5d9f123 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -49,7 +49,9 @@ static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const
 		show_entry(opt, "+", t2, base, baselen);
 		return 1;
 	}
-	if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
+	if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) &&
+	    !DIFF_OPT_TST(opt, DETECT_BULK_MOVES) &&
+	    !hashcmp(sha1, sha2) && mode1 == mode2)
 		return 0;
 
 	/*
-- 
1.7.2.3

[PATCH v7 2/3] Add testcases for the --detect-bulk-moves diffcore flag.

[Yann Dirson]

This notably includes a couple of tests for cases known not to be
working correctly yet.

This patch has been improved by the following contributions:
- Jonathan Nieder: reworked style of test script
- Jonathan Nieder: use "git commit" in test instead of only plumbing,
  and use test_tick
- Sverre Rabbelier: anonymize hashes

Thanks-to: Jonathan Nieder <jrnieder@gmail.com>
Thanks-to: Sverre Rabbelier <srabbelier@gmail.com>
Signed-off-by: Yann Dirson <ydirson@free.fr>
---
 t/t4046-diff-rename-factorize.sh |  296 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 296 insertions(+), 0 deletions(-)
 create mode 100755 t/t4046-diff-rename-factorize.sh

diff --git a/t/t4046-diff-rename-factorize.sh b/t/t4046-diff-rename-factorize.sh
new file mode 100755
index 0000000..88e5b5b
--- /dev/null
+++ b/t/t4046-diff-rename-factorize.sh
@@ -0,0 +1,296 @@
+#!/bin/sh
+#
+# Copyright (c) 2008,2010 Yann Dirson
+# Copyright (c) 2005 Junio C Hamano
+#
+
+# TODO for dir renames:
+# * two dirs or more moving all their files to a single dir
+# * simultaneous bulkmove and rename
+
+test_description='Test rename factorization in diff engine.
+
+'
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/diff-lib.sh
+
+test_expect_success 'setup' '
+	git commit --allow-empty -m "original empty commit"
+
+	mkdir a &&
+	printf "Line %s\n" 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 >a/path0 &&
+	sed <a/path0 >a/path1 s/Line/Record/ &&
+	sed <a/path0 >a/path2 s/Line/Stuff/ &&
+	sed <a/path0 >a/path3 s/Line/Blurb/ &&
+
+	git update-index --add a/path* &&
+	test_tick &&
+	git commit -m "original set of files"
+
+	: rename the directory &&
+	git mv a b
+'
+test_expect_success 'diff-index --detect-bulk-moves after directory move.' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	a/*	b/
+	:100644 100644 X X R#	a/path0	b/path0
+	:100644 100644 X X R#	a/path1	b/path1
+	:100644 100644 X X R#	a/path2	b/path2
+	:100644 100644 X X R#	a/path3	b/path3
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup non-100% rename' '
+	echo "Line 16" >>b/path0 &&
+	git mv b/path2 b/2path &&
+	git rm -f b/path3 &&
+	echo anything >b/path100 &&
+	git add b/path100
+'
+test_expect_success 'diff-index --detect-bulk-moves after content changes.' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	a/*	b/
+	:100644 000000 X X D#	a/path3
+	:100644 100644 X X R#	a/path2	b/2path
+	:100644 100644 X X R#	a/path0	b/path0
+	:100644 100644 X X R#	a/path1	b/path1
+	:000000 100644 X X A#	b/path100
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup bulk move that is not directory move' '
+	git reset -q --hard &&
+
+	mkdir c &&
+	(
+		for i in 0 1 2; do
+			cp a/path$i c/apath$i || exit
+		done
+	) &&
+	git update-index --add c/apath* &&
+	test_tick &&
+	git commit -m "first set of changes" &&
+
+	git mv c/* a/
+'
+test_expect_success 'diff-index --detect-bulk-moves without full-dir rename.' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	c/*	a/
+	:100644 100644 X X R#	c/apath0	a/apath0
+	:100644 100644 X X R#	c/apath1	a/apath1
+	:100644 100644 X X R#	c/apath2	a/apath2
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup bulk move with new file in source dir' '
+	echo > c/anotherpath "How much wood?" &&
+	git update-index --add c/another*
+'
+test_expect_success 'diff-index --detect-bulk-moves with new file in source dir.' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	c/*	a/
+	:100644 100644 X X R#	c/apath0	a/apath0
+	:100644 100644 X X R#	c/apath1	a/apath1
+	:100644 100644 X X R#	c/apath2	a/apath2
+	:000000 100644 X X A#	c/anotherpath
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup bulk move with interfering copy' '
+	rm c/anotherpath &&
+	git update-index --remove c/anotherpath &&
+	mkdir b &&
+	cp a/apath0 b/apath9 &&
+	echo >> a/apath0 "more" &&
+	git update-index --add a/apath0 b/apath9
+'
+# scores select the "wrong" one as "moved" (only a suboptimal detection)
+test_expect_failure 'diff-index --detect-bulk-moves with interfering copy.' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	c/*	a/
+	:100644 100644 X X R#	c/apath0	a/apath0
+	:100644 100644 X X R#	c/apath1	a/apath1
+	:100644 100644 X X R#	c/apath2	a/apath2
+	:100644 100644 X X C#	c/apath0	b/apath9
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup bulk move to toplevel' '
+	git reset -q --hard &&
+	git mv c/* .
+'
+test_expect_success 'diff-index --detect-bulk-moves bulk move to toplevel.' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	c/*	./
+	:100644 100644 X X R#	c/apath0	apath0
+	:100644 100644 X X R#	c/apath1	apath1
+	:100644 100644 X X R#	c/apath2	apath2
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup move including a subdir, with some content changes' '
+	git reset -q --hard &&
+	mv c a/ &&
+	git update-index --add --remove a/c/* c/apath0 c/apath1 c/apath2 &&
+	test_tick &&
+	git commit -m "move as subdir" &&
+
+	git mv a b &&
+	echo foo >>b/c/apath0 &&
+	git update-index --add b/c/apath*
+'
+test_expect_success 'diff-index --detect-bulk-moves on a move including a subdir.' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	a/*	b/
+	:040000 040000 X X R#	a/c/*	b/c/
+	:100644 100644 X X R#	a/c/apath0	b/c/apath0
+	:100644 100644 X X R#	a/c/apath1	b/c/apath1
+	:100644 100644 X X R#	a/c/apath2	b/c/apath2
+	:100644 100644 X X R#	a/path0	b/path0
+	:100644 100644 X X R#	a/path1	b/path1
+	:100644 100644 X X R#	a/path2	b/path2
+	:100644 100644 X X R#	a/path3	b/path3
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup move of only a subdir' '
+	git reset -q --hard &&
+	git mv a/c a/d &&
+	: rename a subdirectory of a/.
+'
+test_expect_success 'moving a subdir only' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	a/c/*	a/d/
+	:100644 100644 X X R#	a/c/apath0	a/d/apath0
+	:100644 100644 X X R#	a/c/apath1	a/d/apath1
+	:100644 100644 X X R#	a/c/apath2	a/d/apath2
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup move without a subdir' '
+	git reset -q --hard &&
+	mkdir b &&
+	: rename files in the directory but not subdir. &&
+	git mv a/path* b/
+'
+test_expect_success 'moving files but not subdirs is not mistaken for dir move' '
+	cat >expected <<-EOF &&
+	:100644 100644 X X R#	a/path0	b/path0
+	:100644 100644 X X R#	a/path1	b/path1
+	:100644 100644 X X R#	a/path2	b/path2
+	:100644 100644 X X R#	a/path3	b/path3
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup move of files and subdirs to different places' '
+	git reset -q --hard &&
+	git mv a/c b &&
+	git mv a d
+'
+test_expect_success 'moving subdirs into one dir and files into another is not mistaken for dir move' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	a/c/*	b/
+	:100644 100644 X X R#	a/c/apath0	b/apath0
+	:100644 100644 X X R#	a/c/apath1	b/apath1
+	:100644 100644 X X R#	a/c/apath2	b/apath2
+	:100644 100644 X X R#	a/path0	d/path0
+	:100644 100644 X X R#	a/path1	d/path1
+	:100644 100644 X X R#	a/path2	d/path2
+	:100644 100644 X X R#	a/path3	d/path3
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+
+# the same with different ordering
+test_expect_success 'setup move of files and subdirs to different places' '
+	git mv d 0
+'
+test_expect_success 'moving subdirs into one dir and files into another is not mistaken for dir move' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	a/c/*	b/
+	:100644 100644 X X R#	a/path0	0/path0
+	:100644 100644 X X R#	a/path1	0/path1
+	:100644 100644 X X R#	a/path2	0/path2
+	:100644 100644 X X R#	a/path3	0/path3
+	:100644 100644 X X R#	a/c/apath0	b/apath0
+	:100644 100644 X X R#	a/c/apath1	b/apath1
+	:100644 100644 X X R#	a/c/apath2	b/apath2
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+
+test_expect_success 'setup move of dir with only subdirs' '
+	git reset -q --hard &&
+	mkdir a/b &&
+	mv a/path* a/b/ &&
+	git update-index --add --remove a/path0 a/path1 a/path2 a/path3 a/b/path* &&
+	test_tick &&
+	git commit -m "move all toplevel files down one level" &&
+
+	git mv a z
+'
+# TODO: only a suboptimal non-detection
+test_expect_failure 'moving a dir with no direct children files' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	a/*	z/
+	:040000 040000 X X R#	a/b/*	z/b/
+	:040000 040000 X X R#	a/c/*	z/c/
+	:100644 100644 X X R#	a/b/path0	z/b/path0
+	:100644 100644 X X R#	a/b/path1	z/b/path1
+	:100644 100644 X X R#	a/b/path2	z/b/path2
+	:100644 100644 X X R#	a/b/path3	z/b/path3
+	:100644 100644 X X R#	a/c/apath0	z/c/apath0
+	:100644 100644 X X R#	a/c/apath1	z/c/apath1
+	:100644 100644 X X R#	a/c/apath2	z/c/apath2
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+# now test moving all files from toplevel into subdir (does not hides file moves) (needs consensus on syntax)
+# Note: this is a special case of move of a dir into one of its own subdirs, which in
+# turn is a variant of new files/dirs being added into a dir after all its contents
+# are moved away
+
+test_expect_success 'setup move from toplevel to subdir' '
+	git reset -q --hard HEAD~3 &&
+	mv a/* . &&
+	git update-index --add --remove a/path0 a/path1 a/path2 a/path3 path* &&
+	test_tick &&
+	git commit -m "move all files to toplevel" &&
+
+	mkdir z &&
+	git mv path* z/
+'
+test_expect_success '--detect-bulk-moves everything from toplevel.' '
+	cat >expected <<-EOF &&
+	:040000 040000 X X R#	./*	z/
+	:100644 100644 X X R#	path0	z/path0
+	:100644 100644 X X R#	path1	z/path1
+	:100644 100644 X X R#	path2	z/path2
+	:100644 100644 X X R#	path3	z/path3
+	EOF
+	git diff-index --detect-bulk-moves HEAD >current &&
+	compare_diff_raw expected current
+'
+
+test_done
-- 
1.7.2.3

[PATCH v7 3/3] [WIP] Allow hiding renames of individual files involved in a directory rename.

[Yann Dirson]

Once has identified groups of bulk-moved files, and then
the --hide-bulk-move-details flag hides those of the individual renames
which carry no other information (further name change, or content changes).

This makes it much easier to a human reader to spot content changes
in a commit that also moves a whole subtree.

Important note: unified diff output is not currently useful, since the "bulk move"
headers are not yet added by --detect-bulk-moves, but the redundant renames are
really removed.

Signed-off-by: Yann Dirson <ydirson@free.fr>
---
 diff.c            |    7 +++++
 diff.h            |    3 ++
 diffcore-rename.c |   68 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 diffcore.h        |    1 +
 4 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/diff.c b/diff.c
index 1d88281..3cc7a55 100644
--- a/diff.c
+++ b/diff.c
@@ -3193,6 +3193,13 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		if (!options->detect_rename)
 			options->detect_rename = DIFF_DETECT_RENAME;
 	}
+	else if (!strcmp(arg, "--hide-bulk-move-details")) {
+		DIFF_OPT_SET(options, HIDE_DIR_RENAME_DETAILS);
+		if (!DIFF_OPT_TST(options, DETECT_BULK_MOVES))
+			DIFF_OPT_SET(options, DETECT_BULK_MOVES);
+		if (!options->detect_rename)
+			options->detect_rename = DIFF_DETECT_RENAME;
+	}
 	else if (!strcmp(arg, "--follow"))
 		DIFF_OPT_SET(options, FOLLOW_RENAMES);
 	else if (!strcmp(arg, "--color"))
diff --git a/diff.h b/diff.h
index b0d6fa6..7f132d0 100644
--- a/diff.h
+++ b/diff.h
@@ -79,6 +79,7 @@ typedef struct strbuf *(*diff_prefix_fn_t)(struct diff_options *opt, void *data)
 #define DIFF_OPT_IGNORE_DIRTY_SUBMODULES (1 << 26)
 #define DIFF_OPT_OVERRIDE_SUBMODULE_CONFIG (1 << 27)
 #define DIFF_OPT_DETECT_BULK_MOVES  (1 << 28)
+#define DIFF_OPT_HIDE_DIR_RENAME_DETAILS (1 << 29)
 
 #define DIFF_OPT_TST(opts, flag)    ((opts)->flags & DIFF_OPT_##flag)
 #define DIFF_OPT_SET(opts, flag)    ((opts)->flags |= DIFF_OPT_##flag)
@@ -268,6 +269,8 @@ extern void diffcore_fix_diff_index(struct diff_options *);
 "                try unchanged files as candidate for copy detection.\n" \
 "  --detect-bulk-moves\n" \
 "                detect wholesale directory renames.\n" \
+"  --hide-bulk-move-details\n" \
+"                hide renames of individual files in a directory rename.\n" \
 "  -l<n>         limit rename attempts up to <n> paths.\n" \
 "  -O<file>      reorder diffs according to the <file>.\n" \
 "  -S<string>    find filepair whose only one side contains the string.\n" \
diff --git a/diffcore-rename.c b/diffcore-rename.c
index fa2ba7c..3a68807 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -503,6 +503,34 @@ static struct diff_bulk_rename *locate_bulkmove_candidate(const char *one_path,
 }
 
 /*
+ * Marks as such file_rename if it is made uninteresting by dir_rename.
+ * Returns -1 if the file_rename is outside of the range in which given
+ * renames concerned by dir_rename are to be found (ie. end of loop),
+ * 0 otherwise.
+ */
+static int maybe_mark_uninteresting(struct diff_rename_dst *file_rename,
+				    struct diff_bulk_rename *dir_rename,
+				    int one_len, int two_len)
+{
+	if (!file_rename->pair) /* file add */
+		return 0;
+	if (strncmp(file_rename->two->path,
+		    dir_rename->two->path, two_len))
+		return -1;
+	if (strncmp(file_rename->pair->one->path,
+		    dir_rename->one->path, one_len) ||
+	    !basename_same(file_rename->pair->one, file_rename->two) ||
+	    file_rename->pair->score != MAX_SCORE)
+		return 0;
+
+	file_rename->pair->uninteresting_rename = 1;
+	fprintf(stderr, "[DBG] %s* -> %s* makes %s -> %s uninteresting\n",
+		dir_rename->one->path, dir_rename->two->path,
+		file_rename->pair->one->path, file_rename->two->path);
+	return 0;
+}
+
+/*
  * Copy dirname of src into dst, suitable to append a filename without
  * an additional "/".
  * Only handles relative paths since there is no absolute path in a git repo.
@@ -705,11 +733,44 @@ static void check_one_bulk_move(struct diff_filepair *dstpair)
  * Take all file renames recorded so far and check if they could cause
  * a bulk move to be detected.
  */
-static void diffcore_bulk_moves(void)
+static void diffcore_bulk_moves(int opt_hide_renames)
 {
 	int i;
 	for (i = 0; i < rename_dst_nr; i++)
 		check_one_bulk_move(rename_dst[i].pair);
+
+	if (opt_hide_renames) {
+		/* flag as "uninteresting" those candidates hidden by dir move */
+		struct diff_bulk_rename *candidate;
+		for (candidate = bulkmove_candidates;
+		     candidate < bulkmove_candidates + bulkmove_candidates_nr;
+		     candidate++) {
+			int two_idx, i, one_len, two_len;
+			struct diff_rename_dst *two_sample;
+			if (candidate->discarded)
+				continue;
+
+			/* bisect to any entry within candidate dst dir */
+			two_sample = locate_rename_dst_dir(candidate->two->path);
+			if (!two_sample) {
+				die("PANIC: %s candidate of rename not in target tree (from %s)\n",
+				    candidate->two->path, candidate->one->path);
+			}
+			two_idx = two_sample - rename_dst;
+
+			/* now remove extraneous 100% files inside. */
+			one_len = strlen(candidate->one->path);
+			two_len = strlen(candidate->two->path);
+			for (i = two_idx; i < rename_dst_nr; i++)
+				if (maybe_mark_uninteresting(rename_dst+i, candidate,
+							     one_len, two_len) < 0)
+					break;
+			for (i = two_idx-1; i >= 0; i--)
+				if (maybe_mark_uninteresting(rename_dst+i, candidate,
+							     one_len, two_len) < 0)
+					break;
+		}
+	}
 }
 
 void diffcore_rename(struct diff_options *options)
@@ -881,7 +942,7 @@ void diffcore_rename(struct diff_options *options)
 
 	/* Now possibly factorize those renames and copies. */
 	if (DIFF_OPT_TST(options, DETECT_BULK_MOVES))
-		diffcore_bulk_moves();
+		diffcore_bulk_moves(DIFF_OPT_TST(options, HIDE_DIR_RENAME_DETAILS));
 
 	DIFF_QUEUE_CLEAR(&outq);
 
@@ -916,7 +977,8 @@ void diffcore_rename(struct diff_options *options)
 			struct diff_rename_dst *dst =
 				locate_rename_dst(p->two, 0);
 			if (dst && dst->pair) {
-				diff_q(&outq, dst->pair);
+				if (!dst->pair->uninteresting_rename)
+					diff_q(&outq, dst->pair);
 				pair_to_free = p;
 			}
 			else
diff --git a/diffcore.h b/diffcore.h
index 6dab95b..a4eb8e1 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -69,6 +69,7 @@ struct diff_filepair {
 	unsigned broken_pair : 1;
 	unsigned renamed_pair : 1;
 	unsigned is_unmerged : 1;
+	unsigned uninteresting_rename : 1;
 	unsigned is_bulkmove : 1;
 };
 #define DIFF_PAIR_UNMERGED(p) ((p)->is_unmerged)
-- 
1.7.2.3

[PATCH] [RFC] Add --detect-bulk-moves output to unidiff format.

[Yann Dirson]

Signed-off-by: Yann Dirson <ydirson@altern.org>
---

This patch is a complement to the v7 "Detection of directory renames"
series.  It produces output like the sample below (taken from kernel
tree).  Does that feel right ?  Is it worth moving the output
production to a separate func filling an strbuf ?

|commit 86c6d4d0acc64543a485c11e197d0bd2c5ae0bb2
|Author: Ralf Baechle <ralf@linux-mips.org>
|Date:   Thu Aug 5 13:25:55 2010 +0100
|
|    MIPS: PNX833x: Move code one directory level up.
|    
|    It was sharing the nxp directory but no code with pnx8550 and will fit
|    better into the new platform makefile scheme, if moved.
|    
|    Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
|
|diff --git --detect-bulk-moves arch/mips/nxp/pnx833x/common/ arch/mips/pnx833x/common/
|similarity index 100%
|bulk move from arch/mips/nxp/pnx833x/common/*
|bulk move to arch/mips/pnx833x/common/
|diff --git --detect-bulk-moves arch/mips/nxp/pnx833x/stb22x/ arch/mips/pnx833x/stb22x/
|similarity index 100%
|bulk move from arch/mips/nxp/pnx833x/stb22x/*
|bulk move to arch/mips/pnx833x/stb22x/
|diff --git a/arch/mips/Makefile b/arch/mips/Makefile
|index 2ba20d9..0556bc4 100644
[...]

 diff.c |   48 +++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/diff.c b/diff.c
index 1d88281..8f2f67f 100644
--- a/diff.c
+++ b/diff.c
@@ -2659,6 +2659,7 @@ static void run_diff_cmd(const char *pgm,
 	const char *xfrm_msg = NULL;
 	int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
 	int must_show_header = 0;
+	int use_color;
 
 	if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
 		pgm = NULL;
@@ -2668,14 +2669,36 @@ static void run_diff_cmd(const char *pgm,
 			pgm = drv->external;
 	}
 
+	/*
+	 * don't use colors when the header is intended for an
+	 * external diff driver
+	 */
+	use_color = DIFF_OPT_TST(o, COLOR_DIFF) && !pgm;
+
+	if (p->is_bulkmove) {
+		const char *set = diff_get_color(use_color, DIFF_METAINFO);
+		const char *reset = diff_get_color(use_color, DIFF_RESET);
+		struct strbuf *msgbuf;
+		char *line_prefix = "";
+
+		if (o->output_prefix) {
+			msgbuf = o->output_prefix(o, o->output_prefix_data);
+			line_prefix = msgbuf->buf;
+		}
+		fprintf(o->file, "%s%sdiff --git --detect-bulk-moves %s %s%s\n",
+			line_prefix, set, one->path, two->path, reset);
+		fprintf(o->file, "%s%ssimilarity index %d%%%s\n",
+			line_prefix, set, similarity_index(p), reset);
+		fprintf(o->file, "%s%sbulk move from %s*%s\n",
+			line_prefix, set, one->path, reset);
+		fprintf(o->file, "%s%sbulk move to %s%s\n",
+			line_prefix, set, two->path, reset);
+		return;
+	}
+
 	if (msg) {
-		/*
-		 * don't use colors when the header is intended for an
-		 * external diff driver
-		 */
 		fill_metainfo(msg, name, other, one, two, o, p,
-			      &must_show_header,
-			      DIFF_OPT_TST(o, COLOR_DIFF) && !pgm);
+			      &must_show_header, use_color);
 		xfrm_msg = msg->len ? msg->buf : NULL;
 	}
 
@@ -2748,8 +2771,10 @@ static void run_diff(struct diff_filepair *p, struct diff_options *o)
 		return;
 	}
 
-	diff_fill_sha1_info(one);
-	diff_fill_sha1_info(two);
+	if (!p->is_bulkmove) {
+		diff_fill_sha1_info(one);
+		diff_fill_sha1_info(two);
+	}
 
 	if (!pgm &&
 	    DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
@@ -3529,9 +3554,10 @@ static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
 	if (diff_unmodified_pair(p))
 		return;
 
-	if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
-	    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
-		return; /* no tree diffs in patch format */
+	if (!p->is_bulkmove &&
+	    ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
+	     (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode))))
+		return; /* no tree diffs in patch format, except for bulk moves */
 
 	run_diff(p, o);
 }
-- 
1.7.2.3

Re: [PATCH v7 1/3] Introduce bulk-move detection in diffcore.

[Junio C Hamano]

Yann Dirson <ydirson@altern.org> writes:

> The output of raw diff is displayed as "Rnnn a/* b/".  Those cannot be
> confused with renames of files named "whatever/*" with a literal star
> character, from the full-zero SHA1's.

I do not particularly like this asterisk here.  It is ambiguous with the
case where you renamed a directory whose name is '*' below a/ to a new
directory whose name is 'b', isn't it?  Using 0{40} as a differentiator
like you did is probably a good idea, but then I do not see a sound reason
you would need nor want that asterisk.

> +Bulk move of all files of a directory into a different one can get
> +detected using the `\--detect-bulk-moves` option.  This adds an
> +additional pass on top of the results of per-file rename detection.
> +They are reported with NULL SHA1 id, in addition to the file renames:
> +
> +------------------------------------------------
> +:040000 040000 0000000... 0000000... R100	a/*	b/
> +:100644 100644 0123456... 1234567... R90	a/file0	b/file3
> +:100644 100644 0123456... 1234567... R100	a/file1	b/file1
> +:100644 100644 0123456... 1234567... R100	a/file2	b/file2

This is kind of interesting.  Let's address two issues that should be
uncontroversial:

 (1) please do not use a/ and b/, as the reader can easily be confused and
     mistakenly think you are referring to the pre-/post- indicator we use
     when writing textual diffs (e.g. "diff --git a/frotz b/frotz").  You
     are illustrating rename between a directory to another directory,
     both of which are tracked paths.

 (2) The last two lines are R100 but with different object names between
     pre- and post-images, which is wrong and unnecessarily puzzling.
     Please make them match.

These obvious two complaints behind us, there is one more interesting
thing in the above, which is _not_ a complaint.

What about renaming of a/file0 to b/file3?  Is this part of "all files
from directory A moved to directory B"?  IOW, is the goal of this series
to use the "A/* -> B/" to label the change as bulk directory rename, if
the preimage has A/{1,2,3} and the postimage has their moved contents in
B/{one,two,three}?

I am wondering about the utility of such an extra information.  If there
were no "a/file0 -> b/file3" entry in the example, I would imagine that we
could use this "a/* -> b/" information to move "a/file5" to "b/file5" when
rebasing this patch to apply to a different preimage that had files other
than file{1,2} in directory "a", and I would further imagine that might be
a wonderful thing.

But if the new "a/* -> b/" hint only gives "things from A/ have migrated
to B/ but I can give no information on what name they took under their new
home", that may probably reduce the utility of this feature.

I dunno.

Re: [PATCH v7 1/3] Introduce bulk-move detection in diffcore.

[Yann Dirson]

On Mon, Oct 25, 2010 at 01:08:46AM -0700, Junio C Hamano wrote:
> Yann Dirson <ydirson@altern.org> writes:
> 
> > The output of raw diff is displayed as "Rnnn a/* b/".  Those cannot be
> > confused with renames of files named "whatever/*" with a literal star
> > character, from the full-zero SHA1's.
> 
> I do not particularly like this asterisk here.  It is ambiguous with the
> case where you renamed a directory whose name is '*' below a/ to a new
> directory whose name is 'b', isn't it?  Using 0{40} as a differentiator
> like you did is probably a good idea, but then I do not see a sound reason
> you would need nor want that asterisk.

It all boils down to one of the original motivations of this patch:
allowing exporters like git-svn to provide the right level of
information on directory renames, instead of only telling svn that the
git-svn user has renamed all individual files separately.

It is only later that I realized that the larger picture was about
bulk moves, and directory renames were only a subset of those.  So to
be able here to provide the right level of information to git-svn, we
need a separate syntax for the special case of dir renaming - and it
appeared natural to me to use something as close as possible to the
usual syntax used for the operation:

git mv foo bar => rename directory "foo" to "bar"
git mv foo/* bar/ => move all contents of "foo" to pre-existing "bar"

(I would still add trailing slashed to the first form for the sake of
ambiguity, obviously).

Now I'm not 100% happy with using 0{40} as differentiator - eg. we may
some day find out that it is indeed useful to output the tree hashes
there.

OTOH, the quoting rules for diff output are quite minimalist, I don't
know whether adding "*" as a character that requires quotes around the
filename would be acceptable: then we'll be able to differentiate
"foo/*" from "foo/"* or "foo"/* (quotes here for emphasis, for
interaction with other possible special chars) - the current code
would have a strong bias towards "foo/"*, but neither seem very sexy
to me (but since they would only appear in "pathologic" situations, do
we care ?)

[off-topic] while playing with (un)quoted filenames I noticed spaces
do not cause quoting, which can cause its own problems, like (not)
making a visual distinction between file "foo" and file "foo " in diff
output - not that it would be good practice, but someone can always
shoot itself in the foot, and it appears we have not thought yet on
how to help him not to shoot himself in this particular way.


> > +Bulk move of all files of a directory into a different one can get
> > +detected using the `\--detect-bulk-moves` option.  This adds an
> > +additional pass on top of the results of per-file rename detection.
> > +They are reported with NULL SHA1 id, in addition to the file renames:
> > +
> > +------------------------------------------------
> > +:040000 040000 0000000... 0000000... R100	a/*	b/
> > +:100644 100644 0123456... 1234567... R90	a/file0	b/file3
> > +:100644 100644 0123456... 1234567... R100	a/file1	b/file1
> > +:100644 100644 0123456... 1234567... R100	a/file2	b/file2
> 
> This is kind of interesting.  Let's address two issues that should be
> uncontroversial:

OK.

> These obvious two complaints behind us, there is one more interesting
> thing in the above, which is _not_ a complaint.
> 
> What about renaming of a/file0 to b/file3?  Is this part of "all files
> from directory A moved to directory B"?

The move+rename is "part of" the bulk rename in that the file is moved
from/two the same dirs as its siblings, but I acknowledge that it is
more than that.

>  IOW, is the goal of this series
> to use the "A/* -> B/" to label the change as bulk directory rename, if
> the preimage has A/{1,2,3} and the postimage has their moved contents in
> B/{one,two,three}?

Yes.  But --hide-bulk-move-details would not hide them, as they would
not be strictly included in the bulk move.  Desite their name change,
they are however a confirmation that the contents of A/ was move to B/.


> I am wondering about the utility of such an extra information.  If there
> were no "a/file0 -> b/file3" entry in the example, I would imagine that we
> could use this "a/* -> b/" information to move "a/file5" to "b/file5" when
> rebasing this patch to apply to a different preimage that had files other
> than file{1,2} in directory "a", and I would further imagine that might be
> a wonderful thing.

I imagined that as well, and that situation would not be a problem:
since "a/file0 -> b/file3" would be there in the rebased patch,
"apply" would be able to spot the possible conflict.

OTOH, I had the vision of "merge does automatic moves" when starting
this project, but got convinced on-list that there are always cases
where the "automatic move" on merge would be wrong, and that we should
report a conflict instead.

That would mostly shift the problem to: how do we provide support for
easily solving this type of problem (regardless of how we want to
represent them, which may not be trivial either).


> But if the new "a/* -> b/" hint only gives "things from A/ have migrated
> to B/ but I can give no information on what name they took under their new
> home", that may probably reduce the utility of this feature.

It would still mean that "ALL things from A/ have migrated", and does
not imply anything more, just like the fact that a file was renamed
does not prevent us to say that while moving it was also modified.

-- 
Yann

Bulk move and some of its close relatives

[Yann Dirson]

On Mon, Oct 25, 2010 at 10:12:27PM +0200, Yann Dirson wrote:
> It is only later that I realized that the larger picture was about
> bulk moves, and directory renames were only a subset of those.

I had a couple of thoughts about this dir-rename -> bulk-moves shift
today while riding to/from work.  So here are some of the fresh air I
got...

Is a bulk-move finally so special ?  There is a close relative to it
which may be of interest too: bulk deletion.  If we implement
detection of bulk deletion, we can build on it to get:

* detection of a new type of conflict: addition in a branch of a new
  file in a dir which is deleted in the other branch (quite similar to
  the one we were talking about, of a new file in a dir that got moved in
  other branch)
* split a good part of the current bulk-move patch in a standalone
  patch, which is something I wondered how to do
* probably a much better base for directory-split detection


Then, since a bulk-move is made of a bulk deletion, and addition
somewhere else of those deleted files, it became tempting to
contemplate the concept of "bulk addition".  At first sight it seems
awkward, I confess, especially "bulk addition into a preexisting dir",
which is a bit hard to define with precision.  OTOH, "bulk addition of
a brand new dir" could bring goodies as well:

* new conflict type: creation in both branches of a new directory with
  same name

That confict type made me think of another one.  Some of you may have
noticed in the v7 commit message a suggestion for future developments
labelled "support other types of bluk-grouping, like prefixes, and
maybe config-specified patterns".  Now if we get the capability of
specifying how we define a "group of files" with something other than
the directory hierarchy (let's say eg. that in t/ every "t[0-9]{4}-"
is a prefix), the "bulk-add/bulk-add" conflict generated by 2 tests
with same numeric ID would be detected as a conflict.

Another grouping example would be by file suffix - source-code reorgs
eg. bulk-moving header files into their own dir are not rare either.


Does that sound sane ?
-- 
Yann

Re: Bulk move and some of its close relatives

[Yann Dirson]

Oh, and another I forgot to mention is detection of bulk copies.  It is
somewhat tricky: while --find-copies-harder will properly work in
combination with --detect-bulk-copies, for the standard case we will
need to use find-copies-harder for those cases where not all of the
copied files have been modified.

For this, maybe it could help to store the unmodified src files in a
separate list to avoid pref degradation for the common case (similar to
my plans to avoid the need of the i_am_not_single flag in the current
bulkmove series by using a separte list for dst files).

-- 
Yann

Re: [PATCH v7 1/3] Introduce bulk-move detection in diffcore.

[Junio C Hamano]

Yann Dirson <ydirson@free.fr> writes:

> OTOH, the quoting rules for diff output are quite minimalist, I don't
> know whether adding "*" as a character that requires quotes around the
> filename would be acceptable.

I suspect that would be an unacceptable entry to a slippery slope.

>> IOW, is the goal of this series
>> to use the "A/* -> B/" to label the change as bulk directory rename, if
>> the preimage has A/{1,2,3} and the postimage has their moved contents in
>> B/{one,two,three}?
>
> Yes.  But --hide-bulk-move-details would not hide them, as they would
> not be strictly included in the bulk move.  Desite their name change,
> they are however a confirmation that the contents of A/ was move to B/.
>
>> I am wondering about the utility of such an extra information.  If there
>> were no "a/file0 -> b/file3" entry in the example, I would imagine that we
>> could use this "a/* -> b/" information to move "a/file5" to "b/file5" when
>> rebasing this patch to apply to a different preimage that had files other
>> than file{1,2} in directory "a", and I would further imagine that might be
>> a wonderful thing.
>
> I imagined that as well, and that situation would not be a problem:
> since "a/file0 -> b/file3" would be there in the rebased patch,
> "apply" would be able to spot the possible conflict.
>
> OTOH, I had the vision of "merge does automatic moves" when starting
> this project, but got convinced on-list that there are always cases
> where the "automatic move" on merge would be wrong, and that we should
> report a conflict instead.
>
> That would mostly shift the problem to...

That would mostly make this patch not worth worrying about, wouldn't it?
What's the point of spending extra cycles to say "many things have moved
in the same direction" without turning it into a usable information?

Re: [PATCH v7 1/3] Introduce bulk-move detection in diffcore.

[Yann Dirson]

On Thu, Oct 28, 2010 at 01:20:00PM -0700, Junio C Hamano wrote:
> Yann Dirson <ydirson@free.fr> writes:
> 
> > OTOH, the quoting rules for diff output are quite minimalist, I don't
> > know whether adding "*" as a character that requires quotes around the
> > filename would be acceptable.
> 
> I suspect that would be an unacceptable entry to a slippery slope.

OK.  I have thought of only 2 remaining options:

* keep using 0{40} sha1 as differentiator
  => will prevent us to ever use this sha1 for something useful
* introducing a new change-type letter
  => another slippery slope, with at least bulk removals and bulk
  copies in sight, with already too few letters to keep them meaningful
  to human reader
* introducing a "bulk" flag
  => needs extension of the raw format
  Would could want to extend the <letter><score> group, for things like
  "RB100" (bulk rename), "CB090" (imperfect bulk copy), "DB096" (imperfect
  bulk removal, meaning there were some files left in source directory)

> >> IOW, is the goal of this series
> >> to use the "A/* -> B/" to label the change as bulk directory rename, if
> >> the preimage has A/{1,2,3} and the postimage has their moved contents in
> >> B/{one,two,three}?
> >
> > Yes.  But --hide-bulk-move-details would not hide them, as they would
> > not be strictly included in the bulk move.  Desite their name change,
> > they are however a confirmation that the contents of A/ was move to B/.
> >
> >> I am wondering about the utility of such an extra information.  If there
> >> were no "a/file0 -> b/file3" entry in the example, I would imagine that we
> >> could use this "a/* -> b/" information to move "a/file5" to "b/file5" when
> >> rebasing this patch to apply to a different preimage that had files other
> >> than file{1,2} in directory "a", and I would further imagine that might be
> >> a wonderful thing.
> >
> > I imagined that as well, and that situation would not be a problem:
> > since "a/file0 -> b/file3" would be there in the rebased patch,
> > "apply" would be able to spot the possible conflict.
> >
> > OTOH, I had the vision of "merge does automatic moves" when starting
> > this project, but got convinced on-list that there are always cases
> > where the "automatic move" on merge would be wrong, and that we should
> > report a conflict instead.
> >
> > That would mostly shift the problem to...
> 
> That would mostly make this patch not worth worrying about, wouldn't it?

(assuming "that" refers to not doing automatic moves on merge)

No, at least the "avoid hiding useful info among less-relevant stuff"
provided by the human-targetted --hide-bulk-move-details would stay
regardless of what we decide here.

> What's the point of spending extra cycles to say "many things have moved
> in the same direction" without turning it into a usable information?

If we issue a conflict, we have already gone farther than where we are
now.  Deciding to have this particular type of conflict auto-resolved
in the way useful to a wider audience could be done (having "adds"
follow the bulkmove), with obviously the option of not auto-resolving,
and possibly, the option of auto-resolving "adds" as they are
(ie. keep current behaviour).

But my feeling is "automatically solving the conflict" would be be
only marginally different from applying a patch generated with (what
in current series is) --hide-bulk-move-details where you cannot know
which individual files were moved in the patch author's tree, and has
no info to decide if his own added files are at the right place or
need to follow the move (which I understood to be your point in [1]).

Or did I miss your point ?

[1] http://marc.info/?l=git&m=122610146506413

-- 
Yann