Merge branch 'en/rename-directory-detection-reboot'

Rename detection logic in "diff" family that is used in "merge" has
learned to guess when all of x/a, x/b and x/c have moved to z/a,
z/b and z/c, it is likely that x/d added in the meantime would also
want to move to z/d by taking the hint that the entire directory
'x' moved to 'z'.  A bug causing dirty files involved in a rename
to be overwritten during merge has also been fixed as part of this
work.  Incidentally, this also avoids updating a file in the
working tree after a (non-trivial) merge whose result matches what
our side originally had.

* en/rename-directory-detection-reboot: (36 commits)
  merge-recursive: fix check for skipability of working tree updates
  merge-recursive: make "Auto-merging" comment show for other merges
  merge-recursive: fix remainder of was_dirty() to use original index
  merge-recursive: fix was_tracked() to quit lying with some renamed paths
  t6046: testcases checking whether updates can be skipped in a merge
  merge-recursive: avoid triggering add_cacheinfo error with dirty mod
  merge-recursive: move more is_dirty handling to merge_content
  merge-recursive: improve add_cacheinfo error handling
  merge-recursive: avoid spurious rename/rename conflict from dir renames
  directory rename detection: new testcases showcasing a pair of bugs
  merge-recursive: fix remaining directory rename + dirty overwrite cases
  merge-recursive: fix overwriting dirty files involved in renames
  merge-recursive: avoid clobbering untracked files with directory renames
  merge-recursive: apply necessary modifications for directory renames
  merge-recursive: when comparing files, don't include trees
  merge-recursive: check for file level conflicts then get new name
  merge-recursive: add computation of collisions due to dir rename & merging
  merge-recursive: check for directory level conflicts
  merge-recursive: add get_directory_renames()
  merge-recursive: make a helper function for cleanup for handle_renames
  ...

Author: gitster

merge-recursive.c

@@ -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 +28,33 @@ 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 index_state orig_index;
+};
+
+/*
+ * For dir_rename_entry, directory names are stored as a full path from the
+ * toplevel of the repository and do not include a trailing '/'.  Also:
+ *
+ *   dir:                original name of directory being renamed
+ *   non_unique_new_dir: if true, could not determine new_dir
+ *   new_dir:            final name of directory being renamed
+ *   possible_new_dirs:  temporary used to help determine new_dir; see comments
+ *                       in get_directory_renames() for details
+ */
+struct dir_rename_entry {
+	struct hashmap_entry ent; /* must be the first member! */
+	char *dir;
+	unsigned non_unique_new_dir:1;
+	struct strbuf new_dir;
+	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 */

merge-recursive.h

@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "refs.h"
+#include "string-list.h"
 #include "utf8.h"
 
 int starts_with(const char *str, const char *prefix)
@@ -180,6 +181,21 @@ struct strbuf **strbuf_split_buf(const char *str, size_t slen,
 	return ret;
 }
 
+void strbuf_add_separated_string_list(struct strbuf *str,
+				      const char *sep,
+				      struct string_list *slist)
+{
+	struct string_list_item *item;
+	int sep_needed = 0;
+
+	for_each_string_list_item(item, slist) {
+		if (sep_needed)
+			strbuf_addstr(str, sep);
+		strbuf_addstr(str, item->string);
+		sep_needed = 1;
+	}
+}
+
 void strbuf_list_free(struct strbuf **sbs)
 {
 	struct strbuf **s = sbs;

strbuf.c

@@ -1,6 +1,8 @@
 #ifndef STRBUF_H
 #define STRBUF_H
 
+struct string_list;
+
 /**
  * strbuf's are meant to be used with all the usual C string and memory
  * APIs. Given that the length of the buffer is known, it's often better to
@@ -537,6 +539,20 @@ static inline struct strbuf **strbuf_split(const struct strbuf *sb,
 	return strbuf_split_max(sb, terminator, 0);
 }
 
+/*
+ * Adds all strings of a string list to the strbuf, separated by the given
+ * separator.  For example, if sep is
+ *   ', '
+ * and slist contains
+ *   ['element1', 'element2', ..., 'elementN'],
+ * then write:
+ *   'element1, element2, ..., elementN'
+ * to str.  If only one element, just write "element1" to str.
+ */
+extern void strbuf_add_separated_string_list(struct strbuf *str,
+					     const char *sep,
+					     struct string_list *slist);
+
 /**
  * Free a NULL-terminated list of strbufs (for example, the return
  * values of the strbuf_split*() functions).

strbuf.h

@@ -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 &&
@@ -150,9 +150,8 @@ test_expect_failure 'cherry-pick works with dirty renamed file' '
 	test_tick &&
 	git commit -m renamed &&
 	echo modified >renamed &&
-	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) &&
+	git cherry-pick refs/heads/unrelated >out &&
+	test $(git rev-parse :0:renamed) = $(git rev-parse HEAD~2:to-rename.t) &&
 	grep -q "^modified$" renamed
 '
 

t/t3501-revert-cherry-pick.sh

@@ -247,7 +247,7 @@ test_expect_success 'merge of identical changes in a renamed file' '
 	git reset --hard HEAD^ &&
 	git checkout change &&
 	GIT_MERGE_VERBOSITY=3 git merge change+rename >out &&
-	test_i18ngrep "^Skipped B" out
+	test_i18ngrep ! "^Skipped B" out
 '
 
 test_expect_success 'setup for rename + d/f conflicts' '