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
diff_filepair under consideration.

Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 186 insertions, 1 deletions

diff --git a/merge-recursive.c b/merge-recursive.c
index f1be349..48a49bd 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -180,6 +180,7 @@ 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,
@@ -610,6 +611,7 @@ struct rename {
 	 */
 	struct stage_data *src_entry;
 	struct stage_data *dst_entry;
+	unsigned add_turned_into_rename:1;
 	unsigned processed:1;
 };
 
@@ -644,6 +646,27 @@ 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_oid(&o.oid) ? NULL : &o,
+			     is_null_oid(&a.oid) ? NULL : &a,
+			     is_null_oid(&b.oid) ? NULL : &b);
+}
+
 static void update_entry(struct stage_data *entry,
 			 struct diff_filespec *o,
 			 struct diff_filespec *a,
@@ -1121,6 +1144,18 @@ 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,
@@ -1390,6 +1425,24 @@ 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);
 	}
@@ -1952,6 +2005,111 @@ 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,
+		       pair->two->path,
+		       &re->dst_entry->stages[stage].oid,
+		       &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.
@@ -2001,6 +2159,7 @@ 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)
@@ -2017,6 +2176,12 @@ 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);
@@ -2186,7 +2351,19 @@ 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,
@@ -2603,6 +2780,14 @@ 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,