Merge branch 'en/merge-dual-dir-renames-fix'

Fixes a long-standing corner case bug around directory renames in
the merge-ort strategy.

* en/merge-dual-dir-renames-fix:
  merge-ort: fix issue with dual rename and add/add conflict
  merge-ort: shuffle the computation and cleanup of potential collisions
  merge-ort: make a separate function for freeing struct collisions
  merge-ort: small cleanups of check_for_directory_rename
  t6423: add tests of dual directory rename plus add/add conflict

1 files changed, 48 insertions, 26 deletions

diff --git a/merge-ort.c b/merge-ort.c
index 01f150ef3b..8b7de0fbd8 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -2398,6 +2398,27 @@ static void compute_collisions(struct strmap *collisions,
 	}
 }
 
+static void free_collisions(struct strmap *collisions)
+{
+	struct hashmap_iter iter;
+	struct strmap_entry *entry;
+
+	/* Free each value in the collisions map */
+	strmap_for_each_entry(collisions, &iter, entry) {
+		struct collision_info *info = entry->value;
+		string_list_clear(&info->source_files, 0);
+	}
+	/*
+	 * In compute_collisions(), we set collisions.strdup_strings to 0
+	 * so that we wouldn't have to make another copy of the new_path
+	 * allocated by apply_dir_rename().  But now that we've used them
+	 * and have no other references to these strings, it is time to
+	 * deallocate them.
+	 */
+	free_strmap_strings(collisions);
+	strmap_clear(collisions, 1);
+}
+
 static char *check_for_directory_rename(struct merge_options *opt,
 					const char *path,
 					unsigned side_index,
@@ -2406,18 +2427,23 @@ static char *check_for_directory_rename(struct merge_options *opt,
 					struct strmap *collisions,
 					int *clean_merge)
 {
-	char *new_path = NULL;
+	char *new_path;
 	struct strmap_entry *rename_info;
-	struct strmap_entry *otherinfo = NULL;
+	struct strmap_entry *otherinfo;
 	const char *new_dir;
+	int other_side = 3 - side_index;
 
+	/*
+	 * Cases where we don't have or don't want a directory rename for
+	 * this path.
+	 */
 	if (strmap_empty(dir_renames))
-		return new_path;
+		return NULL;
+	if (strmap_get(&collisions[other_side], path))
+		return NULL;
 	rename_info = check_dir_renamed(path, dir_renames);
 	if (!rename_info)
-		return new_path;
-	/* old_dir = rename_info->key; */
-	new_dir = rename_info->value;
+		return NULL;
 
 	/*
 	 * This next part is a little weird.  We do not want to do an
@@ -2443,6 +2469,7 @@ static char *check_for_directory_rename(struct merge_options *opt,
 	 * As it turns out, this also prevents N-way transient rename
 	 * confusion; See testcases 9c and 9d of t6043.
 	 */
+	new_dir = rename_info->value; /* old_dir = rename_info->key; */
 	otherinfo = strmap_get_entry(dir_rename_exclusions, new_dir);
 	if (otherinfo) {
 		path_msg(opt, INFO_DIR_RENAME_SKIPPED_DUE_TO_RERENAME, 1,
@@ -2454,7 +2481,8 @@ static char *check_for_directory_rename(struct merge_options *opt,
 	}
 
 	new_path = handle_path_level_conflicts(opt, path, side_index,
-					       rename_info, collisions);
+					       rename_info,
+					       &collisions[side_index]);
 	*clean_merge &= (new_path != NULL);
 
 	return new_path;
@@ -3171,18 +3199,15 @@ static int detect_regular_renames(struct merge_options *opt,
 static int collect_renames(struct merge_options *opt,
 			   struct diff_queue_struct *result,
 			   unsigned side_index,
+			   struct strmap *collisions,
 			   struct strmap *dir_renames_for_side,
 			   struct strmap *rename_exclusions)
 {
 	int i, clean = 1;
-	struct strmap collisions;
 	struct diff_queue_struct *side_pairs;
-	struct hashmap_iter iter;
-	struct strmap_entry *entry;
 	struct rename_info *renames = &opt->priv->renames;
 
 	side_pairs = &renames->pairs[side_index];
-	compute_collisions(&collisions, dir_renames_for_side, side_pairs);
 
 	for (i = 0; i < side_pairs->nr; ++i) {
 		struct diff_filepair *p = side_pairs->queue[i];
@@ -3198,7 +3223,7 @@ static int collect_renames(struct merge_options *opt,
 						      side_index,
 						      dir_renames_for_side,
 						      rename_exclusions,
-						      &collisions,
+						      collisions,
 						      &clean);
 
 		possibly_cache_new_pair(renames, p, side_index, new_path);
@@ -3224,20 +3249,6 @@ static int collect_renames(struct merge_options *opt,
 		result->queue[result->nr++] = p;
 	}
 
-	/* Free each value in the collisions map */
-	strmap_for_each_entry(&collisions, &iter, entry) {
-		struct collision_info *info = entry->value;
-		string_list_clear(&info->source_files, 0);
-	}
-	/*
-	 * In compute_collisions(), we set collisions.strdup_strings to 0
-	 * so that we wouldn't have to make another copy of the new_path
-	 * allocated by apply_dir_rename().  But now that we've used them
-	 * and have no other references to these strings, it is time to
-	 * deallocate them.
-	 */
-	free_strmap_strings(&collisions);
-	strmap_clear(&collisions, 1);
 	return clean;
 }
 
@@ -3248,6 +3259,7 @@ static int detect_and_process_renames(struct merge_options *opt,
 {
 	struct diff_queue_struct combined = { 0 };
 	struct rename_info *renames = &opt->priv->renames;
+	struct strmap collisions[3];
 	int need_dir_renames, s, i, clean = 1;
 	unsigned detection_run = 0;
 
@@ -3297,12 +3309,22 @@ static int detect_and_process_renames(struct merge_options *opt,
 	ALLOC_GROW(combined.queue,
 		   renames->pairs[1].nr + renames->pairs[2].nr,
 		   combined.alloc);
+	for (i = MERGE_SIDE1; i <= MERGE_SIDE2; i++) {
+		int other_side = 3 - i;
+		compute_collisions(&collisions[i],
+				   &renames->dir_renames[other_side],
+				   &renames->pairs[i]);
+	}
 	clean &= collect_renames(opt, &combined, MERGE_SIDE1,
+				 collisions,
 				 &renames->dir_renames[2],
 				 &renames->dir_renames[1]);
 	clean &= collect_renames(opt, &combined, MERGE_SIDE2,
+				 collisions,
 				 &renames->dir_renames[1],
 				 &renames->dir_renames[2]);
+	for (i = MERGE_SIDE1; i <= MERGE_SIDE2; i++)
+		free_collisions(&collisions[i]);
 	STABLE_QSORT(combined.queue, combined.nr, compare_pairs);
 	trace2_region_leave("merge", "directory renames", opt->repo);