From 2734f2e3243ce19af1d9c9c92dffae13af7b0fe5 Mon Sep 17 00:00:00 2001
From: Elijah Newren <newren@gmail.com>
Date: Thu, 20 May 2021 06:09:35 +0000
Subject: [PATCH] merge-ort: populate caches of rename detection results

Fill in cache_pairs, cached_target_names, and cached_irrelevant based on
rename detection results.  Future commits will make use of these values.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 merge-ort.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

diff --git a/merge-ort.c b/merge-ort.c
index 6a06c6e5a3..d515f5cc3f 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -2344,6 +2344,67 @@ static void resolve_diffpair_statuses(struct diff_queue_struct *q)
 	}
 }
 
+static void cache_new_pair(struct rename_info *renames,
+			   int side,
+			   char *old_path,
+			   char *new_path,
+			   int free_old_value)
+{
+	char *old_value;
+	new_path = xstrdup(new_path);
+	old_value = strmap_put(&renames->cached_pairs[side],
+			       old_path, new_path);
+	strset_add(&renames->cached_target_names[side], new_path);
+	if (free_old_value)
+		free(old_value);
+	else
+		assert(!old_value);
+}
+
+static void possibly_cache_new_pair(struct rename_info *renames,
+				    struct diff_filepair *p,
+				    unsigned side,
+				    char *new_path)
+{
+	int dir_renamed_side = 0;
+
+	if (new_path) {
+		/*
+		 * Directory renames happen on the other side of history from
+		 * the side that adds new files to the old directory.
+		 */
+		dir_renamed_side = 3 - side;
+	} else {
+		int val = strintmap_get(&renames->relevant_sources[side],
+					p->one->path);
+		if (val == RELEVANT_NO_MORE) {
+			assert(p->status == 'D');
+			strset_add(&renames->cached_irrelevant[side],
+				   p->one->path);
+		}
+		if (val <= 0)
+			return;
+	}
+
+	if (p->status == 'D') {
+		/*
+		 * If we already had this delete, we'll just set it's value
+		 * to NULL again, so no harm.
+		 */
+		strmap_put(&renames->cached_pairs[side], p->one->path, NULL);
+	} else if (p->status == 'R') {
+		if (!new_path)
+			new_path = p->two->path;
+		else
+			cache_new_pair(renames, dir_renamed_side,
+				       p->two->path, new_path, 0);
+		cache_new_pair(renames, side, p->one->path, new_path, 1);
+	} else if (p->status == 'A' && new_path) {
+		cache_new_pair(renames, dir_renamed_side,
+			       p->two->path, new_path, 0);
+	}
+}
+
 static int compare_pairs(const void *a_, const void *b_)
 {
 	const struct diff_filepair *a = *((const struct diff_filepair **)a_);
@@ -2426,6 +2487,7 @@ static int collect_renames(struct merge_options *opt,
 		char *new_path; /* non-NULL only with directory renames */
 
 		if (p->status != 'A' && p->status != 'R') {
+			possibly_cache_new_pair(renames, p, side_index, NULL);
 			diff_free_filepair(p);
 			continue;
 		}
@@ -2437,6 +2499,7 @@ static int collect_renames(struct merge_options *opt,
 						      &collisions,
 						      &clean);
 
+		possibly_cache_new_pair(renames, p, side_index, new_path);
 		if (p->status != 'R' && !new_path) {
 			diff_free_filepair(p);
 			continue;
@@ -3720,8 +3783,16 @@ static void merge_start(struct merge_options *opt, struct merge_result *result)
 					 NULL, 1);
 		strmap_init_with_options(&renames->dir_renames[i],
 					 NULL, 0);
+		/*
+		 * relevant_sources uses -1 for the default, because we need
+		 * to be able to distinguish not-in-strintmap from valid
+		 * relevant_source values from enum file_rename_relevance.
+		 * In particular, possibly_cache_new_pair() expects a negative
+		 * value for not-found entries.
+		 */
 		strintmap_init_with_options(&renames->relevant_sources[i],
-					    0, NULL, 0);
+					    -1 /* explicitly invalid */,
+					    NULL, 0);
 		strmap_init_with_options(&renames->cached_pairs[i],
 					 NULL, 1);
 		strset_init_with_options(&renames->cached_irrelevant[i],