This just adds dir_rename_entry and the associated functions; code using
these will be added in subsequent commits.

Signed-off-by: Elijah Newren <redacted>
---
 merge-recursive.c | 35 +++++++++++++++++++++++++++++++++++
 merge-recursive.h |  8 ++++++++
 2 files changed, 43 insertions(+)

diff --git a/merge-recursive.c b/merge-recursive.c
index 8ac69e1cbb..3b6d0e3f70 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c

@@ -49,6 +49,41 @@ static unsigned int path_hash(const char *path)
        return ignore_case ? strihash(path) : strhash(path);
 }

+static struct dir_rename_entry *dir_rename_find_entry(struct hashmap *hashmap,
+                                                     char *dir)
+{
+       struct dir_rename_entry key;
+
+       if (dir == NULL)
+               return NULL;
+       hashmap_entry_init(&key, strhash(dir));
+       key.dir = dir;
+       return hashmap_get(hashmap, &key, NULL);
+}
+
+static int dir_rename_cmp(void *unused_cmp_data,
+                         const struct dir_rename_entry *e1,
+                         const struct dir_rename_entry *e2,
+                         const void *unused_keydata)
+{
+       return strcmp(e1->dir, e2->dir);
+}
+
+static void dir_rename_init(struct hashmap *map)
+{
+       hashmap_init(map, (hashmap_cmp_fn) dir_rename_cmp, NULL, 0);

+static void dir_rename_entry_init(struct dir_rename_entry *entry,
+                                 char *directory)
+{
+       hashmap_entry_init(entry, strhash(directory));
+       entry->dir = directory;
+       entry->non_unique_new_dir = 0;
+       strbuf_init(&entry->new_dir, 0);
+       string_list_init(&entry->possible_new_dirs, 0);
+}
+
 static void flush_output(struct merge_options *o)
 {
        if (o->buffer_output < 2 && o->obuf.len) {

diff --git a/merge-recursive.h b/merge-recursive.h
index 80d69d1401..d7f4cc80c1 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h

@@ -29,6 +29,14 @@ struct merge_options {
        struct string_list df_conflict_file_set;
 };

+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;
+};