merge-ort: compute a few more useful fields for collect_merge_info

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/merge-ort.c b/merge-ort.c
index 690c64fe264f0b2420a9a5d34033670f133e7f20..a6876191c02e45de990c787224546e370915173d 100644 (file)
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -220,6 +220,7 @@ static int collect_merge_info_callback(int n,
        size_t len;
        char *fullpath;
        unsigned filemask = mask & ~dirmask;
+       unsigned match_mask = 0; /* will be updated below */
        unsigned mbase_null = !(mask & 1);
        unsigned side1_null = !(mask & 2);
        unsigned side2_null = !(mask & 4);
@@ -233,6 +234,22 @@ static int collect_merge_info_callback(int n,
                                names[1].mode == names[2].mode &&
                                oideq(&names[1].oid, &names[2].oid));
 
+       /*
+        * Note: When a path is a file on one side of history and a directory
+        * in another, we have a directory/file conflict.  In such cases, if
+        * the conflict doesn't resolve from renames and deletions, then we
+        * always leave directories where they are and move files out of the
+        * way.  Thus, while struct conflict_info has a df_conflict field to
+        * track such conflicts, we ignore that field for any directories at
+        * a path and only pay attention to it for files at the given path.
+        * The fact that we leave directories were they are also means that
+        * we do not need to worry about getting additional df_conflict
+        * information propagated from parent directories down to children
+        * (unlike, say traverse_trees_recursive() in unpack-trees.c, which
+        * sets a newinfo.df_conflicts field specifically to propagate it).
+        */
+       unsigned df_conflict = (filemask != 0) && (dirmask != 0);
+
        /* n = 3 is a fundamental assumption. */
        if (n != 3)
                BUG("Called collect_merge_info_callback wrong");
@@ -248,6 +265,14 @@ static int collect_merge_info_callback(int n,
        assert(!mbase_null || !side1_null || !side2_null);
        assert(mask > 0 && mask < 8);
 
+       /* Determine match_mask */
+       if (side1_matches_mbase)
+               match_mask = (side2_matches_mbase ? 7 : 3);
+       else if (side2_matches_mbase)
+               match_mask = 5;
+       else if (sides_match)
+               match_mask = 6;
+
        /*
         * Get the name of the relevant filepath, which we'll pass to
         * setup_path_info() for tracking.
@@ -266,6 +291,8 @@ static int collect_merge_info_callback(int n,
         * so we can resolve later in process_entries.
         */
        ci = xcalloc(1, sizeof(struct conflict_info));
+       ci->df_conflict = df_conflict;
+       ci->match_mask = match_mask;
        strmap_put(&opti->paths, fullpath, ci);
 
        /* If dirmask, recurse into subdirectories */
@@ -282,6 +309,15 @@ static int collect_merge_info_callback(int n,
                newinfo.name = p->path;
                newinfo.namelen = p->pathlen;
                newinfo.pathlen = st_add3(newinfo.pathlen, p->pathlen, 1);
+               /*
+                * If this directory we are about to recurse into cared about
+                * its parent directory (the current directory) having a D/F
+                * conflict, then we'd propagate the masks in this way:
+                *    newinfo.df_conflicts |= (mask & ~dirmask);
+                * But we don't worry about propagating D/F conflicts.  (See
+                * comment near setting of local df_conflict variable near
+                * the beginning of this function).
+                */
 
                for (i = MERGE_BASE; i <= MERGE_SIDE2; i++) {
                        if (i == 1 && side1_matches_mbase)