merge-ort: add some more explanations in collect_merge_info_callback()

The previous patch possibly raises some questions about whether
additional cases in collect_merge_info_callback() can be handled early.
Add some explanations in the form of comments to help explain these
better.  While we're at it, add a few comments to denote what a few
boolean '0' or '1' values stand for.

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 570432697366b9766ee1c5dbb505bd4f8f95e7b9..37aaac38b994d62996f2754256f09d92e286fc3c 100644 (file)
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -1018,8 +1018,8 @@ static int collect_merge_info_callback(int n,
        if (side1_matches_mbase && side2_matches_mbase) {
                /* mbase, side1, & side2 all match; use mbase as resolution */
                setup_path_info(opt, &pi, dirname, info->pathlen, fullpath,
-                               names, names+0, mbase_null, 0,
-                               filemask, dirmask, 1);
+                               names, names+0, mbase_null, 0 /* df_conflict */,
+                               filemask, dirmask, 1 /* resolved */);
                return mask;
        }
 
@@ -1061,14 +1061,24 @@ static int collect_merge_info_callback(int n,
        }
 
        /*
-        * Gather additional information used in rename detection.
+        * Sometimes we can tell that a source path need not be included in
+        * rename detection -- namely, whenever either
+        *    side1_matches_mbase && side2_null
+        * or
+        *    side2_matches_mbase && side1_null
+        * However, we call collect_rename_info() even in those cases,
+        * because exact renames are cheap and would let us remove both a
+        * source and destination path.  We'll cull the unneeded sources
+        * later.
         */
        collect_rename_info(opt, names, dirname, fullpath,
                            filemask, dirmask, match_mask);
 
        /*
-        * Record information about the path so we can resolve later in
-        * process_entries.
+        * None of the special cases above matched, so we have a
+        * provisional conflict.  (Rename detection might allow us to
+        * unconflict some more cases, but that comes later so all we can
+        * do now is record the different non-null file hashes.)
         */
        setup_path_info(opt, &pi, dirname, info->pathlen, fullpath,
                        names, NULL, 0, df_conflict, filemask, dirmask, 0);