merge-ort: add implementation of rename/delete conflicts

Implement rename/delete conflicts, i.e. one side renames a file and the
other deletes the file.  This code replaces the following from
merge-recurisve.c:

  * the code relevant to RENAME_DELETE in process_renames()
  * the RENAME_DELETE case of process_entry()
  * handle_rename_delete()

Also, there is some shared code from merge-recursive.c for multiple
different rename cases which we will no longer need for this case (or
other rename cases):

  * handle_change_delete()
  * setup_rename_conflict_info()

The consolidation of five separate codepaths into one is made possible
by a change in design: process_renames() tweaks the conflict_info
entries within opt->priv->paths such that process_entry() can then
handle all the non-rename conflict types (directory/file, modify/delete,
etc.) orthogonally.  This means we're much less likely to miss special
implementation of some kind of combination of conflict types (see
commits brought in by 66c62eaec6 ("Merge branch 'en/merge-tests'",
2020-11-18), especially commit ef52778708 ("merge tests: expect improved
directory/file conflict handling in ort", 2020-10-26) for more details).
That, together with letting worktree/index updating be handled
orthogonally in the merge_switch_to_result() function, dramatically
simplifies the code for various special rename cases.

To be fair, there is a _slight_ tweak to process_entry() here, because
rename/delete cases will also trigger the modify/delete codepath.
However, we only want a modify/delete message to be printed for a
rename/delete conflict if there is a content change in the renamed file
in addition to the rename.  So process_renames() and process_entry()
aren't quite fully orthogonal, but they are pretty close.

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 19477cfae60c08ca4c9e4a1be59e2c9b2595f4b6..a10c3f5046f861d328ca5f5bd6bf44bd261fdb1b 100644 (file)
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -657,6 +657,7 @@ static int process_renames(struct merge_options *opt,
                unsigned int old_sidemask;
                int target_index, other_source_index;
                int source_deleted, collision, type_changed;
+               const char *rename_branch = NULL, *delete_branch = NULL;
 
                old_ent = strmap_get_entry(&opt->priv->paths, pair->one->path);
                oldpath = old_ent->key;
@@ -779,6 +780,15 @@ static int process_renames(struct merge_options *opt,
                        /* special handling so later blocks can handle this */
                        die("Not yet implemented");
                }
+               if (source_deleted) {
+                       if (target_index == 1) {
+                               rename_branch = opt->branch1;
+                               delete_branch = opt->branch2;
+                       } else {
+                               rename_branch = opt->branch2;
+                               delete_branch = opt->branch1;
+                       }
+               }
 
                assert(source_deleted || oldinfo->filemask & old_sidemask);
 
@@ -790,13 +800,26 @@ static int process_renames(struct merge_options *opt,
                        /* rename/add/delete or rename/rename(2to1)/delete */
                        die("Not yet implemented");
                } else {
-                       /* a few different cases... */
+                       /*
+                        * a few different cases...start by copying the
+                        * existing stage(s) from oldinfo over the newinfo
+                        * and update the pathname(s).
+                        */
+                       memcpy(&newinfo->stages[0], &oldinfo->stages[0],
+                              sizeof(newinfo->stages[0]));
+                       newinfo->filemask |= (1 << MERGE_BASE);
+                       newinfo->pathnames[0] = oldpath;
                        if (type_changed) {
                                /* rename vs. typechange */
                                die("Not yet implemented");
                        } else if (source_deleted) {
                                /* rename/delete */
-                               die("Not yet implemented");
+                               newinfo->path_conflict = 1;
+                               path_msg(opt, newpath, 0,
+                                        _("CONFLICT (rename/delete): %s renamed"
+                                          " to %s in %s, but deleted in %s."),
+                                        oldpath, newpath,
+                                        rename_branch, delete_branch);
                        } else {
                                /* normal rename */
                                die("Not yet implemented");
@@ -1332,12 +1355,21 @@ static void process_entry(struct merge_options *opt,
                modify_branch = (side == 1) ? opt->branch1 : opt->branch2;
                delete_branch = (side == 1) ? opt->branch2 : opt->branch1;
 
-               path_msg(opt, path, 0,
-                        _("CONFLICT (modify/delete): %s deleted in %s "
-                          "and modified in %s.  Version %s of %s left "
-                          "in tree."),
-                        path, delete_branch, modify_branch,
-                        modify_branch, path);
+               if (ci->path_conflict &&
+                   oideq(&ci->stages[0].oid, &ci->stages[side].oid)) {
+                       /*
+                        * This came from a rename/delete; no action to take,
+                        * but avoid printing "modify/delete" conflict notice
+                        * since the contents were not modified.
+                        */
+               } else {
+                       path_msg(opt, path, 0,
+                                _("CONFLICT (modify/delete): %s deleted in %s "
+                                  "and modified in %s.  Version %s of %s left "
+                                  "in tree."),
+                                path, delete_branch, modify_branch,
+                                modify_branch, path);
+               }
        } else if (ci->filemask == 2 || ci->filemask == 4) {
                /* Added on one side */
                int side = (ci->filemask == 4) ? 2 : 1;