From: Elijah Newren <redacted>

Implement rename/rename(1to1) handling, i.e. both sides of history
renaming a file but renaming the same way.  This code replaces the
following from merge-recurisve.c:

  * all the 1to1 code in process_renames()
  * the RENAME_ONE_FILE_TO_ONE case of process_entry()

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_rename_normal()
  * setup_rename_conflict_info()

The consolidation of four 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.

Signed-off-by: Elijah Newren <redacted>
---
 merge-ort.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/merge-ort.c b/merge-ort.c
index faec29db955..085e81196a5 100644
--- a/merge-ort.c
+++ b/merge-ort.c

@@ -647,14 +647,31 @@ static int process_renames(struct merge_options *opt,
 		    !strcmp(oldpath, renames->queue[i+1]->one->path)) {
 			/* Handle rename/rename(1to2) or rename/rename(1to1) */
 			const char *pathnames[3];
+			struct version_info merged;
+			struct conflict_info *base, *side1, *side2;
+			unsigned was_binary_blob = 0;