merge-ort: add basic rename detection

This series builds on en/merge-ort-2 and adds basic rename detection to merge-ort.

Changes since v2 (all due to feedback from Stolee's reviews):

* reordered two of the patches (one depended on vars declared in another)
* a few other adjustments to make patches individually compile (I usually check this; so embarrassing that I somehow missed it)

Elijah Newren (11):
merge-ort: add basic data structures for handling renames
merge-ort: add initial outline for basic rename detection
merge-ort: implement detect_regular_renames()
merge-ort: implement compare_pairs() and collect_renames()
merge-ort: add basic outline for process_renames()
merge-ort: add implementation of both sides renaming identically
merge-ort: add implementation of both sides renaming differently
merge-ort: add implementation of rename/delete conflicts
merge-ort: add implementation of rename collisions
merge-ort: add implementation of normal rename handling
merge-ort: add implementation of type-changed rename handling

 merge-ort.c | 446 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 430 insertions(+), 16 deletions(-)

base-commit: c5a6f65527aa3b6f5d7cf25437a88d8727ab0646
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-812%2Fnewren%2Fort-renames-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-812/newren/ort-renames-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/812

Range-diff vs v2:

  1:  78621ca0788 =  1:  78621ca0788 merge-ort: add basic data structures for handling renames
  2:  d846decf40b =  2:  d846decf40b merge-ort: add initial outline for basic rename detection
  3:  620fc64032d =  3:  620fc64032d merge-ort: implement detect_regular_renames()
  4:  9382dc4d50b =  4:  9382dc4d50b merge-ort: implement compare_pairs() and collect_renames()
  5:  d20fab8d403 =  5:  d20fab8d403 merge-ort: add basic outline for process_renames()
  6:  15fff3dd0c4 !  6:  7ec51feb418 merge-ort: add implementation of both sides renaming identically
     @@ merge-ort.c: static int process_renames(struct merge_options *opt,
       			const char *pathnames[3];
      +			struct version_info merged;
      +			struct conflict_info *base, *side1, *side2;
     -+			unsigned was_binary_blob = 0;
       
       			pathnames[0] = oldpath;
       			pathnames[1] = newpath;

7: d00e26be784 ! 7: d37e2626c30 merge-ort: add implementation of both sides renaming differently
@@ Commit message

## merge-ort.c ##
+@@ merge-ort.c: static int process_renames(struct merge_options *opt,
+ const char *pathnames[3];
+ struct version_info merged;
+ struct conflict_info *base, *side1, *side2;
++ unsigned was_binary_blob = 0;
+
+ pathnames[0] = oldpath;
+ pathnames[1] = newpath;
@@ merge-ort.c: static int process_renames(struct merge_options *opt,
}

  9:  f017534243c !  8:  6b79da5e8a4 merge-ort: add implementation of rename/delete conflicts
     @@ merge-ort.c: static int process_renames(struct merge_options *opt,
       		old_ent = strmap_get_entry(&opt->priv->paths, pair->one->path);
       		oldpath = old_ent->key;
      @@ merge-ort.c: static int process_renames(struct merge_options *opt,
     - 		if (type_changed && collision) {
       			/* special handling so later blocks can handle this */
       			die("Not yet implemented");
     + 		}
      +		if (source_deleted) {
      +			if (target_index == 1) {
      +				rename_branch = opt->branch1;
     @@ merge-ort.c: static int process_renames(struct merge_options *opt,
      +				rename_branch = opt->branch2;
      +				delete_branch = opt->branch1;
      +			}
     - 		}
     ++		}

assert(source_deleted || oldinfo->filemask & old_sidemask);
+
@@ merge-ort.c: static int process_renames(struct merge_options *opt,
- "to %s in %s, but deleted in %s."),
- oldpath, newpath, rename_branch, delete_branch);
+ /* rename/add/delete or rename/rename(2to1)/delete */
+ die("Not yet implemented");
} else {
- /* a few different cases... */
+ /*
8: edd610321a0 ! 9: 065fc0396dc merge-ort: add implementation of rename collisions

     @@ merge-ort.c: static int process_renames(struct merge_options *opt,
      +						     &side1->stages[1],
      +						     &side2->stages[2],
      +						     pathnames,
     -+						     1 + 2*opt->priv->call_depth,
     ++						     1 + 2 * opt->priv->call_depth,
      +						     &merged);
      +
      +			memcpy(&newinfo->stages[target_index], &merged,
     @@ merge-ort.c: static int process_renames(struct merge_options *opt,
      +				   "to %s in %s, but deleted in %s."),
      +				 oldpath, newpath, rename_branch, delete_branch);
       		} else {
     - 			/* a few different cases... */
     - 			if (type_changed) {
     + 			/*
     + 			 * a few different cases...start by copying the
 10:  22cb7110261 = 10:  73426c16687 merge-ort: add implementation of normal rename handling
 11:  ff09ddb9caf ! 11:  8f4662398ab merge-ort: add implementation of type-changed rename handling
     @@ Commit message
      
       ## merge-ort.c ##
      @@ merge-ort.c: static int process_renames(struct merge_options *opt,
     + 			(S_ISREG(oldinfo->stages[other_source_index].mode) !=
       			 S_ISREG(newinfo->stages[target_index].mode));
       		if (type_changed && collision) {
     - 			/* special handling so later blocks can handle this */
     +-			/* special handling so later blocks can handle this */
      -			die("Not yet implemented");
      +			/*
     ++			 * special handling so later blocks can handle this...
     ++			 *
      +			 * if type_changed && collision are both true, then this
      +			 * was really a double rename, but one side wasn't
      +			 * detected due to lack of break detection.  I.e.
     @@ merge-ort.c: static int process_renames(struct merge_options *opt,
      +			 * See also t6430, 'rename vs. rename/symlink'
      +			 */
      +			collision = 0;
     -+		}
     + 		}
       		if (source_deleted) {
       			if (target_index == 1) {
     - 				rename_branch = opt->branch1;
      @@ merge-ort.c: static int process_renames(struct merge_options *opt,
       			newinfo->pathnames[0] = oldpath;
       			if (type_changed) {

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