merge-ort: support subtree shifting

merge-recursive has some simple code to support subtree shifting; copy
it over to merge-ort.  This fixes t6409.12 under
GIT_TEST_MERGE_ALGORITHM=ort.

Signed-off-by: Elijah Newren <newren@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/merge-ort.c b/merge-ort.c
index c7083e3769aa56b71526fca9596cedf7f55199fc..c4fe234d89721650d153fd826111bccc6f072861 100644 (file)
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -3551,6 +3551,23 @@ void merge_finalize(struct merge_options *opt,
 
 /*** Function Grouping: helper functions for merge_incore_*() ***/
 
+static struct tree *shift_tree_object(struct repository *repo,
+                                     struct tree *one, struct tree *two,
+                                     const char *subtree_shift)
+{
+       struct object_id shifted;
+
+       if (!*subtree_shift) {
+               shift_tree(repo, &one->object.oid, &two->object.oid, &shifted, 0);
+       } else {
+               shift_tree_by(repo, &one->object.oid, &two->object.oid, &shifted,
+                             subtree_shift);
+       }
+       if (oideq(&two->object.oid, &shifted))
+               return two;
+       return lookup_tree(repo, &shifted);
+}
+
 static inline void set_commit_tree(struct commit *c, struct tree *t)
 {
        c->maybe_tree = t;
@@ -3680,6 +3697,13 @@ static void merge_ort_nonrecursive_internal(struct merge_options *opt,
 {
        struct object_id working_tree_oid;
 
+       if (opt->subtree_shift) {
+               side2 = shift_tree_object(opt->repo, side1, side2,
+                                         opt->subtree_shift);
+               merge_base = shift_tree_object(opt->repo, side1, merge_base,
+                                              opt->subtree_shift);
+       }
+
        trace2_region_enter("merge", "collect_merge_info", opt->repo);
        if (collect_merge_info(opt, merge_base, side1, side2) != 0) {
                /*