merge-recursive: add merge function arg to merge_recursive_generic

The `merge_recursive_generic` function is a wrapper that allows running a merge
on trees (rather than commits) by wrapping the trees as virtual commits. This
functionality is valuable not only for use with `merge_recursive`, but also
`merge_ort_recursive`. Having the merge function used by
`merge_recursive_generic` be an argument allows greater flexibility of usage.

Signed-off-by: Victoria Dye <[email protected]>

Author: vdye

builtin/am.c

@@ -1585,7 +1585,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 	if (state->quiet)
 		o.verbosity = 0;
 
-	if (merge_recursive_generic(&o, &our_tree, &their_tree, 1, bases, &result)) {
+	if (merge_recursive_generic(&o, &our_tree, &their_tree, 1, bases, merge_recursive, &result)) {
 		repo_rerere(the_repository, state->allow_rerere_autoupdate);
 		free(their_tree_name);
 		return error(_("Failed to merge in the changes."));

builtin/merge-recursive.c

@@ -81,7 +81,7 @@ int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
 	if (o.verbosity >= 3)
 		printf(_("Merging %s with %s\n"), o.branch1, o.branch2);
 
-	failed = merge_recursive_generic(&o, &h1, &h2, bases_count, bases, &result);
+	failed = merge_recursive_generic(&o, &h1, &h2, bases_count, bases, merge_recursive, &result);
 
 	free(better1);
 	free(better2);

builtin/stash.c

@@ -541,7 +541,7 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 	bases[0] = &info->b_tree;
 
 	ret = merge_recursive_generic(&o, &c_tree, &info->w_tree, 1, bases,
-				      &result);
+				      merge_recursive, &result);
 	if (ret) {
 		rerere(0);
 

merge-ort.c

@@ -4652,7 +4652,8 @@ void merge_incore_recursive(struct merge_options *opt,
 	trace2_region_enter("merge", "incore_recursive", opt->repo);
 
 	/* We set the ancestor label based on the merge_bases */
-	assert(opt->ancestor == NULL);
+	assert(opt->ancestor == NULL ||
+	       !strcmp(opt->ancestor, "constructed merge base"));
 
 	trace2_region_enter("merge", "merge_start", opt->repo);
 	merge_start(opt, result);

merge-recursive.c

@@ -3785,6 +3785,7 @@ int merge_recursive_generic(struct merge_options *opt,
 			    const struct object_id *merge,
 			    int num_merge_bases,
 			    const struct object_id **merge_bases,
+			    recursive_merge_fn_t merge_fn,
 			    struct commit **result)
 {
 	int clean;
@@ -3808,8 +3809,7 @@ int merge_recursive_generic(struct merge_options *opt,
 	}
 
 	repo_hold_locked_index(opt->repo, &lock, LOCK_DIE_ON_ERROR);
-	clean = merge_recursive(opt, head_commit, next_commit, ca,
-				result);
+	clean = merge_fn(opt, head_commit, next_commit, ca, result);
 	if (clean < 0) {
 		rollback_lock_file(&lock);
 		return clean;

merge-recursive.h

@@ -51,6 +51,12 @@ struct merge_options {
 	struct merge_options_internal *priv;
 };
 
+typedef int (*recursive_merge_fn_t)(struct merge_options *opt,
+				    struct commit *h1,
+				    struct commit *h2,
+				    struct commit_list *merge_bases,
+				    struct commit **result);
+
 void init_merge_options(struct merge_options *opt, struct repository *repo);
 
 /* parse the option in s and update the relevant field of opt */
@@ -103,7 +109,7 @@ int merge_recursive(struct merge_options *opt,
 
 /*
  * merge_recursive_generic can operate on trees instead of commits, by
- * wrapping the trees into virtual commits, and calling merge_recursive().
+ * wrapping the trees into virtual commits, and calling the provided merge_fn.
  * It also writes out the in-memory index to disk if the merge is successful.
  *
  * Outputs:
@@ -118,6 +124,7 @@ int merge_recursive_generic(struct merge_options *opt,
 			    const struct object_id *merge,
 			    int num_merge_bases,
 			    const struct object_id **merge_bases,
+			    recursive_merge_fn_t merge_fn,
 			    struct commit **result);
 
 #endif