rebase: allow custom merge_options

Allow callers of rebase to specify custom merge options.  This may
allow custom conflict resolution, or failing fast when conflicts
are detected.

include/git2/rebase.h

@@ -58,6 +58,11 @@ typedef struct {
 	const char *rewrite_notes_ref;
 
 	/**
+	 * Options to control how trees are merged during `git_rebase_next`.
+	 */
+	git_merge_options merge_options;
+
+	/**
 	 * Options to control how files are written during `git_rebase_init`,
 	 * `git_checkout_next` and `git_checkout_abort`.  Note that a minimum
 	 * strategy of `GIT_CHECKOUT_SAFE` is defaulted in `init` and `next`,
@@ -110,7 +115,8 @@ typedef enum {
 
 #define GIT_REBASE_OPTIONS_VERSION 1
 #define GIT_REBASE_OPTIONS_INIT \
-	{GIT_REBASE_OPTIONS_VERSION, 0, 0, NULL, GIT_CHECKOUT_OPTIONS_INIT}
+	{ GIT_REBASE_OPTIONS_VERSION, 0, 0, NULL, GIT_MERGE_OPTIONS_INIT, \
+	  GIT_CHECKOUT_OPTIONS_INIT}
 
 /** Indicates that a rebase operation is not (yet) in progress. */
 #define GIT_REBASE_NO_OPERATION SIZE_MAX

src/rebase.c

@@ -813,7 +813,7 @@ static int rebase_next_merge(
 	if ((error = git_indexwriter_init_for_operation(&indexwriter, rebase->repo, &checkout_opts.checkout_strategy)) < 0 ||
 		(error = rebase_setupfile(rebase, MSGNUM_FILE, -1, "%" PRIuZ "\n", rebase->current+1)) < 0 ||
 		(error = rebase_setupfile(rebase, CURRENT_FILE, -1, "%.*s\n", GIT_OID_HEXSZ, current_idstr)) < 0 ||
-		(error = git_merge_trees(&index, rebase->repo, parent_tree, head_tree, current_tree, NULL)) < 0 ||
+		(error = git_merge_trees(&index, rebase->repo, parent_tree, head_tree, current_tree, &rebase->options.merge_options)) < 0 ||
 		(error = git_merge__check_result(rebase->repo, index)) < 0 ||
 		(error = git_checkout_index(rebase->repo, index, &checkout_opts)) < 0 ||
 		(error = git_indexwriter_commit(&indexwriter)) < 0)
@@ -853,7 +853,7 @@ static int rebase_next_inmemory(
 		(error = git_commit_parent(&parent_commit, current_commit, 0)) < 0 ||
 		(error = git_commit_tree(&parent_tree, parent_commit)) < 0 ||
 		(error = git_commit_tree(&head_tree, rebase->last_commit)) < 0 ||
-		(error = git_merge_trees(&index, rebase->repo, parent_tree, head_tree, current_tree, NULL)) < 0)
+		(error = git_merge_trees(&index, rebase->repo, parent_tree, head_tree, current_tree, &rebase->options.merge_options)) < 0)
 		goto done;
 
 	git_index_free(rebase->last_index);

tests/rebase/merge.c

@@ -565,3 +565,33 @@ void test_rebase_merge__custom_checkout_options(void)
 	git_reference_free(upstream_ref);
 	git_rebase_free(rebase);
 }
+
+void test_rebase_merge__custom_merge_options(void)
+{
+	git_rebase *rebase;
+	git_reference *branch_ref, *upstream_ref;
+	git_annotated_commit *branch_head, *upstream_head;
+	git_rebase_options rebase_options = GIT_REBASE_OPTIONS_INIT;
+	git_rebase_operation *rebase_operation;
+
+	rebase_options.merge_options.flags |=
+		GIT_MERGE_FAIL_ON_CONFLICT |
+		GIT_MERGE_SKIP_REUC;
+
+	cl_git_pass(git_reference_lookup(&branch_ref, repo, "refs/heads/asparagus"));
+	cl_git_pass(git_reference_lookup(&upstream_ref, repo, "refs/heads/master"));
+
+	cl_git_pass(git_annotated_commit_from_ref(&branch_head, repo, branch_ref));
+	cl_git_pass(git_annotated_commit_from_ref(&upstream_head, repo, upstream_ref));
+
+	cl_git_pass(git_rebase_init(&rebase, repo, branch_head, upstream_head, NULL, &rebase_options));
+
+	cl_git_fail_with(GIT_EMERGECONFLICT, git_rebase_next(&rebase_operation, rebase));
+
+	git_annotated_commit_free(branch_head);
+	git_annotated_commit_free(upstream_head);
+	git_reference_free(branch_ref);
+	git_reference_free(upstream_ref);
+	git_rebase_free(rebase);
+}
+