Merge pull request #2183 from ethomson/merge_refactor

Refactor the `git_merge` API

29 files changed, 1092 insertions, 999 deletions

diff --git a/include/git2/merge.h b/include/git2/merge.h
index cfec32f4d..21159d832 100644
--- a/include/git2/merge.h
+++ b/include/git2/merge.h
@@ -23,6 +23,43 @@
 GIT_BEGIN_DECL
 
 /**
+ * The file inputs to `git_merge_file`.  Callers should populate the
+ * `git_merge_file_input` structure with descriptions of the files in
+ * each side of the conflict for use in producing the merge file.
+ */
+typedef struct {
+	unsigned int version;
+
+	/** Pointer to the contents of the file. */
+	const char *ptr;
+
+	/** Size of the contents pointed to in `ptr`. */
+	size_t size;
+
+	/** File name of the conflicted file, or `NULL` to not merge the path. */
+	const char *path;
+
+	/** File mode of the conflicted file, or `0` to not merge the mode. */
+	unsigned int mode;
+} git_merge_file_input;
+
+#define GIT_MERGE_FILE_INPUT_VERSION 1
+#define GIT_MERGE_FILE_INPUT_INIT {GIT_MERGE_FILE_INPUT_VERSION}
+
+/**
+ * Initializes a `git_merge_file_input` with default values. Equivalent to
+ * creating an instance with GIT_MERGE_FILE_INPUT_INIT.
+ *
+ * @param opts the `git_merge_file_input` instance to initialize.
+ * @param version the version of the struct; you should pass
+ *        `GIT_MERGE_FILE_INPUT_VERSION` here.
+ * @return Zero on success; -1 on failure.
+ */
+GIT_EXTERN(int) git_merge_file_init_input(
+	git_merge_file_input *opts,
+	int version);
+
+/**
  * Flags for `git_merge_tree` options.  A combination of these flags can be
  * passed in via the `flags` value in the `git_merge_tree_opts`.
  */
@@ -71,6 +108,86 @@ typedef enum {
 	GIT_MERGE_FILE_FAVOR_UNION = 3,
 } git_merge_file_favor_t;
 
+typedef enum {
+	/* Defaults */
+	GIT_MERGE_FILE_DEFAULT = 0,
+
+	/* Create standard conflicted merge files */
+	GIT_MERGE_FILE_STYLE_MERGE = (1 << 0),
+
+	/* Create diff3-style files */
+	GIT_MERGE_FILE_STYLE_DIFF3 = (1 << 1),
+
+	/* Condense non-alphanumeric regions for simplified diff file */
+	GIT_MERGE_FILE_SIMPLIFY_ALNUM = (1 << 2),
+} git_merge_file_flags_t;
+
+typedef struct {
+	unsigned int version;
+
+	/**
+	 * Label for the ancestor file side of the conflict which will be prepended
+	 * to labels in diff3-format merge files.
+	 */
+	const char *ancestor_label;
+
+	/**
+	 * Label for our file side of the conflict which will be prepended
+	 * to labels in merge files.
+	 */
+	const char *our_label;
+
+	/**
+	 * Label for their file side of the conflict which will be prepended
+	 * to labels in merge files.
+	 */
+	const char *their_label;
+
+	/** The file to favor in region conflicts. */
+	git_merge_file_favor_t favor;
+
+	/** Merge file flags. */
+	git_merge_file_flags_t flags;
+} git_merge_file_options;
+
+#define GIT_MERGE_FILE_OPTIONS_VERSION 1
+#define GIT_MERGE_FILE_OPTIONS_INIT {GIT_MERGE_FILE_OPTIONS_VERSION}
+
+/**
+ * Initializes a `git_merge_file_options` with default values. Equivalent to
+ * creating an instance with GIT_MERGE_FILE_OPTIONS_INIT.
+ *
+ * @param opts the `git_merge_file_options` instance to initialize.
+ * @param version the version of the struct; you should pass
+ *        `GIT_MERGE_FILE_OPTIONS_VERSION` here.
+ * @return Zero on success; -1 on failure.
+ */
+GIT_EXTERN(int) git_merge_file_init_options(
+	git_merge_file_options *opts,
+	int version);
+
+typedef struct {
+	/**
+	 * True if the output was automerged, false if the output contains
+	 * conflict markers.
+	 */
+	unsigned int automergeable;
+
+	/**
+	 * The path that the resultant merge file should use, or NULL if a
+	 * filename conflict would occur.
+	 */
+	char *path;
+
+	/** The mode that the resultant merge file should use.  */
+	unsigned int mode;
+
+	/** The contents of the merge. */
+	unsigned char *ptr;
+
+	/** The length of the merge contents. */
+	size_t len;
+} git_merge_file_result;
 
 typedef struct {
 	unsigned int version;
@@ -99,75 +216,73 @@ typedef struct {
 
 	/** Flags for handling conflicting content. */
 	git_merge_file_favor_t file_favor;
-} git_merge_tree_opts;
+} git_merge_options;
 
-#define GIT_MERGE_TREE_OPTS_VERSION 1
-#define GIT_MERGE_TREE_OPTS_INIT {GIT_MERGE_TREE_OPTS_VERSION}
+#define GIT_MERGE_OPTIONS_VERSION 1
+#define GIT_MERGE_OPTIONS_INIT {GIT_MERGE_OPTIONS_VERSION}
 
 /**
- * Initializes a `git_merge_tree_opts` with default values. Equivalent to
- * creating an instance with GIT_MERGE_TREE_OPTS_INIT.
+ * Initializes a `git_merge_options` with default values. Equivalent to
+ * creating an instance with GIT_MERGE_OPTIONS_INIT.
  *
- * @param opts the `git_merge_tree_opts` instance to initialize.
+ * @param opts the `git_merge_options` instance to initialize.
  * @param version the version of the struct; you should pass
- *        `GIT_MERGE_TREE_OPTS_VERSION` here.
+ *        `GIT_MERGE_OPTIONS_VERSION` here.
  * @return Zero on success; -1 on failure.
  */
-GIT_EXTERN(int) git_merge_tree_init_opts(
-	git_merge_tree_opts* opts,
+GIT_EXTERN(int) git_merge_init_options(
+	git_merge_options *opts,
 	int version);
 
 /**
- * Option flags for `git_merge`.
+ * The results of `git_merge_analysis` indicate the merge opportunities.
  */
 typedef enum {
+	/** No merge is possible.  (Unused.) */
+	GIT_MERGE_ANALYSIS_NONE = 0,
+
 	/**
-	 * The default behavior is to allow fast-forwards, returning
-	 * immediately with the commit ID to fast-forward to.
+	 * A "normal" merge; both HEAD and the given merge input have diverged
+	 * from their common ancestor.  The divergent commits must be merged.
 	 */
-	GIT_MERGE_DEFAULT = 0,
+	GIT_MERGE_ANALYSIS_NORMAL = (1 << 0),
 
 	/**
-	 * Do not fast-forward; perform a merge and prepare a merge result even
-	 * if the inputs are eligible for fast-forwarding.
+	 * All given merge inputs are reachable from HEAD, meaning the
+	 * repository is up-to-date and no merge needs to be performed.
 	 */
-	GIT_MERGE_NO_FASTFORWARD = 1,
+	GIT_MERGE_ANALYSIS_UP_TO_DATE = (1 << 1),
 
 	/**
-	 * Ensure that the inputs are eligible for fast-forwarding, error if
-	 * a merge needs to be performed.
+	 * The given merge input is a fast-forward from HEAD and no merge
+	 * needs to be performed.  Instead, the client can check out the
+	 * given merge input.
 	 */
-	GIT_MERGE_FASTFORWARD_ONLY = 2,
-} git_merge_flags_t;
-
-typedef struct {
-	unsigned int version;
-
-	/** Options for handling the commit-level merge. */
-	git_merge_flags_t merge_flags;
-
-	/** Options for handling the merges of individual files. */
-	git_merge_tree_opts merge_tree_opts;
-
-	/** Options for writing the merge result to the working directory. */
-	git_checkout_options checkout_opts;
-} git_merge_opts;
+	GIT_MERGE_ANALYSIS_FASTFORWARD = (1 << 2),
 
-#define GIT_MERGE_OPTS_VERSION 1
-#define GIT_MERGE_OPTS_INIT {GIT_MERGE_OPTS_VERSION, 0, GIT_MERGE_TREE_OPTS_INIT, GIT_CHECKOUT_OPTIONS_INIT}
+	/**
+	 * The HEAD of the current repository is "unborn" and does not point to
+	 * a valid commit.  No merge can be performed, but the caller may wish
+	 * to simply set HEAD to the target commit(s).
+	 */
+	GIT_MERGE_ANALYSIS_UNBORN = (1 << 3),
+} git_merge_analysis_t;
 
 /**
- * Initializes a `git_merge_opts` with default values. Equivalent to creating
- * an instance with GIT_MERGE_OPTS_INIT.
+ * Analyzes the given branch(es) and determines the opportunities for
+ * merging them into the HEAD of the repository.
  *
- * @param opts the `git_merge_opts` instance to initialize.
- * @param version the version of the struct; you should pass
- *        `GIT_MERGE_OPTS_VERSION` here.
- * @return Zero on success; -1 on failure.
+ * @param analysis_out analysis enumeration that the result is written into
+ * @param repo the repository to merge
+ * @param their_heads the heads to merge into
+ * @param their_heads_len the number of heads to merge
+ * @return 0 on success or error code
  */
-GIT_EXTERN(int) git_merge_init_opts(
-	git_merge_opts* opts,
-	int version);
+GIT_EXTERN(int) git_merge_analysis(
+	git_merge_analysis_t *analysis_out,
+	git_repository *repo,
+	const git_merge_head **their_heads,
+	size_t their_heads_len);
 
 /**
  * Find a merge base between two commits
@@ -269,6 +384,58 @@ GIT_EXTERN(void) git_merge_head_free(
 	git_merge_head *head);
 
 /**
+ * Merge two files as they exist in the in-memory data structures, using
+ * the given common ancestor as the baseline, producing a
+ * `git_merge_file_result` that reflects the merge result.  The
+ * `git_merge_file_result` must be freed with `git_merge_file_result_free`.
+ *
+ * Note that this function does not reference a repository and any
+ * configuration must be passed as `git_merge_file_options`.
+ *
+ * @param out The git_merge_file_result to be filled in
+ * @param ancestor The contents of the ancestor file
+ * @param ours The contents of the file in "our" side
+ * @param theirs The contents of the file in "their" side
+ * @param opts The merge file options or `NULL` for defaults
+ * @return 0 on success or error code
+ */
+GIT_EXTERN(int) git_merge_file(
+	git_merge_file_result *out,
+	const git_merge_file_input *ancestor,
+	const git_merge_file_input *ours,
+	const git_merge_file_input *theirs,
+	const git_merge_file_options *opts);
+
+/**
+ * Merge two files as they exist in the index, using the given common
+ * ancestor as the baseline, producing a `git_merge_file_result` that
+ * reflects the merge result.  The `git_merge_file_result` must be freed with
+ * `git_merge_file_result_free`.
+ *
+ * @param out The git_merge_file_result to be filled in
+ * @param repo The repository
+ * @param ancestor The index entry for the ancestor file (stage level 1)
+ * @param our_path The index entry for our file (stage level 2)
+ * @param their_path The index entry for their file (stage level 3)
+ * @param opts The merge file options or NULL
+ * @return 0 on success or error code
+ */
+GIT_EXTERN(int) git_merge_file_from_index(
+	git_merge_file_result *out,
+	git_repository *repo,
+	const git_index_entry *ancestor,
+	const git_index_entry *ours,
+	const git_index_entry *theirs,
+	const git_merge_file_options *opts);
+
+/**
+ * Frees a `git_merge_file_result`.
+ *
+ * @param result The result to free or `NULL`
+ */
+GIT_EXTERN(void) git_merge_file_result_free(git_merge_file_result *result);
+
+/**
  * Merge two trees, producing a `git_index` that reflects the result of
  * the merge.  The index may be written as-is to the working directory
  * or checked out.  If the index is to be converted to a tree, the caller
@@ -290,7 +457,7 @@ GIT_EXTERN(int) git_merge_trees(
 	const git_tree *ancestor_tree,
 	const git_tree *our_tree,
 	const git_tree *their_tree,
-	const git_merge_tree_opts *opts);
+	const git_merge_options *opts);
 
 /**
  * Merge two commits, producing a `git_index` that reflects the result of
@@ -312,81 +479,27 @@ GIT_EXTERN(int) git_merge_commits(
 	git_repository *repo,
 	const git_commit *our_commit,
 	const git_commit *their_commit,
-	const git_merge_tree_opts *opts);
+	const git_merge_options *opts);
 
 /**
- * Merges the given commit(s) into HEAD and either returns immediately
- * if there was no merge to perform (the specified commits have already
- * been merged or would produce a fast-forward) or performs the merge
- * and writes the results into the working directory.
- *
- * Callers should inspect the `git_merge_result`:
- *
- * If `git_merge_result_is_uptodate` is true, there is no work to perform.
+ * Merges the given commit(s) into HEAD, writing the results into the working
+ * directory.  Any changes are staged for commit and any conflicts are written
+ * to the index.  Callers should inspect the repository's index after this
+ * completes, resolve any conflicts and prepare a commit.
  *
- * If `git_merge_result_is_fastforward` is true, the caller should update
- * any necessary references to the commit ID returned by
- * `git_merge_result_fastforward_id` and check that out in order to complete
- * the fast-forward.
- * 
- * Otherwise, callers should inspect the resulting index, resolve any
- * conflicts and prepare a commit.
- *
- * The resultant `git_merge_result` should be free with
- * `git_merge_result_free`.
- *
- * @param out the results of the merge
  * @param repo the repository to merge
  * @param merge_heads the heads to merge into
  * @param merge_heads_len the number of heads to merge
- * @param opts merge options
+ * @param merge_opts merge options
+ * @param checkout_opts checkout options
  * @return 0 on success or error code
  */
 GIT_EXTERN(int) git_merge(
-	git_merge_result **out,
 	git_repository *repo,
 	const git_merge_head **their_heads,
 	size_t their_heads_len,
-	const git_merge_opts *opts);
-
-/**
- * Returns true if a merge is "up-to-date", meaning that the commit(s) 
- * that were provided to `git_merge` are already included in `HEAD`
- * and there is no work to do.
- *
- * @return true if the merge is up-to-date, false otherwise
- */
-GIT_EXTERN(int) git_merge_result_is_uptodate(git_merge_result *merge_result);
-
-/**
- * Returns true if a merge is eligible to be "fast-forwarded", meaning that
- * the commit that was provided to `git_merge` need not be merged, it can
- * simply be checked out, because the current `HEAD` is the merge base of
- * itself and the given commit.  To perform the fast-forward, the caller
- * should check out the results of `git_merge_result_fastforward_id`.
- * 
- * This will never be true if `GIT_MERGE_NO_FASTFORWARD` is supplied as
- * a merge option.
- *
- * @return true if the merge is fast-forwardable, false otherwise
- */
-GIT_EXTERN(int) git_merge_result_is_fastforward(git_merge_result *merge_result);
-
-/**
- * Gets the fast-forward OID if the merge was a fastforward.
- *
- * @param out pointer to populate with the OID of the fast-forward
- * @param merge_result the results of the merge
- * @return 0 on success or error code
- */
-GIT_EXTERN(int) git_merge_result_fastforward_id(git_oid *out, git_merge_result *merge_result);
-
-/**
- * Frees a `git_merge_result`.
- *
- * @param result merge result to free
- */
-GIT_EXTERN(void) git_merge_result_free(git_merge_result *merge_result);
+	const git_merge_options *merge_opts,
+	const git_checkout_options *checkout_opts);
 
 /** @} */
 GIT_END_DECL
diff --git a/include/git2/revert.h b/include/git2/revert.h
index 3f48c4e4b..3a6beb6b8 100644
--- a/include/git2/revert.h
+++ b/include/git2/revert.h
@@ -26,12 +26,12 @@ typedef struct {
 	/** For merge commits, the "mainline" is treated as the parent. */
 	unsigned int mainline;
 
-	git_merge_tree_opts merge_tree_opts;
+	git_merge_options merge_opts;
 	git_checkout_options checkout_opts;
 } git_revert_options;
 
 #define GIT_REVERT_OPTIONS_VERSION 1
-#define GIT_REVERT_OPTIONS_INIT {GIT_REVERT_OPTIONS_VERSION, 0, GIT_MERGE_TREE_OPTS_INIT, GIT_CHECKOUT_OPTIONS_INIT}
+#define GIT_REVERT_OPTIONS_INIT {GIT_REVERT_OPTIONS_VERSION, 0, GIT_MERGE_OPTIONS_INIT, GIT_CHECKOUT_OPTIONS_INIT}
 
 /**
  * Initializes a `git_revert_options` with default values. Equivalent to
@@ -66,7 +66,7 @@ int git_revert_commit(
 	git_commit *revert_commit,
 	git_commit *our_commit,
 	unsigned int mainline,
-	const git_merge_tree_opts *merge_tree_opts);
+	const git_merge_options *merge_options);
 
 /**
  * Reverts the given commit, producing changes in the working directory.
diff --git a/src/checkout.c b/src/checkout.c
index 5dd4ec71c..f882f3593 100644
--- a/src/checkout.c
+++ b/src/checkout.c
@@ -1681,29 +1681,20 @@ static int checkout_write_merge(
 {
 	git_buf our_label = GIT_BUF_INIT, their_label = GIT_BUF_INIT,
 		path_suffixed = GIT_BUF_INIT, path_workdir = GIT_BUF_INIT;
-	git_merge_file_options merge_file_opts = GIT_MERGE_FILE_OPTIONS_INIT;
-	git_merge_file_input ancestor = GIT_MERGE_FILE_INPUT_INIT,
-		ours = GIT_MERGE_FILE_INPUT_INIT,
-		theirs = GIT_MERGE_FILE_INPUT_INIT;
-	git_merge_file_result result = GIT_MERGE_FILE_RESULT_INIT;
+	git_merge_file_options opts = GIT_MERGE_FILE_OPTIONS_INIT;
+	git_merge_file_result result = {0};
 	git_filebuf output = GIT_FILEBUF_INIT;
 	int error = 0;
 
 	if (data->opts.checkout_strategy & GIT_CHECKOUT_CONFLICT_STYLE_DIFF3)
-		merge_file_opts.style = GIT_MERGE_FILE_STYLE_DIFF3;
-
-	if ((conflict->ancestor &&
-		(error = git_merge_file_input_from_index_entry(
-		&ancestor, data->repo, conflict->ancestor)) < 0) ||
-		(error = git_merge_file_input_from_index_entry(
-		&ours, data->repo, conflict->ours)) < 0 ||
-		(error = git_merge_file_input_from_index_entry(
-		&theirs, data->repo, conflict->theirs)) < 0)
-		goto done;
+		opts.flags |= GIT_MERGE_FILE_STYLE_DIFF3;
 
-	ancestor.label = data->opts.ancestor_label ? data->opts.ancestor_label : "ancestor";
-	ours.label = data->opts.our_label ? data->opts.our_label : "ours";
-	theirs.label = data->opts.their_label ? data->opts.their_label : "theirs";
+	opts.ancestor_label = data->opts.ancestor_label ?
+		data->opts.ancestor_label : "ancestor";
+	opts.our_label = data->opts.our_label ?
+		data->opts.our_label : "ours";
+	opts.their_label = data->opts.their_label ?
+		data->opts.their_label : "theirs";
 
 	/* If all the paths are identical, decorate the diff3 file with the branch
 	 * names.  Otherwise, append branch_name:path.
@@ -1712,16 +1703,17 @@ static int checkout_write_merge(
 		strcmp(conflict->ours->path, conflict->theirs->path) != 0) {
 
 		if ((error = conflict_entry_name(
-			&our_label, ours.label, conflict->ours->path)) < 0 ||
+			&our_label, opts.our_label, conflict->ours->path)) < 0 ||
 			(error = conflict_entry_name(
-			&their_label, theirs.label, conflict->theirs->path)) < 0)
+			&their_label, opts.their_label, conflict->theirs->path)) < 0)
 			goto done;
 
-		ours.label = git_buf_cstr(&our_label);
-		theirs.label = git_buf_cstr(&their_label);
+		opts.our_label = git_buf_cstr(&our_label);
+		opts.their_label = git_buf_cstr(&their_label);
 	}
 
-	if ((error = git_merge_files(&result, &ancestor, &ours, &theirs, &merge_file_opts)) < 0)
+	if ((error = git_merge_file_from_index(&result, data->repo,
+		conflict->ancestor, conflict->ours, conflict->theirs, &opts)) < 0)
 		goto done;
 
 	if (result.path == NULL || result.mode == 0) {
@@ -1739,7 +1731,7 @@ static int checkout_write_merge(
 
 	if ((error = git_futils_mkpath2file(path_workdir.ptr, 0755)) < 0 ||
 		(error = git_filebuf_open(&output, path_workdir.ptr, GIT_FILEBUF_DO_NOT_BUFFER, result.mode)) < 0 ||
-		(error = git_filebuf_write(&output, result.data, result.len)) < 0 ||
+		(error = git_filebuf_write(&output, result.ptr, result.len)) < 0 ||
 		(error = git_filebuf_commit(&output)) < 0)
 		goto done;
 
@@ -1747,9 +1739,6 @@ done:
 	git_buf_free(&our_label);
 	git_buf_free(&their_label);
 
-	git_merge_file_input_free(&ancestor);
-	git_merge_file_input_free(&ours);
-	git_merge_file_input_free(&theirs);
 	git_merge_file_result_free(&result);
 	git_buf_free(&path_workdir);
 	git_buf_free(&path_suffixed);
diff --git a/src/index.c b/src/index.c
index 0d7d50668..ea0815e4c 100644
--- a/src/index.c
+++ b/src/index.c
@@ -300,7 +300,7 @@ static void index_entry_free(git_index_entry *entry)
 	git__free(entry);
 }
 
-static unsigned int index_create_mode(unsigned int mode)
+unsigned int git_index__create_mode(unsigned int mode)
 {
 	if (S_ISLNK(mode))
 		return S_IFLNK;
@@ -320,9 +320,9 @@ static unsigned int index_merge_mode(
 
 	if (index->distrust_filemode && S_ISREG(mode))
 		return (existing && S_ISREG(existing->mode)) ?
-			existing->mode : index_create_mode(0666);
+			existing->mode : git_index__create_mode(0666);
 
-	return index_create_mode(mode);
+	return git_index__create_mode(mode);
 }
 
 void git_index__set_ignore_case(git_index *index, bool ignore_case)
@@ -619,7 +619,7 @@ void git_index_entry__init_from_stat(
 	entry->dev  = st->st_rdev;
 	entry->ino  = st->st_ino;
 	entry->mode = (!trust_mode && S_ISREG(st->st_mode)) ?
-		index_create_mode(0666) : index_create_mode(st->st_mode);
+		git_index__create_mode(0666) : git_index__create_mode(st->st_mode);
 	entry->uid  = st->st_uid;
 	entry->gid  = st->st_gid;
 	entry->file_size = st->st_size;
diff --git a/src/index.h b/src/index.h
index f88d110f7..259a3149f 100644
--- a/src/index.h
+++ b/src/index.h
@@ -60,4 +60,6 @@ extern int git_index__find(
 
 extern void git_index__set_ignore_case(git_index *index, bool ignore_case);
 
+extern unsigned int git_index__create_mode(unsigned int mode);
+
 #endif
diff --git a/src/merge.c b/src/merge.c
index 66952c074..42fbd79c9 100644
--- a/src/merge.c
+++ b/src/merge.c
@@ -545,11 +545,9 @@ static int merge_conflict_resolve_automerge(
 	const git_merge_diff *conflict,
 	unsigned int merge_file_favor)
 {
-	git_merge_file_options merge_file_opts = GIT_MERGE_FILE_OPTIONS_INIT;
-	git_merge_file_input ancestor = GIT_MERGE_FILE_INPUT_INIT,
-		ours = GIT_MERGE_FILE_INPUT_INIT,
-		theirs = GIT_MERGE_FILE_INPUT_INIT;
-	git_merge_file_result result = GIT_MERGE_FILE_RESULT_INIT;
+	const git_index_entry *ancestor = NULL, *ours = NULL, *theirs = NULL;
+	git_merge_file_options opts = GIT_MERGE_FILE_OPTIONS_INIT;
+	git_merge_file_result result = {0};
 	git_index_entry *index_entry;
 	git_odb *odb = NULL;
 	git_oid automerge_oid;
@@ -559,7 +557,9 @@ static int merge_conflict_resolve_automerge(
 
 	*resolved = 0;
 
-	merge_file_opts.favor = merge_file_favor;
+	if (!GIT_MERGE_INDEX_ENTRY_EXISTS(conflict->our_entry) ||
+		!GIT_MERGE_INDEX_ENTRY_EXISTS(conflict->their_entry))
+		return 0;
 
 	/* Reject D/F conflicts */
 	if (conflict->type == GIT_MERGE_DIFF_DIRECTORY_FILE)
@@ -590,13 +590,19 @@ static int merge_conflict_resolve_automerge(
 	if (conflict->binary)
 		return 0;
 
+	ancestor = GIT_MERGE_INDEX_ENTRY_EXISTS(conflict->ancestor_entry) ?
+		&conflict->ancestor_entry : NULL;
+	ours = GIT_MERGE_INDEX_ENTRY_EXISTS(conflict->our_entry) ?
+		&conflict->our_entry : NULL;
+	theirs = GIT_MERGE_INDEX_ENTRY_EXISTS(conflict->their_entry) ?
+		&conflict->their_entry : NULL;
+
+	opts.favor = merge_file_favor;
+
 	if ((error = git_repository_odb(&odb, diff_list->repo)) < 0 ||
-		(error = git_merge_file_input_from_index_entry(&ancestor, diff_list->repo, &conflict->ancestor_entry)) < 0 ||
-		(error = git_merge_file_input_from_index_entry(&ours, diff_list->repo, &conflict->our_entry)) < 0 ||
-		(error = git_merge_file_input_from_index_entry(&theirs, diff_list->repo, &conflict->their_entry)) < 0 ||
-		(error = git_merge_files(&result, &ancestor, &ours, &theirs, &merge_file_opts)) < 0 ||
+		(error = git_merge_file_from_index(&result, diff_list->repo, ancestor, ours, theirs, &opts)) < 0 ||
 		!result.automergeable ||
-		(error = git_odb_write(&automerge_oid, odb, result.data, result.len, GIT_OBJ_BLOB)) < 0)
+		(error = git_odb_write(&automerge_oid, odb, result.ptr, result.len, GIT_OBJ_BLOB)) < 0)
 		goto done;
 
 	if ((index_entry = git_pool_malloc(&diff_list->pool, sizeof(git_index_entry))) == NULL)
@@ -615,9 +621,6 @@ static int merge_conflict_resolve_automerge(
 	*resolved = 1;
 
 done:
-	git_merge_file_input_free(&ancestor);
-	git_merge_file_input_free(&ours);
-	git_merge_file_input_free(&theirs);
 	git_merge_file_result_free(&result);
 	git_odb_free(odb);
 
@@ -667,7 +670,7 @@ static int index_entry_similarity_exact(
 	git_index_entry *b,
 	size_t b_idx,
 	void **cache,
-	const git_merge_tree_opts *opts)
+	const git_merge_options *opts)
 {
 	GIT_UNUSED(repo);
 	GIT_UNUSED(a_idx);
@@ -685,7 +688,7 @@ static int index_entry_similarity_calc(
 	void **out,
 	git_repository *repo,
 	git_index_entry *entry,
-	const git_merge_tree_opts *opts)
+	const git_merge_options *opts)
 {
 	git_blob *blob;
 	git_diff_file diff_file = {{{0}}};
@@ -725,7 +728,7 @@ static int index_entry_similarity_inexact(
 	git_index_entry *b,
 	size_t b_idx,
 	void **cache,
-	const git_merge_tree_opts *opts)
+	const git_merge_options *opts)
 {
 	int score = 0;
 	int error = 0;
@@ -762,9 +765,9 @@ static int merge_diff_mark_similarity(
 	git_merge_diff_list *diff_list,
 	struct merge_diff_similarity *similarity_ours,
 	struct merge_diff_similarity *similarity_theirs,
-	int (*similarity_fn)(git_repository *, git_index_entry *, size_t, git_index_entry *, size_t, void **, const git_merge_tree_opts *),
+	int (*similarity_fn)(git_repository *, git_index_entry *, size_t, git_index_entry *, size_t, void **, const git_merge_options *),
 	void **cache,
-	const git_merge_tree_opts *opts)
+	const git_merge_options *opts)
 {
 	size_t i, j;
 	git_merge_diff *conflict_src, *conflict_tgt;
@@ -865,7 +868,7 @@ static void merge_diff_mark_rename_conflict(
 	bool theirs_renamed,
 	size_t theirs_source_idx,
 	git_merge_diff *target,
-	const git_merge_tree_opts *opts)
+	const git_merge_options *opts)
 {
 	git_merge_diff *ours_source = NULL, *theirs_source = NULL;
 
@@ -935,7 +938,7 @@ static void merge_diff_list_coalesce_renames(
 	git_merge_diff_list *diff_list,
 	struct merge_diff_similarity *similarity_ours,
 	struct merge_diff_similarity *similarity_theirs,
-	const git_merge_tree_opts *opts)
+	const git_merge_options *opts)
 {
 	size_t i;
 	bool ours_renamed = 0, theirs_renamed = 0;
@@ -1025,7 +1028,7 @@ static void merge_diff_list_count_candidates(
 int git_merge_diff_list__find_renames(
 	git_repository *repo,
 	git_merge_diff_list *diff_list,
-	const git_merge_tree_opts *opts)
+	const git_merge_options *opts)
 {
 	struct merge_diff_similarity *similarity_ours, *similarity_theirs;
 	void **cache = NULL;
@@ -1453,10 +1456,10 @@ void git_merge_diff_list__free(git_merge_diff_list *diff_list)
 	git__free(diff_list);
 }
 
-static int merge_tree_normalize_opts(
+static int merge_normalize_opts(
 	git_repository *repo,
-	git_merge_tree_opts *opts,
-	const git_merge_tree_opts *given)
+	git_merge_options *opts,
+	const git_merge_options *given)
 {
 	git_config *cfg = NULL;
 	int error = 0;
@@ -1467,9 +1470,9 @@ static int merge_tree_normalize_opts(
 		return error;
 
 	if (given != NULL)
-		memcpy(opts, given, sizeof(git_merge_tree_opts));
+		memcpy(opts, given, sizeof(git_merge_options));
 	else {
-		git_merge_tree_opts init = GIT_MERGE_TREE_OPTS_INIT;
+		git_merge_options init = GIT_MERGE_OPTIONS_INIT;
 		memcpy(opts, &init, sizeof(init));
 
 		opts->flags = GIT_MERGE_TREE_FIND_RENAMES;
@@ -1637,10 +1640,10 @@ int git_merge_trees(
 	const git_tree *ancestor_tree,
 	const git_tree *our_tree,
 	const git_tree *their_tree,
-	const git_merge_tree_opts *given_opts)
+	const git_merge_options *given_opts)
 {
 	git_merge_diff_list *diff_list;
-	git_merge_tree_opts opts;
+	git_merge_options opts;
 	git_merge_diff *conflict;
 	git_vector changes;
 	size_t i;
@@ -1650,9 +1653,9 @@ int git_merge_trees(
 
 	*out = NULL;
 
-	GITERR_CHECK_VERSION(given_opts, GIT_MERGE_TREE_OPTS_VERSION, "git_merge_tree_opts");
+	GITERR_CHECK_VERSION(given_opts, GIT_MERGE_OPTIONS_VERSION, "git_merge_options");
 
-	if ((error = merge_tree_normalize_opts(repo, &opts, given_opts)) < 0)
+	if ((error = merge_normalize_opts(repo, &opts, given_opts)) < 0)
 		return error;
 
 	diff_list = git_merge_diff_list__alloc(repo);
@@ -1691,7 +1694,7 @@ int git_merge_commits(
 	git_repository *repo,
 	const git_commit *our_commit,
 	const git_commit *their_commit,
-	const git_merge_tree_opts *opts)
+	const git_merge_options *opts)
 {
 	git_oid ancestor_oid;
 	git_commit *ancestor_commit = NULL;
@@ -1777,31 +1780,20 @@ cleanup:
 	return error;
 }
 
-static int write_merge_mode(git_repository *repo, unsigned int flags)
+static int write_merge_mode(git_repository *repo)
 {
 	git_filebuf file = GIT_FILEBUF_INIT;
 	git_buf file_path = GIT_BUF_INIT;
 	int error = 0;
 
-	/* For future expansion */
-	GIT_UNUSED(flags);
-
 	assert(repo);
 
 	if ((error = git_buf_joinpath(&file_path, repo->path_repository, GIT_MERGE_MODE_FILE)) < 0 ||
 		(error = git_filebuf_open(&file, file_path.ptr, GIT_FILEBUF_FORCE, GIT_MERGE_FILE_MODE)) < 0)
 		goto cleanup;
 
-	/*
-	 * no-ff is the only thing allowed here at present.  One would
-	 * presume they would be space-delimited when there are more, but
-	 * this needs to be revisited.
-	 */
-
-	if (flags & GIT_MERGE_NO_FASTFORWARD) {
-		if ((error = git_filebuf_write(&file, "no-ff", 5)) < 0)
-			goto cleanup;
-	}
+	if ((error = git_filebuf_write(&file, "no-ff", 5)) < 0)
+		goto cleanup;
 
 	error = git_filebuf_commit(&file);
 
@@ -2117,6 +2109,25 @@ cleanup:
 	return error;
 }
 
+int git_merge__setup(
+	git_repository *repo,
+	const git_merge_head *our_head,
+	const git_merge_head *heads[],
+	size_t heads_len)
+{
+	int error = 0;
+
+	assert (repo && our_head && heads);
+
+	if ((error = write_orig_head(repo, our_head)) == 0 &&
+		(error = write_merge_head(repo, heads, heads_len)) == 0 &&
+		(error = write_merge_mode(repo)) == 0) {
+		error = write_merge_msg(repo, heads, heads_len);
+	}
+
+	return error;
+}
+
 /* Merge branches */
 
 static int merge_ancestor_head(
@@ -2150,37 +2161,6 @@ on_error:
 	return error;
 }
 
-GIT_INLINE(bool) merge_check_uptodate(
-	git_merge_result *result,
-	const git_merge_head *ancestor_head,
-	const git_merge_head *their_head)
-{
-	if (git_oid_cmp(&ancestor_head->oid, &their_head->oid) == 0) {
-		result->is_uptodate = 1;
-		return true;
-	}
-
-	return false;
-}
-
-GIT_INLINE(bool) merge_check_fastforward(
-	git_merge_result *result,
-	const git_merge_head *ancestor_head,
-	const git_merge_head *our_head,
-	const git_merge_head *their_head,
-	unsigned int flags)
-{
-	if ((flags & GIT_MERGE_NO_FASTFORWARD) == 0 &&
-		git_oid_cmp(&ancestor_head->oid, &our_head->oid) == 0) {
-		result->is_fastforward = 1;
-		git_oid_cpy(&result->fastforward_oid, &their_head->oid);
-
-		return true;
-	}
-
-	return false;
-}
-
 const char *merge_their_label(const char *branchname)
 {
 	const char *slash;
@@ -2194,10 +2174,10 @@ const char *merge_their_label(const char *branchname)
 	return slash+1;
 }
 
-static int merge_normalize_opts(
+static int merge_normalize_checkout_opts(
 	git_repository *repo,
-	git_merge_opts *opts,
-	const git_merge_opts *given,
+	git_checkout_options *checkout_opts,
+	const git_checkout_options *given_checkout_opts,
 	const git_merge_head *ancestor_head,
 	const git_merge_head *our_head,
 	size_t their_heads_len,
@@ -2209,38 +2189,38 @@ static int merge_normalize_opts(
 
 	GIT_UNUSED(repo);
 
-	if (given != NULL)
-		memcpy(opts, given, sizeof(git_merge_opts));
+	if (given_checkout_opts != NULL)
+		memcpy(checkout_opts, given_checkout_opts, sizeof(git_checkout_options));
 	else {
-		git_merge_opts default_opts = GIT_MERGE_OPTS_INIT;
-		memcpy(opts, &default_opts, sizeof(git_merge_opts));
+		git_checkout_options default_checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
+		memcpy(checkout_opts, &default_checkout_opts, sizeof(git_checkout_options));
 	}
 
-	if (!opts->checkout_opts.checkout_strategy)
-		opts->checkout_opts.checkout_strategy = default_checkout_strategy;
+	if (!checkout_opts->checkout_strategy)
+		checkout_opts->checkout_strategy = default_checkout_strategy;
 
 	/* TODO: for multiple ancestors in merge-recursive, this is "merged common ancestors" */
-	if (!opts->checkout_opts.ancestor_label) {
+	if (!checkout_opts->ancestor_label) {
 		if (ancestor_head && ancestor_head->commit)
-			opts->checkout_opts.ancestor_label = git_commit_summary(ancestor_head->commit);
+			checkout_opts->ancestor_label = git_commit_summary(ancestor_head->commit);
 		else
-			opts->checkout_opts.ancestor_label = "ancestor";
+			checkout_opts->ancestor_label = "ancestor";
 	}
 
-	if (!opts->checkout_opts.our_label) {
+	if (!checkout_opts->our_label) {
 		if (our_head && our_head->ref_name)
-			opts->checkout_opts.our_label = our_head->ref_name;
+			checkout_opts->our_label = our_head->ref_name;
 		else
-			opts->checkout_opts.our_label = "ours";
+			checkout_opts->our_label = "ours";
 	}
 
-	if (!opts->checkout_opts.their_label) {
+	if (!checkout_opts->their_label) {
 		if (their_heads_len == 1 && their_heads[0]->ref_name)
-			opts->checkout_opts.their_label = merge_their_label(their_heads[0]->ref_name);
+			checkout_opts->their_label = merge_their_label(their_heads[0]->ref_name);
 		else if (their_heads_len == 1)
-			opts->checkout_opts.their_label = their_heads[0]->oid_str;
+			checkout_opts->their_label = their_heads[0]->oid_str;
 		else
-			opts->checkout_opts.their_label = "theirs";
+			checkout_opts->their_label = "theirs";
 	}
 
 	return error;
@@ -2500,71 +2480,128 @@ static int merge_state_cleanup(git_repository *repo)
 	return git_repository__cleanup_files(repo, state_files, ARRAY_SIZE(state_files));
 }
 
-int git_merge(
-	git_merge_result **out,
+static int merge_heads(
+	git_merge_head **ancestor_head_out,
+	git_merge_head **our_head_out,
 	git_repository *repo,
 	const git_merge_head **their_heads,
-	size_t their_heads_len,
-	const git_merge_opts *given_opts)
+	size_t their_heads_len)
 {
-	git_merge_result *result;
-	git_merge_opts opts;
+	git_merge_head *ancestor_head = NULL, *our_head = NULL;
 	git_reference *our_ref = NULL;
+	int error = 0;
+
+	*ancestor_head_out = NULL;
+	*our_head_out = NULL;
+
+	if ((error = git_repository__ensure_not_bare(repo, "merge")) < 0)
+		goto done;
+
+	if ((error = git_reference_lookup(&our_ref, repo, GIT_HEAD_FILE)) < 0 ||
+		(error = git_merge_head_from_ref(&our_head, repo, our_ref)) < 0)
+		goto done;
+
+	if ((error = merge_ancestor_head(&ancestor_head, repo, our_head, their_heads, their_heads_len)) < 0) {
+		if (error != GIT_ENOTFOUND)
+			goto done;
+
+		giterr_clear();
+		error = 0;
+	}
+
+	*ancestor_head_out = ancestor_head;
+	*our_head_out = our_head;
+
+done:
+	if (error < 0) {
+		git_merge_head_free(ancestor_head);
+		git_merge_head_free(our_head);
+	}
+
+	git_reference_free(our_ref);
+
+	return error;
+}
+
+int git_merge_analysis(
+	git_merge_analysis_t *out,
+	git_repository *repo,
+	const git_merge_head **their_heads,
+	size_t their_heads_len)
+{
 	git_merge_head *ancestor_head = NULL, *our_head = NULL;
-	git_tree *ancestor_tree = NULL, *our_tree = NULL, **their_trees = NULL;
-	git_index *index_new = NULL, *index_repo = NULL;
-	size_t i;
 	int error = 0;
 
 	assert(out && repo && their_heads);
 
-	*out = NULL;
+	*out = GIT_MERGE_ANALYSIS_NONE;
 
-	GITERR_CHECK_VERSION(given_opts, GIT_MERGE_OPTS_VERSION, "git_merge_opts");
+	if (git_repository_head_unborn(repo)) {
+		*out = GIT_MERGE_ANALYSIS_FASTFORWARD | GIT_MERGE_ANALYSIS_UNBORN;
+		goto done;
+	}
 
 	if (their_heads_len != 1) {
 		giterr_set(GITERR_MERGE, "Can only merge a single branch");
-		return -1;
+		error = -1;
+		goto done;
 	}
 
-	result = git__calloc(1, sizeof(git_merge_result));
-	GITERR_CHECK_ALLOC(result);
+	if ((error = merge_heads(&ancestor_head, &our_head, repo, their_heads, their_heads_len)) < 0)
+		goto done;
 
-	their_trees = git__calloc(their_heads_len, sizeof(git_tree *));
-	GITERR_CHECK_ALLOC(their_trees);
+	/* We're up-to-date if we're trying to merge our own common ancestor. */
+	if (ancestor_head && git_oid_equal(&ancestor_head->oid, &their_heads[0]->oid))
+		*out = GIT_MERGE_ANALYSIS_UP_TO_DATE;
 
-	if ((error = git_repository__ensure_not_bare(repo, "merge")) < 0)
-		goto on_error;
+	/* We're fastforwardable if we're our own common ancestor. */
+	else if (ancestor_head && git_oid_equal(&ancestor_head->oid, &our_head->oid))
+		*out = GIT_MERGE_ANALYSIS_FASTFORWARD | GIT_MERGE_ANALYSIS_NORMAL;
 
-	if ((error = git_reference_lookup(&our_ref, repo, GIT_HEAD_FILE)) < 0 ||
-		(error = git_merge_head_from_ref(&our_head, repo, our_ref)) < 0)
-		goto on_error;
+	/* Otherwise, just a normal merge is possible. */
+	else
+		*out = GIT_MERGE_ANALYSIS_NORMAL;
 
-	if ((error = merge_ancestor_head(&ancestor_head, repo, our_head, their_heads, their_heads_len)) < 0 &&
-		error != GIT_ENOTFOUND)
-		goto on_error;
+done:
+	git_merge_head_free(ancestor_head);
+	git_merge_head_free(our_head);
+	return error;
+}
 
-	if ((error = merge_normalize_opts(repo, &opts, given_opts, ancestor_head, our_head, their_heads_len, their_heads)) < 0)
-		goto on_error;
+int git_merge(
+	git_repository *repo,
+	const git_merge_head **their_heads,
+	size_t their_heads_len,
+	const git_merge_options *merge_opts,
+	const git_checkout_options *given_checkout_opts)
+{
+	git_reference *our_ref = NULL;
+	git_checkout_options checkout_opts;
+	git_merge_head *ancestor_head = NULL, *our_head = NULL;
+	git_tree *ancestor_tree = NULL, *our_tree = NULL, **their_trees = NULL;
+	git_index *index_new = NULL, *index_repo = NULL;
+	size_t i;
+	int error = 0;
 
-	if (their_heads_len == 1 &&
-		ancestor_head != NULL &&
-		(merge_check_uptodate(result, ancestor_head, their_heads[0]) ||
-		merge_check_fastforward(result, ancestor_head, our_head, their_heads[0], opts.merge_flags))) {
-		*out = result;
-		goto done;
+	assert(repo && their_heads);
+
+	if (their_heads_len != 1) {
+		giterr_set(GITERR_MERGE, "Can only merge a single branch");
+		return -1;
 	}
 
-	/* If FASTFORWARD_ONLY is specified, fail. */
-	if ((opts.merge_flags & GIT_MERGE_FASTFORWARD_ONLY) ==
-		GIT_MERGE_FASTFORWARD_ONLY) {
-		giterr_set(GITERR_MERGE, "Not a fast-forward.");
-		error = GIT_ENONFASTFORWARD;
+	their_trees = git__calloc(their_heads_len, sizeof(git_tree *));
+	GITERR_CHECK_ALLOC(their_trees);
+
+	if ((error = merge_heads(&ancestor_head, &our_head, repo, their_heads, their_heads_len)) < 0)
+		goto on_error;
+
+	if ((error = merge_normalize_checkout_opts(repo, &checkout_opts, given_checkout_opts,
+		ancestor_head, our_head, their_heads_len, their_heads)) < 0)
 		goto on_error;
-	}
 
 	/* Write the merge files to the repository. */
-	if ((error = git_merge__setup(repo, our_head, their_heads, their_heads_len, opts.merge_flags)) < 0)
+	if ((error = git_merge__setup(repo, our_head, their_heads, their_heads_len)) < 0)
 		goto on_error;
 
 	if (ancestor_head != NULL &&
@@ -2581,22 +2618,18 @@ int git_merge(
 
 	/* TODO: recursive, octopus, etc... */
 
-	if ((error = git_merge_trees(&index_new, repo, ancestor_tree, our_tree, their_trees[0], &opts.merge_tree_opts)) < 0 ||
+	if ((error = git_merge_trees(&index_new, repo, ancestor_tree, our_tree, their_trees[0], merge_opts)) < 0 ||
 		(error = git_merge__indexes(repo, index_new)) < 0 ||
 		(error = git_repository_index(&index_repo, repo)) < 0 ||
-		(error = git_checkout_index(repo, index_repo, &opts.checkout_opts)) < 0)
+		(error = git_checkout_index(repo, index_repo, &checkout_opts)) < 0)
 		goto on_error;
 
-	result->index = index_new;
-
-	*out = result;
 	goto done;
 
 on_error:
 	merge_state_cleanup(repo);
 
 	git_index_free(index_new);
-	git__free(result);
 
 done:
 	git_index_free(index_repo);
@@ -2617,61 +2650,6 @@ done:
 	return error;
 }
 
-int git_merge__setup(
-	git_repository *repo,
-	const git_merge_head *our_head,
-	const git_merge_head *heads[],
-	size_t heads_len,
-	unsigned int flags)
-{
-	int error = 0;
-
-	assert (repo && our_head && heads);
-
-	if ((error = write_orig_head(repo, our_head)) == 0 &&
-		(error = write_merge_head(repo, heads, heads_len)) == 0 &&
-		(error = write_merge_mode(repo, flags)) == 0) {
-		error = write_merge_msg(repo, heads, heads_len);
-	}
-
-	return error;
-}
-
-/* Merge result data */
-
-int git_merge_result_is_uptodate(git_merge_result *merge_result)
-{
-	assert(merge_result);
-
-	return merge_result->is_uptodate;
-}
-
-int git_merge_result_is_fastforward(git_merge_result *merge_result)
-{
-	assert(merge_result);
-
-	return merge_result->is_fastforward;
-}
-
-int git_merge_result_fastforward_id(git_oid *out, git_merge_result *merge_result)
-{
-	assert(out && merge_result);
-
-	git_oid_cpy(out, &merge_result->fastforward_oid);
-	return 0;
-}
-
-void git_merge_result_free(git_merge_result *merge_result)
-{
-	if (merge_result == NULL)
-		return;
-
-	git_index_free(merge_result->index);
-	merge_result->index = NULL;
-
-	git__free(merge_result);
-}
-
 /* Merge heads are the input to merge */
 
 static int merge_head_init(
@@ -2776,25 +2754,37 @@ void git_merge_head_free(git_merge_head *head)
 	git__free(head);
 }
 
-int git_merge_init_opts(git_merge_opts* opts, int version)
+int git_merge_init_options(git_merge_options *opts, int version)
 {
-	if (version != GIT_MERGE_OPTS_VERSION) {
-		giterr_set(GITERR_INVALID, "Invalid version %d for git_merge_opts", version);
+	if (version != GIT_MERGE_OPTIONS_VERSION) {
+		giterr_set(GITERR_INVALID, "Invalid version %d for git_merge_options", version);
 		return -1;
 	} else {
-		git_merge_opts o = GIT_MERGE_OPTS_INIT;
-		memcpy(opts, &o, sizeof(o));
+		git_merge_options default_opts = GIT_MERGE_OPTIONS_INIT;
+		memcpy(opts, &default_opts, sizeof(git_merge_options));
+		return 0;
+	}
+}
+
+int git_merge_file_init_input(git_merge_file_input *input, int version)
+{
+	if (version != GIT_MERGE_FILE_INPUT_VERSION) {
+		giterr_set(GITERR_INVALID, "Invalid version %d for git_merge_file_input", version);
+		return -1;
+	} else {
+		git_merge_file_input i = GIT_MERGE_FILE_INPUT_INIT;
+		memcpy(input, &i, sizeof(i));
 		return 0;
 	}
 }
 
-int git_merge_tree_init_opts(git_merge_tree_opts* opts, int version)
+int git_merge_file_init_options(git_merge_file_options *opts, int version)
 {
-	if (version != GIT_MERGE_TREE_OPTS_VERSION) {
-		giterr_set(GITERR_INVALID, "Invalid version %d for git_merge_tree_opts", version);
+	if (version != GIT_MERGE_FILE_OPTIONS_VERSION) {
+		giterr_set(GITERR_INVALID, "Invalid version %d for git_merge_file_options", version);
 		return -1;
 	} else {
-		git_merge_tree_opts o = GIT_MERGE_TREE_OPTS_INIT;
+		git_merge_file_options o = GIT_MERGE_FILE_OPTIONS_INIT;
 		memcpy(opts, &o, sizeof(o));
 		return 0;
 	}
diff --git a/src/merge.h b/src/merge.h
index dda023528..2362da04d 100644
--- a/src/merge.h
+++ b/src/merge.h
@@ -120,16 +120,6 @@ struct git_merge_head {
 	git_commit *commit;
 };
 
-/** Internal structure for merge results */
-struct git_merge_result {
-	bool is_uptodate;
-
-	bool is_fastforward;
-	git_oid fastforward_oid;
-
-	git_index *index;
-};
-
 int git_merge__bases_many(
 	git_commit_list **out,
 	git_revwalk *walk,
@@ -147,7 +137,7 @@ int git_merge_diff_list__find_differences(git_merge_diff_list *merge_diff_list,
 	const git_tree *ours_tree,
 	const git_tree *theirs_tree);
 
-int git_merge_diff_list__find_renames(git_repository *repo, git_merge_diff_list *merge_diff_list, const git_merge_tree_opts *opts);
+int git_merge_diff_list__find_renames(git_repository *repo, git_merge_diff_list *merge_diff_list, const git_merge_options *opts);
 
 void git_merge_diff_list__free(git_merge_diff_list *diff_list);
 
@@ -156,9 +146,8 @@ void git_merge_diff_list__free(git_merge_diff_list *diff_list);
 int git_merge__setup(
 	git_repository *repo,
 	const git_merge_head *our_head,
-	const git_merge_head *their_heads[],
-	size_t their_heads_len,
-	unsigned int flags);
+	const git_merge_head *heads[],
+	size_t heads_len);
 
 int git_merge__indexes(git_repository *repo, git_index *index_new);
 
diff --git a/src/merge_file.c b/src/merge_file.c
index 986fbf9fe..fc45cbfbf 100644
--- a/src/merge_file.c
+++ b/src/merge_file.c
@@ -8,6 +8,9 @@
 #include "common.h"
 #include "repository.h"
 #include "merge_file.h"
+#include "posix.h"
+#include "fileops.h"
+#include "index.h"
 
 #include "git2/repository.h"
 #include "git2/object.h"
@@ -22,17 +25,17 @@ GIT_INLINE(const char *) merge_file_best_path(
 	const git_merge_file_input *ours,
 	const git_merge_file_input *theirs)
 {
-	if (!GIT_MERGE_FILE_SIDE_EXISTS(ancestor)) {
-		if (strcmp(ours->path, theirs->path) == 0)
+	if (!ancestor) {
+		if (ours && theirs && strcmp(ours->path, theirs->path) == 0)
 			return ours->path;
 
 		return NULL;
 	}
 
-	if (strcmp(ancestor->path, ours->path) == 0)
-		return theirs->path;
-	else if(strcmp(ancestor->path, theirs->path) == 0)
-		return ours->path;
+	if (ours && strcmp(ancestor->path, ours->path) == 0)
+		return theirs ? theirs->path : NULL;
+	else if(theirs && strcmp(ancestor->path, theirs->path) == 0)
+		return ours ? ours->path : NULL;
 
 	return NULL;
 }
@@ -47,136 +50,230 @@ GIT_INLINE(int) merge_file_best_mode(
 	 * assume executable.  Otherwise, if any mode changed from the ancestor,
 	 * use that one.
 	 */
-	if (!GIT_MERGE_FILE_SIDE_EXISTS(ancestor)) {
-		if (ours->mode == GIT_FILEMODE_BLOB_EXECUTABLE ||
-			theirs->mode == GIT_FILEMODE_BLOB_EXECUTABLE)
+	if (!ancestor) {
+		if ((ours && ours->mode == GIT_FILEMODE_BLOB_EXECUTABLE) ||
+			(theirs && theirs->mode == GIT_FILEMODE_BLOB_EXECUTABLE))
 			return GIT_FILEMODE_BLOB_EXECUTABLE;
 
 		return GIT_FILEMODE_BLOB;
-	}
+	} else if (ours && theirs) {
+		if (ancestor->mode == ours->mode)
+			return theirs->mode;
 
-	if (ancestor->mode == ours->mode)
-		return theirs->mode;
-	else if(ancestor->mode == theirs->mode)
 		return ours->mode;
+	}
 
 	return 0;
 }
 
-int git_merge_file_input_from_index_entry(
-	git_merge_file_input *input,
-	git_repository *repo,
+int git_merge_file__input_from_index(
+	git_merge_file_input *input_out,
+	git_odb_object **odb_object_out,
+	git_odb *odb,
 	const git_index_entry *entry)
 {
-	git_odb *odb = NULL;
 	int error = 0;
 
-	assert(input && repo && entry);
-
-	if (entry->mode == 0)
-		return 0;
+	assert(input_out && odb_object_out && odb && entry);
 
-	if ((error = git_repository_odb(&odb, repo)) < 0 ||
-		(error = git_odb_read(&input->odb_object, odb, &entry->id)) < 0)
+	if ((error = git_odb_read(odb_object_out, odb, &entry->id)) < 0)
 		goto done;
 
-	input->mode = entry->mode;
-	input->path = git__strdup(entry->path);
-	input->mmfile.size = git_odb_object_size(input->odb_object);
-	input->mmfile.ptr = (char *)git_odb_object_data(input->odb_object);
-
-	if (input->label == NULL)
-		input->label = entry->path;
+	input_out->path = entry->path;
+	input_out->mode = entry->mode;
+	input_out->ptr = (char *)git_odb_object_data(*odb_object_out);
+	input_out->size = git_odb_object_size(*odb_object_out);
 
 done:
-	git_odb_free(odb);
-
 	return error;
 }
 
-int git_merge_file_input_from_diff_file(
-	git_merge_file_input *input,
-	git_repository *repo,
-	const git_diff_file *file)
+static void merge_file_normalize_opts(
+	git_merge_file_options *out,
+	const git_merge_file_options *given_opts)
 {
-	git_odb *odb = NULL;
-	int error = 0;
-
-	assert(input && repo && file);
-
-	if (file->mode == 0)
-		return 0;
-
-	if ((error = git_repository_odb(&odb, repo)) < 0 ||
-		(error = git_odb_read(&input->odb_object, odb, &file->id)) < 0)
-		goto done;
-
-	input->mode = file->mode;
-	input->path = git__strdup(file->path);
-	input->mmfile.size = git_odb_object_size(input->odb_object);
-	input->mmfile.ptr = (char *)git_odb_object_data(input->odb_object);
-
-	if (input->label == NULL)
-		input->label = file->path;
-
-done:
-	git_odb_free(odb);
-
-	return error;
+	if (given_opts)
+		memcpy(out, given_opts, sizeof(git_merge_file_options));
+	else {
+		git_merge_file_options default_opts = GIT_MERGE_FILE_OPTIONS_INIT;
+		memcpy(out, &default_opts, sizeof(git_merge_file_options));
+	}
 }
 
-int git_merge_files(
+static int git_merge_file__from_inputs(
 	git_merge_file_result *out,
-	git_merge_file_input *ancestor,
-	git_merge_file_input *ours,
-	git_merge_file_input *theirs,
-	git_merge_file_options *opts)
+	const git_merge_file_input *ancestor,
+	const git_merge_file_input *ours,
+	const git_merge_file_input *theirs,
+	const git_merge_file_options *given_opts)
 {
 	xmparam_t xmparam;
+	mmfile_t ancestor_mmfile = {0}, our_mmfile = {0}, their_mmfile = {0};
 	mmbuffer_t mmbuffer;
+	git_merge_file_options options = GIT_MERGE_FILE_OPTIONS_INIT;
+	const char *path;
 	int xdl_result;
 	int error = 0;
 
-	assert(out && ancestor && ours && theirs);
-
 	memset(out, 0x0, sizeof(git_merge_file_result));
 
-	if (!GIT_MERGE_FILE_SIDE_EXISTS(ours) || !GIT_MERGE_FILE_SIDE_EXISTS(theirs))
-		return 0;
+	merge_file_normalize_opts(&options, given_opts);		
 
 	memset(&xmparam, 0x0, sizeof(xmparam_t));
-	xmparam.ancestor = ancestor->label;
-	xmparam.file1 = ours->label;
-	xmparam.file2 = theirs->label;
 
-	out->path = merge_file_best_path(ancestor, ours, theirs);
-	out->mode = merge_file_best_mode(ancestor, ours, theirs);
+	if (ancestor) {
+		xmparam.ancestor = (options.ancestor_label) ?
+			options.ancestor_label : ancestor->path;
+		ancestor_mmfile.ptr = (char *)ancestor->ptr;
+		ancestor_mmfile.size = ancestor->size;
+	}
 
-	if (opts && opts->favor == GIT_MERGE_FILE_FAVOR_OURS)
+	xmparam.file1 = (options.our_label) ?
+		options.our_label : ours->path;
+	our_mmfile.ptr = (char *)ours->ptr;
+	our_mmfile.size = ours->size;
+
+	xmparam.file2 = (options.their_label) ?
+		options.their_label : theirs->path;
+	their_mmfile.ptr = (char *)theirs->ptr;
+	their_mmfile.size = theirs->size;
+
+	if (options.favor == GIT_MERGE_FILE_FAVOR_OURS)
 		xmparam.favor = XDL_MERGE_FAVOR_OURS;
-	else if (opts && opts->favor == GIT_MERGE_FILE_FAVOR_THEIRS)
+	else if (options.favor == GIT_MERGE_FILE_FAVOR_THEIRS)
 		xmparam.favor = XDL_MERGE_FAVOR_THEIRS;
-	else if (opts && opts->favor == GIT_MERGE_FILE_FAVOR_UNION)
+	else if (options.favor == GIT_MERGE_FILE_FAVOR_UNION)
 		xmparam.favor = XDL_MERGE_FAVOR_UNION;
 
-	xmparam.level = 
-		(opts && (opts->flags & GIT_MERGE_FILE_SIMPLIFY_ALNUM)) ?
+	xmparam.level = (options.flags & GIT_MERGE_FILE_SIMPLIFY_ALNUM) ?
 		XDL_MERGE_ZEALOUS_ALNUM : XDL_MERGE_ZEALOUS;
 
-	if (opts && opts->style == GIT_MERGE_FILE_STYLE_DIFF3)
+	if (options.flags & GIT_MERGE_FILE_STYLE_DIFF3)
 		xmparam.style = XDL_MERGE_DIFF3;
 
-	if ((xdl_result = xdl_merge(&ancestor->mmfile, &ours->mmfile,
-		&theirs->mmfile, &xmparam, &mmbuffer)) < 0) {
+	if ((xdl_result = xdl_merge(&ancestor_mmfile, &our_mmfile,
+		&their_mmfile, &xmparam, &mmbuffer)) < 0) {
 		giterr_set(GITERR_MERGE, "Failed to merge files.");
 		error = -1;
 		goto done;
 	}
 
+	if ((path = merge_file_best_path(ancestor, ours, theirs)) != NULL &&
+		(out->path = strdup(path)) == NULL) {
+		error = -1;
+		goto done;
+	}
+
 	out->automergeable = (xdl_result == 0);
-	out->data = (unsigned char *)mmbuffer.ptr;
+	out->ptr = (unsigned char *)mmbuffer.ptr;
 	out->len = mmbuffer.size;
+	out->mode = merge_file_best_mode(ancestor, ours, theirs);
 
 done:
+	if (error < 0)
+		git_merge_file_result_free(out);
+
 	return error;
 }
+
+static git_merge_file_input *git_merge_file__normalize_inputs(
+	git_merge_file_input *out,
+	const git_merge_file_input *given)
+{
+	memcpy(out, given, sizeof(git_merge_file_input));
+
+	if (!out->path)
+		out->path = "file.txt";
+
+	if (!out->mode)
+		out->mode = 0100644;
+
+	return out;
+}
+
+int git_merge_file(
+	git_merge_file_result *out,
+	const git_merge_file_input *ancestor,
+	const git_merge_file_input *ours,
+	const git_merge_file_input *theirs,
+	const git_merge_file_options *options)
+{
+	git_merge_file_input inputs[3] = { {0} };
+
+	assert(out && ours && theirs);
+
+	memset(out, 0x0, sizeof(git_merge_file_result));
+
+	if (ancestor)
+		ancestor = git_merge_file__normalize_inputs(&inputs[0], ancestor);
+
+	ours = git_merge_file__normalize_inputs(&inputs[1], ours);
+	theirs = git_merge_file__normalize_inputs(&inputs[2], theirs);
+
+	return git_merge_file__from_inputs(out, ancestor, ours, theirs, options);
+}
+
+int git_merge_file_from_index(
+	git_merge_file_result *out,
+	git_repository *repo,
+	const git_index_entry *ancestor,
+	const git_index_entry *ours,
+	const git_index_entry *theirs,
+	const git_merge_file_options *options)
+{
+	git_merge_file_input inputs[3] = { {0} },
+		*ancestor_input = NULL, *our_input = NULL, *their_input = NULL;
+	git_odb *odb = NULL;
+	git_odb_object *odb_object[3] = { 0 };
+	int error = 0;
+
+	assert(out && repo && ours && theirs);
+
+	memset(out, 0x0, sizeof(git_merge_file_result));
+
+	if ((error = git_repository_odb(&odb, repo)) < 0)
+		goto done;
+
+	if (ancestor) {
+		if ((error = git_merge_file__input_from_index(
+			&inputs[0], &odb_object[0], odb, ancestor)) < 0)
+			goto done;
+
+		ancestor_input = &inputs[0];
+	}
+
+	if ((error = git_merge_file__input_from_index(
+		&inputs[1], &odb_object[1], odb, ours)) < 0)
+		goto done;
+
+	our_input = &inputs[1];
+
+	if ((error = git_merge_file__input_from_index(
+		&inputs[2], &odb_object[2], odb, theirs)) < 0)
+		goto done;
+
+	their_input = &inputs[2];
+
+	if ((error = git_merge_file__from_inputs(out,
+		ancestor_input, our_input, their_input, options)) < 0)
+		goto done;
+
+done:
+	git_odb_object_free(odb_object[0]);
+	git_odb_object_free(odb_object[1]);
+	git_odb_object_free(odb_object[2]);
+	git_odb_free(odb);
+
+	return error;
+}
+
+void git_merge_file_result_free(git_merge_file_result *result)
+{
+	if (result == NULL)
+		return;
+
+	git__free(result->path);
+
+	/* xdiff uses malloc() not git_malloc, so we use free(), not git_free() */
+	free(result->ptr);
+}
diff --git a/src/merge_file.h b/src/merge_file.h
index 332be490b..263391ee3 100644
--- a/src/merge_file.h
+++ b/src/merge_file.h
@@ -11,82 +11,4 @@
 
 #include "git2/merge.h"
 
-typedef struct {
-	const char *label;
-	char *path;
-	unsigned int mode;
-	mmfile_t mmfile;
-
-	git_odb_object *odb_object;
-} git_merge_file_input;
-
-#define GIT_MERGE_FILE_INPUT_INIT	{0}
-
-typedef struct {
-	bool automergeable;
-
-	const char *path;
-	int mode;
-
-	unsigned char *data;
-	size_t len;
-} git_merge_file_result;
-
-#define GIT_MERGE_FILE_RESULT_INIT	{0}
-
-typedef enum {
-	/* Condense non-alphanumeric regions for simplified diff file */
-	GIT_MERGE_FILE_SIMPLIFY_ALNUM = (1 << 0),
-} git_merge_file_flags_t;
-
-typedef enum {
-	/* Create standard conflicted merge files */
-	GIT_MERGE_FILE_STYLE_MERGE = 0,
-
-	/* Create diff3-style files */
-	GIT_MERGE_FILE_STYLE_DIFF3 = 1,
-} git_merge_file_style_t;
-
-typedef struct {
-	git_merge_file_favor_t favor;
-	git_merge_file_flags_t flags;
-	git_merge_file_style_t style;
-} git_merge_file_options;
-
-#define GIT_MERGE_FILE_OPTIONS_INIT	{0}
-
-int git_merge_file_input_from_index_entry(
-	git_merge_file_input *input,
-	git_repository *repo,
-	const git_index_entry *entry);
-
-int git_merge_file_input_from_diff_file(
-	git_merge_file_input *input,
-	git_repository *repo,
-	const git_diff_file *file);
-
-int git_merge_files(
-	git_merge_file_result *out,
-	git_merge_file_input *ancestor,
-	git_merge_file_input *ours,
-	git_merge_file_input *theirs,
-	git_merge_file_options *opts);
-
-GIT_INLINE(void) git_merge_file_input_free(git_merge_file_input *input)
-{
-	assert(input);
-	git__free(input->path);
-	git_odb_object_free(input->odb_object);
-}
-
-GIT_INLINE(void) git_merge_file_result_free(git_merge_file_result *filediff)
-{
-	if (filediff == NULL)
-		return;
-
-	/* xdiff uses malloc() not git_malloc, so we use free(), not git_free() */
-	if (filediff->data != NULL)
-		free(filediff->data);
-}
-
 #endif
diff --git a/src/revert.c b/src/revert.c
index 8e84463db..4039ec34c 100644
--- a/src/revert.c
+++ b/src/revert.c
@@ -121,7 +121,7 @@ int git_revert_commit(
 	git_commit *revert_commit,
 	git_commit *our_commit,
 	unsigned int mainline,
-	const git_merge_tree_opts *merge_tree_opts)
+	const git_merge_options *merge_opts)
 {
 	git_commit *parent_commit = NULL;
 	git_tree *parent_tree = NULL, *our_tree = NULL, *revert_tree = NULL;
@@ -152,7 +152,7 @@ int git_revert_commit(
 		(error = git_commit_tree(&our_tree, our_commit)) < 0)
 		goto done;
 
-	error = git_merge_trees(out, repo, revert_tree, our_tree, parent_tree, merge_tree_opts);
+	error = git_merge_trees(out, repo, revert_tree, our_tree, parent_tree, merge_opts);
 
 done:
 	git_tree_free(parent_tree);
@@ -198,7 +198,7 @@ int git_revert(
 		(error = write_merge_msg(repo, commit_oidstr, commit_msg)) < 0 ||
 		(error = git_repository_head(&our_ref, repo)) < 0 ||
 		(error = git_reference_peel((git_object **)&our_commit, our_ref, GIT_OBJ_COMMIT)) < 0 ||
-		(error = git_revert_commit(&index_new, repo, commit, our_commit, opts.mainline, &opts.merge_tree_opts)) < 0 ||
+		(error = git_revert_commit(&index_new, repo, commit, our_commit, opts.mainline, &opts.merge_opts)) < 0 ||
 		(error = git_merge__indexes(repo, index_new)) < 0 ||
 		(error = git_repository_index(&index_repo, repo)) < 0 ||
 		(error = git_checkout_index(repo, index_repo, &opts.checkout_opts)) < 0)
diff --git a/tests/merge/files.c b/tests/merge/files.c
new file mode 100644
index 000000000..c377471e2
--- /dev/null
+++ b/tests/merge/files.c
@@ -0,0 +1,175 @@
+#include "clar_libgit2.h"
+#include "git2/repository.h"
+#include "git2/merge.h"
+#include "buffer.h"
+#include "merge.h"
+#include "merge_helpers.h"
+#include "refs.h"
+#include "fileops.h"
+
+#define TEST_REPO_PATH "merge-resolve"
+#define TEST_INDEX_PATH TEST_REPO_PATH "/.git/index"
+
+static git_repository *repo;
+static git_index *repo_index;
+
+// Fixture setup and teardown
+void test_merge_files__initialize(void)
+{
+	git_config *cfg;
+
+	repo = cl_git_sandbox_init(TEST_REPO_PATH);
+	git_repository_index(&repo_index, repo);
+
+	/* Ensure that the user's merge.conflictstyle doesn't interfere */
+	cl_git_pass(git_repository_config(&cfg, repo));
+	cl_git_pass(git_config_set_string(cfg, "merge.conflictstyle", "merge"));
+	git_config_free(cfg);
+}
+
+void test_merge_files__cleanup(void)
+{
+	git_index_free(repo_index);
+	cl_git_sandbox_cleanup();
+}
+
+void test_merge_files__automerge_from_bufs(void)
+{
+	git_merge_file_input ancestor = GIT_MERGE_FILE_INPUT_INIT,
+		ours = GIT_MERGE_FILE_INPUT_INIT,
+		theirs = GIT_MERGE_FILE_INPUT_INIT;
+	git_merge_file_result result = {0};
+	const char *expected = "Zero\n1\n2\n3\n4\n5\n6\n7\n8\n9\nTen\n";
+
+	ancestor.ptr = "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n";
+	ancestor.size = strlen(ancestor.ptr);
+	ancestor.path = "testfile.txt";
+	ancestor.mode = 0100755;
+
+	ours.ptr = "Zero\n1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n";
+	ours.size = strlen(ours.ptr);
+	ours.path = "testfile.txt";
+	ours.mode = 0100755;
+
+	theirs.ptr = "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\nTen\n";
+	theirs.size = strlen(theirs.ptr);
+	theirs.path = "testfile.txt";
+	theirs.mode = 0100755;
+
+	cl_git_pass(git_merge_file(&result, &ancestor, &ours, &theirs, 0));
+
+	cl_assert_equal_i(1, result.automergeable);
+
+	cl_assert_equal_s("testfile.txt", result.path);
+	cl_assert_equal_i(0100755, result.mode);
+
+	cl_assert_equal_i(strlen(expected), result.len);
+	cl_assert_equal_strn(expected, result.ptr, result.len);
+
+	git_merge_file_result_free(&result);
+}
+
+void test_merge_files__automerge_use_best_path_and_mode(void)
+{
+	git_merge_file_input ancestor = GIT_MERGE_FILE_INPUT_INIT,
+		ours = GIT_MERGE_FILE_INPUT_INIT,
+		theirs = GIT_MERGE_FILE_INPUT_INIT;
+	git_merge_file_result result = {0};
+	const char *expected = "Zero\n1\n2\n3\n4\n5\n6\n7\n8\n9\nTen\n";
+
+	ancestor.ptr = "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n";
+	ancestor.size = strlen(ancestor.ptr);
+	ancestor.path = "testfile.txt";
+	ancestor.mode = 0100755;
+
+	ours.ptr = "Zero\n1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n";
+	ours.size = strlen(ours.ptr);
+	ours.path = "testfile.txt";
+	ours.mode = 0100644;
+
+	theirs.ptr = "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\nTen\n";
+	theirs.size = strlen(theirs.ptr);
+	theirs.path = "theirs.txt";
+	theirs.mode = 0100755;
+
+	cl_git_pass(git_merge_file(&result, &ancestor, &ours, &theirs, 0));
+
+	cl_assert_equal_i(1, result.automergeable);
+
+	cl_assert_equal_s("theirs.txt", result.path);
+	cl_assert_equal_i(0100644, result.mode);
+
+	cl_assert_equal_i(strlen(expected), result.len);
+	cl_assert_equal_strn(expected, result.ptr, result.len);
+
+	git_merge_file_result_free(&result);
+}
+
+void test_merge_files__conflict_from_bufs(void)
+{
+	git_merge_file_input ancestor = GIT_MERGE_FILE_INPUT_INIT,
+		ours = GIT_MERGE_FILE_INPUT_INIT,
+		theirs = GIT_MERGE_FILE_INPUT_INIT;
+	git_merge_file_result result = {0};
+
+	const char *expected = "<<<<<<< testfile.txt\nAloha!\nOurs.\n=======\nHi!\nTheirs.\n>>>>>>> theirs.txt\n";
+	size_t expected_len = strlen(expected);
+
+	ancestor.ptr = "Hello!\nAncestor!\n";
+	ancestor.size = strlen(ancestor.ptr);
+	ancestor.path = "testfile.txt";
+	ancestor.mode = 0100755;
+
+	ours.ptr =  "Aloha!\nOurs.\n";
+	ours.size = strlen(ours.ptr);
+	ours.path = "testfile.txt";
+	ours.mode = 0100644;
+
+	theirs.ptr = "Hi!\nTheirs.\n";
+	theirs.size = strlen(theirs.ptr);
+	theirs.path = "theirs.txt";
+	theirs.mode = 0100755;
+
+	cl_git_pass(git_merge_file(&result, &ancestor, &ours, &theirs, NULL));
+
+	cl_assert_equal_i(0, result.automergeable);
+
+	cl_assert_equal_s("theirs.txt", result.path);
+	cl_assert_equal_i(0100644, result.mode);
+
+	cl_assert_equal_i(expected_len, result.len);
+	cl_assert_equal_strn(expected, result.ptr, expected_len);
+
+	git_merge_file_result_free(&result);
+}
+
+void test_merge_files__automerge_from_index(void)
+{
+	git_merge_file_result result = {0};
+	git_index_entry ancestor, ours, theirs;
+
+	git_oid_fromstr(&ancestor.id, "6212c31dab5e482247d7977e4f0dd3601decf13b");
+	ancestor.path = "automergeable.txt";
+	ancestor.mode = 0100644;
+
+	git_oid_fromstr(&ours.id, "ee3fa1b8c00aff7fe02065fdb50864bb0d932ccf");
+	ours.path = "automergeable.txt";
+	ours.mode = 0100755;
+
+	git_oid_fromstr(&theirs.id, "058541fc37114bfc1dddf6bd6bffc7fae5c2e6fe");
+	theirs.path = "newname.txt";
+	theirs.mode = 0100644;
+
+	cl_git_pass(git_merge_file_from_index(&result, repo,
+		&ancestor, &ours, &theirs, 0));
+
+	cl_assert_equal_i(1, result.automergeable);
+
+	cl_assert_equal_s("newname.txt", result.path);
+	cl_assert_equal_i(0100755, result.mode);
+
+	cl_assert_equal_i(strlen(AUTOMERGEABLE_MERGED_FILE), result.len);
+	cl_assert_equal_strn(AUTOMERGEABLE_MERGED_FILE, result.ptr, result.len);
+
+	git_merge_file_result_free(&result);
+}
diff --git a/tests/merge/merge_helpers.c b/tests/merge/merge_helpers.c
index 14a30b288..154985f11 100644
--- a/tests/merge/merge_helpers.c
+++ b/tests/merge/merge_helpers.c
@@ -10,7 +10,7 @@
 int merge_trees_from_branches(
 	git_index **index, git_repository *repo,
 	const char *ours_name, const char *theirs_name,
-	git_merge_tree_opts *opts)
+	git_merge_options *opts)
 {
 	git_commit *our_commit, *their_commit, *ancestor_commit = NULL;
 	git_tree *our_tree, *their_tree, *ancestor_tree = NULL;
@@ -55,7 +55,7 @@ int merge_trees_from_branches(
 int merge_commits_from_branches(
 	git_index **index, git_repository *repo,
 	const char *ours_name, const char *theirs_name,
-	git_merge_tree_opts *opts)
+	git_merge_options *opts)
 {
 	git_commit *our_commit, *their_commit;
 	git_oid our_oid, their_oid;
@@ -79,7 +79,9 @@ int merge_commits_from_branches(
 	return 0;
 }
 
-int merge_branches(git_merge_result **result, git_repository *repo, const char *ours_branch, const char *theirs_branch, git_merge_opts *opts)
+int merge_branches(git_repository *repo,
+	const char *ours_branch, const char *theirs_branch,
+	git_merge_options *merge_opts, git_checkout_options *checkout_opts)
 {
 	git_reference *head_ref, *theirs_ref;
 	git_merge_head *theirs_head;
@@ -93,7 +95,7 @@ int merge_branches(git_merge_result **result, git_repository *repo, const char *
 	cl_git_pass(git_reference_lookup(&theirs_ref, repo, theirs_branch));
 	cl_git_pass(git_merge_head_from_ref(&theirs_head, repo, theirs_ref));
 
-	cl_git_pass(git_merge(result, repo, (const git_merge_head **)&theirs_head, 1, opts));
+	cl_git_pass(git_merge(repo, (const git_merge_head **)&theirs_head, 1, merge_opts, checkout_opts));
 
 	git_reference_free(head_ref);
 	git_reference_free(theirs_ref);
diff --git a/tests/merge/merge_helpers.h b/tests/merge/merge_helpers.h
index 3f53abc7c..fddf8fab1 100644
--- a/tests/merge/merge_helpers.h
+++ b/tests/merge/merge_helpers.h
@@ -4,6 +4,49 @@
 #include "merge.h"
 #include "git2/merge.h"
 
+#define AUTOMERGEABLE_MERGED_FILE \
+	"this file is changed in master\n" \
+	"this file is automergeable\n" \
+	"this file is automergeable\n" \
+	"this file is automergeable\n" \
+	"this file is automergeable\n" \
+	"this file is automergeable\n" \
+	"this file is automergeable\n" \
+	"this file is automergeable\n" \
+	"this file is changed in branch\n"
+
+#define AUTOMERGEABLE_MERGED_FILE_CRLF \
+	"this file is changed in master\r\n" \
+	"this file is automergeable\r\n" \
+	"this file is automergeable\r\n" \
+	"this file is automergeable\r\n" \
+	"this file is automergeable\r\n" \
+	"this file is automergeable\r\n" \
+	"this file is automergeable\r\n" \
+	"this file is automergeable\r\n" \
+	"this file is changed in branch\r\n"
+
+#define CONFLICTING_MERGE_FILE \
+	"<<<<<<< HEAD\n" \
+	"this file is changed in master and branch\n" \
+	"=======\n" \
+	"this file is changed in branch and master\n" \
+	">>>>>>> 7cb63eed597130ba4abb87b3e544b85021905520\n"
+
+#define CONFLICTING_DIFF3_FILE \
+	"<<<<<<< HEAD\n" \
+	"this file is changed in master and branch\n" \
+	"||||||| initial\n" \
+	"this file is a conflict\n" \
+	"=======\n" \
+	"this file is changed in branch and master\n" \
+	">>>>>>> 7cb63eed597130ba4abb87b3e544b85021905520\n"
+
+#define CONFLICTING_UNION_FILE \
+	"this file is changed in master and branch\n" \
+	"this file is changed in branch and master\n"
+
+
 struct merge_index_entry {
 	uint16_t mode;
 	char oid_str[41];
@@ -42,15 +85,16 @@ struct merge_index_conflict_data {
 int merge_trees_from_branches(
 	git_index **index, git_repository *repo,
 	const char *ours_name, const char *theirs_name,
-	git_merge_tree_opts *opts);
+	git_merge_options *opts);
 
 int merge_commits_from_branches(
 	git_index **index, git_repository *repo,
 	const char *ours_name, const char *theirs_name,
-	git_merge_tree_opts *opts);
+	git_merge_options *opts);
 
-int merge_branches(git_merge_result **result, git_repository *repo,
-	const char *ours_branch, const char *theirs_branch, git_merge_opts *opts);
+int merge_branches(git_repository *repo,
+	const char *ours_branch, const char *theirs_branch,
+	git_merge_options *merge_opts, git_checkout_options *checkout_opts);
 
 int merge_test_diff_list(git_merge_diff_list *diff_list, const struct merge_index_entry expected[], size_t expected_len);
 
diff --git a/tests/merge/trees/automerge.c b/tests/merge/trees/automerge.c
index bd710e6d8..c18881d7c 100644
--- a/tests/merge/trees/automerge.c
+++ b/tests/merge/trees/automerge.c
@@ -54,28 +54,6 @@ static git_repository *repo;
 	  "", \
 	  "5c3b68a71fc4fa5d362fd3875e53137c6a5ab7a5" }
 
-#define AUTOMERGEABLE_MERGED_FILE \
-	"this file is changed in master\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is changed in branch\n"
-
-#define AUTOMERGEABLE_MERGED_FILE_CRLF \
-	"this file is changed in master\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is changed in branch\r\n"
-
 // Fixture setup and teardown
 void test_merge_trees_automerge__initialize(void)
 {
@@ -91,7 +69,7 @@ void test_merge_trees_automerge__automerge(void)
 {
 	git_index *index;
 	const git_index_entry *entry;
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 	git_blob *blob;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -131,7 +109,7 @@ void test_merge_trees_automerge__automerge(void)
 void test_merge_trees_automerge__favor_ours(void)
 {
 	git_index *index;
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		ADDED_IN_MASTER_INDEX_ENTRY,
@@ -162,7 +140,7 @@ void test_merge_trees_automerge__favor_ours(void)
 void test_merge_trees_automerge__favor_theirs(void)
 {
 	git_index *index;
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		ADDED_IN_MASTER_INDEX_ENTRY,
@@ -193,7 +171,7 @@ void test_merge_trees_automerge__favor_theirs(void)
 void test_merge_trees_automerge__unrelated(void)
 {
 	git_index *index;
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "233c0919c998ed110a4b6ff36f353aec8b713487", 0, "added-in-master.txt" },
diff --git a/tests/merge/trees/commits.c b/tests/merge/trees/commits.c
index eeb30dae5..c4e470997 100644
--- a/tests/merge/trees/commits.c
+++ b/tests/merge/trees/commits.c
@@ -8,17 +8,6 @@ static git_repository *repo;
 
 #define TEST_REPO_PATH "merge-resolve"
 
-#define AUTOMERGEABLE_MERGED_FILE \
-	"this file is changed in master\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is changed in branch\n"
-
 void test_merge_trees_commits__initialize(void)
 {
 	repo = cl_git_sandbox_init(TEST_REPO_PATH);
@@ -33,7 +22,7 @@ void test_merge_trees_commits__automerge(void)
 {
 	git_index *index;
 	const git_index_entry *entry;
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 	git_blob *blob;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -82,7 +71,7 @@ void test_merge_trees_commits__automerge(void)
 void test_merge_trees_commits__no_ancestor(void)
 {
 	git_index *index;
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "233c0919c998ed110a4b6ff36f353aec8b713487", 0, "added-in-master.txt" },
@@ -109,7 +98,7 @@ void test_merge_trees_commits__no_ancestor(void)
 void test_merge_trees_commits__df_conflict(void)
 {
 	git_index *index;
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "49130a28ef567af9a6a6104c38773fedfa5f9742", 2, "dir-10" },
diff --git a/tests/merge/trees/renames.c b/tests/merge/trees/renames.c
index 427b6bd8f..d7721c894 100644
--- a/tests/merge/trees/renames.c
+++ b/tests/merge/trees/renames.c
@@ -27,7 +27,7 @@ void test_merge_trees_renames__cleanup(void)
 void test_merge_trees_renames__index(void)
 {
 	git_index *index;
-	git_merge_tree_opts *opts = NULL;
+	git_merge_options *opts = NULL;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "68c6c84b091926c7d90aa6a79b2bc3bb6adccd8e", 0, "0a-no-change.txt" },
@@ -205,7 +205,7 @@ void test_merge_trees_renames__index(void)
 void test_merge_trees_renames__no_rename_index(void)
 {
 	git_index *index;
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "68c6c84b091926c7d90aa6a79b2bc3bb6adccd8e", 0, "0a-no-change.txt" },
diff --git a/tests/merge/trees/treediff.c b/tests/merge/trees/treediff.c
index 357859df3..2298a302b 100644
--- a/tests/merge/trees/treediff.c
+++ b/tests/merge/trees/treediff.c
@@ -44,7 +44,7 @@ static void test_find_differences(
     git_oid ancestor_oid, ours_oid, theirs_oid;
     git_tree *ancestor_tree, *ours_tree, *theirs_tree;
 
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 	opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
 	opts.target_limit = 1000;
 	opts.rename_threshold = 50;
diff --git a/tests/merge/trees/trivial.c b/tests/merge/trees/trivial.c
index 377b24742..62a4574b8 100644
--- a/tests/merge/trees/trivial.c
+++ b/tests/merge/trees/trivial.c
@@ -31,7 +31,7 @@ static int merge_trivial(git_index **index, const char *ours, const char *theirs
 	git_tree *our_tree, *their_tree, *ancestor_tree;
 	git_oid our_oid, their_oid, ancestor_oid;
 	git_buf branch_buf = GIT_BUF_INIT;
-	git_merge_tree_opts opts = GIT_MERGE_TREE_OPTS_INIT;
+	git_merge_options opts = GIT_MERGE_OPTIONS_INIT;
 
 	git_buf_printf(&branch_buf, "%s%s", GIT_REFS_HEADS_DIR, ours);
 	cl_git_pass(git_reference_name_to_id(&our_oid, repo, branch_buf.ptr));
diff --git a/tests/merge/workdir/analysis.c b/tests/merge/workdir/analysis.c
new file mode 100644
index 000000000..0e937857f
--- /dev/null
+++ b/tests/merge/workdir/analysis.c
@@ -0,0 +1,107 @@
+#include "clar_libgit2.h"
+#include "git2/repository.h"
+#include "git2/merge.h"
+#include "git2/sys/index.h"
+#include "merge.h"
+#include "../merge_helpers.h"
+#include "refs.h"
+#include "posix.h"
+
+static git_repository *repo;
+static git_index *repo_index;
+
+#define TEST_REPO_PATH "merge-resolve"
+#define TEST_INDEX_PATH TEST_REPO_PATH "/.git/index"
+
+#define UPTODATE_BRANCH			"master"
+#define PREVIOUS_BRANCH			"previous"
+
+#define FASTFORWARD_BRANCH		"ff_branch"
+#define FASTFORWARD_ID			"fd89f8cffb663ac89095a0f9764902e93ceaca6a"
+
+#define NOFASTFORWARD_BRANCH	"branch"
+#define NOFASTFORWARD_ID		"7cb63eed597130ba4abb87b3e544b85021905520"
+
+
+// Fixture setup and teardown
+void test_merge_workdir_analysis__initialize(void)
+{
+	repo = cl_git_sandbox_init(TEST_REPO_PATH);
+	git_repository_index(&repo_index, repo);
+}
+
+void test_merge_workdir_analysis__cleanup(void)
+{
+	git_index_free(repo_index);
+	cl_git_sandbox_cleanup();
+}
+
+static git_merge_analysis_t analysis_from_branch(const char *branchname)
+{
+	git_buf refname = GIT_BUF_INIT;
+	git_reference *their_ref;
+	git_merge_head *their_head;
+	git_merge_analysis_t analysis;
+
+	git_buf_printf(&refname, "%s%s", GIT_REFS_HEADS_DIR, branchname);
+
+	cl_git_pass(git_reference_lookup(&their_ref, repo, git_buf_cstr(&refname)));
+	cl_git_pass(git_merge_head_from_ref(&their_head, repo, their_ref));
+
+	cl_git_pass(git_merge_analysis(&analysis, repo, (const git_merge_head **)&their_head, 1));
+
+	git_buf_free(&refname);
+	git_merge_head_free(their_head);
+	git_reference_free(their_ref);
+
+	return analysis;
+}
+
+void test_merge_workdir_analysis__fastforward(void)
+{
+	git_merge_analysis_t analysis;
+
+	analysis = analysis_from_branch(FASTFORWARD_BRANCH);
+	cl_assert_equal_i(GIT_MERGE_ANALYSIS_FASTFORWARD, (analysis & GIT_MERGE_ANALYSIS_FASTFORWARD));
+	cl_assert_equal_i(GIT_MERGE_ANALYSIS_NORMAL, (analysis & GIT_MERGE_ANALYSIS_NORMAL));
+}
+
+void test_merge_workdir_analysis__no_fastforward(void)
+{
+	git_merge_analysis_t analysis;
+
+	analysis = analysis_from_branch(NOFASTFORWARD_BRANCH);
+	cl_assert_equal_i(GIT_MERGE_ANALYSIS_NORMAL, analysis);
+}
+
+void test_merge_workdir_analysis__uptodate(void)
+{
+	git_merge_analysis_t analysis;
+
+	analysis = analysis_from_branch(UPTODATE_BRANCH);
+	cl_assert_equal_i(GIT_MERGE_ANALYSIS_UP_TO_DATE, analysis);
+}
+
+void test_merge_workdir_analysis__uptodate_merging_prev_commit(void)
+{
+	git_merge_analysis_t analysis;
+
+	analysis = analysis_from_branch(PREVIOUS_BRANCH);
+	cl_assert_equal_i(GIT_MERGE_ANALYSIS_UP_TO_DATE, analysis);
+}
+
+void test_merge_workdir_analysis__unborn(void)
+{
+	git_merge_analysis_t analysis;
+	git_buf master = GIT_BUF_INIT;
+
+	git_buf_joinpath(&master, git_repository_path(repo), "refs/heads/master");
+	p_unlink(git_buf_cstr(&master));
+
+	analysis = analysis_from_branch(NOFASTFORWARD_BRANCH);
+	cl_assert_equal_i(GIT_MERGE_ANALYSIS_FASTFORWARD, (analysis & GIT_MERGE_ANALYSIS_FASTFORWARD));
+	cl_assert_equal_i(GIT_MERGE_ANALYSIS_UNBORN, (analysis & GIT_MERGE_ANALYSIS_UNBORN));
+
+	git_buf_free(&master);
+}
+
diff --git a/tests/merge/workdir/dirty.c b/tests/merge/workdir/dirty.c
index a77f9b205..1d596c51a 100644
--- a/tests/merge/workdir/dirty.c
+++ b/tests/merge/workdir/dirty.c
@@ -86,19 +86,20 @@ static void set_core_autocrlf_to(git_repository *repo, bool value)
 	git_config_free(cfg);
 }
 
-static int merge_branch(git_merge_result **result, int merge_file_favor, int checkout_strategy)
+static int merge_branch(int merge_file_favor, int checkout_strategy)
 {
 	git_oid their_oids[1];
 	git_merge_head *their_heads[1];
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
+	git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
+	git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
 	int error;
 
 	cl_git_pass(git_oid_fromstr(&their_oids[0], MERGE_BRANCH_OID));
 	cl_git_pass(git_merge_head_from_id(&their_heads[0], repo, &their_oids[0]));
 
-	opts.merge_tree_opts.file_favor = merge_file_favor;
-	opts.checkout_opts.checkout_strategy = checkout_strategy;
-	error = git_merge(result, repo, (const git_merge_head **)their_heads, 1, &opts);
+	merge_opts.file_favor = merge_file_favor;
+	checkout_opts.checkout_strategy = checkout_strategy;
+	error = git_merge(repo, (const git_merge_head **)their_heads, 1, &merge_opts, &checkout_opts);
 
 	git_merge_head_free(their_heads[0]);
 
@@ -176,7 +177,6 @@ static void stage_content(char *content[])
 {
 	git_reference *head;
 	git_object *head_object;
-	git_merge_result *result = NULL;
 	git_buf path = GIT_BUF_INIT;
 	char *filename, *text;
 	size_t i;
@@ -197,7 +197,6 @@ static void stage_content(char *content[])
 		cl_git_pass(git_index_add_bypath(repo_index, filename));
 	}
 
-	git_merge_result_free(result);
 	git_object_free(head_object);
 	git_reference_free(head);
 	git_buf_free(&path);
@@ -207,7 +206,6 @@ static int merge_dirty_files(char *dirty_files[])
 {
 	git_reference *head;
 	git_object *head_object;
-	git_merge_result *result = NULL;
 	int error;
 
 	cl_git_pass(git_repository_head(&head, repo));
@@ -216,9 +214,8 @@ static int merge_dirty_files(char *dirty_files[])
 
 	write_files(dirty_files);
 
-	error = merge_branch(&result, 0, 0);
+	error = merge_branch(0, 0);
 
-	git_merge_result_free(result);
 	git_object_free(head_object);
 	git_reference_free(head);
 
@@ -229,7 +226,6 @@ static int merge_differently_filtered_files(char *files[])
 {
 	git_reference *head;
 	git_object *head_object;
-	git_merge_result *result = NULL;
 	int error;
 
 	cl_git_pass(git_repository_head(&head, repo));
@@ -241,9 +237,8 @@ static int merge_differently_filtered_files(char *files[])
 
 	cl_git_pass(git_index_write(repo_index));
 
-	error = merge_branch(&result, 0, 0);
+	error = merge_branch(0, 0);
 
-	git_merge_result_free(result);
 	git_object_free(head_object);
 	git_reference_free(head);
 
@@ -251,17 +246,9 @@ static int merge_differently_filtered_files(char *files[])
 }
 
 static int merge_staged_files(char *staged_files[])
-{
-	git_merge_result *result = NULL;
-	int error;
-	
+{	
 	stage_random_files(staged_files);
-
-	error = merge_branch(&result, 0, 0);
-
-	git_merge_result_free(result);
-
-	return error;
+	return merge_branch(0, 0);
 }
 
 void test_merge_workdir_dirty__unaffected_dirty_files_allowed(void)
@@ -296,7 +283,6 @@ void test_merge_workdir_dirty__staged_files_in_index_disallowed(void)
 
 void test_merge_workdir_dirty__identical_staged_files_allowed(void)
 {
-	git_merge_result *result;
 	char **content;
 	size_t i;
 
@@ -306,9 +292,7 @@ void test_merge_workdir_dirty__identical_staged_files_allowed(void)
 		stage_content(content);
 
 		git_index_write(repo_index);
-		cl_git_pass(merge_branch(&result, 0, 0));
-
-		git_merge_result_free(result);
+		cl_git_pass(merge_branch(0, 0));
 	}
 }
 
diff --git a/tests/merge/workdir/fastforward.c b/tests/merge/workdir/fastforward.c
deleted file mode 100644
index d6b31481f..000000000
--- a/tests/merge/workdir/fastforward.c
+++ /dev/null
@@ -1,148 +0,0 @@
-#include "clar_libgit2.h"
-#include "git2/repository.h"
-#include "git2/merge.h"
-#include "git2/sys/index.h"
-#include "merge.h"
-#include "../merge_helpers.h"
-#include "refs.h"
-
-static git_repository *repo;
-static git_index *repo_index;
-
-#define TEST_REPO_PATH "merge-resolve"
-#define TEST_INDEX_PATH TEST_REPO_PATH "/.git/index"
-
-#define THEIRS_FASTFORWARD_BRANCH	"ff_branch"
-#define THEIRS_FASTFORWARD_ID		"fd89f8cffb663ac89095a0f9764902e93ceaca6a"
-
-#define THEIRS_NOFASTFORWARD_BRANCH	"branch"
-#define THEIRS_NOFASTFORWARD_ID	"7cb63eed597130ba4abb87b3e544b85021905520"
-
-
-// Fixture setup and teardown
-void test_merge_workdir_fastforward__initialize(void)
-{
-	repo = cl_git_sandbox_init(TEST_REPO_PATH);
-	git_repository_index(&repo_index, repo);
-}
-
-void test_merge_workdir_fastforward__cleanup(void)
-{
-	git_index_free(repo_index);
-	cl_git_sandbox_cleanup();
-}
-
-static git_merge_result *merge_fastforward_branch(int flags)
-{
-	git_reference *their_ref;
-	git_merge_head *their_heads[1];
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
-
-	opts.merge_flags = flags;
-
-	cl_git_pass(git_reference_lookup(&their_ref, repo, GIT_REFS_HEADS_DIR THEIRS_FASTFORWARD_BRANCH));
-	cl_git_pass(git_merge_head_from_ref(&their_heads[0], repo, their_ref));
-
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)their_heads, 1, &opts));
-
-	git_merge_head_free(their_heads[0]);
-	git_reference_free(their_ref);
-
-	return result;
-}
-
-void test_merge_workdir_fastforward__fastforward(void)
-{
-	git_merge_result *result;
-	git_oid expected, ff_oid;
-
-	cl_git_pass(git_oid_fromstr(&expected, THEIRS_FASTFORWARD_ID));
-
-	cl_assert(result = merge_fastforward_branch(0));
-	cl_assert(git_merge_result_is_fastforward(result));
-	cl_git_pass(git_merge_result_fastforward_id(&ff_oid, result));
-	cl_assert(git_oid_cmp(&ff_oid, &expected) == 0);
-
-	git_merge_result_free(result);
-}
-
-void test_merge_workdir_fastforward__fastforward_only(void)
-{
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
-	git_reference *their_ref;
-	git_merge_head *their_head;
-	int error;
-
-	opts.merge_flags = GIT_MERGE_FASTFORWARD_ONLY;
-
-	cl_git_pass(git_reference_lookup(&their_ref, repo, GIT_REFS_HEADS_DIR THEIRS_NOFASTFORWARD_BRANCH));
-	cl_git_pass(git_merge_head_from_ref(&their_head, repo, their_ref));
-
-	cl_git_fail((error = git_merge(&result, repo, (const git_merge_head **)&their_head, 1, &opts)));
-	cl_assert(error == GIT_ENONFASTFORWARD);
-
-	git_merge_head_free(their_head);
-	git_reference_free(their_ref);
-}
-
-void test_merge_workdir_fastforward__no_fastforward(void)
-{
-	git_merge_result *result;
-
-	struct merge_index_entry merge_index_entries[] = {
-		{ 0100644, "233c0919c998ed110a4b6ff36f353aec8b713487", 0, "added-in-master.txt" },
-		{ 0100644, "ee3fa1b8c00aff7fe02065fdb50864bb0d932ccf", 0, "automergeable.txt" },
-		{ 0100644, "ab6c44a2e84492ad4b41bb6bac87353e9d02ac8b", 0, "changed-in-branch.txt" },
-		{ 0100644, "bd9cb4cd0a770cb9adcb5fce212142ef40ea1c35", 0, "changed-in-master.txt" },
-		{ 0100644, "4e886e602529caa9ab11d71f86634bd1b6e0de10", 0, "conflicting.txt" },
-		{ 0100644, "364bbe4ce80c7bd31e6307dce77d46e3e1759fb3", 0, "new-in-ff.txt" },
-		{ 0100644, "dfe3f22baa1f6fce5447901c3086bae368de6bdd", 0, "removed-in-branch.txt" },
-		{ 0100644, "c8f06f2e3bb2964174677e91f0abead0e43c9e5d", 0, "unchanged.txt" },
-	};
-
-	cl_assert(result = merge_fastforward_branch(GIT_MERGE_NO_FASTFORWARD));
-	cl_assert(!git_merge_result_is_fastforward(result));
-
-	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
-	cl_assert(git_index_reuc_entrycount(repo_index) == 0);
-
-	git_merge_result_free(result);
-}
-
-void test_merge_workdir_fastforward__uptodate(void)
-{
-	git_reference *their_ref;
-	git_merge_head *their_heads[1];
-	git_merge_result *result;
-
-	cl_git_pass(git_reference_lookup(&their_ref, repo, GIT_HEAD_FILE));
-	cl_git_pass(git_merge_head_from_ref(&their_heads[0], repo, their_ref));
-
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)their_heads, 1, NULL));
-
-	cl_assert(git_merge_result_is_uptodate(result));
-
-	git_merge_head_free(their_heads[0]);
-	git_reference_free(their_ref);
-	git_merge_result_free(result);
-}
-
-void test_merge_workdir_fastforward__uptodate_merging_prev_commit(void)
-{
-	git_oid their_oid;
-	git_merge_head *their_heads[1];
-	git_merge_result *result;
-
-	cl_git_pass(git_oid_fromstr(&their_oid, "c607fc30883e335def28cd686b51f6cfa02b06ec"));
-	cl_git_pass(git_merge_head_from_id(&their_heads[0], repo, &their_oid));
-
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)their_heads, 1, NULL));
-
-	cl_assert(git_merge_result_is_uptodate(result));
-
-	git_merge_head_free(their_heads[0]);
-	git_merge_result_free(result);
-}
-
diff --git a/tests/merge/workdir/renames.c b/tests/merge/workdir/renames.c
index 27747720e..807a88f4c 100644
--- a/tests/merge/workdir/renames.c
+++ b/tests/merge/workdir/renames.c
@@ -34,8 +34,7 @@ void test_merge_workdir_renames__cleanup(void)
 
 void test_merge_workdir_renames__renames(void)
 {
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
+	git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "68c6c84b091926c7d90aa6a79b2bc3bb6adccd8e", 0, "0a-no-change.txt" },
@@ -64,20 +63,18 @@ void test_merge_workdir_renames__renames(void)
 		{ 0100644, "b69fe837e4cecfd4c9a40cdca7c138468687df07", 0, "7-both-renamed.txt~rename_conflict_theirs" },
 	};
 
-	opts.merge_tree_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
-	opts.merge_tree_opts.rename_threshold = 50;
+	merge_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
+	merge_opts.rename_threshold = 50;
 
-	cl_git_pass(merge_branches(&result, repo, GIT_REFS_HEADS_DIR BRANCH_RENAME_OURS, GIT_REFS_HEADS_DIR BRANCH_RENAME_THEIRS, &opts));
+	cl_git_pass(merge_branches(repo, GIT_REFS_HEADS_DIR BRANCH_RENAME_OURS, GIT_REFS_HEADS_DIR BRANCH_RENAME_THEIRS, &merge_opts, NULL));
 	cl_assert(merge_test_workdir(repo, merge_index_entries, 24));
-
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_renames__ours(void)
 {
 	git_index *index;
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
+	git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
+	git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "68c6c84b091926c7d90aa6a79b2bc3bb6adccd8e", 0, "0a-no-change.txt" },
@@ -102,23 +99,21 @@ void test_merge_workdir_renames__ours(void)
 		{ 0100644, "b42712cfe99a1a500b2a51fe984e0b8a7702ba11", 0, "7-both-renamed.txt" },
 	};
 
-	opts.merge_tree_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
-	opts.merge_tree_opts.rename_threshold = 50;
-	opts.checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE | GIT_CHECKOUT_USE_OURS;
+	merge_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
+	merge_opts.rename_threshold = 50;
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE | GIT_CHECKOUT_USE_OURS;
 
-	cl_git_pass(merge_branches(&result, repo, GIT_REFS_HEADS_DIR BRANCH_RENAME_OURS, GIT_REFS_HEADS_DIR BRANCH_RENAME_THEIRS, &opts));
+	cl_git_pass(merge_branches(repo, GIT_REFS_HEADS_DIR BRANCH_RENAME_OURS, GIT_REFS_HEADS_DIR BRANCH_RENAME_THEIRS, &merge_opts, &checkout_opts));
 	cl_git_pass(git_repository_index(&index, repo));
 	cl_git_pass(git_index_write(index));
 	cl_assert(merge_test_workdir(repo, merge_index_entries, 20));
 
-	git_merge_result_free(result);
 	git_index_free(index);
 }
 
 void test_merge_workdir_renames__similar(void)
 {
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
+	git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
 
 	/*
 	 * Note: this differs slightly from the core git merge result - there, 4a is
@@ -152,12 +147,10 @@ void test_merge_workdir_renames__similar(void)
 		{ 0100644, "b69fe837e4cecfd4c9a40cdca7c138468687df07", 0, "7-both-renamed.txt~rename_conflict_theirs" },
 	};
 
-	opts.merge_tree_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
-	opts.merge_tree_opts.rename_threshold = 50;
+	merge_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
+	merge_opts.rename_threshold = 50;
 
-	cl_git_pass(merge_branches(&result, repo, GIT_REFS_HEADS_DIR BRANCH_RENAME_OURS, GIT_REFS_HEADS_DIR BRANCH_RENAME_THEIRS, &opts));
+	cl_git_pass(merge_branches(repo, GIT_REFS_HEADS_DIR BRANCH_RENAME_OURS, GIT_REFS_HEADS_DIR BRANCH_RENAME_THEIRS, &merge_opts, NULL));
 	cl_assert(merge_test_workdir(repo, merge_index_entries, 24));
-
-	git_merge_result_free(result);
 }
 
diff --git a/tests/merge/workdir/setup.c b/tests/merge/workdir/setup.c
index 05f994ecd..49b38b246 100644
--- a/tests/merge/workdir/setup.c
+++ b/tests/merge/workdir/setup.c
@@ -71,7 +71,7 @@ static void write_file_contents(const char *filename, const char *output)
 	git_buf_free(&file_path_buf);
 }
 
-/* git merge octo1 */
+/* git merge --no-ff octo1 */
 void test_merge_workdir_setup__one_branch(void)
 {
 	git_oid our_oid;
@@ -84,33 +84,7 @@ void test_merge_workdir_setup__one_branch(void)
 	cl_git_pass(git_reference_lookup(&octo1_ref, repo, GIT_REFS_HEADS_DIR OCTO1_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[0], repo, octo1_ref));
 	
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 1, 0));
-
-	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n"));
-	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
-	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branch '" OCTO1_BRANCH "'\n"));
-
-	git_reference_free(octo1_ref);
-	
-	git_merge_head_free(our_head);
-	git_merge_head_free(their_heads[0]);
-}
-
-/* git merge --no-ff octo1 */
-void test_merge_workdir_setup__no_fastforward(void)
-{
-	git_oid our_oid;
-	git_reference *octo1_ref;
-	git_merge_head *our_head, *their_heads[1];
-
-	cl_git_pass(git_oid_fromstr(&our_oid, ORIG_HEAD));
-	cl_git_pass(git_merge_head_from_id(&our_head, repo, &our_oid));
-
-	cl_git_pass(git_reference_lookup(&octo1_ref, repo, GIT_REFS_HEADS_DIR OCTO1_BRANCH));
-	cl_git_pass(git_merge_head_from_ref(&their_heads[0], repo, octo1_ref));
-
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 1, GIT_MERGE_NO_FASTFORWARD));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 1));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
@@ -118,12 +92,12 @@ void test_merge_workdir_setup__no_fastforward(void)
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branch '" OCTO1_BRANCH "'\n"));
 
 	git_reference_free(octo1_ref);
-
+	
 	git_merge_head_free(our_head);
 	git_merge_head_free(their_heads[0]);
 }
 
-/* git merge  16f825815cfd20a07a75c71554e82d8eede0b061 */
+/* git merge --no-ff 16f825815cfd20a07a75c71554e82d8eede0b061 */
 void test_merge_workdir_setup__one_oid(void)
 {
 	git_oid our_oid;
@@ -136,11 +110,11 @@ void test_merge_workdir_setup__one_oid(void)
 	cl_git_pass(git_oid_fromstr(&octo1_oid, OCTO1_OID));
 	cl_git_pass(git_merge_head_from_id(&their_heads[0], repo, &octo1_oid));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 1, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 1));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge commit '" OCTO1_OID "'\n"));
 
 	git_merge_head_free(our_head);
@@ -164,11 +138,11 @@ void test_merge_workdir_setup__two_branches(void)
 	cl_git_pass(git_reference_lookup(&octo2_ref, repo, GIT_REFS_HEADS_DIR OCTO2_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[1], repo, octo2_ref));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2));
 	
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branches '" OCTO1_BRANCH "' and '" OCTO2_BRANCH "'\n"));
 	
 	git_reference_free(octo1_ref);
@@ -200,11 +174,11 @@ void test_merge_workdir_setup__three_branches(void)
 	cl_git_pass(git_reference_lookup(&octo3_ref, repo, GIT_REFS_HEADS_DIR OCTO3_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[2], repo, octo3_ref));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branches '" OCTO1_BRANCH "', '" OCTO2_BRANCH "' and '" OCTO3_BRANCH "'\n"));
 	
 	git_reference_free(octo1_ref);
@@ -238,11 +212,11 @@ void test_merge_workdir_setup__three_oids(void)
 	cl_git_pass(git_oid_fromstr(&octo3_oid, OCTO3_OID));
 	cl_git_pass(git_merge_head_from_id(&their_heads[2], repo, &octo3_oid));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge commit '" OCTO1_OID "'; commit '" OCTO2_OID "'; commit '" OCTO3_OID "'\n"));
 	
 	git_merge_head_free(our_head);
@@ -268,11 +242,11 @@ void test_merge_workdir_setup__branches_and_oids_1(void)
 	cl_git_pass(git_oid_fromstr(&octo2_oid, OCTO2_OID));
 	cl_git_pass(git_merge_head_from_id(&their_heads[1], repo, &octo2_oid));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branch '" OCTO1_BRANCH "'; commit '" OCTO2_OID "'\n"));
 	
 	git_reference_free(octo1_ref);
@@ -307,11 +281,11 @@ void test_merge_workdir_setup__branches_and_oids_2(void)
 	cl_git_pass(git_oid_fromstr(&octo4_oid, OCTO4_OID));
 	cl_git_pass(git_merge_head_from_id(&their_heads[3], repo, &octo4_oid));
 	
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 4, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 4));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n" OCTO4_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branches '" OCTO1_BRANCH "' and '" OCTO3_BRANCH "'; commit '" OCTO2_OID "'; commit '" OCTO4_OID "'\n"));
 	
 	git_reference_free(octo1_ref);
@@ -349,11 +323,11 @@ void test_merge_workdir_setup__branches_and_oids_3(void)
 	cl_git_pass(git_reference_lookup(&octo4_ref, repo, GIT_REFS_HEADS_DIR OCTO4_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[3], repo, octo4_ref));
 	
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 4, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 4));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n" OCTO4_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge commit '" OCTO1_OID "'; branches '" OCTO2_BRANCH "' and '" OCTO4_BRANCH "'; commit '" OCTO3_OID "'\n"));
 	
 	git_reference_free(octo2_ref);
@@ -395,11 +369,11 @@ void test_merge_workdir_setup__branches_and_oids_4(void)
 	cl_git_pass(git_reference_lookup(&octo5_ref, repo, GIT_REFS_HEADS_DIR OCTO5_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[4], repo, octo5_ref));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 5, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 5));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n" OCTO4_OID "\n" OCTO5_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge commit '" OCTO1_OID "'; branches '" OCTO2_BRANCH "', '" OCTO4_BRANCH "' and '" OCTO5_BRANCH "'; commit '" OCTO3_OID "'\n"));
 	
 	git_reference_free(octo2_ref);
@@ -435,11 +409,11 @@ void test_merge_workdir_setup__three_same_branches(void)
 	cl_git_pass(git_reference_lookup(&octo1_3_ref, repo, GIT_REFS_HEADS_DIR OCTO1_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[2], repo, octo1_3_ref));
 	
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO1_OID "\n" OCTO1_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branches '" OCTO1_BRANCH "', '" OCTO1_BRANCH "' and '" OCTO1_BRANCH "'\n"));
 	
 	git_reference_free(octo1_1_ref);
@@ -473,11 +447,11 @@ void test_merge_workdir_setup__three_same_oids(void)
 	cl_git_pass(git_oid_fromstr(&octo1_3_oid, OCTO1_OID));
 	cl_git_pass(git_merge_head_from_id(&their_heads[2], repo, &octo1_3_oid));
 	
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3));
 	
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO1_OID "\n" OCTO1_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge commit '" OCTO1_OID "'; commit '" OCTO1_OID "'; commit '" OCTO1_OID "'\n"));
 	
 	git_merge_head_free(our_head);
@@ -544,11 +518,11 @@ void test_merge_workdir_setup__remote_tracking_one_branch(void)
 	cl_git_pass(git_reference_lookup(&octo1_ref, repo, GIT_REFS_REMOTES_DIR "origin/" OCTO1_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[0], repo, octo1_ref));
 	
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 1, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 1));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge remote-tracking branch 'refs/remotes/origin/" OCTO1_BRANCH "'\n"));
 
 	git_reference_free(octo1_ref);
@@ -577,11 +551,11 @@ void test_merge_workdir_setup__remote_tracking_two_branches(void)
 	cl_git_pass(git_reference_lookup(&octo2_ref, repo, GIT_REFS_REMOTES_DIR "origin/" OCTO2_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[1], repo, octo2_ref));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2));
 	
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge remote-tracking branches 'refs/remotes/origin/" OCTO1_BRANCH "' and 'refs/remotes/origin/" OCTO2_BRANCH "'\n"));
 	
 	git_reference_free(octo1_ref);
@@ -617,11 +591,11 @@ void test_merge_workdir_setup__remote_tracking_three_branches(void)
 	cl_git_pass(git_reference_lookup(&octo3_ref, repo, GIT_REFS_REMOTES_DIR "origin/" OCTO3_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[2], repo, octo3_ref));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge remote-tracking branches 'refs/remotes/origin/" OCTO1_BRANCH "', 'refs/remotes/origin/" OCTO2_BRANCH "' and 'refs/remotes/origin/" OCTO3_BRANCH "'\n"));
 	
 	git_reference_free(octo1_ref);
@@ -653,11 +627,11 @@ void test_merge_workdir_setup__normal_branch_and_remote_tracking_branch(void)
 	cl_git_pass(git_reference_lookup(&octo2_ref, repo, GIT_REFS_REMOTES_DIR "origin/" OCTO2_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[1], repo, octo2_ref));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2));
 	
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branch '" OCTO1_BRANCH "', remote-tracking branch 'refs/remotes/origin/" OCTO2_BRANCH "'\n"));
 	
 	git_reference_free(octo1_ref);
@@ -687,11 +661,11 @@ void test_merge_workdir_setup__remote_tracking_branch_and_normal_branch(void)
 	cl_git_pass(git_reference_lookup(&octo2_ref, repo, GIT_REFS_HEADS_DIR OCTO2_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[1], repo, octo2_ref));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2));
 	
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branch '" OCTO2_BRANCH "', remote-tracking branch 'refs/remotes/origin/" OCTO1_BRANCH "'\n"));
 	
 	git_reference_free(octo1_ref);
@@ -730,11 +704,11 @@ void test_merge_workdir_setup__two_remote_tracking_branch_and_two_normal_branche
 	cl_git_pass(git_reference_lookup(&octo4_ref, repo, GIT_REFS_REMOTES_DIR "origin/" OCTO4_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[3], repo, octo4_ref));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 4, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 4));
 	
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n" OCTO4_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branches '" OCTO1_BRANCH "' and '" OCTO3_BRANCH "', remote-tracking branches 'refs/remotes/origin/" OCTO2_BRANCH "' and 'refs/remotes/origin/" OCTO4_BRANCH "'\n"));
 	
 	git_reference_free(octo1_ref);
@@ -762,11 +736,11 @@ void test_merge_workdir_setup__pull_one(void)
 	cl_git_pass(git_oid_fromstr(&octo1_1_oid, OCTO1_OID));
 	cl_git_pass(git_merge_head_from_fetchhead(&their_heads[0], repo, GIT_REFS_HEADS_DIR OCTO1_BRANCH, "http://remote.url/repo.git", &octo1_1_oid));
 	
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 1, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 1));
 	
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branch 'octo1' of http://remote.url/repo.git\n"));
 	
 	git_merge_head_free(our_head);
@@ -790,11 +764,11 @@ void test_merge_workdir_setup__pull_two(void)
 	cl_git_pass(git_oid_fromstr(&octo2_oid, OCTO2_OID));
 	cl_git_pass(git_merge_head_from_fetchhead(&their_heads[1], repo, GIT_REFS_HEADS_DIR OCTO2_BRANCH, "http://remote.url/repo.git", &octo2_oid));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 2));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branches '" OCTO1_BRANCH "' and '" OCTO2_BRANCH "' of http://remote.url/repo.git\n"));
 	
 	git_merge_head_free(our_head);
@@ -823,11 +797,11 @@ void test_merge_workdir_setup__pull_three(void)
 	cl_git_pass(git_oid_fromstr(&octo3_oid, OCTO3_OID));
 	cl_git_pass(git_merge_head_from_fetchhead(&their_heads[2], repo, GIT_REFS_HEADS_DIR OCTO3_BRANCH, "http://remote.url/repo.git", &octo3_oid));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branches '" OCTO1_BRANCH "', '" OCTO2_BRANCH "' and '" OCTO3_BRANCH "' of http://remote.url/repo.git\n"));
 	
 	git_merge_head_free(our_head);
@@ -856,11 +830,11 @@ void test_merge_workdir_setup__three_remotes(void)
 	cl_git_pass(git_oid_fromstr(&octo3_oid, OCTO3_OID));
 	cl_git_pass(git_merge_head_from_fetchhead(&their_heads[2], repo, GIT_REFS_HEADS_DIR OCTO3_BRANCH, "http://remote.third/repo.git", &octo3_oid));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 3));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branch '" OCTO1_BRANCH "' of http://remote.first/repo.git, branch '" OCTO2_BRANCH "' of http://remote.second/repo.git, branch '" OCTO3_BRANCH "' of http://remote.third/repo.git\n"));
 	
 	git_merge_head_free(our_head);
@@ -893,11 +867,11 @@ void test_merge_workdir_setup__two_remotes(void)
 	cl_git_pass(git_oid_fromstr(&octo4_oid, OCTO4_OID));
 	cl_git_pass(git_merge_head_from_fetchhead(&their_heads[3], repo, GIT_REFS_HEADS_DIR OCTO4_BRANCH, "http://remote.second/repo.git", &octo4_oid));
 
-	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 4, 0));
+	cl_git_pass(git_merge__setup(repo, our_head, (const git_merge_head **)their_heads, 4));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n" OCTO2_OID "\n" OCTO3_OID "\n" OCTO4_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
-	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, ""));
+	cl_assert(test_file_contents(GIT_MERGE_MODE_FILE, "no-ff"));
 	cl_assert(test_file_contents(GIT_MERGE_MSG_FILE, "Merge branches '" OCTO1_BRANCH "' and '" OCTO3_BRANCH "' of http://remote.first/repo.git, branches '" OCTO2_BRANCH "' and '" OCTO4_BRANCH "' of http://remote.second/repo.git\n"));
 	
 	git_merge_head_free(our_head);
@@ -996,10 +970,6 @@ void test_merge_workdir_setup__retained_after_success(void)
 	git_oid our_oid;
 	git_reference *octo1_ref;
 	git_merge_head *our_head, *their_heads[1];
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
-
-	opts.merge_flags |= GIT_MERGE_NO_FASTFORWARD;
 
 	cl_git_pass(git_oid_fromstr(&our_oid, ORIG_HEAD));
 	cl_git_pass(git_merge_head_from_id(&our_head, repo, &our_oid));
@@ -1008,7 +978,7 @@ void test_merge_workdir_setup__retained_after_success(void)
 
 	cl_git_pass(git_merge_head_from_ref(&their_heads[0], repo, octo1_ref));
 
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)&their_heads[0], 1, &opts));
+	cl_git_pass(git_merge(repo, (const git_merge_head **)&their_heads[0], 1, NULL, NULL));
 
 	cl_assert(test_file_contents(GIT_MERGE_HEAD_FILE, OCTO1_OID "\n"));
 	cl_assert(test_file_contents(GIT_ORIG_HEAD_FILE, ORIG_HEAD "\n"));
@@ -1019,7 +989,6 @@ void test_merge_workdir_setup__retained_after_success(void)
 
 	git_merge_head_free(our_head);
 	git_merge_head_free(their_heads[0]);
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_setup__removed_after_failure(void)
@@ -1027,10 +996,6 @@ void test_merge_workdir_setup__removed_after_failure(void)
 	git_oid our_oid;
 	git_reference *octo1_ref;
 	git_merge_head *our_head, *their_heads[1];
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
-
-	opts.merge_flags |= GIT_MERGE_NO_FASTFORWARD;
 
 	cl_git_pass(git_oid_fromstr(&our_oid, ORIG_HEAD));
 	cl_git_pass(git_merge_head_from_id(&our_head, repo, &our_oid));
@@ -1042,7 +1007,7 @@ void test_merge_workdir_setup__removed_after_failure(void)
 		"Conflicting file!\n\nMerge will fail!\n");
 
 	cl_git_fail(git_merge(
-		&result, repo, (const git_merge_head **)&their_heads[0], 1, &opts));
+		repo, (const git_merge_head **)&their_heads[0], 1, NULL, NULL));
 
 	cl_assert(!git_path_exists("merge-resolve/" GIT_MERGE_HEAD_FILE));
 	cl_assert(!git_path_exists("merge-resolve/" GIT_ORIG_HEAD_FILE));
@@ -1053,5 +1018,4 @@ void test_merge_workdir_setup__removed_after_failure(void)
 
 	git_merge_head_free(our_head);
 	git_merge_head_free(their_heads[0]);
-	git_merge_result_free(result);
 }
diff --git a/tests/merge/workdir/simple.c b/tests/merge/workdir/simple.c
index a9a63651c..032e97f8d 100644
--- a/tests/merge/workdir/simple.c
+++ b/tests/merge/workdir/simple.c
@@ -71,47 +71,6 @@ static git_index *repo_index;
 	  "", \
 	  "5c3b68a71fc4fa5d362fd3875e53137c6a5ab7a5" }
 
-#define AUTOMERGEABLE_MERGED_FILE \
-	"this file is changed in master\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is automergeable\n" \
-	"this file is changed in branch\n"
-
-#define AUTOMERGEABLE_MERGED_FILE_CRLF \
-	"this file is changed in master\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is automergeable\r\n" \
-	"this file is changed in branch\r\n"
-
-#define CONFLICTING_MERGE_FILE \
-	"<<<<<<< HEAD\n" \
-	"this file is changed in master and branch\n" \
-	"=======\n" \
-	"this file is changed in branch and master\n" \
-	">>>>>>> 7cb63eed597130ba4abb87b3e544b85021905520\n"
-
-#define CONFLICTING_DIFF3_FILE \
-	"<<<<<<< HEAD\n" \
-	"this file is changed in master and branch\n" \
-	"||||||| initial\n" \
-	"this file is a conflict\n" \
-	"=======\n" \
-	"this file is changed in branch and master\n" \
-	">>>>>>> 7cb63eed597130ba4abb87b3e544b85021905520\n"
-
-#define CONFLICTING_UNION_FILE \
-	"this file is changed in master and branch\n" \
-	"this file is changed in branch and master\n"
 
 // Fixture setup and teardown
 void test_merge_workdir_simple__initialize(void)
@@ -133,23 +92,21 @@ void test_merge_workdir_simple__cleanup(void)
 	cl_git_sandbox_cleanup();
 }
 
-static git_merge_result *merge_simple_branch(int merge_file_favor, int checkout_strategy)
+static void merge_simple_branch(int merge_file_favor, int checkout_strategy)
 {
 	git_oid their_oids[1];
 	git_merge_head *their_heads[1];
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
+	git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
+	git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
 
 	cl_git_pass(git_oid_fromstr(&their_oids[0], THEIRS_SIMPLE_OID));
 	cl_git_pass(git_merge_head_from_id(&their_heads[0], repo, &their_oids[0]));
 
-	opts.merge_tree_opts.file_favor = merge_file_favor;
-	opts.checkout_opts.checkout_strategy = checkout_strategy;
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)their_heads, 1, &opts));
+	merge_opts.file_favor = merge_file_favor;
+	checkout_opts.checkout_strategy = checkout_strategy;
+	cl_git_pass(git_merge(repo, (const git_merge_head **)their_heads, 1, &merge_opts, &checkout_opts));
 
 	git_merge_head_free(their_heads[0]);
-
-	return result;
 }
 
 static void set_core_autocrlf_to(git_repository *repo, bool value)
@@ -166,7 +123,6 @@ void test_merge_workdir_simple__automerge(void)
 {
 	git_index *index;
 	const git_index_entry *entry;
-	git_merge_result *result;
 	git_buf automergeable_buf = GIT_BUF_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -191,8 +147,7 @@ void test_merge_workdir_simple__automerge(void)
 
 	set_core_autocrlf_to(repo, false);
 
-	cl_assert(result = merge_simple_branch(0, 0));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(0, 0);
 
 	cl_git_pass(git_futils_readbuffer(&automergeable_buf,
 		TEST_REPO_PATH "/automergeable.txt"));
@@ -202,8 +157,6 @@ void test_merge_workdir_simple__automerge(void)
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
 
-	git_merge_result_free(result);
-
 	git_repository_index(&index, repo);
 
 	cl_assert((entry = git_index_get_bypath(index, "automergeable.txt", 0)) != NULL);
@@ -217,8 +170,6 @@ void test_merge_workdir_simple__automerge_crlf(void)
 #ifdef GIT_WIN32
 	git_index *index;
 	const git_index_entry *entry;
-
-	git_merge_result *result;
 	git_buf automergeable_buf = GIT_BUF_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -242,8 +193,7 @@ void test_merge_workdir_simple__automerge_crlf(void)
 
 	set_core_autocrlf_to(repo, true);
 
-	cl_assert(result = merge_simple_branch(0, 0));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(0, 0);
 
 	cl_git_pass(git_futils_readbuffer(&automergeable_buf,
 		TEST_REPO_PATH "/automergeable.txt"));
@@ -253,8 +203,6 @@ void test_merge_workdir_simple__automerge_crlf(void)
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
 
-	git_merge_result_free(result);
-
 	git_repository_index(&index, repo);
 
 	cl_assert((entry = git_index_get_bypath(index, "automergeable.txt", 0)) != NULL);
@@ -266,7 +214,6 @@ void test_merge_workdir_simple__automerge_crlf(void)
 
 void test_merge_workdir_simple__mergefile(void)
 {
-	git_merge_result *result;
 	git_buf conflicting_buf = GIT_BUF_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -288,8 +235,7 @@ void test_merge_workdir_simple__mergefile(void)
 		REMOVED_IN_MASTER_REUC_ENTRY
 	};
 
-	cl_assert(result = merge_simple_branch(0, 0));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(0, 0);
 
 	cl_git_pass(git_futils_readbuffer(&conflicting_buf,
 		TEST_REPO_PATH "/conflicting.txt"));
@@ -298,13 +244,10 @@ void test_merge_workdir_simple__mergefile(void)
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
-
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_simple__diff3(void)
 {
-	git_merge_result *result;
 	git_buf conflicting_buf = GIT_BUF_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -326,8 +269,7 @@ void test_merge_workdir_simple__diff3(void)
 		REMOVED_IN_MASTER_REUC_ENTRY
 	};
 
-	cl_assert(result = merge_simple_branch(0, GIT_CHECKOUT_CONFLICT_STYLE_DIFF3));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(0, GIT_CHECKOUT_CONFLICT_STYLE_DIFF3);
 
 	cl_git_pass(git_futils_readbuffer(&conflicting_buf,
 		TEST_REPO_PATH "/conflicting.txt"));
@@ -336,13 +278,10 @@ void test_merge_workdir_simple__diff3(void)
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
-
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_simple__union(void)
 {
-	git_merge_result *result;
 	git_buf conflicting_buf = GIT_BUF_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -365,8 +304,7 @@ void test_merge_workdir_simple__union(void)
 
 	set_core_autocrlf_to(repo, false);
 
-	cl_assert(result = merge_simple_branch(GIT_MERGE_FILE_FAVOR_UNION, 0));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(GIT_MERGE_FILE_FAVOR_UNION, 0);
 
 	cl_git_pass(git_futils_readbuffer(&conflicting_buf,
 		TEST_REPO_PATH "/conflicting.txt"));
@@ -375,13 +313,10 @@ void test_merge_workdir_simple__union(void)
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 6));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 4));
-
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_simple__diff3_from_config(void)
 {
-	git_merge_result *result;
 	git_config *config;
 	git_buf conflicting_buf = GIT_BUF_INIT;
 
@@ -407,8 +342,7 @@ void test_merge_workdir_simple__diff3_from_config(void)
 	cl_git_pass(git_repository_config(&config, repo));
 	cl_git_pass(git_config_set_string(config, "merge.conflictstyle", "diff3"));
 
-	cl_assert(result = merge_simple_branch(0, 0));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(0, 0);
 
 	cl_git_pass(git_futils_readbuffer(&conflicting_buf,
 		TEST_REPO_PATH "/conflicting.txt"));
@@ -418,13 +352,11 @@ void test_merge_workdir_simple__diff3_from_config(void)
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
 
-	git_merge_result_free(result);
 	git_config_free(config);
 }
 
 void test_merge_workdir_simple__merge_overrides_config(void)
 {
-	git_merge_result *result;
 	git_config *config;
 	git_buf conflicting_buf = GIT_BUF_INIT;
 
@@ -450,8 +382,7 @@ void test_merge_workdir_simple__merge_overrides_config(void)
 	cl_git_pass(git_repository_config(&config, repo));
 	cl_git_pass(git_config_set_string(config, "merge.conflictstyle", "diff3"));
 
-	cl_assert(result = merge_simple_branch(0, GIT_CHECKOUT_CONFLICT_STYLE_MERGE));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(0, GIT_CHECKOUT_CONFLICT_STYLE_MERGE);
 
 	cl_git_pass(git_futils_readbuffer(&conflicting_buf,
 		TEST_REPO_PATH "/conflicting.txt"));
@@ -461,14 +392,11 @@ void test_merge_workdir_simple__merge_overrides_config(void)
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
 
-	git_merge_result_free(result);
 	git_config_free(config);
 }
 
 void test_merge_workdir_simple__checkout_ours(void)
 {
-	git_merge_result *result;
-
 	struct merge_index_entry merge_index_entries[] = {
 		ADDED_IN_MASTER_INDEX_ENTRY,
 		AUTOMERGEABLE_INDEX_ENTRY,
@@ -488,21 +416,16 @@ void test_merge_workdir_simple__checkout_ours(void)
 		REMOVED_IN_MASTER_REUC_ENTRY
 	};
 
-	cl_assert(result = merge_simple_branch(0, GIT_CHECKOUT_SAFE | GIT_CHECKOUT_USE_OURS));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(0, GIT_CHECKOUT_SAFE | GIT_CHECKOUT_USE_OURS);
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 8));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 3));
 
 	cl_assert(git_path_exists(TEST_REPO_PATH "/conflicting.txt"));
-
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_simple__favor_ours(void)
 {
-	git_merge_result *result;
-
 	struct merge_index_entry merge_index_entries[] = {
 		ADDED_IN_MASTER_INDEX_ENTRY,
 		AUTOMERGEABLE_INDEX_ENTRY,
@@ -519,19 +442,14 @@ void test_merge_workdir_simple__favor_ours(void)
 		REMOVED_IN_MASTER_REUC_ENTRY,
 	};
 
-	cl_assert(result = merge_simple_branch(GIT_MERGE_FILE_FAVOR_OURS, 0));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(GIT_MERGE_FILE_FAVOR_OURS, 0);
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 6));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 4));
-
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_simple__favor_theirs(void)
 {
-	git_merge_result *result;
-
 	struct merge_index_entry merge_index_entries[] = {
 		ADDED_IN_MASTER_INDEX_ENTRY,
 		AUTOMERGEABLE_INDEX_ENTRY,
@@ -548,13 +466,10 @@ void test_merge_workdir_simple__favor_theirs(void)
 		REMOVED_IN_MASTER_REUC_ENTRY,
 	};
 
-	cl_assert(result = merge_simple_branch(GIT_MERGE_FILE_FAVOR_THEIRS, 0));
-	cl_assert(!git_merge_result_is_fastforward(result));
+	merge_simple_branch(GIT_MERGE_FILE_FAVOR_THEIRS, 0);
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 6));
 	cl_assert(merge_test_reuc(repo_index, merge_reuc_entries, 4));
-
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_simple__directory_file(void)
@@ -562,8 +477,7 @@ void test_merge_workdir_simple__directory_file(void)
 	git_reference *head;
 	git_oid their_oids[1], head_commit_id;
 	git_merge_head *their_heads[1];
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
+	git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
 	git_commit *head_commit;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -597,23 +511,21 @@ void test_merge_workdir_simple__directory_file(void)
 	cl_git_pass(git_oid_fromstr(&their_oids[0], THEIRS_DIRECTORY_FILE));
 	cl_git_pass(git_merge_head_from_id(&their_heads[0], repo, &their_oids[0]));
 
-	opts.merge_tree_opts.file_favor = 0;
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)their_heads, 1, &opts));
+	merge_opts.file_favor = 0;
+	cl_git_pass(git_merge(repo, (const git_merge_head **)their_heads, 1, &merge_opts, NULL));
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 20));
 
 	git_reference_free(head);
 	git_commit_free(head_commit);
 	git_merge_head_free(their_heads[0]);
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_simple__unrelated(void)
 {
 	git_oid their_oids[1];
 	git_merge_head *their_heads[1];
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
+	git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "233c0919c998ed110a4b6ff36f353aec8b713487", 0, "added-in-master.txt" },
@@ -630,21 +542,19 @@ void test_merge_workdir_simple__unrelated(void)
 	cl_git_pass(git_oid_fromstr(&their_oids[0], THEIRS_UNRELATED_PARENT));
 	cl_git_pass(git_merge_head_from_id(&their_heads[0], repo, &their_oids[0]));
 
-	opts.merge_tree_opts.file_favor = 0;
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)their_heads, 1, &opts));
+	merge_opts.file_favor = 0;
+	cl_git_pass(git_merge(repo, (const git_merge_head **)their_heads, 1, &merge_opts, NULL));
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 9));
 
 	git_merge_head_free(their_heads[0]);
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_simple__unrelated_with_conflicts(void)
 {
 	git_oid their_oids[1];
 	git_merge_head *their_heads[1];
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
+	git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "233c0919c998ed110a4b6ff36f353aec8b713487", 0, "added-in-master.txt" },
@@ -663,13 +573,12 @@ void test_merge_workdir_simple__unrelated_with_conflicts(void)
 	cl_git_pass(git_oid_fromstr(&their_oids[0], THEIRS_UNRELATED_OID));
 	cl_git_pass(git_merge_head_from_id(&their_heads[0], repo, &their_oids[0]));
 
-	opts.merge_tree_opts.file_favor = 0;
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)their_heads, 1, &opts));
+	merge_opts.file_favor = 0;
+	cl_git_pass(git_merge(repo, (const git_merge_head **)their_heads, 1, &merge_opts, NULL));
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 11));
 
 	git_merge_head_free(their_heads[0]);
-	git_merge_result_free(result);
 }
 
 void test_merge_workdir_simple__binary(void)
@@ -677,9 +586,7 @@ void test_merge_workdir_simple__binary(void)
 	git_oid our_oid, their_oid, our_file_oid;
 	git_commit *our_commit;
 	git_merge_head *their_head;
-	git_merge_result *result;
 	const git_index_entry *binary_entry;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
 
 	struct merge_index_entry merge_index_entries[] = {
 		{ 0100644, "1c51d885170f57a0c4e8c69ff6363d91a5b51f85", 1, "binary" },
@@ -695,7 +602,7 @@ void test_merge_workdir_simple__binary(void)
 
 	cl_git_pass(git_merge_head_from_id(&their_head, repo, &their_oid));
 
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)&their_head, 1, &opts));
+	cl_git_pass(git_merge(repo, (const git_merge_head **)&their_head, 1, NULL, NULL));
 
 	cl_assert(merge_test_index(repo_index, merge_index_entries, 3));
 
@@ -706,6 +613,5 @@ void test_merge_workdir_simple__binary(void)
 	cl_assert(git_oid_cmp(&binary_entry->id, &our_file_oid) == 0);
 
 	git_merge_head_free(their_head);
-	git_merge_result_free(result);
 	git_commit_free(our_commit);
 }
diff --git a/tests/merge/workdir/submodules.c b/tests/merge/workdir/submodules.c
index 42451bde7..e093e77ab 100644
--- a/tests/merge/workdir/submodules.c
+++ b/tests/merge/workdir/submodules.c
@@ -31,8 +31,6 @@ void test_merge_workdir_submodules__automerge(void)
 	git_reference *our_ref, *their_ref;
 	git_commit *our_commit;
 	git_merge_head *their_head;
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
 	git_index *index;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -51,13 +49,12 @@ void test_merge_workdir_submodules__automerge(void)
 	cl_git_pass(git_reference_lookup(&their_ref, repo, "refs/heads/" SUBMODULE_OTHER_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_head, repo, their_ref));
 
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)&their_head, 1, &opts));
+	cl_git_pass(git_merge(repo, (const git_merge_head **)&their_head, 1, NULL, NULL));
 
 	cl_git_pass(git_repository_index(&index, repo));
 	cl_assert(merge_test_index(index, merge_index_entries, 6));
 
 	git_index_free(index);
-	git_merge_result_free(result);
 	git_merge_head_free(their_head);
 	git_commit_free(our_commit);
 	git_reference_free(their_ref);
@@ -69,8 +66,6 @@ void test_merge_workdir_submodules__take_changed(void)
 	git_reference *our_ref, *their_ref;
 	git_commit *our_commit;
 	git_merge_head *their_head;
-	git_merge_result *result;
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
 	git_index *index;
 
 	struct merge_index_entry merge_index_entries[] = {
@@ -87,13 +82,12 @@ void test_merge_workdir_submodules__take_changed(void)
 	cl_git_pass(git_reference_lookup(&their_ref, repo, "refs/heads/" SUBMODULE_OTHER2_BRANCH));
 	cl_git_pass(git_merge_head_from_ref(&their_head, repo, their_ref));
 
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)&their_head, 1, &opts));
+	cl_git_pass(git_merge(repo, (const git_merge_head **)&their_head, 1, NULL, NULL));
 
 	cl_git_pass(git_repository_index(&index, repo));
 	cl_assert(merge_test_index(index, merge_index_entries, 4));
 
 	git_index_free(index);
-	git_merge_result_free(result);
 	git_merge_head_free(their_head);
 	git_commit_free(our_commit);
 	git_reference_free(their_ref);
diff --git a/tests/merge/workdir/trivial.c b/tests/merge/workdir/trivial.c
index 8b0d32894..cc82d990c 100644
--- a/tests/merge/workdir/trivial.c
+++ b/tests/merge/workdir/trivial.c
@@ -34,8 +34,6 @@ static int merge_trivial(const char *ours, const char *theirs)
 	git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
 	git_reference *our_ref, *their_ref;
 	git_merge_head *their_heads[1];
-	git_merge_opts opts = GIT_MERGE_OPTS_INIT;
-	git_merge_result *result;
 
 	checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE;
 
@@ -49,13 +47,12 @@ static int merge_trivial(const char *ours, const char *theirs)
 	cl_git_pass(git_reference_lookup(&their_ref, repo, branch_buf.ptr));
 	cl_git_pass(git_merge_head_from_ref(&their_heads[0], repo, their_ref));
 
-	cl_git_pass(git_merge(&result, repo, (const git_merge_head **)their_heads, 1, &opts));
+	cl_git_pass(git_merge(repo, (const git_merge_head **)their_heads, 1, NULL, NULL));
 
 	git_buf_free(&branch_buf);
 	git_reference_free(our_ref);
 	git_reference_free(their_ref);
 	git_merge_head_free(their_heads[0]);
-	git_merge_result_free(result);
 
 	return 0;
 }
diff --git a/tests/resources/merge-resolve/.gitted/refs/heads/previous b/tests/resources/merge-resolve/.gitted/refs/heads/previous
new file mode 100644
index 000000000..7bc1a8d15
--- /dev/null
+++ b/tests/resources/merge-resolve/.gitted/refs/heads/previous
@@ -0,0 +1 @@
+c607fc30883e335def28cd686b51f6cfa02b06ec
diff --git a/tests/revert/workdir.c b/tests/revert/workdir.c
index afbdffefa..694f24710 100644
--- a/tests/revert/workdir.c
+++ b/tests/revert/workdir.c
@@ -398,8 +398,8 @@ void test_revert_workdir__rename_1_of_2(void)
 		{ 0100644, "0f5bfcf58c558d865da6be0281d7795993646cee", 2, "file6.txt" },
 	};
 
-	opts.merge_tree_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
-	opts.merge_tree_opts.rename_threshold = 50;
+	opts.merge_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
+	opts.merge_opts.rename_threshold = 50;
 
 	git_oid_fromstr(&head_oid, "cef56612d71a6af8d8015691e4865f7fece905b5");
 	cl_git_pass(git_commit_lookup(&head, repo, &head_oid));
@@ -432,8 +432,8 @@ void test_revert_workdir__rename(void)
 		{ "file4.txt", "file5.txt", "" },
 	};
 
-	opts.merge_tree_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
-	opts.merge_tree_opts.rename_threshold = 50;
+	opts.merge_opts.flags |= GIT_MERGE_TREE_FIND_RENAMES;
+	opts.merge_opts.rename_threshold = 50;
 
 	git_oid_fromstr(&head_oid, "55568c8de5322ff9a95d72747a239cdb64a19965");
 	cl_git_pass(git_commit_lookup(&head, repo, &head_oid));
diff --git a/tests/structinit/structinit.c b/tests/structinit/structinit.c
index 1df970d49..2942099dd 100644
--- a/tests/structinit/structinit.c
+++ b/tests/structinit/structinit.c
@@ -65,15 +65,20 @@ void test_structinit_structinit__compare(void)
 		git_diff_find_options, GIT_DIFF_FIND_OPTIONS_VERSION, \
 		GIT_DIFF_FIND_OPTIONS_INIT, git_diff_find_init_options);
 
-	/* merge_tree */
+	/* merge_file_input */
+	CHECK_MACRO_FUNC_INIT_EQUAL( \
+		git_merge_file_input, GIT_MERGE_FILE_INPUT_VERSION, \
+		GIT_MERGE_FILE_INPUT_INIT, git_merge_file_init_input);
+
+	/* merge_file */
 	CHECK_MACRO_FUNC_INIT_EQUAL( \
-		git_merge_tree_opts, GIT_MERGE_TREE_OPTS_VERSION, \
-		GIT_MERGE_TREE_OPTS_INIT, git_merge_tree_init_opts);
+		git_merge_file_options, GIT_MERGE_FILE_OPTIONS_VERSION, \
+		GIT_MERGE_FILE_OPTIONS_INIT, git_merge_file_init_options);
 
-	/* merge */
+	/* merge_tree */
 	CHECK_MACRO_FUNC_INIT_EQUAL( \
-		git_merge_opts, GIT_MERGE_OPTS_VERSION, \
-		GIT_MERGE_OPTS_INIT, git_merge_init_opts);
+		git_merge_options, GIT_MERGE_OPTIONS_VERSION, \
+		GIT_MERGE_OPTIONS_INIT, git_merge_init_options);
 
 	/* push */
 	CHECK_MACRO_FUNC_INIT_EQUAL( \