Fix diff API to better parameter order

The diff API is not in the parameter order one would expect from
other libgit2 APIs.  This fixes that.

include/git2/diff.h

@@ -317,52 +317,52 @@ GIT_EXTERN(void) git_diff_list_free(git_diff_list *diff);
  *
  * This is equivalent to `git diff <treeish> <treeish>`
  *
+ * @param diff Output pointer to a git_diff_list pointer to be allocated.
  * @param repo The repository containing the trees.
- * @param opts Structure with options to influence diff or NULL for defaults.
  * @param old_tree A git_tree object to diff from.
  * @param new_tree A git_tree object to diff to.
- * @param diff A pointer to a git_diff_list pointer that will be allocated.
+ * @param opts Structure with options to influence diff or NULL for defaults.
  */
 GIT_EXTERN(int) git_diff_tree_to_tree(
+	git_diff_list **diff,
 	git_repository *repo,
-	const git_diff_options *opts, /**< can be NULL for defaults */
 	git_tree *old_tree,
 	git_tree *new_tree,
-	git_diff_list **diff);
+	const git_diff_options *opts); /**< can be NULL for defaults */
 
 /**
- * Compute a difference between a tree and the index.
+ * Compute a difference between a tree and the repository index.
  *
  * This is equivalent to `git diff --cached <treeish>` or if you pass
  * the HEAD tree, then like `git diff --cached`.
  *
+ * @param diff Output pointer to a git_diff_list pointer to be allocated.
  * @param repo The repository containing the tree and index.
- * @param opts Structure with options to influence diff or NULL for defaults.
  * @param old_tree A git_tree object to diff from.
- * @param diff A pointer to a git_diff_list pointer that will be allocated.
+ * @param opts Structure with options to influence diff or NULL for defaults.
  */
 GIT_EXTERN(int) git_diff_index_to_tree(
+	git_diff_list **diff,
 	git_repository *repo,
-	const git_diff_options *opts, /**< can be NULL for defaults */
 	git_tree *old_tree,
-	git_diff_list **diff);
+	const git_diff_options *opts); /**< can be NULL for defaults */
 
 /**
- * Compute a difference between the working directory and the index.
+ * Compute a difference between the working directory and the repository index.
  *
  * This matches the `git diff` command.  See the note below on
  * `git_diff_workdir_to_tree` for a discussion of the difference between
  * `git diff` and `git diff HEAD` and how to emulate a `git diff <treeish>`
  * using libgit2.
  *
+ * @param diff Output pointer to a git_diff_list pointer to be allocated.
  * @param repo The repository.
  * @param opts Structure with options to influence diff or NULL for defaults.
- * @param diff A pointer to a git_diff_list pointer that will be allocated.
  */
 GIT_EXTERN(int) git_diff_workdir_to_index(
+	git_diff_list **diff,
 	git_repository *repo,
-	const git_diff_options *opts, /**< can be NULL for defaults */
-	git_diff_list **diff);
+	const git_diff_options *opts); /**< can be NULL for defaults */
 
 /**
  * Compute a difference between the working directory and a tree.
@@ -386,16 +386,16 @@ GIT_EXTERN(int) git_diff_workdir_to_index(
  * The tree-to-workdir diff for that file is 'modified', but core git would
  * show status 'deleted' since there is a pending deletion in the index.
  *
+ * @param diff A pointer to a git_diff_list pointer that will be allocated.
  * @param repo The repository containing the tree.
- * @param opts Structure with options to influence diff or NULL for defaults.
  * @param old_tree A git_tree object to diff from.
- * @param diff A pointer to a git_diff_list pointer that will be allocated.
+ * @param opts Structure with options to influence diff or NULL for defaults.
  */
 GIT_EXTERN(int) git_diff_workdir_to_tree(
+	git_diff_list **diff,
 	git_repository *repo,
-	const git_diff_options *opts, /**< can be NULL for defaults */
 	git_tree *old_tree,
-	git_diff_list **diff);
+	const git_diff_options *opts); /**< can be NULL for defaults */
 
 /**
  * Merge one diff list into another.

src/checkout.c

@@ -625,7 +625,7 @@ int git_checkout_index(
 	if (opts && opts->paths.count > 0)
 		diff_opts.pathspec = opts->paths;
 
-	if ((error = git_diff_workdir_to_index(repo, &diff_opts, &diff)) < 0)
+	if ((error = git_diff_workdir_to_index(&diff, repo, &diff_opts)) < 0)
 		goto cleanup;
 
 	if ((error = git_buf_puts(&workdir, git_repository_workdir(repo))) < 0)

src/diff.c

@@ -568,11 +568,11 @@ static int diff_list_init_from_iterators(
 }
 
 static int diff_from_iterators(
+	git_diff_list **diff_ptr,
 	git_repository *repo,
-	const git_diff_options *opts, /**< can be NULL for defaults */
 	git_iterator *old_iter,
 	git_iterator *new_iter,
-	git_diff_list **diff_ptr)
+	const git_diff_options *opts)
 {
 	int error = 0;
 	const git_index_entry *oitem, *nitem;
@@ -747,108 +747,71 @@ fail:
 		error = -1;
 	}
 
-	git_iterator_free(old_iter);
-	git_iterator_free(new_iter);
 	git_buf_free(&ignore_prefix);
 
 	return error;
 }
 
 
+#define DIFF_FROM_ITERATORS(SETUP, MAKE_FIRST, MAKE_SECOND) \
+	int error; \
+	git_iterator *a = NULL, *b = NULL; \
+	char *pfx = opts ? git_pathspec_prefix(&opts->pathspec) : NULL; \
+	SETUP; \
+    if (!(error = MAKE_FIRST) && !(error = MAKE_SECOND)) \
+		error = diff_from_iterators(diff, repo, a, b, opts); \
+	git__free(pfx); git_iterator_free(a); git_iterator_free(b); \
+    return error
+
 int git_diff_tree_to_tree(
+	git_diff_list **diff,
 	git_repository *repo,
-	const git_diff_options *opts, /**< can be NULL for defaults */
 	git_tree *old_tree,
 	git_tree *new_tree,
-	git_diff_list **diff)
+	const git_diff_options *opts)
 {
-	git_iterator *a = NULL, *b = NULL;
-	char *pfx = opts ? git_pathspec_prefix(&opts->pathspec) : NULL;
-
-	assert(repo && old_tree && new_tree && diff);
-
-	if (git_iterator_for_tree_range(&a, repo, old_tree, pfx, pfx) < 0 ||
-		git_iterator_for_tree_range(&b, repo, new_tree, pfx, pfx) < 0)
-		return -1;
-
-	git__free(pfx);
-
-	return diff_from_iterators(repo, opts, a, b, diff);
+	DIFF_FROM_ITERATORS(
+		assert(repo && old_tree && new_tree && diff),
+		git_iterator_for_tree_range(&a, repo, old_tree, pfx, pfx),
+		git_iterator_for_tree_range(&b, repo, new_tree, pfx, pfx)
+	);
 }
 
 int git_diff_index_to_tree(
+	git_diff_list **diff,
 	git_repository *repo,
-	const git_diff_options *opts,
 	git_tree *old_tree,
-	git_diff_list **diff)
+	const git_diff_options *opts)
 {
-	git_iterator *a = NULL, *b = NULL;
-	char *pfx = opts ? git_pathspec_prefix(&opts->pathspec) : NULL;
-
-	assert(repo && diff);
-
-	if (git_iterator_for_tree_range(&a, repo, old_tree, pfx, pfx) < 0 ||
-	    git_iterator_for_index_range(&b, repo, pfx, pfx) < 0)
-		goto on_error;
-
-	git__free(pfx);
-
-	return diff_from_iterators(repo, opts, a, b, diff);
-
-on_error:
-	git__free(pfx);
-	git_iterator_free(a);
-	return -1;
+	DIFF_FROM_ITERATORS(
+		assert(repo && diff),
+		git_iterator_for_tree_range(&a, repo, old_tree, pfx, pfx),
+	    git_iterator_for_index_range(&b, repo, pfx, pfx)
+	);
 }
 
 int git_diff_workdir_to_index(
+	git_diff_list **diff,
 	git_repository *repo,
-	const git_diff_options *opts,
-	git_diff_list **diff)
+	const git_diff_options *opts)
 {
-	int error;
-	git_iterator *a = NULL, *b = NULL;
-	char *pfx = opts ? git_pathspec_prefix(&opts->pathspec) : NULL;
-
-	assert(repo && diff);
-
-	if ((error = git_iterator_for_index_range(&a, repo, pfx, pfx)) < 0 ||
-	    (error = git_iterator_for_workdir_range(&b, repo, pfx, pfx)) < 0)
-		goto on_error;
-
-	git__free(pfx);
-
-	return diff_from_iterators(repo, opts, a, b, diff);
-
-on_error:
-	git__free(pfx);
-	git_iterator_free(a);
-	return error;
+	DIFF_FROM_ITERATORS(
+		assert(repo && diff),
+		git_iterator_for_index_range(&a, repo, pfx, pfx),
+	    git_iterator_for_workdir_range(&b, repo, pfx, pfx)
+	);
 }
 
 
 int git_diff_workdir_to_tree(
+	git_diff_list **diff,
 	git_repository *repo,
-	const git_diff_options *opts,
-	git_tree *tree,
-	git_diff_list **diff)
+	git_tree *old_tree,
+	const git_diff_options *opts)
 {
-	int error;
-	git_iterator *a = NULL, *b = NULL;
-	char *pfx = opts ? git_pathspec_prefix(&opts->pathspec) : NULL;
-
-	assert(repo && tree && diff);
-
-	if ((error = git_iterator_for_tree_range(&a, repo, tree, pfx, pfx)) < 0 ||
-	    (error = git_iterator_for_workdir_range(&b, repo, pfx, pfx)) < 0)
-		goto on_error;
-
-	git__free(pfx);
-
-	return diff_from_iterators(repo, opts, a, b, diff);
-
-on_error:
-	git__free(pfx);
-	git_iterator_free(a);
-	return error;
+	DIFF_FROM_ITERATORS(
+		assert(repo && diff),
+		git_iterator_for_tree_range(&a, repo, old_tree, pfx, pfx),
+	    git_iterator_for_workdir_range(&b, repo, pfx, pfx)
+	);
 }

src/stash.c

@@ -250,7 +250,7 @@ static int build_untracked_tree(
 	if (git_commit_tree(&i_tree, i_commit) < 0)
 		goto cleanup;
 
-	if (git_diff_workdir_to_tree(git_index_owner(index), &opts, i_tree, &diff) < 0)
+	if (git_diff_workdir_to_tree(&diff, git_index_owner(index), i_tree, &opts) < 0)
 		goto cleanup;
 
 	if (git_diff_foreach(diff, &data, update_index_cb, NULL, NULL) < 0)
@@ -312,6 +312,7 @@ static int build_workdir_tree(
 	git_index *index,
 	git_commit *b_commit)
 {
+	git_repository *repo = git_index_owner(index);
 	git_tree *b_tree = NULL;
 	git_diff_list *diff = NULL, *diff2 = NULL;
 	git_diff_options opts = {0};
@@ -321,10 +322,10 @@ static int build_workdir_tree(
 	if (git_commit_tree(&b_tree, b_commit) < 0)
 		goto cleanup;
 
-	if (git_diff_index_to_tree(git_index_owner(index), &opts, b_tree, &diff) < 0)
+	if (git_diff_index_to_tree(&diff, repo, b_tree, &opts) < 0)
 		goto cleanup;
 
-	if (git_diff_workdir_to_index(git_index_owner(index), &opts, &diff2) < 0)
+	if (git_diff_workdir_to_index(&diff2, repo, &opts) < 0)
 		goto cleanup;
 
 	if (git_diff_merge(diff, diff2) < 0)

src/status.c

@@ -142,11 +142,11 @@ int git_status_foreach_ext(
 	/* TODO: support EXCLUDE_SUBMODULES flag */
 
 	if (show != GIT_STATUS_SHOW_WORKDIR_ONLY &&
-		(err = git_diff_index_to_tree(repo, &diffopt, head, &idx2head)) < 0)
+		(err = git_diff_index_to_tree(&idx2head, repo, head, &diffopt)) < 0)
 		goto cleanup;
 
 	if (show != GIT_STATUS_SHOW_INDEX_ONLY &&
-		(err = git_diff_workdir_to_index(repo, &diffopt, &wd2idx)) < 0)
+		(err = git_diff_workdir_to_index(&wd2idx, repo, &diffopt)) < 0)
 		goto cleanup;
 
 	usercb.cb = cb;

src/submodule.c

@@ -1455,7 +1455,7 @@ static int submodule_wd_status(unsigned int *status, git_submodule *sm)
 		if (sm->ignore == GIT_SUBMODULE_IGNORE_NONE)
 			opt.flags |= GIT_DIFF_INCLUDE_UNTRACKED;
 
-		error = git_diff_index_to_tree(sm_repo, &opt, sm_head, &diff);
+		error = git_diff_index_to_tree(&diff, sm_repo, sm_head, &opt);
 
 		if (!error) {
 			if (git_diff_num_deltas(diff) > 0)
@@ -1472,7 +1472,7 @@ static int submodule_wd_status(unsigned int *status, git_submodule *sm)
 
 		/* perform index-to-workdir diff on submodule */
 
-		error = git_diff_workdir_to_index(sm_repo, &opt, &diff);
+		error = git_diff_workdir_to_index(&diff, sm_repo, &opt);
 
 		if (!error) {
 			size_t untracked =

tests-clar/diff/diffiter.c

@@ -16,7 +16,7 @@ void test_diff_diffiter__create(void)
 	git_diff_list *diff;
 	size_t d, num_d;
 
-	cl_git_pass(git_diff_workdir_to_index(repo, NULL, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, repo, NULL));
 
 	num_d = git_diff_num_deltas(diff);
 	for (d = 0; d < num_d; ++d) {
@@ -34,7 +34,7 @@ void test_diff_diffiter__iterate_files(void)
 	size_t d, num_d;
 	int count = 0;
 
-	cl_git_pass(git_diff_workdir_to_index(repo, NULL, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, repo, NULL));
 
 	num_d = git_diff_num_deltas(diff);
 	cl_assert_equal_i(6, (int)num_d);
@@ -57,7 +57,7 @@ void test_diff_diffiter__iterate_files_2(void)
 	size_t d, num_d;
 	int count = 0;
 
-	cl_git_pass(git_diff_workdir_to_index(repo, NULL, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, repo, NULL));
 
 	num_d = git_diff_num_deltas(diff);
 	cl_assert_equal_i(8, (int)num_d);
@@ -85,7 +85,7 @@ void test_diff_diffiter__iterate_files_and_hunks(void)
 	opts.interhunk_lines = 1;
 	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
 
-	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, repo, &opts));
 
 	num_d = git_diff_num_deltas(diff);
 
@@ -138,7 +138,7 @@ void test_diff_diffiter__max_size_threshold(void)
 	opts.interhunk_lines = 1;
 	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
 
-	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, repo, &opts));
 	num_d = git_diff_num_deltas(diff);
 
 	for (d = 0; d < num_d; ++d) {
@@ -173,7 +173,7 @@ void test_diff_diffiter__max_size_threshold(void)
 	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
 	opts.max_size = 50; /* treat anything over 50 bytes as binary! */
 
-	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, repo, &opts));
 	num_d = git_diff_num_deltas(diff);
 
 	for (d = 0; d < num_d; ++d) {
@@ -216,7 +216,7 @@ void test_diff_diffiter__iterate_all(void)
 	opts.interhunk_lines = 1;
 	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
 
-	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, repo, &opts));
 
 	num_d = git_diff_num_deltas(diff);
 	for (d = 0; d < num_d; ++d) {
@@ -292,7 +292,7 @@ void test_diff_diffiter__iterate_randomly_while_saving_state(void)
 	opts.interhunk_lines = 1;
 	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
 
-	cl_git_pass(git_diff_workdir_to_index(repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, repo, &opts));
 
 	num_d = git_diff_num_deltas(diff);
 
@@ -419,7 +419,7 @@ void test_diff_diffiter__iterate_and_generate_patch_text(void)
 	git_diff_list *diff;
 	size_t d, num_d;
 
-	cl_git_pass(git_diff_workdir_to_index(repo, NULL, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, repo, NULL));
 
 	num_d = git_diff_num_deltas(diff);
 	cl_assert_equal_i(8, (int)num_d);

tests-clar/diff/index.c

@@ -32,7 +32,7 @@ void test_diff_index__0(void)
 
 	memset(&exp, 0, sizeof(exp));
 
-	cl_git_pass(git_diff_index_to_tree(g_repo, &opts, a, &diff));
+	cl_git_pass(git_diff_index_to_tree(&diff, g_repo, a, &opts));
 
 	cl_git_pass(git_diff_foreach(
 		diff, &exp, diff_file_fn, diff_hunk_fn, diff_line_fn));
@@ -60,7 +60,7 @@ void test_diff_index__0(void)
 	diff = NULL;
 	memset(&exp, 0, sizeof(exp));
 
-	cl_git_pass(git_diff_index_to_tree(g_repo, &opts, b, &diff));
+	cl_git_pass(git_diff_index_to_tree(&diff, g_repo, b, &opts));
 
 	cl_git_pass(git_diff_foreach(
 		diff, &exp, diff_file_fn, diff_hunk_fn, diff_line_fn));
@@ -125,7 +125,7 @@ void test_diff_index__1(void)
 
 	memset(&exp, 0, sizeof(exp));
 
-	cl_git_pass(git_diff_index_to_tree(g_repo, &opts, a, &diff));
+	cl_git_pass(git_diff_index_to_tree(&diff, g_repo, a, &opts));
 
 	cl_assert_equal_i(
 		GIT_EUSER,

tests-clar/diff/patch.c

@@ -88,7 +88,7 @@ void test_diff_patch__can_properly_display_the_removal_of_a_file(void)
 	one = resolve_commit_oid_to_tree(g_repo, one_sha);
 	another = resolve_commit_oid_to_tree(g_repo, another_sha);
 
-	cl_git_pass(git_diff_tree_to_tree(g_repo, NULL, one, another, &diff));
+	cl_git_pass(git_diff_tree_to_tree(&diff, g_repo, one, another, NULL));
 
 	cl_git_pass(git_diff_print_patch(diff, NULL, check_removal_cb));
 
@@ -111,7 +111,7 @@ void test_diff_patch__to_string(void)
 	one = resolve_commit_oid_to_tree(g_repo, one_sha);
 	another = resolve_commit_oid_to_tree(g_repo, another_sha);
 
-	cl_git_pass(git_diff_tree_to_tree(g_repo, NULL, one, another, &diff));
+	cl_git_pass(git_diff_tree_to_tree(&diff, g_repo, one, another, NULL));
 
 	cl_assert_equal_i(1, git_diff_num_deltas(diff));
 

tests-clar/diff/rename.c

@@ -47,7 +47,7 @@ void test_diff_rename__match_oid(void)
 	diffopts.flags |= GIT_DIFF_INCLUDE_UNMODIFIED;
 
 	cl_git_pass(git_diff_tree_to_tree(
-		g_repo, &diffopts, old_tree, new_tree, &diff));
+		&diff, g_repo, old_tree, new_tree, &diffopts));
 
 	/* git diff --no-renames \
 	 *          31e47d8c1fa36d7f8d537b96158e3f024de0a9f2 \
@@ -79,7 +79,7 @@ void test_diff_rename__match_oid(void)
 	git_diff_list_free(diff);
 
 	cl_git_pass(git_diff_tree_to_tree(
-		g_repo, &diffopts, old_tree, new_tree, &diff));
+		&diff, g_repo, old_tree, new_tree, &diffopts));
 
 	/* git diff --find-copies-harder \
 	 *          31e47d8c1fa36d7f8d537b96158e3f024de0a9f2 \

tests-clar/diff/tree.c

@@ -34,7 +34,7 @@ void test_diff_tree__0(void)
 
 	memset(&exp, 0, sizeof(exp));
 
-	cl_git_pass(git_diff_tree_to_tree(g_repo, &opts, a, b, &diff));
+	cl_git_pass(git_diff_tree_to_tree(&diff, g_repo, a, b, &opts));
 
 	cl_git_pass(git_diff_foreach(
 		diff, &exp, diff_file_fn, diff_hunk_fn, diff_line_fn));
@@ -56,7 +56,7 @@ void test_diff_tree__0(void)
 
 	memset(&exp, 0, sizeof(exp));
 
-	cl_git_pass(git_diff_tree_to_tree(g_repo, &opts, c, b, &diff));
+	cl_git_pass(git_diff_tree_to_tree(&diff, g_repo, c, b, &opts));
 
 	cl_git_pass(git_diff_foreach(
 		diff, &exp, diff_file_fn, diff_hunk_fn, diff_line_fn));
@@ -141,9 +141,9 @@ void test_diff_tree__options(void)
 		opts = test_options[i];
 
 		if (test_ab_or_cd[i] == 0)
-			cl_git_pass(git_diff_tree_to_tree(g_repo, &opts, a, b, &diff));
+			cl_git_pass(git_diff_tree_to_tree(&diff, g_repo, a, b, &opts));
 		else
-			cl_git_pass(git_diff_tree_to_tree(g_repo, &opts, c, d, &diff));
+			cl_git_pass(git_diff_tree_to_tree(&diff, g_repo, c, d, &opts));
 
 		cl_git_pass(git_diff_foreach(
 			diff, &actual, diff_file_fn, diff_hunk_fn, diff_line_fn));
@@ -187,7 +187,7 @@ void test_diff_tree__bare(void)
 
 	memset(&exp, 0, sizeof(exp));
 
-	cl_git_pass(git_diff_tree_to_tree(g_repo, &opts, a, b, &diff));
+	cl_git_pass(git_diff_tree_to_tree(&diff, g_repo, a, b, &opts));
 
 	cl_git_pass(git_diff_foreach(
 		diff, &exp, diff_file_fn, diff_hunk_fn, diff_line_fn));
@@ -225,9 +225,9 @@ void test_diff_tree__merge(void)
 	cl_assert((b = resolve_commit_oid_to_tree(g_repo, b_commit)) != NULL);
 	cl_assert((c = resolve_commit_oid_to_tree(g_repo, c_commit)) != NULL);
 
-	cl_git_pass(git_diff_tree_to_tree(g_repo, NULL, a, b, &diff1));
+	cl_git_pass(git_diff_tree_to_tree(&diff1, g_repo, a, b, NULL));
 
-	cl_git_pass(git_diff_tree_to_tree(g_repo, NULL, c, b, &diff2));
+	cl_git_pass(git_diff_tree_to_tree(&diff2, g_repo, c, b, NULL));
 
 	git_tree_free(a);
 	git_tree_free(b);
@@ -279,7 +279,7 @@ void test_diff_tree__larger_hunks(void)
 	opts.context_lines = 1;
 	opts.interhunk_lines = 0;
 
-	cl_git_pass(git_diff_tree_to_tree(g_repo, &opts, a, b, &diff));
+	cl_git_pass(git_diff_tree_to_tree(&diff, g_repo, a, b, &opts));
 
 	num_d = git_diff_num_deltas(diff);
 	for (d = 0; d < num_d; ++d) {

tests-clar/diff/workdir.c

@@ -26,7 +26,7 @@ void test_diff_workdir__to_index(void)
 	opts.interhunk_lines = 1;
 	opts.flags |= GIT_DIFF_INCLUDE_IGNORED | GIT_DIFF_INCLUDE_UNTRACKED;
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -94,7 +94,7 @@ void test_diff_workdir__to_tree(void)
 	 * The results are documented at the bottom of this file in the
 	 * long comment entitled "PREPARATION OF TEST DATA".
 	 */
-	cl_git_pass(git_diff_workdir_to_tree(g_repo, &opts, a, &diff));
+	cl_git_pass(git_diff_workdir_to_tree(&diff, g_repo, a, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -127,8 +127,8 @@ void test_diff_workdir__to_tree(void)
 	 * a workdir to tree diff (even though it is not really).  This is what
 	 * you would get from "git diff --name-status 26a125ee1bf"
 	 */
-	cl_git_pass(git_diff_index_to_tree(g_repo, &opts, a, &diff));
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff2));
+	cl_git_pass(git_diff_index_to_tree(&diff, g_repo, a, &opts));
+	cl_git_pass(git_diff_workdir_to_index(&diff2, g_repo, &opts));
 	cl_git_pass(git_diff_merge(diff, diff2));
 	git_diff_list_free(diff2);
 
@@ -164,8 +164,8 @@ void test_diff_workdir__to_tree(void)
 	/* Again, emulating "git diff <sha>" for testing purposes using
 	 * "git diff --name-status 0017bd4ab1ec3" instead.
 	 */
-	cl_git_pass(git_diff_index_to_tree(g_repo, &opts, b, &diff));
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff2));
+	cl_git_pass(git_diff_index_to_tree(&diff, g_repo, b, &opts));
+	cl_git_pass(git_diff_workdir_to_index(&diff2, g_repo, &opts));
 	cl_git_pass(git_diff_merge(diff, diff2));
 	git_diff_list_free(diff2);
 
@@ -216,7 +216,7 @@ void test_diff_workdir__to_index_with_pathspec(void)
 	opts.pathspec.strings = &pathspec;
 	opts.pathspec.count   = 1;
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -239,7 +239,7 @@ void test_diff_workdir__to_index_with_pathspec(void)
 
 	pathspec = "modified_file";
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -262,7 +262,7 @@ void test_diff_workdir__to_index_with_pathspec(void)
 
 	pathspec = "subdir";
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -285,7 +285,7 @@ void test_diff_workdir__to_index_with_pathspec(void)
 
 	pathspec = "*_deleted";
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -324,7 +324,7 @@ void test_diff_workdir__filemode_changes(void)
 
 	/* test once with no mods */
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, NULL, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, NULL));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -347,7 +347,7 @@ void test_diff_workdir__filemode_changes(void)
 
 	cl_assert(cl_toggle_filemode("issue_592/a.txt"));
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, NULL, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, NULL));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -386,7 +386,7 @@ void test_diff_workdir__filemode_changes_with_filemode_false(void)
 
 	/* test once with no mods */
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, NULL, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, NULL));
 
 	memset(&exp, 0, sizeof(exp));
 	cl_git_pass(git_diff_foreach(
@@ -402,7 +402,7 @@ void test_diff_workdir__filemode_changes_with_filemode_false(void)
 
 	cl_assert(cl_toggle_filemode("issue_592/a.txt"));
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, NULL, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, NULL));
 
 	memset(&exp, 0, sizeof(exp));
 	cl_git_pass(git_diff_foreach(
@@ -442,8 +442,8 @@ void test_diff_workdir__head_index_and_workdir_all_differ(void)
 	opts.pathspec.strings = &pathspec;
 	opts.pathspec.count   = 1;
 
-	cl_git_pass(git_diff_index_to_tree(g_repo, &opts, tree, &diff_i2t));
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff_w2i));
+	cl_git_pass(git_diff_index_to_tree(&diff_i2t, g_repo, tree, &opts));
+	cl_git_pass(git_diff_workdir_to_index(&diff_w2i, g_repo, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -529,7 +529,7 @@ void test_diff_workdir__eof_newline_changes(void)
 	opts.pathspec.strings = &pathspec;
 	opts.pathspec.count   = 1;
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -556,7 +556,7 @@ void test_diff_workdir__eof_newline_changes(void)
 
 	cl_git_append2file("status/current_file", "\n");
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -583,7 +583,7 @@ void test_diff_workdir__eof_newline_changes(void)
 
 	cl_git_rewritefile("status/current_file", "current_file");
 
-	cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff));
+	cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, &opts));
 
 	for (use_iterator = 0; use_iterator <= 1; use_iterator++) {
 		memset(&exp, 0, sizeof(exp));
@@ -699,13 +699,13 @@ void test_diff_workdir__larger_hunks(void)
 		/* okay, this is a bit silly, but oh well */
 		switch (i) {
 		case 0:
-			cl_git_pass(git_diff_workdir_to_index(g_repo, &opts, &diff));
+			cl_git_pass(git_diff_workdir_to_index(&diff, g_repo, &opts));
 			break;
 		case 1:
-			cl_git_pass(git_diff_workdir_to_tree(g_repo, &opts, a, &diff));
+			cl_git_pass(git_diff_workdir_to_tree(&diff, g_repo, a, &opts));
 			break;
 		case 2:
-			cl_git_pass(git_diff_workdir_to_tree(g_repo, &opts, b, &diff));
+			cl_git_pass(git_diff_workdir_to_tree(&diff, g_repo, b, &opts));
 			break;
 		}
 
@@ -784,7 +784,7 @@ void test_diff_workdir__submodules(void)
 		GIT_DIFF_RECURSE_UNTRACKED_DIRS |
 		GIT_DIFF_INCLUDE_UNTRACKED_CONTENT;
 
-	cl_git_pass(git_diff_workdir_to_tree(g_repo, &opts, a, &diff));
+	cl_git_pass(git_diff_workdir_to_tree(&diff, g_repo, a, &opts));
 
 	/* diff_print(stderr, diff); */
 
@@ -828,10 +828,13 @@ void test_diff_workdir__cannot_diff_against_a_bare_repository(void)
 
 	g_repo = cl_git_sandbox_init("testrepo.git");
 
-	cl_assert_equal_i(GIT_EBAREREPO, git_diff_workdir_to_index(g_repo, &opts, &diff));
+	cl_assert_equal_i(
+		GIT_EBAREREPO, git_diff_workdir_to_index(&diff, g_repo, &opts));
 
 	cl_git_pass(git_repository_head_tree(&tree, g_repo));
-	cl_assert_equal_i(GIT_EBAREREPO, git_diff_workdir_to_tree(g_repo, &opts, tree, &diff));
+
+	cl_assert_equal_i(
+		GIT_EBAREREPO, git_diff_workdir_to_tree(&diff, g_repo, tree, &opts));
 
 	git_tree_free(tree);
 }