Add const to all shared pointers in diff API

There are a lot of places where the diff API gives the user access
to internal data structures and many of these were being exposed
through non-const pointers.  This replaces them all with const
pointers for any object that the user can access but is still
owned internally to the git_diff_list or git_diff_patch objects.

This will probably break some bindings...  Sorry!

include/git2/diff.h

@@ -122,7 +122,7 @@ typedef enum {
  */
 typedef struct {
 	git_oid oid;
-	char *path;
+	const char *path;
 	git_off_t size;
 	unsigned int flags;
 	uint16_t mode;
@@ -154,7 +154,7 @@ typedef struct {
  */
 typedef int (*git_diff_file_fn)(
 	void *cb_data,
-	git_diff_delta *delta,
+	const git_diff_delta *delta,
 	float progress);
 
 /**
@@ -172,8 +172,8 @@ typedef struct {
  */
 typedef int (*git_diff_hunk_fn)(
 	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	const char *header,
 	size_t header_len);
 
@@ -213,8 +213,8 @@ enum {
  */
 typedef int (*git_diff_data_fn)(
 	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	char line_origin, /**< GIT_DIFF_LINE_... value from above */
 	const char *content,
 	size_t content_len);
@@ -486,7 +486,7 @@ GIT_EXTERN(size_t) git_diff_num_deltas_of_type(
  */
 GIT_EXTERN(int) git_diff_get_patch(
 	git_diff_patch **patch,
-	git_diff_delta **delta,
+	const git_diff_delta **delta,
 	git_diff_list *diff,
 	size_t idx);
 
@@ -525,7 +525,7 @@ GIT_EXTERN(size_t) git_diff_patch_num_hunks(
  * @return 0 on success, GIT_ENOTFOUND if hunk_idx out of range, <0 on error
  */
 GIT_EXTERN(int) git_diff_patch_get_hunk(
-	git_diff_range **range,
+	const git_diff_range **range,
 	const char **header,
 	size_t *header_len,
 	size_t *lines_in_hunk,
@@ -595,7 +595,7 @@ GIT_EXTERN(int) git_diff_patch_get_line_in_hunk(
 GIT_EXTERN(int) git_diff_blobs(
 	git_blob *old_blob,
 	git_blob *new_blob,
-	git_diff_options *options,
+	const git_diff_options *options,
 	void *cb_data,
 	git_diff_file_fn file_cb,
 	git_diff_hunk_fn hunk_cb,

src/checkout.c

@@ -126,7 +126,7 @@ static int blob_content_to_link(git_blob *blob, const char *path, bool can_symli
 
 static int checkout_blob(
 	git_repository *repo,
-	git_oid *blob_oid,
+	const git_oid *blob_oid,
 	const char *path,
 	mode_t filemode,
 	bool can_symlink,
@@ -150,7 +150,7 @@ static int checkout_blob(
 
 static int checkout_diff_fn(
 	void *cb_data,
-	git_diff_delta *delta,
+	const git_diff_delta *delta,
 	float progress)
 {
 	struct checkout_diff_data *data;

src/diff.c

@@ -809,7 +809,7 @@ on_error:
 
 
 bool git_diff_delta__should_skip(
-	git_diff_options *opts, git_diff_delta *delta)
+	const git_diff_options *opts, const git_diff_delta *delta)
 {
 	uint32_t flags = opts ? opts->flags : 0;
 

src/diff.h

@@ -51,7 +51,7 @@ extern void git_diff__cleanup_modes(
 extern void git_diff_list_addref(git_diff_list *diff);
 
 extern bool git_diff_delta__should_skip(
-	git_diff_options *opts, git_diff_delta *delta);
+	const git_diff_options *opts, const git_diff_delta *delta);
 
 #endif
 

src/diff_output.c

@@ -177,7 +177,7 @@ static int diff_delta_is_binary_by_size(
 }
 
 static void setup_xdiff_options(
-	git_diff_options *opts, xdemitconf_t *cfg, xpparam_t *param)
+	const git_diff_options *opts, xdemitconf_t *cfg, xpparam_t *param)
 {
 	memset(cfg, 0, sizeof(xdemitconf_t));
 	memset(param, 0, sizeof(xpparam_t));
@@ -371,7 +371,7 @@ static void diff_context_init(
 	diff_context *ctxt,
 	git_diff_list *diff,
 	git_repository *repo,
-	git_diff_options *opts,
+	const git_diff_options *opts,
 	void *data,
 	git_diff_file_fn file_cb,
 	git_diff_hunk_fn hunk_cb,
@@ -696,8 +696,8 @@ static void diff_patch_free(git_diff_patch *patch)
 
 static int diff_patch_hunk_cb(
 	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	const char *header,
 	size_t header_len)
 {
@@ -743,8 +743,8 @@ static int diff_patch_hunk_cb(
 
 static int diff_patch_line_cb(
 	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	char line_origin,
 	const char *content,
 	size_t content_len)
@@ -905,7 +905,8 @@ char git_diff_status_char(git_delta_t status)
 	return code;
 }
 
-static int print_compact(void *data, git_diff_delta *delta, float progress)
+static int print_compact(
+	void *data, const git_diff_delta *delta, float progress)
 {
 	diff_print_info *pi = data;
 	char old_suffix, new_suffix, code = git_diff_status_char(delta->status);
@@ -967,7 +968,7 @@ int git_diff_print_compact(
 	return error;
 }
 
-static int print_oid_range(diff_print_info *pi, git_diff_delta *delta)
+static int print_oid_range(diff_print_info *pi, const git_diff_delta *delta)
 {
 	char start_oid[8], end_oid[8];
 
@@ -997,7 +998,8 @@ static int print_oid_range(diff_print_info *pi, git_diff_delta *delta)
 	return 0;
 }
 
-static int print_patch_file(void *data, git_diff_delta *delta, float progress)
+static int print_patch_file(
+	void *data, const git_diff_delta *delta, float progress)
 {
 	diff_print_info *pi = data;
 	const char *oldpfx = pi->diff->opts.old_prefix;
@@ -1064,8 +1066,8 @@ static int print_patch_file(void *data, git_diff_delta *delta, float progress)
 
 static int print_patch_hunk(
 	void *data,
-	git_diff_delta *d,
-	git_diff_range *r,
+	const git_diff_delta *d,
+	const git_diff_range *r,
 	const char *header,
 	size_t header_len)
 {
@@ -1087,8 +1089,8 @@ static int print_patch_hunk(
 
 static int print_patch_line(
 	void *data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	char line_origin, /* GIT_DIFF_LINE value from above */
 	const char *content,
 	size_t content_len)
@@ -1158,7 +1160,7 @@ static void set_data_from_blob(
 int git_diff_blobs(
 	git_blob *old_blob,
 	git_blob *new_blob,
-	git_diff_options *options,
+	const git_diff_options *options,
 	void *cb_data,
 	git_diff_file_fn file_cb,
 	git_diff_hunk_fn hunk_cb,
@@ -1253,7 +1255,7 @@ size_t git_diff_num_deltas_of_type(git_diff_list *diff, git_delta_t type)
 
 int git_diff_get_patch(
 	git_diff_patch **patch_ptr,
-	git_diff_delta **delta_ptr,
+	const git_diff_delta **delta_ptr,
 	git_diff_list *diff,
 	size_t idx)
 {
@@ -1326,7 +1328,7 @@ size_t git_diff_patch_num_hunks(git_diff_patch *patch)
 }
 
 int git_diff_patch_get_hunk(
-	git_diff_range **range,
+	const git_diff_range **range,
 	const char **header,
 	size_t *header_len,
 	size_t *lines_in_hunk,

src/diff_output.h

@@ -26,7 +26,7 @@ enum {
 typedef struct {
 	git_repository   *repo;
 	git_diff_list    *diff;
-	git_diff_options *opts;
+	const git_diff_options *opts;
 	git_diff_file_fn  file_cb;
 	git_diff_hunk_fn  hunk_cb;
 	git_diff_data_fn  data_cb;

tests-clar/diff/diff_helpers.c

@@ -23,7 +23,7 @@ git_tree *resolve_commit_oid_to_tree(
 
 int diff_file_fn(
 	void *cb_data,
-	git_diff_delta *delta,
+	const git_diff_delta *delta,
 	float progress)
 {
 	diff_expects *e = cb_data;
@@ -48,8 +48,8 @@ int diff_file_fn(
 
 int diff_hunk_fn(
 	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	const char *header,
 	size_t header_len)
 {
@@ -67,8 +67,8 @@ int diff_hunk_fn(
 
 int diff_line_fn(
 	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	char line_origin,
 	const char *content,
 	size_t content_len)
@@ -116,7 +116,7 @@ int diff_foreach_via_iterator(
 
 	for (d = 0; d < num_d; ++d) {
 		git_diff_patch *patch;
-		git_diff_delta *delta;
+		const git_diff_delta *delta;
 		size_t h, num_h;
 
 		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
@@ -142,7 +142,7 @@ int diff_foreach_via_iterator(
 		num_h = git_diff_patch_num_hunks(patch);
 
 		for (h = 0; h < num_h; h++) {
-			git_diff_range *range;
+			const git_diff_range *range;
 			const char *hdr;
 			size_t hdr_len, l, num_l;
 

tests-clar/diff/diff_helpers.h

@@ -27,20 +27,20 @@ typedef struct {
 
 extern int diff_file_fn(
 	void *cb_data,
-	git_diff_delta *delta,
+	const git_diff_delta *delta,
 	float progress);
 
 extern int diff_hunk_fn(
 	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	const char *header,
 	size_t header_len);
 
 extern int diff_line_fn(
 	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	char line_origin,
 	const char *content,
 	size_t content_len);

tests-clar/diff/diffiter.c

@@ -20,7 +20,7 @@ void test_diff_diffiter__create(void)
 
 	num_d = git_diff_num_deltas(diff);
 	for (d = 0; d < num_d; ++d) {
-		git_diff_delta *delta;
+		const git_diff_delta *delta;
 		cl_git_pass(git_diff_get_patch(NULL, &delta, diff, d));
 	}
 
@@ -40,7 +40,7 @@ void test_diff_diffiter__iterate_files(void)
 	cl_assert_equal_i(6, num_d);
 
 	for (d = 0; d < num_d; ++d) {
-		git_diff_delta *delta;
+		const git_diff_delta *delta;
 		cl_git_pass(git_diff_get_patch(NULL, &delta, diff, d));
 		cl_assert(delta != NULL);
 		count++;
@@ -63,7 +63,7 @@ void test_diff_diffiter__iterate_files_2(void)
 	cl_assert_equal_i(8, num_d);
 
 	for (d = 0; d < num_d; ++d) {
-		git_diff_delta *delta;
+		const git_diff_delta *delta;
 		cl_git_pass(git_diff_get_patch(NULL, &delta, diff, d));
 		cl_assert(delta != NULL);
 		count++;
@@ -91,7 +91,7 @@ void test_diff_diffiter__iterate_files_and_hunks(void)
 
 	for (d = 0; d < num_d; ++d) {
 		git_diff_patch *patch;
-		git_diff_delta *delta;
+		const git_diff_delta *delta;
 		size_t h, num_h;
 
 		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
@@ -104,7 +104,7 @@ void test_diff_diffiter__iterate_files_and_hunks(void)
 		num_h = git_diff_patch_num_hunks(patch);
 
 		for (h = 0; h < num_h; h++) {
-			git_diff_range *range;
+			const git_diff_range *range;
 			const char *header;
 			size_t header_len, num_l;
 
@@ -143,7 +143,7 @@ void test_diff_diffiter__max_size_threshold(void)
 
 	for (d = 0; d < num_d; ++d) {
 		git_diff_patch *patch;
-		git_diff_delta *delta;
+		const git_diff_delta *delta;
 
 		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
 		cl_assert(delta);
@@ -178,7 +178,7 @@ void test_diff_diffiter__max_size_threshold(void)
 
 	for (d = 0; d < num_d; ++d) {
 		git_diff_patch *patch;
-		git_diff_delta *delta;
+		const git_diff_delta *delta;
 
 		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
 
@@ -221,7 +221,7 @@ void test_diff_diffiter__iterate_all(void)
 	num_d = git_diff_num_deltas(diff);
 	for (d = 0; d < num_d; ++d) {
 		git_diff_patch *patch;
-		git_diff_delta *delta;
+		const git_diff_delta *delta;
 		size_t h, num_h;
 
 		cl_git_pass(git_diff_get_patch(&patch, &delta, diff, d));
@@ -230,7 +230,7 @@ void test_diff_diffiter__iterate_all(void)
 
 		num_h = git_diff_patch_num_hunks(patch);
 		for (h = 0; h < num_h; h++) {
-			git_diff_range *range;
+			const git_diff_range *range;
 			const char *header;
 			size_t header_len, l, num_l;
 

tests-clar/diff/index.c

@@ -93,7 +93,7 @@ void test_diff_index__0(void)
 
 static int diff_stop_after_2_files(
 	void *cb_data,
-	git_diff_delta *delta,
+	const git_diff_delta *delta,
 	float progress)
 {
 	diff_expects *e = cb_data;

tests-clar/diff/patch.c

@@ -23,8 +23,8 @@ void test_diff_patch__cleanup(void)
 
 static int check_removal_cb(
 	void *cb_data,
-	git_diff_delta *delta,
-	git_diff_range *range,
+	const git_diff_delta *delta,
+	const git_diff_range *range,
 	char line_origin,
 	const char *formatted_output,
 	size_t output_len)

tests-clar/diff/tree.c

@@ -265,9 +265,9 @@ void test_diff_tree__larger_hunks(void)
 	git_diff_options opts = {0};
 	git_diff_list *diff = NULL;
 	size_t d, num_d, h, num_h, l, num_l, header_len, line_len;
-	git_diff_delta *delta;
+	const git_diff_delta *delta;
 	git_diff_patch *patch;
-	git_diff_range *range;
+	const git_diff_range *range;
 	const char *header, *line;
 	char origin;
 

tests-clar/diff/workdir.c

@@ -691,7 +691,7 @@ void test_diff_workdir__larger_hunks(void)
 	for (i = 0; i <= 2; ++i) {
 		git_diff_list *diff = NULL;
 		git_diff_patch *patch;
-		git_diff_range *range;
+		const git_diff_range *range;
 		const char *header, *line;
 		char origin;