1 files changed, 297 insertions, 107 deletions

diff --git a/diff.c b/diff.c
index 469e18aed2..472479eb10 100644
--- a/diff.c
+++ b/diff.c
@@ -1,34 +1,48 @@
 /*
  * Copyright (C) 2005 Junio C Hamano
  */
-#include "cache.h"
+
+#define USE_THE_REPOSITORY_VARIABLE
+
+#include "git-compat-util.h"
+#include "abspath.h"
+#include "base85.h"
 #include "config.h"
+#include "convert.h"
+#include "environment.h"
+#include "gettext.h"
 #include "tempfile.h"
 #include "quote.h"
 #include "diff.h"
 #include "diffcore.h"
 #include "delta.h"
+#include "hex.h"
 #include "xdiff-interface.h"
 #include "color.h"
-#include "attr.h"
 #include "run-command.h"
 #include "utf8.h"
-#include "object-store.h"
+#include "object-store-ll.h"
 #include "userdiff.h"
-#include "submodule-config.h"
 #include "submodule.h"
 #include "hashmap.h"
 #include "mem-pool.h"
-#include "ll-merge.h"
+#include "merge-ll.h"
 #include "string-list.h"
 #include "strvec.h"
 #include "graph.h"
+#include "oid-array.h"
 #include "packfile.h"
+#include "pager.h"
 #include "parse-options.h"
 #include "help.h"
 #include "promisor-remote.h"
 #include "dir.h"
+#include "object-file.h"
+#include "object-name.h"
+#include "read-cache-ll.h"
+#include "setup.h"
 #include "strmap.h"
+#include "ws.h"
 
 #ifdef NO_FAST_WORKING_DIRECTORY
 #define FAST_WORKING_DIRECTORY 0
@@ -45,13 +59,16 @@ static int diff_color_moved_default;
 static int diff_color_moved_ws_default;
 static int diff_context_default = 3;
 static int diff_interhunk_context_default;
-static const char *diff_word_regex_cfg;
-static const char *external_diff_cmd_cfg;
-static const char *diff_order_file_cfg;
+static char *diff_word_regex_cfg;
+static struct external_diff external_diff_cfg;
+static char *diff_order_file_cfg;
 int diff_auto_refresh_index = 1;
 static int diff_mnemonic_prefix;
 static int diff_no_prefix;
+static char *diff_src_prefix;
+static char *diff_dst_prefix;
 static int diff_relative;
+static int diff_stat_name_width;
 static int diff_stat_graph_width;
 static int diff_dirstat_permille_default = 30;
 static struct diff_options default_diff_options;
@@ -127,7 +144,7 @@ static int parse_dirstat_params(struct diff_options *options, const char *params
 	int i;
 
 	if (*params_copy)
-		string_list_split_in_place(&params, params_copy, ',', -1);
+		string_list_split_in_place(&params, params_copy, ",", -1);
 	for (i = 0; i < params.nr; i++) {
 		const char *p = params.items[i].string;
 		if (!strcmp(p, "changes")) {
@@ -343,7 +360,8 @@ static unsigned parse_color_moved_ws(const char *arg)
 	return ret;
 }
 
-int git_diff_ui_config(const char *var, const char *value, void *cb)
+int git_diff_ui_config(const char *var, const char *value,
+		       const struct config_context *ctx, void *cb)
 {
 	if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
 		diff_use_color_default = git_config_colorbool(var, value);
@@ -357,20 +375,24 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 	if (!strcmp(var, "diff.colormovedws")) {
-		unsigned cm = parse_color_moved_ws(value);
+		unsigned cm;
+		if (!value)
+			return config_error_nonbool(var);
+		cm = parse_color_moved_ws(value);
 		if (cm & COLOR_MOVED_WS_ERROR)
 			return -1;
 		diff_color_moved_ws_default = cm;
 		return 0;
 	}
 	if (!strcmp(var, "diff.context")) {
-		diff_context_default = git_config_int(var, value);
+		diff_context_default = git_config_int(var, value, ctx->kvi);
 		if (diff_context_default < 0)
 			return -1;
 		return 0;
 	}
 	if (!strcmp(var, "diff.interhunkcontext")) {
-		diff_interhunk_context_default = git_config_int(var, value);
+		diff_interhunk_context_default = git_config_int(var, value,
+								ctx->kvi);
 		if (diff_interhunk_context_default < 0)
 			return -1;
 		return 0;
@@ -391,25 +413,46 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 		diff_no_prefix = git_config_bool(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "diff.srcprefix")) {
+		FREE_AND_NULL(diff_src_prefix);
+		return git_config_string(&diff_src_prefix, var, value);
+	}
+	if (!strcmp(var, "diff.dstprefix")) {
+		FREE_AND_NULL(diff_dst_prefix);
+		return git_config_string(&diff_dst_prefix, var, value);
+	}
 	if (!strcmp(var, "diff.relative")) {
 		diff_relative = git_config_bool(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "diff.statnamewidth")) {
+		diff_stat_name_width = git_config_int(var, value, ctx->kvi);
+		return 0;
+	}
 	if (!strcmp(var, "diff.statgraphwidth")) {
-		diff_stat_graph_width = git_config_int(var, value);
+		diff_stat_graph_width = git_config_int(var, value, ctx->kvi);
 		return 0;
 	}
 	if (!strcmp(var, "diff.external"))
-		return git_config_string(&external_diff_cmd_cfg, var, value);
+		return git_config_string(&external_diff_cfg.cmd, var, value);
+	if (!strcmp(var, "diff.trustexitcode")) {
+		external_diff_cfg.trust_exit_code = git_config_bool(var, value);
+		return 0;
+	}
 	if (!strcmp(var, "diff.wordregex"))
 		return git_config_string(&diff_word_regex_cfg, var, value);
 	if (!strcmp(var, "diff.orderfile"))
 		return git_config_pathname(&diff_order_file_cfg, var, value);
 
-	if (!strcmp(var, "diff.ignoresubmodules"))
+	if (!strcmp(var, "diff.ignoresubmodules")) {
+		if (!value)
+			return config_error_nonbool(var);
 		handle_ignore_submodules_arg(&default_diff_options, value);
+	}
 
 	if (!strcmp(var, "diff.submodule")) {
+		if (!value)
+			return config_error_nonbool(var);
 		if (parse_submodule_params(&default_diff_options, value))
 			warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
 				value);
@@ -417,24 +460,28 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 	}
 
 	if (!strcmp(var, "diff.algorithm")) {
+		if (!value)
+			return config_error_nonbool(var);
 		diff_algorithm = parse_algorithm_value(value);
 		if (diff_algorithm < 0)
-			return -1;
+			return error(_("unknown value for config '%s': %s"),
+				     var, value);
 		return 0;
 	}
 
 	if (git_color_config(var, value, cb) < 0)
 		return -1;
 
-	return git_diff_basic_config(var, value, cb);
+	return git_diff_basic_config(var, value, ctx, cb);
 }
 
-int git_diff_basic_config(const char *var, const char *value, void *cb)
+int git_diff_basic_config(const char *var, const char *value,
+			  const struct config_context *ctx, void *cb)
 {
 	const char *name;
 
 	if (!strcmp(var, "diff.renamelimit")) {
-		diff_rename_limit_default = git_config_int(var, value);
+		diff_rename_limit_default = git_config_int(var, value, ctx->kvi);
 		return 0;
 	}
 
@@ -452,9 +499,13 @@ int git_diff_basic_config(const char *var, const char *value, void *cb)
 	}
 
 	if (!strcmp(var, "diff.wserrorhighlight")) {
-		int val = parse_ws_error_highlight(value);
+		int val;
+		if (!value)
+			return config_error_nonbool(var);
+		val = parse_ws_error_highlight(value);
 		if (val < 0)
-			return -1;
+			return error(_("unknown value for config '%s': %s"),
+				     var, value);
 		ws_error_highlight_default = val;
 		return 0;
 	}
@@ -469,6 +520,8 @@ int git_diff_basic_config(const char *var, const char *value, void *cb)
 
 	if (!strcmp(var, "diff.dirstat")) {
 		struct strbuf errmsg = STRBUF_INIT;
+		if (!value)
+			return config_error_nonbool(var);
 		default_diff_options.dirstat_permille = diff_dirstat_permille_default;
 		if (parse_dirstat_params(&default_diff_options, value, &errmsg))
 			warning(_("Found errors in 'diff.dirstat' config variable:\n%s"),
@@ -481,7 +534,7 @@ int git_diff_basic_config(const char *var, const char *value, void *cb)
 	if (git_diff_heuristic_config(var, value, cb) < 0)
 		return -1;
 
-	return git_default_config(var, value, cb);
+	return git_default_config(var, value, ctx, cb);
 }
 
 static char *quote_two(const char *one, const char *two)
@@ -502,18 +555,22 @@ static char *quote_two(const char *one, const char *two)
 	return strbuf_detach(&res, NULL);
 }
 
-static const char *external_diff(void)
+static const struct external_diff *external_diff(void)
 {
-	static const char *external_diff_cmd = NULL;
+	static struct external_diff external_diff_env, *external_diff_ptr;
 	static int done_preparing = 0;
 
 	if (done_preparing)
-		return external_diff_cmd;
-	external_diff_cmd = xstrdup_or_null(getenv("GIT_EXTERNAL_DIFF"));
-	if (!external_diff_cmd)
-		external_diff_cmd = external_diff_cmd_cfg;
+		return external_diff_ptr;
+	external_diff_env.cmd = xstrdup_or_null(getenv("GIT_EXTERNAL_DIFF"));
+	if (git_env_bool("GIT_EXTERNAL_DIFF_TRUST_EXIT_CODE", 0))
+		external_diff_env.trust_exit_code = 1;
+	if (external_diff_env.cmd)
+		external_diff_ptr = &external_diff_env;
+	else if (external_diff_cfg.cmd)
+		external_diff_ptr = &external_diff_cfg;
 	done_preparing = 1;
-	return external_diff_cmd;
+	return external_diff_ptr;
 }
 
 /*
@@ -2688,12 +2745,14 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 	number_width = decimal_width(max_change) > number_width ?
 		decimal_width(max_change) : number_width;
 
+	if (options->stat_name_width == -1)
+		options->stat_name_width = diff_stat_name_width;
 	if (options->stat_graph_width == -1)
 		options->stat_graph_width = diff_stat_graph_width;
 
 	/*
-	 * Guarantee 3/8*16==6 for the graph part
-	 * and 5/8*16==10 for the filename part
+	 * Guarantee 3/8*16 == 6 for the graph part
+	 * and 5/8*16 == 10 for the filename part
 	 */
 	if (width < 16 + 6 + number_width)
 		width = 16 + 6 + number_width;
@@ -2993,6 +3052,24 @@ static int dirstat_compare(const void *_a, const void *_b)
 	return strcmp(a->name, b->name);
 }
 
+static void conclude_dirstat(struct diff_options *options,
+			     struct dirstat_dir *dir,
+			     unsigned long changed)
+{
+	struct dirstat_file *to_free = dir->files;
+
+	if (!changed) {
+		/* This can happen even with many files, if everything was renames */
+		;
+	} else {
+		/* Show all directories with more than x% of the changes */
+		QSORT(dir->files, dir->nr, dirstat_compare);
+		gather_dirstat(options, dir, changed, "", 0);
+	}
+
+	free(to_free);
+}
+
 static void show_dirstat(struct diff_options *options)
 {
 	int i;
@@ -3082,13 +3159,7 @@ found_damage:
 		dir.nr++;
 	}
 
-	/* This can happen even with many files, if everything was renames */
-	if (!changed)
-		return;
-
-	/* Show all directories with more than x% of the changes */
-	QSORT(dir.files, dir.nr, dirstat_compare);
-	gather_dirstat(options, &dir, changed, "", 0);
+	conclude_dirstat(options, &dir, changed);
 }
 
 static void show_dirstat_by_line(struct diffstat_t *data, struct diff_options *options)
@@ -3126,13 +3197,7 @@ static void show_dirstat_by_line(struct diffstat_t *data, struct diff_options *o
 		dir.nr++;
 	}
 
-	/* This can happen even with many files, if everything was renames */
-	if (!changed)
-		return;
-
-	/* Show all directories with more than x% of the changes */
-	QSORT(dir.files, dir.nr, dirstat_compare);
-	gather_dirstat(options, &dir, changed, "", 0);
+	conclude_dirstat(options, &dir, changed);
 }
 
 static void free_diffstat_file(struct diffstat_file *f)
@@ -3374,6 +3439,17 @@ void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const
 		options->b_prefix = b;
 }
 
+void diff_set_noprefix(struct diff_options *options)
+{
+	options->a_prefix = options->b_prefix = "";
+}
+
+void diff_set_default_prefix(struct diff_options *options)
+{
+	options->a_prefix = diff_src_prefix ? diff_src_prefix : "a/";
+	options->b_prefix = diff_dst_prefix ? diff_dst_prefix : "b/";
+}
+
 struct userdiff_driver *get_textconv(struct repository *r,
 				     struct diff_filespec *one)
 {
@@ -3489,6 +3565,7 @@ static void builtin_diff(const char *name_a,
 		show_submodule_diff_summary(o, one->path ? one->path : two->path,
 				&one->oid, &two->oid,
 				two->dirty_submodule);
+		o->found_changes = 1;
 		return;
 	} else if (o->submodule_format == DIFF_SUBMODULE_INLINE_DIFF &&
 		   (!one->mode || S_ISGITLINK(one->mode)) &&
@@ -3497,6 +3574,7 @@ static void builtin_diff(const char *name_a,
 		show_submodule_inline_diff(o, one->path ? one->path : two->path,
 				&one->oid, &two->oid,
 				two->dirty_submodule);
+		o->found_changes = 1;
 		return;
 	}
 
@@ -3530,18 +3608,21 @@ static void builtin_diff(const char *name_a,
 		strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, meta, two->mode, reset);
 		if (xfrm_msg)
 			strbuf_addstr(&header, xfrm_msg);
+		o->found_changes = 1;
 		must_show_header = 1;
 	}
 	else if (lbl[1][0] == '/') {
 		strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, meta, one->mode, reset);
 		if (xfrm_msg)
 			strbuf_addstr(&header, xfrm_msg);
+		o->found_changes = 1;
 		must_show_header = 1;
 	}
 	else {
 		if (one->mode != two->mode) {
 			strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, meta, one->mode, reset);
 			strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, meta, two->mode, reset);
+			o->found_changes = 1;
 			must_show_header = 1;
 		}
 		if (xfrm_msg)
@@ -3696,7 +3777,7 @@ static void builtin_diff(const char *name_a,
 	return;
 }
 
-static char *get_compact_summary(const struct diff_filepair *p, int is_renamed)
+static const char *get_compact_summary(const struct diff_filepair *p, int is_renamed)
 {
 	if (!is_renamed) {
 		if (p->status == DIFF_STATUS_ADDED) {
@@ -4008,7 +4089,7 @@ static int reuse_worktree_file(struct index_state *istate,
 static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
 {
 	struct strbuf buf = STRBUF_INIT;
-	char *dirty = "";
+	const char *dirty = "";
 
 	/* Are we looking at the work tree? */
 	if (s->dirty_submodule)
@@ -4307,7 +4388,7 @@ static void add_external_diff_name(struct repository *r,
  *               infile2 infile2-sha1 infile2-mode [ rename-to ]
  *
  */
-static void run_external_diff(const char *pgm,
+static void run_external_diff(const struct external_diff *pgm,
 			      const char *name,
 			      const char *other,
 			      struct diff_filespec *one,
@@ -4317,8 +4398,21 @@ static void run_external_diff(const char *pgm,
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	struct diff_queue_struct *q = &diff_queued_diff;
+	int quiet = !(o->output_format & DIFF_FORMAT_PATCH);
+	int rc;
 
-	strvec_push(&cmd.args, pgm);
+	/*
+	 * Trivial equality is handled by diff_unmodified_pair() before
+	 * we get here.  If we don't need to show the diff and the
+	 * external diff program lacks the ability to tell us whether
+	 * it's empty then we consider it non-empty without even asking.
+	 */
+	if (!pgm->trust_exit_code && quiet) {
+		o->found_changes = 1;
+		return;
+	}
+
+	strvec_push(&cmd.args, pgm->cmd);
 	strvec_push(&cmd.args, name);
 
 	if (one && two) {
@@ -4326,7 +4420,8 @@ static void run_external_diff(const char *pgm,
 		add_external_diff_name(o->repo, &cmd.args, two);
 		if (other) {
 			strvec_push(&cmd.args, other);
-			strvec_push(&cmd.args, xfrm_msg);
+			if (xfrm_msg)
+				strvec_push(&cmd.args, xfrm_msg);
 		}
 	}
 
@@ -4337,7 +4432,15 @@ static void run_external_diff(const char *pgm,
 	diff_free_filespec_data(one);
 	diff_free_filespec_data(two);
 	cmd.use_shell = 1;
-	if (run_command(&cmd))
+	cmd.no_stdout = quiet;
+	rc = run_command(&cmd);
+	if (!pgm->trust_exit_code && rc == 0)
+		o->found_changes = 1;
+	else if (pgm->trust_exit_code && rc == 0)
+		; /* nothing */
+	else if (pgm->trust_exit_code && rc == 1)
+		o->found_changes = 1;
+	else
 		die(_("external diff died, stopping at %s"), name);
 
 	remove_tempfile();
@@ -4351,7 +4454,7 @@ static int similarity_index(struct diff_filepair *p)
 static const char *diff_abbrev_oid(const struct object_id *oid, int abbrev)
 {
 	if (startup_info->have_repository)
-		return find_unique_abbrev(oid, abbrev);
+		return repo_find_unique_abbrev(the_repository, oid, abbrev);
 	else {
 		char *hex = oid_to_hex(oid);
 		if (abbrev < 0)
@@ -4443,7 +4546,7 @@ static void fill_metainfo(struct strbuf *msg,
 	}
 }
 
-static void run_diff_cmd(const char *pgm,
+static void run_diff_cmd(const struct external_diff *pgm,
 			 const char *name,
 			 const char *other,
 			 const char *attr_path,
@@ -4461,8 +4564,8 @@ static void run_diff_cmd(const char *pgm,
 	if (o->flags.allow_external || !o->ignore_driver_algorithm)
 		drv = userdiff_find_by_path(o->repo->index, attr_path);
 
-	if (o->flags.allow_external && drv && drv->external)
-		pgm = drv->external;
+	if (o->flags.allow_external && drv && drv->external.cmd)
+		pgm = &drv->external;
 
 	if (msg) {
 		/*
@@ -4486,8 +4589,12 @@ static void run_diff_cmd(const char *pgm,
 		builtin_diff(name, other ? other : name,
 			     one, two, xfrm_msg, must_show_header,
 			     o, complete_rewrite);
+		if (p->status == DIFF_STATUS_COPIED ||
+		    p->status == DIFF_STATUS_RENAMED)
+			o->found_changes = 1;
 	} else {
 		fprintf(o->file, "* Unmerged path %s\n", name);
+		o->found_changes = 1;
 	}
 }
 
@@ -4497,7 +4604,7 @@ static void diff_fill_oid_info(struct diff_filespec *one, struct index_state *is
 		if (!one->oid_valid) {
 			struct stat st;
 			if (one->is_stdin) {
-				oidclr(&one->oid);
+				oidclr(&one->oid, the_repository->hash_algo);
 				return;
 			}
 			if (lstat(one->path, &st) < 0)
@@ -4507,7 +4614,7 @@ static void diff_fill_oid_info(struct diff_filespec *one, struct index_state *is
 		}
 	}
 	else
-		oidclr(&one->oid);
+		oidclr(&one->oid, the_repository->hash_algo);
 }
 
 static void strip_prefix(int prefix_length, const char **namep, const char **otherp)
@@ -4527,7 +4634,7 @@ static void strip_prefix(int prefix_length, const char **namep, const char **oth
 
 static void run_diff(struct diff_filepair *p, struct diff_options *o)
 {
-	const char *pgm = external_diff();
+	const struct external_diff *pgm = external_diff();
 	struct strbuf msg;
 	struct diff_filespec *one = p->one;
 	struct diff_filespec *two = p->two;
@@ -4674,10 +4781,9 @@ void repo_diff_setup(struct repository *r, struct diff_options *options)
 		options->flags.ignore_untracked_in_submodules = 1;
 
 	if (diff_no_prefix) {
-		options->a_prefix = options->b_prefix = "";
+		diff_set_noprefix(options);
 	} else if (!diff_mnemonic_prefix) {
-		options->a_prefix = "a/";
-		options->b_prefix = "b/";
+		diff_set_default_prefix(options);
 	}
 
 	options->color_moved = diff_color_moved_default;
@@ -4721,6 +4827,31 @@ unsigned diff_filter_bit(char status)
 	return filter_bit[(int) status];
 }
 
+int diff_check_follow_pathspec(struct pathspec *ps, int die_on_error)
+{
+	unsigned forbidden_magic;
+
+	if (ps->nr != 1) {
+		if (die_on_error)
+			die(_("--follow requires exactly one pathspec"));
+		return 0;
+	}
+
+	forbidden_magic = ps->items[0].magic & ~(PATHSPEC_FROMTOP |
+						 PATHSPEC_LITERAL);
+	if (forbidden_magic) {
+		if (die_on_error) {
+			struct strbuf sb = STRBUF_INIT;
+			pathspec_magic_names(forbidden_magic, &sb);
+			die(_("pathspec magic not supported by --follow: %s"),
+			    sb.buf);
+		}
+		return 0;
+	}
+
+	return 1;
+}
+
 void diff_setup_done(struct diff_options *options)
 {
 	unsigned check_mask = DIFF_FORMAT_NAME |
@@ -4775,6 +4906,10 @@ void diff_setup_done(struct diff_options *options)
 	else
 		options->prefix_length = 0;
 
+	/*
+	 * --name-only, --name-status, --checkdiff, and -s
+	 * turn other output format off.
+	 */
 	if (options->output_format & (DIFF_FORMAT_NAME |
 				      DIFF_FORMAT_NAME_STATUS |
 				      DIFF_FORMAT_CHECKDIFF |
@@ -4826,12 +4961,20 @@ void diff_setup_done(struct diff_options *options)
 		options->flags.exit_with_status = 1;
 	}
 
+	/*
+	 * External diffs could declare non-identical contents equal
+	 * (think diff --ignore-space-change).
+	 */
+	if (options->flags.allow_external && options->flags.exit_with_status)
+		options->flags.diff_from_contents = 1;
+
 	options->diff_path_counter = 0;
 
-	if (options->flags.follow_renames && options->pathspec.nr != 1)
-		die(_("--follow requires exactly one pathspec"));
+	if (options->flags.follow_renames)
+		diff_check_follow_pathspec(&options->pathspec, 1);
 
-	if (!options->use_color || external_diff())
+	if (!options->use_color ||
+	    (options->flags.allow_external && external_diff()))
 		options->color_moved = 0;
 
 	if (options->filter_not) {
@@ -4906,6 +5049,7 @@ static int diff_opt_stat(const struct option *opt, const char *value, int unset)
 	} else
 		BUG("%s should not get here", opt->long_name);
 
+	options->output_format &= ~DIFF_FORMAT_NO_OUTPUT;
 	options->output_format |= DIFF_FORMAT_DIFFSTAT;
 	options->stat_name_width = name_width;
 	options->stat_graph_width = graph_width;
@@ -4925,6 +5069,7 @@ static int parse_dirstat_opt(struct diff_options *options, const char *params)
 	 * The caller knows a dirstat-related option is given from the command
 	 * line; allow it to say "return this_function();"
 	 */
+	options->output_format &= ~DIFF_FORMAT_NO_OUTPUT;
 	options->output_format |= DIFF_FORMAT_DIRSTAT;
 	return 1;
 }
@@ -4988,7 +5133,7 @@ static int diff_opt_find_object(const struct option *option,
 	struct object_id oid;
 
 	BUG_ON_OPT_NEG(unset);
-	if (get_oid(arg, &oid))
+	if (repo_get_oid(the_repository, arg, &oid))
 		return error(_("unable to resolve '%s'"), arg);
 
 	if (!opt->objfind)
@@ -5124,6 +5269,7 @@ static int diff_opt_compact_summary(const struct option *opt,
 		options->flags.stat_with_summary = 0;
 	} else {
 		options->flags.stat_with_summary = 1;
+		options->output_format &= ~DIFF_FORMAT_NO_OUTPUT;
 		options->output_format |= DIFF_FORMAT_DIFFSTAT;
 	}
 	return 0;
@@ -5261,8 +5407,20 @@ static int diff_opt_no_prefix(const struct option *opt,
 
 	BUG_ON_OPT_NEG(unset);
 	BUG_ON_OPT_ARG(optarg);
-	options->a_prefix = "";
-	options->b_prefix = "";
+	diff_set_noprefix(options);
+	return 0;
+}
+
+static int diff_opt_default_prefix(const struct option *opt,
+				   const char *optarg, int unset)
+{
+	struct diff_options *options = opt->value;
+
+	BUG_ON_OPT_NEG(unset);
+	BUG_ON_OPT_ARG(optarg);
+	FREE_AND_NULL(diff_src_prefix);
+	FREE_AND_NULL(diff_dst_prefix);
+	diff_set_default_prefix(options);
 	return 0;
 }
 
@@ -5311,9 +5469,13 @@ static int diff_opt_ignore_regex(const struct option *opt,
 	regex_t *regex;
 
 	BUG_ON_OPT_NEG(unset);
+
 	regex = xmalloc(sizeof(*regex));
-	if (regcomp(regex, arg, REG_EXTENDED | REG_NEWLINE))
+	if (regcomp(regex, arg, REG_EXTENDED | REG_NEWLINE)) {
+		free(regex);
 		return error(_("invalid regex given to -I: '%s'"), arg);
+	}
+
 	ALLOC_GROW(options->ignore_regex, options->ignore_regex_nr + 1,
 		   options->ignore_regex_alloc);
 	options->ignore_regex[options->ignore_regex_nr++] = regex;
@@ -5451,6 +5613,10 @@ static int diff_opt_rotate_to(const struct option *opt, const char *arg, int uns
 	return 0;
 }
 
+/*
+ * Consider adding new flags to __git_diff_common_options
+ * in contrib/completion/git-completion.bash
+ */
 struct option *add_diff_options(const struct option *opts,
 				struct diff_options *options)
 {
@@ -5459,9 +5625,8 @@ struct option *add_diff_options(const struct option *opts,
 		OPT_BITOP('p', "patch", &options->output_format,
 			  N_("generate patch"),
 			  DIFF_FORMAT_PATCH, DIFF_FORMAT_NO_OUTPUT),
-		OPT_BIT_F('s', "no-patch", &options->output_format,
-			  N_("suppress diff output"),
-			  DIFF_FORMAT_NO_OUTPUT, PARSE_OPT_NONEG),
+		OPT_SET_INT('s', "no-patch", &options->output_format,
+			    N_("suppress diff output"), DIFF_FORMAT_NO_OUTPUT),
 		OPT_BITOP('u', NULL, &options->output_format,
 			  N_("generate patch"),
 			  DIFF_FORMAT_PATCH, DIFF_FORMAT_NO_OUTPUT),
@@ -5470,9 +5635,9 @@ struct option *add_diff_options(const struct option *opts,
 			       PARSE_OPT_NONEG | PARSE_OPT_OPTARG, diff_opt_unified),
 		OPT_BOOL('W', "function-context", &options->flags.funccontext,
 			 N_("generate diffs with <n> lines context")),
-		OPT_BIT_F(0, "raw", &options->output_format,
+		OPT_BITOP(0, "raw", &options->output_format,
 			  N_("generate the diff in raw format"),
-			  DIFF_FORMAT_RAW, PARSE_OPT_NONEG),
+			  DIFF_FORMAT_RAW, DIFF_FORMAT_NO_OUTPUT),
 		OPT_BITOP(0, "patch-with-raw", &options->output_format,
 			  N_("synonym for '-p --raw'"),
 			  DIFF_FORMAT_PATCH | DIFF_FORMAT_RAW,
@@ -5481,13 +5646,13 @@ struct option *add_diff_options(const struct option *opts,
 			  N_("synonym for '-p --stat'"),
 			  DIFF_FORMAT_PATCH | DIFF_FORMAT_DIFFSTAT,
 			  DIFF_FORMAT_NO_OUTPUT),
-		OPT_BIT_F(0, "numstat", &options->output_format,
+		OPT_BITOP(0, "numstat", &options->output_format,
 			  N_("machine friendly --stat"),
-			  DIFF_FORMAT_NUMSTAT, PARSE_OPT_NONEG),
-		OPT_BIT_F(0, "shortstat", &options->output_format,
+			  DIFF_FORMAT_NUMSTAT, DIFF_FORMAT_NO_OUTPUT),
+		OPT_BITOP(0, "shortstat", &options->output_format,
 			  N_("output only the last line of --stat"),
-			  DIFF_FORMAT_SHORTSTAT, PARSE_OPT_NONEG),
-		OPT_CALLBACK_F('X', "dirstat", options, N_("<param1,param2>..."),
+			  DIFF_FORMAT_SHORTSTAT, DIFF_FORMAT_NO_OUTPUT),
+		OPT_CALLBACK_F('X', "dirstat", options, N_("<param1>,<param2>..."),
 			       N_("output the distribution of relative amount of changes for each sub-directory"),
 			       PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
 			       diff_opt_dirstat),
@@ -5495,16 +5660,16 @@ struct option *add_diff_options(const struct option *opts,
 			       N_("synonym for --dirstat=cumulative"),
 			       PARSE_OPT_NONEG | PARSE_OPT_NOARG,
 			       diff_opt_dirstat),
-		OPT_CALLBACK_F(0, "dirstat-by-file", options, N_("<param1,param2>..."),
-			       N_("synonym for --dirstat=files,param1,param2..."),
+		OPT_CALLBACK_F(0, "dirstat-by-file", options, N_("<param1>,<param2>..."),
+			       N_("synonym for --dirstat=files,<param1>,<param2>..."),
 			       PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
 			       diff_opt_dirstat),
 		OPT_BIT_F(0, "check", &options->output_format,
 			  N_("warn if changes introduce conflict markers or whitespace errors"),
 			  DIFF_FORMAT_CHECKDIFF, PARSE_OPT_NONEG),
-		OPT_BIT_F(0, "summary", &options->output_format,
+		OPT_BITOP(0, "summary", &options->output_format,
 			  N_("condensed summary such as creations, renames and mode changes"),
-			  DIFF_FORMAT_SUMMARY, PARSE_OPT_NONEG),
+			  DIFF_FORMAT_SUMMARY, DIFF_FORMAT_NO_OUTPUT),
 		OPT_BIT_F(0, "name-only", &options->output_format,
 			  N_("show only names of changed files"),
 			  DIFF_FORMAT_NAME, PARSE_OPT_NONEG),
@@ -5555,6 +5720,9 @@ struct option *add_diff_options(const struct option *opts,
 		OPT_CALLBACK_F(0, "no-prefix", options, NULL,
 			       N_("do not show any source or destination prefix"),
 			       PARSE_OPT_NONEG | PARSE_OPT_NOARG, diff_opt_no_prefix),
+		OPT_CALLBACK_F(0, "default-prefix", options, NULL,
+			       N_("use default prefixes a/ and b/"),
+			       PARSE_OPT_NONEG | PARSE_OPT_NOARG, diff_opt_default_prefix),
 		OPT_INTEGER_F(0, "inter-hunk-context", &options->interhunkcontext,
 			      N_("show context between diff hunks up to the specified number of lines"),
 			      PARSE_OPT_NONEG),
@@ -6130,6 +6298,8 @@ static void flush_one_pair(struct diff_filepair *p, struct diff_options *opt)
 		fprintf(opt->file, "%s", diff_line_prefix(opt));
 		write_name_quoted(name_a, opt->file, opt->line_termination);
 	}
+
+	opt->found_changes = 1;
 }
 
 static void show_file_mode_name(struct diff_options *opt, const char *newdelete, struct diff_filespec *fs)
@@ -6283,7 +6453,7 @@ static int diff_get_patch_id(struct diff_options *options, struct object_id *oid
 	the_hash_algo->init_fn(&ctx);
 	memset(&data, 0, sizeof(struct patch_id_t));
 	data.ctx = &ctx;
-	oidclr(oid);
+	oidclr(oid, the_repository->hash_algo);
 
 	for (i = 0; i < q->nr; i++) {
 		xpparam_t xpp;
@@ -6528,8 +6698,10 @@ static void diff_flush_patch_all_file_pairs(struct diff_options *o)
 
 static void diff_free_file(struct diff_options *options)
 {
-	if (options->close_file)
+	if (options->close_file && options->file) {
 		fclose(options->file);
+		options->file = NULL;
+	}
 }
 
 static void diff_free_ignore_regex(struct diff_options *options)
@@ -6540,7 +6712,9 @@ static void diff_free_ignore_regex(struct diff_options *options)
 		regfree(options->ignore_regex[i]);
 		free(options->ignore_regex[i]);
 	}
-	free(options->ignore_regex);
+
+	FREE_AND_NULL(options->ignore_regex);
+	options->ignore_regex_nr = 0;
 }
 
 void diff_free(struct diff_options *options)
@@ -6548,6 +6722,16 @@ void diff_free(struct diff_options *options)
 	if (options->no_free)
 		return;
 
+	if (options->objfind) {
+		oidset_clear(options->objfind);
+		FREE_AND_NULL(options->objfind);
+	}
+
+	for (size_t i = 0; i < options->anchors_nr; i++)
+		free(options->anchors[i]);
+	FREE_AND_NULL(options->anchors);
+	options->anchors_nr = options->anchors_alloc = 0;
+
 	diff_free_file(options);
 	diff_free_ignore_regex(options);
 	clear_pathspec(&options->pathspec);
@@ -6608,6 +6792,21 @@ void diff_flush(struct diff_options *options)
 		separator++;
 	}
 
+	if (output_format & DIFF_FORMAT_PATCH) {
+		if (separator) {
+			emit_diff_symbol(options, DIFF_SYMBOL_SEPARATOR, NULL, 0, 0);
+			if (options->stat_sep)
+				/* attach patch instead of inline */
+				emit_diff_symbol(options, DIFF_SYMBOL_STAT_SEP,
+						 NULL, 0, 0);
+		}
+
+		diff_flush_patch_all_file_pairs(options);
+	}
+
+	if (output_format & DIFF_FORMAT_CALLBACK)
+		options->format_callback(q, options, options->format_callback_data);
+
 	if (output_format & DIFF_FORMAT_NO_OUTPUT &&
 	    options->flags.exit_with_status &&
 	    options->flags.diff_from_contents) {
@@ -6629,21 +6828,6 @@ void diff_flush(struct diff_options *options)
 		}
 	}
 
-	if (output_format & DIFF_FORMAT_PATCH) {
-		if (separator) {
-			emit_diff_symbol(options, DIFF_SYMBOL_SEPARATOR, NULL, 0, 0);
-			if (options->stat_sep)
-				/* attach patch instead of inline */
-				emit_diff_symbol(options, DIFF_SYMBOL_STAT_SEP,
-						 NULL, 0, 0);
-		}
-
-		diff_flush_patch_all_file_pairs(options);
-	}
-
-	if (output_format & DIFF_FORMAT_CALLBACK)
-		options->format_callback(q, options, options->format_callback_data);
-
 free_queue:
 	diff_free_queue(q);
 	DIFF_QUEUE_CLEAR(q);
@@ -6844,6 +7028,13 @@ void diff_queued_diff_prefetch(void *repository)
 	oid_array_clear(&to_fetch);
 }
 
+void init_diffstat_widths(struct diff_options *options)
+{
+	options->stat_width = -1;        /* use full terminal width */
+	options->stat_name_width = -1;   /* respect diff.statNameWidth config */
+	options->stat_graph_width = -1;  /* respect diff.statGraphWidth config */
+}
+
 void diffcore_std(struct diff_options *options)
 {
 	int output_formats_to_prefetch = DIFF_FORMAT_DIFFSTAT |
@@ -6860,7 +7051,7 @@ void diffcore_std(struct diff_options *options)
 	 * If no prefetching occurs, diffcore_rename() will prefetch if it
 	 * decides that it needs inexact rename detection.
 	 */
-	if (options->repo == the_repository && has_promisor_remote() &&
+	if (options->repo == the_repository && repo_has_promisor_remote(the_repository) &&
 	    (options->output_format & output_formats_to_prefetch ||
 	     options->pickaxe_opts & DIFF_PICKAXE_KINDS_MASK))
 		diff_queued_diff_prefetch(options->repo);
@@ -6897,16 +7088,14 @@ void diffcore_std(struct diff_options *options)
 	options->found_follow = 0;
 }
 
-int diff_result_code(struct diff_options *opt, int status)
+int diff_result_code(struct diff_options *opt)
 {
 	int result = 0;
 
 	diff_warn_rename_limit("diff.renameLimit",
 			       opt->needed_rename_limit,
 			       opt->degraded_cc_to_c);
-	if (!opt->flags.exit_with_status &&
-	    !(opt->output_format & DIFF_FORMAT_CHECKDIFF))
-		return status;
+
 	if (opt->flags.exit_with_status &&
 	    opt->flags.has_changes)
 		result |= 01;
@@ -6953,6 +7142,7 @@ void compute_diffstat(struct diff_options *options,
 		if (check_pair_status(p))
 			diff_flush_stat(p, options, diffstat);
 	}
+	options->found_changes = !!diffstat->nr;
 }
 
 void diff_addremove(struct diff_options *options,
@@ -7108,7 +7298,7 @@ size_t fill_textconv(struct repository *r,
 
 	if (!driver) {
 		if (!DIFF_FILE_VALID(df)) {
-			*outbuf = "";
+			*outbuf = (char *) "";
 			return 0;
 		}
 		if (diff_populate_filespec(r, df, NULL))