Merge branch 'ly/diff-name-only-with-diff-from-content' into seen

Various options to "git diff" that makes comparison ignore certain
aspects of the differences (like "space changes are ignored",
"differences in lines that match these regular expressions are
ignored") did not work well with "--name-only" and friends.

Looking better.

* ly/diff-name-only-with-diff-from-content:
  fixup! diff: ensure consistent diff behavior with ignore options
  diff: ensure consistent diff behavior with ignore options

Author: gitster

diff.c

@@ -2438,6 +2438,15 @@ static int fn_out_consume(void *priv, char *line, unsigned long len)
 	return 0;
 }
 
+static int quick_consume(void *priv, char *line UNUSED, unsigned long len UNUSED)
+{
+	struct emit_callback *ecbdata = priv;
+	struct diff_options *o = ecbdata->opt;
+
+	o->found_changes = 1;
+	return 1;
+}
+
 static void pprint_rename(struct strbuf *name, const char *a, const char *b)
 {
 	const char *old_name = a;
@@ -3703,6 +3712,7 @@ static void builtin_diff(const char *name_a,
 		xdemitconf_t xecfg;
 		struct emit_callback ecbdata;
 		const struct userdiff_funcname *pe;
+		int dry_run = o->diff_optimize == DIFF_OPT_DRY_RUN;
 
 		if (must_show_header) {
 			emit_diff_symbol(o, DIFF_SYMBOL_HEADER,
@@ -3735,16 +3745,17 @@ static void builtin_diff(const char *name_a,
 		xpp.ignore_regex_nr = o->ignore_regex_nr;
 		xpp.anchors = o->anchors;
 		xpp.anchors_nr = o->anchors_nr;
-		xecfg.ctxlen = o->context;
-		xecfg.interhunkctxlen = o->interhunkcontext;
+		xecfg.ctxlen = dry_run ? 0 : o->context;
+		xecfg.interhunkctxlen = dry_run ? 0 : o->interhunkcontext;
 		xecfg.flags = XDL_EMIT_FUNCNAMES;
 		if (o->flags.funccontext)
 			xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
 		if (pe)
 			xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
 
 		diffopts = getenv("GIT_DIFF_OPTS");
-		if (!diffopts)
+		/* ignore ctxlen if we are in dry run mode */
+		if (!diffopts || dry_run)
 			;
 		else if (skip_prefix(diffopts, "--unified=", &v))
 			xecfg.ctxlen = strtoul(v, NULL, 10);
@@ -3753,8 +3764,11 @@ static void builtin_diff(const char *name_a,
 
 		if (o->word_diff)
 			init_diff_words_data(&ecbdata, o, one, two);
-		if (xdi_diff_outf(&mf1, &mf2, NULL, fn_out_consume,
-				  &ecbdata, &xpp, &xecfg))
+		if (dry_run)
+			xdi_diff_outf(&mf1, &mf2, NULL, quick_consume,
+				      &ecbdata, &xpp, &xecfg);
+		else if (xdi_diff_outf(&mf1, &mf2, NULL, fn_out_consume,
+				       &ecbdata, &xpp, &xecfg))
 			die("unable to generate diff for %s", one->path);
 		if (o->word_diff)
 			free_diff_words_data(&ecbdata);
@@ -4985,6 +4999,8 @@ void diff_setup_done(struct diff_options *options)
 
 	if (options->pathspec.has_wildcard && options->max_depth_valid)
 		die("max-depth cannot be used with wildcard pathspecs");
+
+	options->diff_optimize = DIFF_OPT_NONE;
 }
 
 int parse_long_opt(const char *opt, const char **argv,
@@ -6163,6 +6179,22 @@ static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
 	run_diff(p, o);
 }
 
+/* return 1 if any change is found; otherwise, return 0 */
+static int diff_flush_patch_quiet(struct diff_filepair *p, struct diff_options *o)
+{
+	int diff_opt = o->diff_optimize;
+	int found_changes = o->found_changes;
+	int ret;
+
+	o->diff_optimize = DIFF_OPT_DRY_RUN;
+	o->found_changes = 0;
+	diff_flush_patch(p, o);
+	ret = o->found_changes;
+	o->diff_optimize = diff_opt;
+	o->found_changes |= found_changes;
+	return ret;
+}
+
 static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
 			    struct diffstat_t *diffstat)
 {
@@ -6791,7 +6823,19 @@ void diff_flush(struct diff_options *options)
 			     DIFF_FORMAT_CHECKDIFF)) {
 		for (i = 0; i < q->nr; i++) {
 			struct diff_filepair *p = q->queue[i];
-			if (check_pair_status(p))
+			int need_flush = 1;
+
+			if (!check_pair_status(p))
+				continue;
+
+			if (options->flags.diff_from_contents) {
+				if (diff_flush_patch_quiet(p, options))
+					need_flush = 1;
+				else
+					need_flush = 0;
+			}
+
+			if (need_flush)
 				flush_one_pair(p, options);
 		}
 		separator++;
@@ -6844,19 +6888,10 @@ void diff_flush(struct diff_options *options)
 	if (output_format & DIFF_FORMAT_NO_OUTPUT &&
 	    options->flags.exit_with_status &&
 	    options->flags.diff_from_contents) {
-		/*
-		 * run diff_flush_patch for the exit status. setting
-		 * options->file to /dev/null should be safe, because we
-		 * aren't supposed to produce any output anyway.
-		 */
-		diff_free_file(options);
-		options->file = xfopen("/dev/null", "w");
-		options->close_file = 1;
-		options->color_moved = 0;
 		for (i = 0; i < q->nr; i++) {
 			struct diff_filepair *p = q->queue[i];
 			if (check_pair_status(p))
-				diff_flush_patch(p, options);
+				diff_flush_patch_quiet(p, options);
 			if (options->found_changes)
 				break;
 		}

diff.h

@@ -400,6 +400,11 @@ struct diff_options {
 	#define COLOR_MOVED_WS_ERROR (1<<0)
 	unsigned color_moved_ws_handling;
 
+	enum {
+		DIFF_OPT_NONE = 0,
+		DIFF_OPT_DRY_RUN = 1,
+	} diff_optimize;
+
 	struct repository *repo;
 	struct strmap *additional_path_headers;
 

t/t4013-diff-various.sh

@@ -648,6 +648,20 @@ test_expect_success 'diff -I<regex>: detect malformed regex' '
 	test_grep "invalid regex given to -I: " error
 '
 
+test_expect_success 'diff -I<regex>: ignore matching file' '
+	test_seq 50 >file1 &&
+	git add file1 &&
+	test_seq 50 | sed -e "s/13/ten and three/" -e "s/^[124-9].*/& /" >file1 &&
+
+	: >actual &&
+	git diff --raw --ignore-blank-lines -I"ten.*e" -I"^[124-9]" >>actual &&
+	git diff --name-only --ignore-blank-lines -I"ten.*e" -I"^[124-9]" >>actual &&
+	git diff --name-status --ignore-blank-lines -I"ten.*e" -I"^[124-9]" >>actual &&
+	! grep "file1" actual &&
+
+	git rm -f file1
+'
+
 # check_prefix <patch> <src> <dst>
 # check only lines with paths to avoid dependency on exact oid/contents
 check_prefix () {

t/t4015-diff-whitespace.sh

@@ -11,7 +11,7 @@ test_description='Test special whitespace in diff engine.
 . "$TEST_DIRECTORY"/lib-diff.sh
 
 for opt_res in --patch --quiet -s --stat --shortstat --dirstat=lines \
-	       --raw! --name-only! --name-status!
+	       --raw --name-only --name-status
 do
 	opts=${opt_res%!} expect_failure=
 	test "$opts" = "$opt_res" ||

xdiff-interface.h

@@ -28,9 +28,9 @@
  * from an error internal to xdiff, xdiff itself will see that
  * non-zero return and translate it to -1.
  *
- * See "diff_grep" in diffcore-pickaxe.c for a trick to work around
- * this, i.e. using the "consume_callback_data" to note the desired
- * early return.
+ * See "diff_grep" in diffcore-pickaxe.c and "quick_consume" in diff.c
+ * for a trick to work around this, i.e. using the "consume_callback_data"
+ * to note the desired early return.
  */
 typedef int (*xdiff_emit_line_fn)(void *, char *, unsigned long);
 typedef void (*xdiff_emit_hunk_fn)(void *data,