Merge branch 'ly/diff-name-only-with-diff-from-content' into maint-2.51

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.

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

5 files changed, 70 insertions, 23 deletions

diff --git a/diff.c b/diff.c
index dca87e164f..cb04a9a6f2 100644
--- a/diff.c
+++ b/diff.c
@@ -2444,6 +2444,15 @@ 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;
@@ -3759,8 +3768,21 @@ 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 (o->dry_run) {
+			/*
+			 * Unlike the !dry_run case, we need to ignore the
+			 * return value from xdi_diff_outf() here, because
+			 * xdi_diff_outf() takes non-zero return from its
+			 * callback function as a sign of error and returns
+			 * early (which is why we return non-zero from our
+			 * callback, quick_consume()).  Unfortunately,
+			 * xdi_diff_outf() signals an error by returning
+			 * non-zero.
+			 */
+			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);
@@ -6150,6 +6172,22 @@ 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_quietly(struct diff_filepair *p, struct diff_options *o)
+{
+	int saved_dry_run = o->dry_run;
+	int saved_found_changes = o->found_changes;
+	int ret;
+
+	o->dry_run = 1;
+	o->found_changes = 0;
+	diff_flush_patch(p, o);
+	ret = o->found_changes;
+	o->dry_run = saved_dry_run;
+	o->found_changes |= saved_found_changes;
+	return ret;
+}
+
 static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
 			    struct diffstat_t *diffstat)
 {
@@ -6778,8 +6816,15 @@ 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))
-				flush_one_pair(p, options);
+
+			if (!check_pair_status(p))
+				continue;
+
+			if (options->flags.diff_from_contents &&
+			    !diff_flush_patch_quietly(p, options))
+				continue;
+
+			flush_one_pair(p, options);
 		}
 		separator++;
 	}
@@ -6831,19 +6876,10 @@ 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_quietly(p, options);
 			if (options->found_changes)
 				break;
 		}
diff --git a/diff.h b/diff.h
index 62e5768a9a..91b3e1c5cf 100644
--- a/diff.h
+++ b/diff.h
@@ -400,6 +400,8 @@ struct diff_options {
 	#define COLOR_MOVED_WS_ERROR (1<<0)
 	unsigned color_moved_ws_handling;
 
+	bool dry_run;
+
 	struct repository *repo;
 	struct strmap *additional_path_headers;
 
diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index 8ebd170451..cfeec239e0 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -648,6 +648,19 @@ 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_when_finished "git rm -f file1" &&
+	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 &&
+	test_grep ! "file1" actual
+'
+
 # check_prefix <patch> <src> <dst>
 # check only lines with paths to avoid dependency on exact oid/contents
 check_prefix () {
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 52e3e476ff..9de7f73f42 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -11,12 +11,8 @@ 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" ||
-		expect_failure="test_expect_code 1"
-
 	test_expect_success "status with $opts (different)" '
 		echo foo >x &&
 		git add x &&
@@ -43,7 +39,7 @@ do
 		echo foo >x &&
 		git add x &&
 		echo " foo" >x &&
-		$expect_failure git diff -w $opts --exit-code x
+		git diff -w $opts --exit-code x
 	'
 done
 
diff --git a/xdiff-interface.h b/xdiff-interface.h
index 1ed430b622..dfc55daddf 100644
--- a/xdiff-interface.h
+++ b/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,