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

Regression fixes for a topic that has already been merged.

* ly/diff-name-only-with-diff-from-content:
  diff: stop output garbled message in dry run mode

Author: gitster

diff.c

@@ -1351,6 +1351,9 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 	int len = eds->len;
 	unsigned flags = eds->flags;
 
+	if (o->dry_run)
+		return;
+
 	switch (s) {
 	case DIFF_SYMBOL_NO_LF_EOF:
 		context = diff_get_color_opt(o, DIFF_CONTEXT);
@@ -4420,7 +4423,7 @@ static void run_external_diff(const struct external_diff *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 quiet = !(o->output_format & DIFF_FORMAT_PATCH) || o->dry_run;
 	int rc;
 
 	/*
@@ -4615,7 +4618,8 @@ static void run_diff_cmd(const struct external_diff *pgm,
 		    p->status == DIFF_STATUS_RENAMED)
 			o->found_changes = 1;
 	} else {
-		fprintf(o->file, "* Unmerged path %s\n", name);
+		if (!o->dry_run)
+			fprintf(o->file, "* Unmerged path %s\n", name);
 		o->found_changes = 1;
 	}
 }

t/t4013-diff-various.sh

@@ -661,6 +661,43 @@ test_expect_success 'diff -I<regex>: ignore matching file' '
 	test_grep ! "file1" actual
 '
 
+test_expect_success 'diff -I<regex>: ignore all content changes' '
+	test_when_finished "git rm -f file1 file2 file3" &&
+	: >file1 &&
+	git add file1 &&
+	: >file2 &&
+	git add file2 &&
+	: >file3 &&
+	git add file3 &&
+
+	rm -f file1 file2 &&
+	mkdir file2 &&
+	echo "A" >file3 &&
+	A_hash=$(git hash-object -w file3) &&
+	echo "B" >file3 &&
+	B_hash=$(git hash-object -w file3) &&
+	cat <<-EOF | git update-index --index-info &&
+	100644 $A_hash 1	file3
+	100644 $B_hash 2	file3
+	EOF
+
+	test_diff_no_content_changes () {
+		git diff $1 --ignore-blank-lines -I".*" >actual &&
+		test_line_count = 3 actual &&
+		test_grep "file1" actual &&
+		test_grep "file2" actual &&
+		test_grep "file3" actual &&
+		test_grep ! "diff --git" actual
+	} &&
+	test_diff_no_content_changes "--raw" &&
+	test_diff_no_content_changes "--name-only" &&
+	test_diff_no_content_changes "--name-status" &&
+
+	: >actual &&
+	test_must_fail git diff --quiet -I".*" >actual &&
+	test_must_be_empty actual
+'
+
 # check_prefix <patch> <src> <dst>
 # check only lines with paths to avoid dependency on exact oid/contents
 check_prefix () {