commit 0fadf0cd7e23607dcada424bc3b5f8b3b1b1b5b1
Author: Gearnode <bryan@frimin.fr>
Date:   Sat Apr 11 18:04:27 2020 +0200

    add %q sprintf option format

diff --git a/sprintf.c b/sprintf.c
index f726b7ebe6..2ac2c1ae4f 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -473,9 +473,9 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 		}
 	    }
 	    break;
-
-	  case 's':
-	  case 'p':
+         case 'q':
+         case 's':
+         case 'p':
 	  format_s:
 	    {
 		VALUE arg = GETARG();
@@ -484,9 +484,14 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 		if (*p == 'p') {
 		    str = rb_inspect(arg);
 		}
+               else if (*p == 'q') {
+                   str = rb_obj_as_string(arg);
+                   str = rb_str_dump(str);
+               }
 		else {
 		    str = rb_obj_as_string(arg);
 		}
+
 		len = RSTRING_LEN(str);
 		rb_str_set_len(result, blen);
 		if (coderange != ENC_CODERANGE_BROKEN && scanned < blen) {
diff --git a/test/ruby/test_sprintf.rb b/test/ruby/test_sprintf.rb
index 7986e9d141..4d968748e4 100644
--- a/test/ruby/test_sprintf.rb
+++ b/test/ruby/test_sprintf.rb
@@ -378,6 +378,12 @@ def test_string
     assert_equal("foo" + " " * BSIZ, sprintf("%-#{ BSIZ + 3 }s", "foo"))
   end
 
+  def test_quoted_string
+    assert_equal(%q{"foo"}, sprintf("%q", "foo"))
+    assert_equal(%q{"foo\n bar"}, sprintf("%q", "foo\n bar"))
+    assert_equal(%q{"foo\r bar"}, sprintf("%q", "foo\r bar"))
+  end
+
   def test_integer
     assert_equal("01", sprintf("%#o", 1))
     assert_equal("0x1", sprintf("%#x", 1))