From 01a8d8498fc3c1b107b303661d06b858858fce26 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Mon, 6 Jul 2020 23:11:51 +0900
Subject: [PATCH] Avoid infinite loop when converting objects to strings.

---
 src/object.c | 1 +
 src/string.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/src/object.c b/src/object.c
index db9dfb568e..7257f402d7 100644
--- a/src/object.c
+++ b/src/object.c
@@ -338,6 +338,7 @@ mrb_convert_type(mrb_state *mrb, mrb_value val, enum mrb_vtype type, const char
   if (mrb_type(val) == type) return val;
   v = convert_type(mrb, val, tname, method, TRUE);
   if (mrb_type(v) != type) {
+    if (type == MRB_TT_STRING) return mrb_any_to_s(mrb, val);
     mrb_raisef(mrb, E_TYPE_ERROR, "%v cannot be converted to %s by #%s", val, tname, method);
   }
   return v;
diff --git a/src/string.c b/src/string.c
index f1ffbe43d2..78c41c5f38 100644
--- a/src/string.c
+++ b/src/string.c
@@ -1121,6 +1121,7 @@ mrb_str_to_str(mrb_state *mrb, mrb_value str)
     return mrb_sym_str(mrb, mrb_symbol(str));
   case MRB_TT_FIXNUM:
     return mrb_fixnum_to_str(mrb, str, 10);
+  case MRB_TT_SCLASS:
   case MRB_TT_CLASS:
   case MRB_TT_MODULE:
     return mrb_mod_to_s(mrb, str);