From 824f85e18c1f54ced687757e4063ec792f18e31d Mon Sep 17 00:00:00 2001
From: Shunsuke Shibayama <sbym1346@gmail.com>
Date: Tue, 30 Aug 2022 21:23:08 +0900
Subject: [PATCH] Update tyvar.rs

---
 compiler/erg_compiler/context/tyvar.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/erg_compiler/context/tyvar.rs b/compiler/erg_compiler/context/tyvar.rs
index a8dc366f..d6b0e23b 100644
--- a/compiler/erg_compiler/context/tyvar.rs
+++ b/compiler/erg_compiler/context/tyvar.rs
@@ -1001,7 +1001,7 @@ impl Context {
         erg_common::log!(info "trying sub_unify:\nmaybe_sub: {maybe_sub}\nmaybe_sup: {maybe_sup}");
         // In this case, there is no new information to be gained
         // この場合、特に新しく得られる情報はない
-        if maybe_sub == &Type::Never || maybe_sup == &Type::Obj {
+        if maybe_sub == &Type::Never || maybe_sup == &Type::Obj || maybe_sup == maybe_sub {
             return Ok(());
         }
         let maybe_sub_is_sub = self.rec_subtype_of(maybe_sub, maybe_sup);