From 90cf7177cae8e3f1ff90c6ab37243c06d6b07f2a Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Mon, 1 Feb 2021 16:56:02 +0100
Subject: [PATCH] fixes #16897 [backport:1.2] (#16900)

(cherry picked from commit 91ace2188a243b4453412ed1e79e2efcc62d95a6)
---
 compiler/types.nim | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/types.nim b/compiler/types.nim
index ecbe371e2f..ab3395bc46 100644
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -71,7 +71,7 @@ const
                tyInferred, tySink, tyLent, tyOwned}
   # typedescX is used if we're sure tyTypeDesc should be included (or skipped)
   typedescPtrs* = abstractPtrs + {tyTypeDesc}
-  typedescInst* = abstractInst + {tyTypeDesc, tyOwned}
+  typedescInst* = abstractInst + {tyTypeDesc, tyOwned, tyUserTypeClass}
 
 proc invalidGenericInst*(f: PType): bool =
   result = f.kind == tyGenericInst and lastSon(f) == nil