From fc0bcccc15ec5cf3351cf65b22c7a038d82d4b35 Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Tue, 17 Jul 2018 16:43:05 +0200
Subject: [PATCH] fixes #8230

---
 compiler/semtypes.nim | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/compiler/semtypes.nim b/compiler/semtypes.nim
index 25d8674b86..05a9d9882a 100644
--- a/compiler/semtypes.nim
+++ b/compiler/semtypes.nim
@@ -1344,6 +1344,10 @@ proc semTypeClass(c: PContext, n: PNode, prev: PType): PType =
       dummyName = param
       dummyType = candidateTypeSlot
 
+    # this can be true for 'nim check' on incomplete concepts,
+    # see bug #8230
+    if dummyName.kind == nkEmpty: continue
+
     internalAssert c.config, dummyName.kind == nkIdent
     var dummyParam = newSym(if modifier == tyTypeDesc: skType else: skVar,
                             dummyName.ident, owner, param.info)