From 1c0b81528224703f433ddc56e40aba59aec76081 Mon Sep 17 00:00:00 2001
From: Araq <rumpf_a@web.de>
Date: Fri, 18 Sep 2015 01:50:28 +0200
Subject: [PATCH] fixes #3305; error message will improve with later
 improvements for concepts

---
 compiler/sigmatch.nim | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index d28800d9af..642f50330e 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -511,6 +511,9 @@ proc typeRangeRel(f, a: PType): TTypeRelation {.noinline.} =
 proc matchUserTypeClass*(c: PContext, m: var TCandidate,
                          ff, a: PType): TTypeRelation =
   var body = ff.skipTypes({tyUserTypeClassInst})
+  if c.inTypeClass > 20:
+    localError(body.n[3].info, $body.n[3] & " too nested for type matching")
+    return isNone
 
   openScope(c)
   inc c.inTypeClass