From 3df9d2bd0ce3e7af872cb99cae96d8108510b64c Mon Sep 17 00:00:00 2001
From: Araq <rumpf_a@web.de>
Date: Fri, 3 Jul 2015 00:06:13 +0200
Subject: [PATCH] fixes #2540

---
 compiler/semtypinst.nim | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/compiler/semtypinst.nim b/compiler/semtypinst.nim
index c5caf8b92..fc7807228 100644
--- a/compiler/semtypinst.nim
+++ b/compiler/semtypinst.nim
@@ -440,8 +440,14 @@ proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType =
 
       for i in countup(0, sonsLen(result) - 1):
         if result.sons[i] != nil:
-          result.sons[i] = replaceTypeVarsT(cl, result.sons[i])
-          propagateToOwner(result, result.sons[i])
+          var r = replaceTypeVarsT(cl, result.sons[i])
+          if result.kind == tyObject:
+            # carefully coded to not skip the precious tyGenericInst:
+            let r2 = r.skipTypes({tyGenericInst})
+            if r2.kind in {tyPtr, tyRef}:
+              r = skipTypes(r2, {tyPtr, tyRef})
+          result.sons[i] = r
+          propagateToOwner(result, r)
 
       result.n = replaceTypeVarsN(cl, result.n)