fix #5654

compiler/ccgexprs.nim

@@ -267,7 +267,7 @@ proc genAssignment(p: BProc, dest, src: TLoc, flags: TAssignmentFlags) =
     # little HACK to support the new 'var T' as return type:
     linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
     return
-  let ty = skipTypes(dest.t, abstractRange)
+  let ty = skipTypes(dest.t, abstractRange + tyUserTypeClasses)
   case ty.kind
   of tyRef:
     genRefAssign(p, dest, src, flags)

compiler/ccgtypes.nim

@@ -164,7 +164,7 @@ proc mapType(typ: PType): TCTypeKind =
   of tySet: result = mapSetType(typ)
   of tyOpenArray, tyArray, tyVarargs: result = ctArray
   of tyObject, tyTuple: result = ctStruct
-  of tyUserTypeClass, tyUserTypeClassInst:
+  of tyUserTypeClasses:
     internalAssert typ.isResolvedUserTypeClass
     return mapType(typ.lastSon)
   of tyGenericBody, tyGenericInst, tyGenericParam, tyDistinct, tyOrdinal,
@@ -1131,6 +1131,9 @@ proc genTypeInfo(m: BModule, t: PType): Rope =
   of tyStatic:
     if t.n != nil: result = genTypeInfo(m, lastSon t)
     else: internalError("genTypeInfo(" & $t.kind & ')')
+  of tyUserTypeClasses:
+    internalAssert t.isResolvedUserTypeClass
+    return genTypeInfo(m, t.lastSon)
   of tyProc:
     if t.callConv != ccClosure:
       genTypeInfoAuxBase(m, t, t, result, rope"0")