generic multi-methods should work now

compiler/semstmts.nim

@@ -1352,7 +1352,19 @@ proc semMethod(c: PContext, n: PNode): PNode =
   # macros can transform methods to nothing:
   if namePos >= result.safeLen: return result
   var s = result.sons[namePos].sym
-  if not isGenericRoutine(s):
+  if isGenericRoutine(s):
+    let tt = s.typ
+    var foundObj = false
+    for col in countup(0, sonsLen(tt)-1):
+      let t = tt.sons[col]
+      if t != nil and t.kind == tyGenericInvocation:
+        var x = skipTypes(t.sons[0], {tyVar, tyPtr, tyRef, tyGenericInst, tyGenericInvocation, tyGenericBody})
+        if x.kind == tyObject:
+          foundObj = true
+          x.methods.safeAdd((col,s))
+    if not foundObj:
+      message(n.info, warnDeprecated, "generic method not attachable to object type")
+  else:
     # why check for the body? bug #2400 has none. Checking for sfForward makes
     # no sense either.
     # and result.sons[bodyPos].kind != nkEmpty: