From 2bb2e6975e397bef1b320cd5dbafb6b3338fdaf0 Mon Sep 17 00:00:00 2001
From: Dominik Picheta <dominikpicheta@gmail.com>
Date: Thu, 30 Nov 2017 18:43:34 +0000
Subject: Fix infinite recursion when using json.to on ref with cycle.

---
 lib/pure/json.nim | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'lib')

diff --git a/lib/pure/json.nim b/lib/pure/json.nim
index 1d2f480c4..9e7510e45 100644
--- a/lib/pure/json.nim
+++ b/lib/pure/json.nim
@@ -1651,6 +1651,13 @@ import options
 proc workaroundMacroNone[T](): Option[T] =
   none(T)
 
+proc depth(n: NimNode, current = 0): int =
+  result = 1
+  for child in n:
+    let d = 1 + child.depth(current + 1)
+    if d > result:
+      result = d
+
 proc createConstructor(typeSym, jsonNode: NimNode): NimNode =
   ## Accepts a type description, i.e. "ref Type", "seq[Type]", "Type" etc.
   ##
@@ -1660,6 +1667,9 @@ proc createConstructor(typeSym, jsonNode: NimNode): NimNode =
   # echo("--createConsuctor-- \n", treeRepr(typeSym))
   # echo()
 
+  if depth(jsonNode) > 150:
+    error("The `to` macro does not support ref objects with cycles.", jsonNode)
+
   case typeSym.kind
   of nnkBracketExpr:
     var bracketName = ($typeSym[0]).normalize
-- 
cgit 1.4.1-2-gfad0