From a04fd162fc1919ebfc22ddf8d506abbac9e066b1 Mon Sep 17 00:00:00 2001
From: withgit-contributor <withgit.contributor@gmail.com>
Date: Fri, 1 Sep 2017 16:32:09 +0900
Subject: [PATCH] util: use proper circular reference checking

Circular references are conceptually nothing that should be checked
for objects (or Sets or Maps) only, but applies to recursive structures
in general, so move the `seen` checks into a position where it is part
of the recursion itself.

Fixes: https://github.com/with-git/node/issues/1
PR-URL: https://github.com/with-git/node/pull/2
---
 lib/util.js | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/lib/util.js b/lib/util.js
index 8fe811f812..0664f94cd2 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -612,10 +612,13 @@ function formatValue(ctx, value, recurseTimes) {
     }
   }
 
-  ctx.seen.push(value);
-
-  var output = formatter(ctx, value, recurseTimes, visibleKeys, keys);
+  // TODO(addaleax): Make `seen` a Set to avoid linear-time lookup.
+  if (ctx.seen.includes(value)) {
+    return ctx.stylize('[Circular]', 'special');
+  }
 
+  ctx.seen.push(value);
+  const output = formatter(ctx, value, recurseTimes, visibleKeys, keys);
   ctx.seen.pop();
 
   return reduceToSingleString(output, base, braces, ctx.breakLength);
@@ -835,21 +838,17 @@ function formatProperty(ctx, value, recurseTimes, visibleKeys, key, array) {
     }
   }
   if (!str) {
-    if (ctx.seen.indexOf(desc.value) < 0) {
-      if (recurseTimes === null) {
-        str = formatValue(ctx, desc.value, null);
+    if (recurseTimes === null) {
+      str = formatValue(ctx, desc.value, null);
+    } else {
+      str = formatValue(ctx, desc.value, recurseTimes - 1);
+    }
+    if (str.indexOf('\n') > -1) {
+      if (array) {
+        str = str.replace(/\n/g, '\n  ');
       } else {
-        str = formatValue(ctx, desc.value, recurseTimes - 1);
-      }
-      if (str.indexOf('\n') > -1) {
-        if (array) {
-          str = str.replace(/\n/g, '\n  ');
-        } else {
-          str = str.replace(/^|\n/g, '\n   ');
-        }
+        str = str.replace(/^|\n/g, '\n   ');
       }
-    } else {
-      str = ctx.stylize('[Circular]', 'special');
     }
   }
   if (name === undefined) {