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: #14758
PR-URL: #14790
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Evan Lucas <[email protected]>
Reviewed-By: Timothy Gu <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>
Reviewed-By: Yuta Hiroto <[email protected]>
Reviewed-By: Alexey Orlenko <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>

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) {