[Fix] jsx-max-depth: Prevent getting stuck in circular references

Author: AriPerkkio

lib/rules/jsx-max-depth.js

@@ -10,6 +10,10 @@ const variableUtil = require('../util/variable');
 const jsxUtil = require('../util/jsx');
 const docsUrl = require('../util/docsUrl');
 
+function includes(array, item) {
+  return !!array.some((i) => i === item);
+}
+
 // ------------------------------------------------------------------------------
 // Rule Definition
 // ------------------------------------------------------------------------------
@@ -83,8 +87,8 @@ module.exports = {
       });
     }
 
-    function findJSXElementOrFragment(variables, name) {
-      function find(refs) {
+    function findJSXElementOrFragment(variables, name, previousReferences) {
+      function find(refs, prevRefs) {
         let i = refs.length;
 
         while (--i >= 0) {
@@ -94,15 +98,26 @@ module.exports = {
             return (jsxUtil.isJSX(writeExpr)
               && writeExpr)
               || ((writeExpr && writeExpr.type === 'Identifier')
-              && findJSXElementOrFragment(variables, writeExpr.name));
+              && findJSXElementOrFragment(variables, writeExpr.name, prevRefs));
           }
         }
 
         return null;
       }
 
       const variable = variableUtil.getVariable(variables, name);
-      return variable && variable.references && find(variable.references);
+      if (variable && variable.references) {
+        const containDuplicates = previousReferences.some((ref) => includes(variable.references, ref));
+
+        // Prevent getting stuck in circular references
+        if (containDuplicates) {
+          return false;
+        }
+
+        return find(variable.references, previousReferences.concat(variable.references));
+      }
+
+      return false;
     }
 
     function checkDescendant(baseDepth, children) {
@@ -141,7 +156,7 @@ module.exports = {
         }
 
         const variables = variableUtil.variablesInScope(context);
-        const element = findJSXElementOrFragment(variables, node.expression.name);
+        const element = findJSXElementOrFragment(variables, node.expression.name, []);
 
         if (element) {
           const baseDepth = getDepth(node);

tests/lib/rules/jsx-max-depth.js

@@ -114,6 +114,33 @@ ruleTester.run('jsx-max-depth', rule, {
       '  return <div>{A}</div>;',
       '}'
     ].join('\n')
+  }, {
+    // Validates circular references don't get rule stuck
+    code: `
+      function Component() {
+        let first = "";
+        const second = first;
+        first = second;
+        return <div id={first} />;
+      };
+    `
+  },
+  {
+    // Validates circular references are checked at multiple levels
+    code: `
+      function Component() {
+        let first = "";
+        let second = "";
+        let third = "";
+        let fourth = "";
+        const fifth = first;
+        first = second;
+        second = third;
+        third = fourth;
+        fourth = fifth;
+        return <div id={first} />;
+      };
+    `
   }],
 
   invalid: [{