Clone engine262 in /engine262

engine262/test/eslint-plugin-engine262/no-use-in-def.js

@@ -0,0 +1,68 @@
+'use strict';
+
+// https://github.com/eslint/eslint/blob/master/lib/rules/no-use-before-define.js
+
+const SENTINEL_TYPE = /^(?:(?:Function|Class)(?:Declaration|Expression)|ArrowFunctionExpression|CatchClause|ImportDeclaration|ExportNamedDeclaration)$/u;
+const FOR_IN_OF_TYPE = /^For(?:In|Of)Statement$/u;
+
+function isInRange(node, location) {
+  return node && node.range[0] <= location && location <= node.range[1];
+}
+
+function isUsedInDef(reference) {
+  const variable = reference.resolved;
+  if (!variable || variable.scope !== reference.from) {
+    return false;
+  }
+
+  let node = variable.identifiers[0].parent;
+  const location = reference.identifier.range[1];
+
+  while (node) {
+    if (node.type === 'VariableDeclarator') {
+      if (isInRange(node.init, location)) {
+        return true;
+      }
+      if (FOR_IN_OF_TYPE.test(node.parent.parent.type) && isInRange(node.parent.parent.right, location)) {
+        return true;
+      }
+      break;
+    }
+
+    if (node.type === 'AssignmentPattern' && isInRange(node.right, location)) {
+      return true;
+    }
+
+    if (SENTINEL_TYPE.test(node.type)) {
+      break;
+    }
+
+    node = node.parent;
+  }
+
+  return false;
+}
+
+module.exports = {
+  create(context) {
+    function findVariablesInScope(scope) {
+      scope.references.forEach((reference) => {
+        if (isUsedInDef(reference)) {
+          context.report({
+            node: reference.identifier,
+            message: '{{name}} was used in its own definition',
+            data: reference.identifier,
+          });
+        }
+      });
+
+      scope.childScopes.forEach((s) => findVariablesInScope(s));
+    }
+
+    return {
+      Program() {
+        findVariablesInScope(context.getScope());
+      },
+    };
+  },
+};