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286 lines
9.3 KiB
286 lines
9.3 KiB
/**
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* @fileoverview Rule to flag use of eval() statement
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* @author Nicholas C. Zakas
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require("./utils/ast-utils");
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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const candidatesOfGlobalObject = Object.freeze([
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"global",
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"window",
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"globalThis"
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]);
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/**
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* Checks a given node is a MemberExpression node which has the specified name's
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* property.
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* @param {ASTNode} node A node to check.
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* @param {string} name A name to check.
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* @returns {boolean} `true` if the node is a MemberExpression node which has
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* the specified name's property
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*/
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function isMember(node, name) {
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return astUtils.isSpecificMemberAccess(node, null, name);
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}
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../shared/types').Rule} */
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module.exports = {
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meta: {
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type: "suggestion",
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docs: {
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description: "Disallow the use of `eval()`",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/no-eval"
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},
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schema: [
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{
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type: "object",
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properties: {
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allowIndirect: { type: "boolean", default: false }
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},
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additionalProperties: false
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}
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],
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messages: {
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unexpected: "eval can be harmful."
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}
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},
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create(context) {
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const allowIndirect = Boolean(
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context.options[0] &&
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context.options[0].allowIndirect
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);
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const sourceCode = context.sourceCode;
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let funcInfo = null;
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/**
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* Pushes a `this` scope (non-arrow function, class static block, or class field initializer) information to the stack.
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* Top-level scopes are handled separately.
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*
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* This is used in order to check whether or not `this` binding is a
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* reference to the global object.
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* @param {ASTNode} node A node of the scope.
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* For functions, this is one of FunctionDeclaration, FunctionExpression.
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* For class static blocks, this is StaticBlock.
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* For class field initializers, this can be any node that is PropertyDefinition#value.
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* @returns {void}
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*/
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function enterThisScope(node) {
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const strict = sourceCode.getScope(node).isStrict;
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funcInfo = {
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upper: funcInfo,
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node,
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strict,
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isTopLevelOfScript: false,
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defaultThis: false,
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initialized: strict
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};
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}
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/**
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* Pops a variable scope from the stack.
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* @returns {void}
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*/
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function exitThisScope() {
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funcInfo = funcInfo.upper;
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}
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/**
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* Reports a given node.
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*
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* `node` is `Identifier` or `MemberExpression`.
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* The parent of `node` might be `CallExpression`.
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*
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* The location of the report is always `eval` `Identifier` (or possibly
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* `Literal`). The type of the report is `CallExpression` if the parent is
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* `CallExpression`. Otherwise, it's the given node type.
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* @param {ASTNode} node A node to report.
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* @returns {void}
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*/
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function report(node) {
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const parent = node.parent;
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const locationNode = node.type === "MemberExpression"
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? node.property
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: node;
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const reportNode = parent.type === "CallExpression" && parent.callee === node
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? parent
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: node;
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context.report({
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node: reportNode,
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loc: locationNode.loc,
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messageId: "unexpected"
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});
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}
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/**
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* Reports accesses of `eval` via the global object.
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* @param {eslint-scope.Scope} globalScope The global scope.
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* @returns {void}
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*/
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function reportAccessingEvalViaGlobalObject(globalScope) {
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for (let i = 0; i < candidatesOfGlobalObject.length; ++i) {
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const name = candidatesOfGlobalObject[i];
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const variable = astUtils.getVariableByName(globalScope, name);
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if (!variable) {
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continue;
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}
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const references = variable.references;
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for (let j = 0; j < references.length; ++j) {
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const identifier = references[j].identifier;
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let node = identifier.parent;
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// To detect code like `window.window.eval`.
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while (isMember(node, name)) {
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node = node.parent;
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}
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// Reports.
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if (isMember(node, "eval")) {
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report(node);
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}
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}
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}
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}
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/**
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* Reports all accesses of `eval` (excludes direct calls to eval).
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* @param {eslint-scope.Scope} globalScope The global scope.
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* @returns {void}
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*/
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function reportAccessingEval(globalScope) {
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const variable = astUtils.getVariableByName(globalScope, "eval");
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if (!variable) {
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return;
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}
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const references = variable.references;
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for (let i = 0; i < references.length; ++i) {
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const reference = references[i];
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const id = reference.identifier;
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if (id.name === "eval" && !astUtils.isCallee(id)) {
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// Is accessing to eval (excludes direct calls to eval)
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report(id);
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}
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}
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}
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if (allowIndirect) {
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// Checks only direct calls to eval. It's simple!
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return {
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"CallExpression:exit"(node) {
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const callee = node.callee;
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/*
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* Optional call (`eval?.("code")`) is not direct eval.
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* The direct eval is only step 6.a.vi of https://tc39.es/ecma262/#sec-function-calls-runtime-semantics-evaluation
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* But the optional call is https://tc39.es/ecma262/#sec-optional-chaining-chain-evaluation
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*/
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if (!node.optional && astUtils.isSpecificId(callee, "eval")) {
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report(callee);
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}
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}
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};
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}
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return {
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"CallExpression:exit"(node) {
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const callee = node.callee;
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if (astUtils.isSpecificId(callee, "eval")) {
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report(callee);
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}
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},
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Program(node) {
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const scope = sourceCode.getScope(node),
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features = context.parserOptions.ecmaFeatures || {},
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strict =
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scope.isStrict ||
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node.sourceType === "module" ||
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(features.globalReturn && scope.childScopes[0].isStrict),
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isTopLevelOfScript = node.sourceType !== "module" && !features.globalReturn;
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funcInfo = {
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upper: null,
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node,
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strict,
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isTopLevelOfScript,
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defaultThis: true,
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initialized: true
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};
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},
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"Program:exit"(node) {
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const globalScope = sourceCode.getScope(node);
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exitThisScope();
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reportAccessingEval(globalScope);
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reportAccessingEvalViaGlobalObject(globalScope);
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},
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FunctionDeclaration: enterThisScope,
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"FunctionDeclaration:exit": exitThisScope,
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FunctionExpression: enterThisScope,
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"FunctionExpression:exit": exitThisScope,
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"PropertyDefinition > *.value": enterThisScope,
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"PropertyDefinition > *.value:exit": exitThisScope,
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StaticBlock: enterThisScope,
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"StaticBlock:exit": exitThisScope,
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ThisExpression(node) {
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if (!isMember(node.parent, "eval")) {
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return;
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}
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/*
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* `this.eval` is found.
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* Checks whether or not the value of `this` is the global object.
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*/
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if (!funcInfo.initialized) {
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funcInfo.initialized = true;
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funcInfo.defaultThis = astUtils.isDefaultThisBinding(
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funcInfo.node,
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sourceCode
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);
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}
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// `this` at the top level of scripts always refers to the global object
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if (funcInfo.isTopLevelOfScript || (!funcInfo.strict && funcInfo.defaultThis)) {
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// `this.eval` is possible built-in `eval`.
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report(node.parent);
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}
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}
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};
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}
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};
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