1 | /**
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2 | * @fileoverview Rule to flag updates of imported bindings.
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3 | * @author Toru Nagashima <https://github.com/mysticatea>
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4 | */
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5 |
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6 | "use strict";
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7 |
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8 | //------------------------------------------------------------------------------
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9 | // Helpers
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10 | //------------------------------------------------------------------------------
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11 |
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12 | const { findVariable } = require("@eslint-community/eslint-utils");
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13 | const astUtils = require("./utils/ast-utils");
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14 |
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15 | const WellKnownMutationFunctions = {
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16 | Object: /^(?:assign|definePropert(?:y|ies)|freeze|setPrototypeOf)$/u,
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17 | Reflect: /^(?:(?:define|delete)Property|set(?:PrototypeOf)?)$/u
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18 | };
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19 |
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20 | /**
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21 | * Check if a given node is LHS of an assignment node.
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22 | * @param {ASTNode} node The node to check.
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23 | * @returns {boolean} `true` if the node is LHS.
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24 | */
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25 | function isAssignmentLeft(node) {
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26 | const { parent } = node;
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27 |
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28 | return (
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29 | (
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30 | parent.type === "AssignmentExpression" &&
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31 | parent.left === node
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32 | ) ||
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33 |
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34 | // Destructuring assignments
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35 | parent.type === "ArrayPattern" ||
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36 | (
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37 | parent.type === "Property" &&
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38 | parent.value === node &&
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39 | parent.parent.type === "ObjectPattern"
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40 | ) ||
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41 | parent.type === "RestElement" ||
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42 | (
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43 | parent.type === "AssignmentPattern" &&
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44 | parent.left === node
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45 | )
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46 | );
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47 | }
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48 |
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49 | /**
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50 | * Check if a given node is the operand of mutation unary operator.
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51 | * @param {ASTNode} node The node to check.
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52 | * @returns {boolean} `true` if the node is the operand of mutation unary operator.
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53 | */
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54 | function isOperandOfMutationUnaryOperator(node) {
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55 | const argumentNode = node.parent.type === "ChainExpression"
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56 | ? node.parent
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57 | : node;
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58 | const { parent } = argumentNode;
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59 |
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60 | return (
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61 | (
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62 | parent.type === "UpdateExpression" &&
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63 | parent.argument === argumentNode
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64 | ) ||
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65 | (
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66 | parent.type === "UnaryExpression" &&
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67 | parent.operator === "delete" &&
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68 | parent.argument === argumentNode
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69 | )
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70 | );
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71 | }
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72 |
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73 | /**
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74 | * Check if a given node is the iteration variable of `for-in`/`for-of` syntax.
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75 | * @param {ASTNode} node The node to check.
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76 | * @returns {boolean} `true` if the node is the iteration variable.
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77 | */
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78 | function isIterationVariable(node) {
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79 | const { parent } = node;
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80 |
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81 | return (
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82 | (
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83 | parent.type === "ForInStatement" &&
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84 | parent.left === node
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85 | ) ||
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86 | (
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87 | parent.type === "ForOfStatement" &&
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88 | parent.left === node
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89 | )
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90 | );
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91 | }
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92 |
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93 | /**
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94 | * Check if a given node is at the first argument of a well-known mutation function.
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95 | * - `Object.assign`
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96 | * - `Object.defineProperty`
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97 | * - `Object.defineProperties`
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98 | * - `Object.freeze`
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99 | * - `Object.setPrototypeOf`
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100 | * - `Reflect.defineProperty`
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101 | * - `Reflect.deleteProperty`
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102 | * - `Reflect.set`
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103 | * - `Reflect.setPrototypeOf`
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104 | * @param {ASTNode} node The node to check.
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105 | * @param {Scope} scope A `escope.Scope` object to find variable (whichever).
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106 | * @returns {boolean} `true` if the node is at the first argument of a well-known mutation function.
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107 | */
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108 | function isArgumentOfWellKnownMutationFunction(node, scope) {
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109 | const { parent } = node;
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110 |
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111 | if (parent.type !== "CallExpression" || parent.arguments[0] !== node) {
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112 | return false;
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113 | }
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114 | const callee = astUtils.skipChainExpression(parent.callee);
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115 |
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116 | if (
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117 | !astUtils.isSpecificMemberAccess(callee, "Object", WellKnownMutationFunctions.Object) &&
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118 | !astUtils.isSpecificMemberAccess(callee, "Reflect", WellKnownMutationFunctions.Reflect)
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119 | ) {
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120 | return false;
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121 | }
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122 | const variable = findVariable(scope, callee.object);
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123 |
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124 | return variable !== null && variable.scope.type === "global";
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125 | }
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126 |
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127 | /**
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128 | * Check if the identifier node is placed at to update members.
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129 | * @param {ASTNode} id The Identifier node to check.
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130 | * @param {Scope} scope A `escope.Scope` object to find variable (whichever).
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131 | * @returns {boolean} `true` if the member of `id` was updated.
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132 | */
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133 | function isMemberWrite(id, scope) {
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134 | const { parent } = id;
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135 |
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136 | return (
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137 | (
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138 | parent.type === "MemberExpression" &&
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139 | parent.object === id &&
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140 | (
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141 | isAssignmentLeft(parent) ||
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142 | isOperandOfMutationUnaryOperator(parent) ||
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143 | isIterationVariable(parent)
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144 | )
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145 | ) ||
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146 | isArgumentOfWellKnownMutationFunction(id, scope)
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147 | );
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148 | }
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149 |
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150 | /**
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151 | * Get the mutation node.
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152 | * @param {ASTNode} id The Identifier node to get.
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153 | * @returns {ASTNode} The mutation node.
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154 | */
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155 | function getWriteNode(id) {
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156 | let node = id.parent;
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157 |
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158 | while (
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159 | node &&
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160 | node.type !== "AssignmentExpression" &&
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161 | node.type !== "UpdateExpression" &&
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162 | node.type !== "UnaryExpression" &&
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163 | node.type !== "CallExpression" &&
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164 | node.type !== "ForInStatement" &&
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165 | node.type !== "ForOfStatement"
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166 | ) {
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167 | node = node.parent;
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168 | }
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169 |
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170 | return node || id;
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171 | }
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172 |
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173 | //------------------------------------------------------------------------------
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174 | // Rule Definition
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175 | //------------------------------------------------------------------------------
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176 |
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177 | /** @type {import('../shared/types').Rule} */
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178 | module.exports = {
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179 | meta: {
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180 | type: "problem",
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181 |
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182 | docs: {
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183 | description: "Disallow assigning to imported bindings",
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184 | recommended: true,
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185 | url: "https://eslint.org/docs/latest/rules/no-import-assign"
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186 | },
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187 |
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188 | schema: [],
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189 |
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190 | messages: {
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191 | readonly: "'{{name}}' is read-only.",
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192 | readonlyMember: "The members of '{{name}}' are read-only."
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193 | }
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194 | },
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195 |
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196 | create(context) {
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197 | const sourceCode = context.sourceCode;
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198 |
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199 | return {
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200 | ImportDeclaration(node) {
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201 | const scope = sourceCode.getScope(node);
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202 |
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203 | for (const variable of sourceCode.getDeclaredVariables(node)) {
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204 | const shouldCheckMembers = variable.defs.some(
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205 | d => d.node.type === "ImportNamespaceSpecifier"
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206 | );
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207 | let prevIdNode = null;
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208 |
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209 | for (const reference of variable.references) {
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210 | const idNode = reference.identifier;
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211 |
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212 | /*
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213 | * AssignmentPattern (e.g. `[a = 0] = b`) makes two write
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214 | * references for the same identifier. This should skip
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215 | * the one of the two in order to prevent redundant reports.
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216 | */
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217 | if (idNode === prevIdNode) {
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218 | continue;
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219 | }
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220 | prevIdNode = idNode;
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221 |
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222 | if (reference.isWrite()) {
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223 | context.report({
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224 | node: getWriteNode(idNode),
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225 | messageId: "readonly",
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226 | data: { name: idNode.name }
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227 | });
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228 | } else if (shouldCheckMembers && isMemberWrite(idNode, scope)) {
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229 | context.report({
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230 | node: getWriteNode(idNode),
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231 | messageId: "readonlyMember",
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232 | data: { name: idNode.name }
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233 | });
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234 | }
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235 | }
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236 | }
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237 | }
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238 | };
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239 |
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240 | }
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241 | };
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