625 lines
17 KiB
JavaScript
625 lines
17 KiB
JavaScript
/**
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* @fileoverview Rule to flag on declaring variables already declared in the outer scope
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* @author Ilya Volodin
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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 FUNC_EXPR_NODE_TYPES = new Set([
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"ArrowFunctionExpression",
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"FunctionExpression",
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]);
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const CALL_EXPR_NODE_TYPE = new Set(["CallExpression"]);
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const FOR_IN_OF_TYPE = /^For(?:In|Of)Statement$/u;
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const SENTINEL_TYPE =
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/^(?:(?:Function|Class)(?:Declaration|Expression)|ArrowFunctionExpression|CatchClause|ImportDeclaration|ExportNamedDeclaration)$/u;
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// TS-specific node types
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const TYPES_HOISTED_NODES = new Set([
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"TSInterfaceDeclaration",
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"TSTypeAliasDeclaration",
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]);
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// TS-specific function variable def types
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const ALLOWED_FUNCTION_VARIABLE_DEF_TYPES = new Set([
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"TSCallSignatureDeclaration",
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"TSFunctionType",
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"TSMethodSignature",
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"TSEmptyBodyFunctionExpression",
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"TSDeclareFunction",
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"TSConstructSignatureDeclaration",
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"TSConstructorType",
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]);
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../types').Rule.RuleModule} */
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module.exports = {
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meta: {
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type: "suggestion",
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dialects: ["typescript", "javascript"],
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language: "javascript",
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defaultOptions: [
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{
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allow: [],
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builtinGlobals: false,
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hoist: "functions",
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ignoreOnInitialization: false,
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ignoreTypeValueShadow: true,
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ignoreFunctionTypeParameterNameValueShadow: true,
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},
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],
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docs: {
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description:
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"Disallow variable declarations from shadowing variables declared in the outer scope",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/no-shadow",
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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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builtinGlobals: { type: "boolean" },
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hoist: {
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enum: [
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"all",
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"functions",
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"never",
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"types",
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"functions-and-types",
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],
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},
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allow: {
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type: "array",
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items: {
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type: "string",
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},
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},
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ignoreOnInitialization: { type: "boolean" },
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ignoreTypeValueShadow: { type: "boolean" },
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ignoreFunctionTypeParameterNameValueShadow: {
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type: "boolean",
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},
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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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noShadow:
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"'{{name}}' is already declared in the upper scope on line {{shadowedLine}} column {{shadowedColumn}}.",
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noShadowGlobal: "'{{name}}' is already a global variable.",
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},
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},
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create(context) {
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const [
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{
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builtinGlobals,
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hoist,
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allow,
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ignoreOnInitialization,
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ignoreTypeValueShadow,
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ignoreFunctionTypeParameterNameValueShadow,
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},
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] = context.options;
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const sourceCode = context.sourceCode;
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/**
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* Check if a scope is a TypeScript module augmenting the global namespace.
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* @param {Scope} scope The scope to check
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* @returns {boolean} Whether the scope is a global augmentation
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*/
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function isGlobalAugmentation(scope) {
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return (
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scope.block.kind === "global" ||
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(!!scope.upper && isGlobalAugmentation(scope.upper))
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);
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}
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/**
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* Check if variable is a `this` parameter.
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* @param {Object} variable The variable to check
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* @returns {boolean} Whether the variable is a this parameter
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*/
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function isThisParam(variable) {
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return variable.name === "this";
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}
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/**
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* Checks if type and value shadows each other
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* @param {Object} variable The variable to check
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* @param {Object} shadowedVariable The shadowed variable
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* @returns {boolean} Whether it's a type/value shadow case to ignore
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*/
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function isTypeValueShadow(variable, shadowedVariable) {
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if (ignoreTypeValueShadow !== true) {
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return false;
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}
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if (!("isValueVariable" in variable)) {
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return false;
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}
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const firstDefinition = shadowedVariable.defs[0];
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// Check if shadowedVariable is a type import
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const isTypeImport =
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firstDefinition &&
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firstDefinition.parent?.type === "ImportDeclaration" &&
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(firstDefinition.parent.importKind === "type" ||
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firstDefinition.parent.specifiers.some(
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s => s.importKind === "type",
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));
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const isShadowedValue =
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!firstDefinition ||
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(isTypeImport ? false : shadowedVariable.isValueVariable);
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return variable.isValueVariable !== isShadowedValue;
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}
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/**
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* Checks if it's a function type parameter shadow
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* @param {Object} variable The variable to check
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* @returns {boolean} Whether it's a function type parameter shadow case to ignore
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*/
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function isFunctionTypeParameterNameValueShadow(variable) {
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if (ignoreFunctionTypeParameterNameValueShadow !== true) {
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return false;
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}
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return variable.defs.some(def =>
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ALLOWED_FUNCTION_VARIABLE_DEF_TYPES.has(def.node.type),
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);
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}
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/**
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* Checks if the variable is a generic of a static method
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* @param {Object} variable The variable to check
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* @returns {boolean} Whether the variable is a generic of a static method
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*/
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function isTypeParameterOfStaticMethod(variable) {
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const typeParameter = variable.identifiers[0].parent;
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const typeParameterDecl = typeParameter.parent;
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if (typeParameterDecl.type !== "TSTypeParameterDeclaration") {
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return false;
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}
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const functionExpr = typeParameterDecl.parent;
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const methodDefinition = functionExpr.parent;
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return methodDefinition.static;
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}
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/**
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* Checks for static method generic shadowing class generic
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* @param {Object} variable The variable to check
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* @returns {boolean} Whether it's a static method generic shadowing class generic
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*/
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function isGenericOfAStaticMethodShadow(variable) {
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return isTypeParameterOfStaticMethod(variable);
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}
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/**
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* Checks whether or not a given location is inside of the range of a given node.
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* @param {ASTNode} node An node to check.
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* @param {number} location A location to check.
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* @returns {boolean} `true` if the location is inside of the range of the node.
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*/
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function isInRange(node, location) {
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return (
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node && node.range[0] <= location && location <= node.range[1]
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);
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}
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/**
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* Searches from the current node through its ancestry to find a matching node.
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* @param {ASTNode} node a node to get.
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* @param {(node: ASTNode) => boolean} match a callback that checks whether or not the node verifies its condition or not.
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* @returns {ASTNode|null} the matching node.
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*/
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function findSelfOrAncestor(node, match) {
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let currentNode = node;
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while (currentNode && !match(currentNode)) {
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currentNode = currentNode.parent;
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}
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return currentNode;
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}
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/**
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* Finds function's outer scope.
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* @param {Scope} scope Function's own scope.
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* @returns {Scope} Function's outer scope.
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*/
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function getOuterScope(scope) {
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const upper = scope.upper;
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if (upper && upper.type === "function-expression-name") {
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return upper.upper;
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}
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return upper;
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}
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/**
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* Checks if a variable and a shadowedVariable have the same init pattern ancestor.
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* @param {Object} variable a variable to check.
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* @param {Object} shadowedVariable a shadowedVariable to check.
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* @returns {boolean} Whether or not the variable and the shadowedVariable have the same init pattern ancestor.
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*/
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function isInitPatternNode(variable, shadowedVariable) {
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const outerDef = shadowedVariable.defs[0];
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if (!outerDef) {
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return false;
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}
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const { variableScope } = variable.scope;
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if (
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!(
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FUNC_EXPR_NODE_TYPES.has(variableScope.block.type) &&
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getOuterScope(variableScope) === shadowedVariable.scope
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)
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) {
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return false;
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}
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const fun = variableScope.block;
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const { parent } = fun;
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const callExpression = findSelfOrAncestor(parent, node =>
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CALL_EXPR_NODE_TYPE.has(node.type),
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);
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if (!callExpression) {
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return false;
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}
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let node = outerDef.name;
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const location = callExpression.range[1];
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while (node) {
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if (node.type === "VariableDeclarator") {
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if (isInRange(node.init, location)) {
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return true;
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}
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if (
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FOR_IN_OF_TYPE.test(node.parent.parent.type) &&
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isInRange(node.parent.parent.right, location)
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) {
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return true;
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}
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break;
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} else if (node.type === "AssignmentPattern") {
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if (isInRange(node.right, location)) {
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return true;
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}
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} else if (SENTINEL_TYPE.test(node.type)) {
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break;
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}
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node = node.parent;
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}
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return false;
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}
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/**
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* Check if variable name is allowed.
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* @param {ASTNode} variable The variable to check.
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* @returns {boolean} Whether or not the variable name is allowed.
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*/
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function isAllowed(variable) {
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return allow.includes(variable.name);
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}
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/**
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* Checks if a variable of the class name in the class scope of ClassDeclaration.
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*
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* ClassDeclaration creates two variables of its name into its outer scope and its class scope.
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* So we should ignore the variable in the class scope.
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* @param {Object} variable The variable to check.
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* @returns {boolean} Whether or not the variable of the class name in the class scope of ClassDeclaration.
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*/
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function isDuplicatedClassNameVariable(variable) {
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const block = variable.scope.block;
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return (
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block.type === "ClassDeclaration" &&
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block.id === variable.identifiers[0]
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);
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}
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/**
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* Checks if a variable is inside the initializer of scopeVar.
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*
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* To avoid reporting at declarations such as `var a = function a() {};`.
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* But it should report `var a = function(a) {};` or `var a = function() { function a() {} };`.
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* @param {Object} variable The variable to check.
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* @param {Object} scopeVar The scope variable to look for.
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* @returns {boolean} Whether or not the variable is inside initializer of scopeVar.
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*/
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function isOnInitializer(variable, scopeVar) {
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const outerScope = scopeVar.scope;
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const outerDef = scopeVar.defs[0];
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const outer = outerDef && outerDef.parent && outerDef.parent.range;
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const innerScope = variable.scope;
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const innerDef = variable.defs[0];
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const inner = innerDef && innerDef.name.range;
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return (
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outer &&
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inner &&
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outer[0] < inner[0] &&
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inner[1] < outer[1] &&
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((innerDef.type === "FunctionName" &&
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innerDef.node.type === "FunctionExpression") ||
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innerDef.node.type === "ClassExpression") &&
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outerScope === innerScope.upper
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);
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}
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/**
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* Get a range of a variable's identifier node.
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* @param {Object} variable The variable to get.
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* @returns {Array|undefined} The range of the variable's identifier node.
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*/
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function getNameRange(variable) {
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const def = variable.defs[0];
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return def && def.name.range;
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}
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/**
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* Get declared line and column of a variable.
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* @param {eslint-scope.Variable} variable The variable to get.
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* @returns {Object} The declared line and column of the variable.
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*/
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function getDeclaredLocation(variable) {
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const identifier = variable.identifiers[0];
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let obj;
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if (identifier) {
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obj = {
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global: false,
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line: identifier.loc.start.line,
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column: identifier.loc.start.column + 1,
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};
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} else {
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obj = {
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global: true,
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};
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}
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return obj;
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}
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/**
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* Checks if a variable is in TDZ of scopeVar.
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* @param {Object} variable The variable to check.
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* @param {Object} scopeVar The variable of TDZ.
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* @returns {boolean} Whether or not the variable is in TDZ of scopeVar.
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*/
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function isInTdz(variable, scopeVar) {
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const outerDef = scopeVar.defs[0];
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const inner = getNameRange(variable);
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const outer = getNameRange(scopeVar);
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if (!outer || inner[1] >= outer[0]) {
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return false;
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}
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if (hoist === "types") {
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return !TYPES_HOISTED_NODES.has(outerDef.node.type);
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}
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if (hoist === "functions-and-types") {
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return (
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outerDef.node.type !== "FunctionDeclaration" &&
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!TYPES_HOISTED_NODES.has(outerDef.node.type)
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);
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}
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return (
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inner &&
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outer &&
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inner[1] < outer[0] &&
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// Excepts FunctionDeclaration if is {"hoist":"function"}.
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(hoist !== "functions" ||
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!outerDef ||
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outerDef.node.type !== "FunctionDeclaration")
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);
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}
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/**
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* Checks if the initialization of a variable has the declare modifier in a
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* definition file.
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* @param {Object} variable The variable to check
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* @returns {boolean} Whether the variable is declared in a definition file
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*/
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function isDeclareInDTSFile(variable) {
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const fileName = context.filename;
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if (
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!fileName.endsWith(".d.ts") &&
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!fileName.endsWith(".d.cts") &&
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!fileName.endsWith(".d.mts")
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) {
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return false;
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}
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return variable.defs.some(
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def =>
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(def.type === "Variable" && def.parent.declare) ||
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(def.type === "ClassName" && def.node.declare) ||
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(def.type === "TSEnumName" && def.node.declare) ||
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(def.type === "TSModuleName" && def.node.declare),
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);
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}
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/**
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* Checks if a variable is a duplicate of an enum name in the enum scope
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* @param {Object} variable The variable to check
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* @returns {boolean} Whether it's a duplicate enum name variable
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*/
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function isDuplicatedEnumNameVariable(variable) {
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const block = variable.scope.block;
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return (
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block.type === "TSEnumDeclaration" &&
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block.id === variable.identifiers[0]
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);
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}
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/**
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* Check if this is an external module declaration merging with a type import
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* @param {Scope} scope Current scope
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* @param {Object} variable Current variable
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* @param {Object} shadowedVariable Shadowed variable
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* @returns {boolean} Whether it's an external declaration merging
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*/
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function isExternalDeclarationMerging(
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scope,
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variable,
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shadowedVariable,
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) {
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const firstDefinition = shadowedVariable.defs[0];
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if (!firstDefinition || !firstDefinition.parent) {
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return false;
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}
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// Check if the shadowed variable is a type import
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const isTypeImport =
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firstDefinition.parent.type === "ImportDeclaration" &&
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(firstDefinition.parent.importKind === "type" ||
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firstDefinition.parent.specifiers?.some(
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s =>
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s.type === "ImportSpecifier" &&
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s.importKind === "type" &&
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s.local.name === shadowedVariable.name,
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));
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if (!isTypeImport) {
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return false;
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}
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|
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// Check if the current variable is within a module declaration
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const moduleDecl = findSelfOrAncestor(
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variable.identifiers[0]?.parent,
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node => node.type === "TSModuleDeclaration",
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);
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if (!moduleDecl) {
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return false;
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}
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/*
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* Module declaration merging should only happen within the same module
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* Check if the module name matches the import source
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*/
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const importSource = firstDefinition.parent.source.value;
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const moduleName =
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moduleDecl.id.type === "Literal"
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? moduleDecl.id.value
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: moduleDecl.id.name;
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return importSource === moduleName;
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}
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/**
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* Checks the current context for shadowed variables.
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* @param {Scope} scope Fixme
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* @returns {void}
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*/
|
|
function checkForShadows(scope) {
|
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// ignore global augmentation
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if (isGlobalAugmentation(scope)) {
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return;
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}
|
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|
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const variables = scope.variables;
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|
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for (let i = 0; i < variables.length; ++i) {
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const variable = variables[i];
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|
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// Skips "arguments" or variables of a class name in the class scope of ClassDeclaration.
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|
if (
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variable.identifiers.length === 0 ||
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isDuplicatedClassNameVariable(variable) ||
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isDuplicatedEnumNameVariable(variable) ||
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isAllowed(variable) ||
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isDeclareInDTSFile(variable) ||
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isThisParam(variable)
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) {
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continue;
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}
|
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|
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// Gets shadowed variable.
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|
const shadowed = astUtils.getVariableByName(
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scope.upper,
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variable.name,
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);
|
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|
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if (
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shadowed &&
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(shadowed.identifiers.length > 0 ||
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(builtinGlobals && "writeable" in shadowed)) &&
|
|
!isOnInitializer(variable, shadowed) &&
|
|
!(
|
|
ignoreOnInitialization &&
|
|
isInitPatternNode(variable, shadowed)
|
|
) &&
|
|
!(hoist !== "all" && isInTdz(variable, shadowed)) &&
|
|
!isTypeValueShadow(variable, shadowed) &&
|
|
!isFunctionTypeParameterNameValueShadow(variable) &&
|
|
!isGenericOfAStaticMethodShadow(variable, shadowed) &&
|
|
!isExternalDeclarationMerging(scope, variable, shadowed)
|
|
) {
|
|
const location = getDeclaredLocation(shadowed);
|
|
const messageId = location.global
|
|
? "noShadowGlobal"
|
|
: "noShadow";
|
|
const data = { name: variable.name };
|
|
|
|
if (!location.global) {
|
|
data.shadowedLine = location.line;
|
|
data.shadowedColumn = location.column;
|
|
}
|
|
context.report({
|
|
node: variable.identifiers[0],
|
|
messageId,
|
|
data,
|
|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
return {
|
|
"Program:exit"(node) {
|
|
const globalScope = sourceCode.getScope(node);
|
|
const stack = globalScope.childScopes.slice();
|
|
|
|
while (stack.length) {
|
|
const scope = stack.pop();
|
|
|
|
stack.push(...scope.childScopes);
|
|
checkForShadows(scope);
|
|
}
|
|
},
|
|
};
|
|
},
|
|
};
|