/
no-shadow.ts
657 lines (588 loc) · 19.3 KB
/
no-shadow.ts
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import type {
Definition,
ImportBindingDefinition,
} from '@typescript-eslint/scope-manager';
import { DefinitionType, ScopeType } from '@typescript-eslint/scope-manager';
import type { TSESLint, TSESTree } from '@typescript-eslint/utils';
import { AST_NODE_TYPES, ASTUtils } from '@typescript-eslint/utils';
import * as util from '../util';
type MessageIds = 'noShadow' | 'noShadowGlobal';
type Options = [
{
allow?: string[];
builtinGlobals?: boolean;
hoist?: 'all' | 'functions' | 'never';
ignoreOnInitialization?: boolean;
ignoreTypeValueShadow?: boolean;
ignoreFunctionTypeParameterNameValueShadow?: boolean;
},
];
export default util.createRule<Options, MessageIds>({
name: 'no-shadow',
meta: {
type: 'suggestion',
docs: {
description:
'Disallow variable declarations from shadowing variables declared in the outer scope',
recommended: false,
extendsBaseRule: true,
},
schema: [
{
type: 'object',
properties: {
builtinGlobals: {
type: 'boolean',
},
hoist: {
enum: ['all', 'functions', 'never'],
},
allow: {
type: 'array',
items: {
type: 'string',
},
},
ignoreOnInitialization: {
type: 'boolean',
},
ignoreTypeValueShadow: {
type: 'boolean',
},
ignoreFunctionTypeParameterNameValueShadow: {
type: 'boolean',
},
},
additionalProperties: false,
},
],
messages: {
noShadow:
"'{{name}}' is already declared in the upper scope on line {{shadowedLine}} column {{shadowedColumn}}.",
noShadowGlobal: "'{{name}}' is already a global variable.",
},
},
defaultOptions: [
{
allow: [],
builtinGlobals: false,
hoist: 'functions',
ignoreOnInitialization: false,
ignoreTypeValueShadow: true,
ignoreFunctionTypeParameterNameValueShadow: true,
},
],
create(context, [options]) {
/**
* Check if a scope is a TypeScript module augmenting the global namespace.
*/
function isGlobalAugmentation(scope: TSESLint.Scope.Scope): boolean {
return (
(scope.type === ScopeType.tsModule && !!scope.block.global) ||
(!!scope.upper && isGlobalAugmentation(scope.upper))
);
}
/**
* Check if variable is a `this` parameter.
*/
function isThisParam(variable: TSESLint.Scope.Variable): boolean {
return (
variable.defs[0].type === DefinitionType.Parameter &&
variable.name === 'this'
);
}
function isTypeImport(
definition?: Definition,
): definition is ImportBindingDefinition {
return (
definition?.type === DefinitionType.ImportBinding &&
(definition.parent.importKind === 'type' ||
(definition.node.type === AST_NODE_TYPES.ImportSpecifier &&
definition.node.importKind === 'type'))
);
}
function isTypeValueShadow(
variable: TSESLint.Scope.Variable,
shadowed: TSESLint.Scope.Variable,
): boolean {
if (options.ignoreTypeValueShadow !== true) {
return false;
}
if (!('isValueVariable' in variable)) {
// this shouldn't happen...
return false;
}
const [firstDefinition] = shadowed.defs;
const isShadowedValue =
!('isValueVariable' in shadowed) ||
!firstDefinition ||
(!isTypeImport(firstDefinition) && shadowed.isValueVariable);
return variable.isValueVariable !== isShadowedValue;
}
function isFunctionTypeParameterNameValueShadow(
variable: TSESLint.Scope.Variable,
shadowed: TSESLint.Scope.Variable,
): boolean {
if (options.ignoreFunctionTypeParameterNameValueShadow !== true) {
return false;
}
if (!('isValueVariable' in variable)) {
// this shouldn't happen...
return false;
}
const isShadowedValue =
'isValueVariable' in shadowed ? shadowed.isValueVariable : true;
if (!isShadowedValue) {
return false;
}
return variable.defs.every(
def => def.node.type === AST_NODE_TYPES.TSFunctionType,
);
}
function isGenericOfStaticMethod(
variable: TSESLint.Scope.Variable,
): boolean {
if (!('isTypeVariable' in variable)) {
// this shouldn't happen...
return false;
}
if (!variable.isTypeVariable) {
return false;
}
if (variable.identifiers.length === 0) {
return false;
}
const typeParameter = variable.identifiers[0].parent;
if (typeParameter?.type !== AST_NODE_TYPES.TSTypeParameter) {
return false;
}
const typeParameterDecl = typeParameter.parent;
if (
typeParameterDecl?.type !== AST_NODE_TYPES.TSTypeParameterDeclaration
) {
return false;
}
const functionExpr = typeParameterDecl.parent;
if (
!functionExpr ||
(functionExpr.type !== AST_NODE_TYPES.FunctionExpression &&
functionExpr.type !== AST_NODE_TYPES.TSEmptyBodyFunctionExpression)
) {
return false;
}
const methodDefinition = functionExpr.parent;
if (methodDefinition?.type !== AST_NODE_TYPES.MethodDefinition) {
return false;
}
return methodDefinition.static;
}
function isGenericOfClassDecl(variable: TSESLint.Scope.Variable): boolean {
if (!('isTypeVariable' in variable)) {
// this shouldn't happen...
return false;
}
if (!variable.isTypeVariable) {
return false;
}
if (variable.identifiers.length === 0) {
return false;
}
const typeParameter = variable.identifiers[0].parent;
if (typeParameter?.type !== AST_NODE_TYPES.TSTypeParameter) {
return false;
}
const typeParameterDecl = typeParameter.parent;
if (
typeParameterDecl?.type !== AST_NODE_TYPES.TSTypeParameterDeclaration
) {
return false;
}
const classDecl = typeParameterDecl.parent;
return classDecl?.type === AST_NODE_TYPES.ClassDeclaration;
}
function isGenericOfAStaticMethodShadow(
variable: TSESLint.Scope.Variable,
shadowed: TSESLint.Scope.Variable,
): boolean {
return (
isGenericOfStaticMethod(variable) && isGenericOfClassDecl(shadowed)
);
}
function isImportDeclaration(
definition:
| TSESTree.ImportDeclaration
| TSESTree.TSImportEqualsDeclaration,
): definition is TSESTree.ImportDeclaration {
return definition.type === AST_NODE_TYPES.ImportDeclaration;
}
function isExternalModuleDeclarationWithName(
scope: TSESLint.Scope.Scope,
name: string,
): boolean {
return (
scope.type === ScopeType.tsModule &&
scope.block.type === AST_NODE_TYPES.TSModuleDeclaration &&
scope.block.id.type === AST_NODE_TYPES.Literal &&
scope.block.id.value === name
);
}
function isExternalDeclarationMerging(
scope: TSESLint.Scope.Scope,
variable: TSESLint.Scope.Variable,
shadowed: TSESLint.Scope.Variable,
): boolean {
const [firstDefinition] = shadowed.defs;
const [secondDefinition] = variable.defs;
return (
isTypeImport(firstDefinition) &&
isImportDeclaration(firstDefinition.parent) &&
isExternalModuleDeclarationWithName(
scope,
firstDefinition.parent.source.value,
) &&
secondDefinition.node.type === AST_NODE_TYPES.TSInterfaceDeclaration &&
secondDefinition.node.parent?.type ===
AST_NODE_TYPES.ExportNamedDeclaration
);
}
/**
* Check if variable name is allowed.
* @param variable The variable to check.
* @returns Whether or not the variable name is allowed.
*/
function isAllowed(variable: TSESLint.Scope.Variable): boolean {
return options.allow!.indexOf(variable.name) !== -1;
}
/**
* Checks if a variable of the class name in the class scope of ClassDeclaration.
*
* ClassDeclaration creates two variables of its name into its outer scope and its class scope.
* So we should ignore the variable in the class scope.
* @param variable The variable to check.
* @returns Whether or not the variable of the class name in the class scope of ClassDeclaration.
*/
function isDuplicatedClassNameVariable(
variable: TSESLint.Scope.Variable,
): boolean {
const block = variable.scope.block;
return (
block.type === AST_NODE_TYPES.ClassDeclaration &&
block.id === variable.identifiers[0]
);
}
/**
* Checks if a variable of the class name in the class scope of TSEnumDeclaration.
*
* TSEnumDeclaration creates two variables of its name into its outer scope and its class scope.
* So we should ignore the variable in the class scope.
* @param variable The variable to check.
* @returns Whether or not the variable of the class name in the class scope of TSEnumDeclaration.
*/
function isDuplicatedEnumNameVariable(
variable: TSESLint.Scope.Variable,
): boolean {
const block = variable.scope.block;
return (
block.type === AST_NODE_TYPES.TSEnumDeclaration &&
block.id === variable.identifiers[0]
);
}
/**
* Checks whether or not a given location is inside of the range of a given node.
* @param node An node to check.
* @param location A location to check.
* @returns `true` if the location is inside of the range of the node.
*/
function isInRange(
node: TSESTree.Node | null,
location: number,
): boolean | null {
return node && node.range[0] <= location && location <= node.range[1];
}
/**
* Searches from the current node through its ancestry to find a matching node.
* @param node a node to get.
* @param match a callback that checks whether or not the node verifies its condition or not.
* @returns the matching node.
*/
function findSelfOrAncestor(
node: TSESTree.Node | undefined,
match: (node: TSESTree.Node) => boolean,
): TSESTree.Node | undefined {
let currentNode = node;
while (currentNode && !match(currentNode)) {
currentNode = currentNode.parent;
}
return currentNode;
}
/**
* Finds function's outer scope.
* @param scope Function's own scope.
* @returns Function's outer scope.
*/
function getOuterScope(
scope: TSESLint.Scope.Scope,
): TSESLint.Scope.Scope | null {
const upper = scope.upper;
if (upper?.type === 'function-expression-name') {
return upper.upper;
}
return upper;
}
/**
* Checks if a variable and a shadowedVariable have the same init pattern ancestor.
* @param variable a variable to check.
* @param shadowedVariable a shadowedVariable to check.
* @returns Whether or not the variable and the shadowedVariable have the same init pattern ancestor.
*/
function isInitPatternNode(
variable: TSESLint.Scope.Variable,
shadowedVariable: TSESLint.Scope.Variable,
): boolean {
const outerDef = shadowedVariable.defs[0];
if (!outerDef) {
return false;
}
const { variableScope } = variable.scope;
if (
!(
(variableScope.block.type ===
AST_NODE_TYPES.ArrowFunctionExpression ||
variableScope.block.type === AST_NODE_TYPES.FunctionExpression) &&
getOuterScope(variableScope) === shadowedVariable.scope
)
) {
return false;
}
const fun = variableScope.block;
const { parent } = fun;
const callExpression = findSelfOrAncestor(
parent,
node => node.type === AST_NODE_TYPES.CallExpression,
);
if (!callExpression) {
return false;
}
let node: TSESTree.Node | undefined = outerDef.name;
const location = callExpression.range[1];
while (node) {
if (node.type === AST_NODE_TYPES.VariableDeclarator) {
if (isInRange(node.init, location)) {
return true;
}
if (
(node.parent?.parent?.type === AST_NODE_TYPES.ForInStatement ||
node.parent?.parent?.type === AST_NODE_TYPES.ForOfStatement) &&
isInRange(node.parent.parent.right, location)
) {
return true;
}
break;
} else if (node.type === AST_NODE_TYPES.AssignmentPattern) {
if (isInRange(node.right, location)) {
return true;
}
} else if (
[
AST_NODE_TYPES.FunctionDeclaration,
AST_NODE_TYPES.ClassDeclaration,
AST_NODE_TYPES.FunctionExpression,
AST_NODE_TYPES.ClassExpression,
AST_NODE_TYPES.ArrowFunctionExpression,
AST_NODE_TYPES.CatchClause,
AST_NODE_TYPES.ImportDeclaration,
AST_NODE_TYPES.ExportNamedDeclaration,
].includes(node.type)
) {
break;
}
node = node.parent;
}
return false;
}
/**
* Checks if a variable is inside the initializer of scopeVar.
*
* To avoid reporting at declarations such as `var a = function a() {};`.
* But it should report `var a = function(a) {};` or `var a = function() { function a() {} };`.
* @param variable The variable to check.
* @param scopeVar The scope variable to look for.
* @returns Whether or not the variable is inside initializer of scopeVar.
*/
function isOnInitializer(
variable: TSESLint.Scope.Variable,
scopeVar: TSESLint.Scope.Variable,
): boolean {
const outerScope = scopeVar.scope;
const outerDef = scopeVar.defs[0];
const outer = outerDef?.parent?.range;
const innerScope = variable.scope;
const innerDef = variable.defs[0];
const inner = innerDef?.name.range;
return !!(
outer &&
inner &&
outer[0] < inner[0] &&
inner[1] < outer[1] &&
((innerDef.type === DefinitionType.FunctionName &&
innerDef.node.type === AST_NODE_TYPES.FunctionExpression) ||
innerDef.node.type === AST_NODE_TYPES.ClassExpression) &&
outerScope === innerScope.upper
);
}
/**
* Get a range of a variable's identifier node.
* @param variable The variable to get.
* @returns The range of the variable's identifier node.
*/
function getNameRange(
variable: TSESLint.Scope.Variable,
): TSESTree.Range | undefined {
const def = variable.defs[0];
return def?.name.range;
}
/**
* Checks if a variable is in TDZ of scopeVar.
* @param variable The variable to check.
* @param scopeVar The variable of TDZ.
* @returns Whether or not the variable is in TDZ of scopeVar.
*/
function isInTdz(
variable: TSESLint.Scope.Variable,
scopeVar: TSESLint.Scope.Variable,
): boolean {
const outerDef = scopeVar.defs[0];
const inner = getNameRange(variable);
const outer = getNameRange(scopeVar);
return !!(
inner &&
outer &&
inner[1] < outer[0] &&
// Excepts FunctionDeclaration if is {"hoist":"function"}.
(options.hoist !== 'functions' ||
!outerDef ||
outerDef.node.type !== AST_NODE_TYPES.FunctionDeclaration)
);
}
/**
* Get declared line and column of a variable.
* @param variable The variable to get.
* @returns The declared line and column of the variable.
*/
function getDeclaredLocation(
variable: TSESLint.Scope.Variable,
): { global: true } | { global: false; line: number; column: number } {
const identifier = variable.identifiers[0];
if (identifier) {
return {
global: false,
line: identifier.loc.start.line,
column: identifier.loc.start.column + 1,
};
} else {
return {
global: true,
};
}
}
/**
* Checks the current context for shadowed variables.
* @param {Scope} scope Fixme
*/
function checkForShadows(scope: TSESLint.Scope.Scope): void {
// ignore global augmentation
if (isGlobalAugmentation(scope)) {
return;
}
const variables = scope.variables;
for (const variable of variables) {
// ignore "arguments"
if (variable.identifiers.length === 0) {
continue;
}
// this params are pseudo-params that cannot be shadowed
if (isThisParam(variable)) {
continue;
}
// ignore variables of a class name in the class scope of ClassDeclaration
if (isDuplicatedClassNameVariable(variable)) {
continue;
}
// ignore variables of a class name in the class scope of ClassDeclaration
if (isDuplicatedEnumNameVariable(variable)) {
continue;
}
// ignore configured allowed names
if (isAllowed(variable)) {
continue;
}
// Gets shadowed variable.
const shadowed = scope.upper
? ASTUtils.findVariable(scope.upper, variable.name)
: null;
if (!shadowed) {
continue;
}
// ignore type value variable shadowing if configured
if (isTypeValueShadow(variable, shadowed)) {
continue;
}
// ignore function type parameter name shadowing if configured
if (isFunctionTypeParameterNameValueShadow(variable, shadowed)) {
continue;
}
// ignore static class method generic shadowing class generic
// this is impossible for the scope analyser to understand
// so we have to handle this manually in this rule
if (isGenericOfAStaticMethodShadow(variable, shadowed)) {
continue;
}
if (isExternalDeclarationMerging(scope, variable, shadowed)) {
continue;
}
const isESLintGlobal = 'writeable' in shadowed;
if (
(shadowed.identifiers.length > 0 ||
(options.builtinGlobals && isESLintGlobal)) &&
!isOnInitializer(variable, shadowed) &&
!(
options.ignoreOnInitialization &&
isInitPatternNode(variable, shadowed)
) &&
!(options.hoist !== 'all' && isInTdz(variable, shadowed))
) {
const location = getDeclaredLocation(shadowed);
context.report({
node: variable.identifiers[0],
...(location.global
? {
messageId: 'noShadowGlobal',
data: {
name: variable.name,
},
}
: {
messageId: 'noShadow',
data: {
name: variable.name,
shadowedLine: location.line,
shadowedColumn: location.column,
},
}),
});
}
}
}
return {
'Program:exit'(): void {
const globalScope = context.getScope();
const stack = globalScope.childScopes.slice();
while (stack.length) {
const scope = stack.pop()!;
stack.push(...scope.childScopes);
checkForShadows(scope);
}
},
};
},
});