📄 `no-shadow`¶

📊 Analysis Summary¶

Metric	Count
🔧 Functions	25
📦 Imports	9
📊 Variables & Constants	3
📑 Type Aliases	2

📚 Table of Contents¶

Default Export
Imports
Variables & Constants
Functions
Type Aliases

🛠️ File Location:¶

📂 packages/eslint-plugin/src/rules/no-shadow.ts

📤 Default Export¶

export default createRule<Options, MessageIds>({ ... })

Property	Value
`name`	'no-shadow'
`meta.type`	'suggestion'
`meta.docs.description`	'Disallow variable declarations from shadowing variables declared in the outer scope'
`meta.docs.extendsBaseRule`	true
`meta.messages.noEnumShadow`	"Enum members are added to the enum scope, so references to '{{name}}' in enum member initializers resolve to this me...
`meta.messages.noShadow`	"'{{name}}' is already declared in the upper scope on line {{shadowedLine}} column {{shadowedColumn}}."
`meta.messages.noShadowGlobal`	"'{{name}}' is already a global variable."
`meta.schema`	[ { type: 'object', additionalProperties: false, properties: { allow: { type: 'array', description: 'Identifier names...
`defaultOptions`	[ { allow: [], builtinGlobals: false, hoist: 'functions-and-types', ignoreFunctionTypeParameterNameValueShadow: true,...

Entry point: create — documented under Functions.

📦 Imports¶

Name	Source
`TSESLint`	`@typescript-eslint/utils`
`TSESTree`	`@typescript-eslint/utils`
`DefinitionType`	`@typescript-eslint/scope-manager`
`ScopeType`	`@typescript-eslint/scope-manager`
`AST_NODE_TYPES`	`@typescript-eslint/utils`
`ASTUtils`	`@typescript-eslint/utils`
`createRule`	`../util`
`isDefinitionFile`	`../util`
`isTypeImport`	`../util/isTypeImport`

Variables & Constants¶

Name	Type	Kind	Value	Exported
`allowedFunctionVariableDefT...`	`Set<any>`	const	`new Set([ AST_NODE_TYPES.TSCallSignatureDeclaration, AST_NODE_TYPES.TSFunctio...`	✗
`functionsHoistedNodes`	`Set<any>`	const	`new Set([AST_NODE_TYPES.FunctionDeclaration])`	✗
`typesHoistedNodes`	`Set<any>`	const	`new Set([ AST_NODE_TYPES.TSInterfaceDeclaration, AST_NODE_TYPES.TSTypeAliasDe...`	✗

Functions¶

`create(context: any, [options]: any): { 'Program:exit'(node: any): void; }`¶

Parameters:

context any
[options] any

Returns: { 'Program:exit'(node: any): void; }

Calls:

isGlobalAugmentation
shadowed.defs.at
isTypeImport (from ../util/isTypeImport)
variable.defs.every
allowedFunctionVariableDefTypes.has
isGenericOfStaticMethod
isGenericOfClass
isImportDeclaration
isExternalModuleDeclarationWithName
options.allow!.includes
match
shadowedVariable.defs.at
getOuterScope
findSelfOrAncestor
isInRange
[ AST_NODE_TYPES.ArrowFunctionExpression, AST_NODE_TYPES.CatchClause, AST_NODE_TYPES.ClassDeclaration, AST_NODE_TYPES.ClassExpression, AST_NODE_TYPES.ExportNamedDeclaration, AST_NODE_TYPES.FunctionDeclaration, AST_NODE_TYPES.FunctionExpression, AST_NODE_TYPES.ImportDeclaration, ].includes
unwrapExpression
scopeVar.defs.at
variable.defs.at
getNameRange
functionsHoistedNodes.has
typesHoistedNodes.has
variable.identifiers.at
isDefinitionFile (from ../util)
variable.defs.some
isThisParam
isDuplicatedClassNameVariable
isDuplicatedEnumNameVariable
isAllowed
isDeclareInDTSFile
ASTUtils.findVariable
isTypeValueShadow
isFunctionTypeParameterNameValueShadow
isGenericOfAStaticMethodShadow
isExternalDeclarationMerging
isOnInitializer
isInitPatternNode
isInTdz
getDeclaredLocation
shadowed.defs.some
context.report
context.sourceCode.getScope
stack.pop
stack.push
checkForShadows

Internal Comments:

  /**   // /**     //                                                                                // // // // // // // // // // // //

name="__codelineno-1-1" href="#__codelineno-1-1">/** * Check if a scope is a TypeScript module augmenting the global namespace. */ * Check if variable is a `this` parameter. */ this shouldn't happen... (x4) * Check if variable name is allowed. * @param variable The variable to check. * @returns Whether or not the variable name is allowed. */ eslint-disable-next-line @typescript-eslint/no-non-null-assertion (x3) /** * 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. */ /** * 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. */ /** * 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. */ /** * 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. */ /** * Finds function's outer scope. * @param scope Function's own scope. * @returns Function's outer scope. */ /** * 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. */ /** * Finds the uppermost expression node that can evaluate to the given one, * unwrapping through LogicalExpression and non-test ConditionalExpression branches. * @param node The node to unwrap. * @returns The topmost unwrapped node. */ /** * Checks if a variable is the name of a function or class expression that is * directly assigned (or transparently through `||`/`?:`) as the initializer * of scopeVar. * * Allows `var a = function a() {}` but reports `var a = wrap(function a() {})`. * @param variable The variable to check. * @param scopeVar The scope variable to look for. * @returns Whether or not the variable is the direct initializer name of scopeVar. */ /** * Get a range of a variable's identifier node. * @param variable The variable to get. * @returns The range of the variable's identifier node. */ /** * 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. */ /** * Get declared line and column of a variable. * @param variable The variable to get. * @returns The declared line and column of the variable. */ /** * Checks if the initialization of a variable has the declare modifier in a * definition file. */ /** * Checks the current context for shadowed variables. * @param scope Fixme */ ignore global augmentation ignore "arguments" this params are pseudo-params that cannot be shadowed ignore variables of a class name in the class scope of ClassDeclaration (x2) ignore configured allowed names ignore variables with the declare keyword in .d.ts files Gets shadowed variable. (x2) ignore type value variable shadowing if configured ignore function type parameter name shadowing if configured 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

Code

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.kind === '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 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.at(0);
      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 =>
        allowedFunctionVariableDefTypes.has(def.node.type),
      );
    }

    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.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 isGenericOfClass(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 ||
        classDecl.type === AST_NODE_TYPES.ClassExpression
      );
    }

    function isGenericOfAStaticMethodShadow(
      variable: TSESLint.Scope.Variable,
      shadowed: TSESLint.Scope.Variable,
    ): boolean {
      return isGenericOfStaticMethod(variable) && isGenericOfClass(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.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.type === AST_NODE_TYPES.TSTypeAliasDeclaration)
      );
    }

    /**
     * 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 {
      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
      return options.allow!.includes(variable.name);
    }

    /**
     * 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 === ScopeType.functionExpressionName) {
        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.at(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 = outerDef.name as TSESTree.Node | undefined;
      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.ArrowFunctionExpression,
            AST_NODE_TYPES.CatchClause,
            AST_NODE_TYPES.ClassDeclaration,
            AST_NODE_TYPES.ClassExpression,
            AST_NODE_TYPES.ExportNamedDeclaration,
            AST_NODE_TYPES.FunctionDeclaration,
            AST_NODE_TYPES.FunctionExpression,
            AST_NODE_TYPES.ImportDeclaration,
          ].includes(node.type)
        ) {
          break;
        }

        node = node.parent;
      }

      return false;
    }

    /**
     * Finds the uppermost expression node that can evaluate to the given one,
     * unwrapping through LogicalExpression and non-test ConditionalExpression branches.
     * @param node The node to unwrap.
     * @returns The topmost unwrapped node.
     */
    function unwrapExpression(node: TSESTree.Node): TSESTree.Node {
      const { parent } = node;
      if (
        parent?.type === AST_NODE_TYPES.LogicalExpression ||
        (parent?.type === AST_NODE_TYPES.ConditionalExpression &&
          parent.test !== node)
      ) {
        return unwrapExpression(parent);
      }
      return node;
    }

    /**
     * Checks if a variable is the name of a function or class expression that is
     * directly assigned (or transparently through `||`/`?:`) as the initializer
     * of scopeVar.
     *
     * Allows `var a = function a() {}` but reports `var a = wrap(function a() {})`.
     * @param variable The variable to check.
     * @param scopeVar The scope variable to look for.
     * @returns Whether or not the variable is the direct initializer name of scopeVar.
     */
    function isOnInitializer(
      variable: TSESLint.Scope.Variable,
      scopeVar: TSESLint.Scope.Variable,
    ): boolean {
      const outerDef = scopeVar.defs.at(0);
      const innerDef = variable.defs.at(0);

      if (!outerDef || !innerDef) {
        return false;
      }

      if (!(
        (innerDef.type === DefinitionType.FunctionName &&
          innerDef.node.type === AST_NODE_TYPES.FunctionExpression) ||
        (innerDef.type === DefinitionType.ClassName &&
          innerDef.node.type === AST_NODE_TYPES.ClassExpression)
      )) {
        return false;
      }

      const outerIdentifier = outerDef.name;
      let initializerNode: TSESTree.Node | null | undefined;

      if (outerIdentifier.parent.type === AST_NODE_TYPES.VariableDeclarator) {
        initializerNode = outerIdentifier.parent.init;
      } else if (
        outerIdentifier.parent.type === AST_NODE_TYPES.AssignmentPattern
      ) {
        initializerNode = outerIdentifier.parent.right;
      }

      if (!initializerNode) {
        return false;
      }

      const nodeToCheck = innerDef.node;

      if (!(
        initializerNode.range[0] <= nodeToCheck.range[0] &&
        nodeToCheck.range[1] <= initializerNode.range[1]
      )) {
        return false;
      }

      return initializerNode === unwrapExpression(nodeToCheck);
    }

    /**
     * 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.at(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.at(0);
      const inner = getNameRange(variable);
      const outer = getNameRange(scopeVar);

      if (!inner || !outer || inner[1] >= outer[0]) {
        return false;
      }

      if (!outerDef) {
        return true;
      }

      if (options.hoist === 'functions') {
        return !functionsHoistedNodes.has(outerDef.node.type);
      }

      if (options.hoist === 'types') {
        return !typesHoistedNodes.has(outerDef.node.type);
      }

      if (options.hoist === 'functions-and-types') {
        return (
          !functionsHoistedNodes.has(outerDef.node.type) &&
          !typesHoistedNodes.has(outerDef.node.type)
        );
      }

      return true;
    }

    /**
     * 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,
    ): { column: number; global: false; line: number } | { global: true } {
      const identifier = variable.identifiers.at(0);
      if (identifier) {
        return {
          column: identifier.loc.start.column + 1,
          global: false,
          line: identifier.loc.start.line,
        };
      }
      return {
        global: true,
      };
    }

    /**
     * Checks if the initialization of a variable has the declare modifier in a
     * definition file.
     */
    function isDeclareInDTSFile(variable: TSESLint.Scope.Variable): boolean {
      const fileName = context.filename;
      if (!isDefinitionFile(fileName)) {
        return false;
      }
      return variable.defs.some(def => {
        return (
          (def.type === DefinitionType.Variable && def.parent.declare) ||
          (def.type === DefinitionType.ClassName && def.node.declare) ||
          (def.type === DefinitionType.TSEnumName && def.node.declare) ||
          (def.type === DefinitionType.TSModuleName && def.node.declare)
        );
      });
    }

    /**
     * Checks the current context for shadowed variables.
     * @param 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;
        }

        // ignore variables with the declare keyword in .d.ts files
        if (isDeclareInDTSFile(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);

          const isEnumDeclaration = shadowed.defs.some(
            def => def.type === DefinitionType.TSEnumName,
          );

          context.report({
            node: variable.identifiers[0],
            ...(location.global
              ? {
                  messageId: 'noShadowGlobal',
                  data: {
                    name: variable.name,
                  },
                }
              : {
                  messageId: isEnumDeclaration ? 'noEnumShadow' : 'noShadow',
                  data: {
                    name: variable.name,
                    shadowedColumn: location.column,
                    shadowedLine: location.line,
                  },
                }),
          });
        }
      }
    }

    return {
      'Program:exit'(node): void {
        const globalScope = context.sourceCode.getScope(node);
        const stack = [...globalScope.childScopes];

        while (stack.length) {
          // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
          const scope = stack.pop()!;

          stack.push(...scope.childScopes);
          checkForShadows(scope);
        }
      },
    };
  }

Internal helpers¶

Declared inside another function in this file.

`isGlobalAugmentation(scope: TSESLint.Scope.Scope): boolean`¶

Check if a scope is a TypeScript module augmenting the global namespace.

Raw JSDoc

/**
     * Check if a scope is a TypeScript module augmenting the global namespace.
     */

Calls:

isGlobalAugmentation

Code

function isGlobalAugmentation(scope: TSESLint.Scope.Scope): boolean {
      return (
        (scope.type === ScopeType.tsModule && scope.block.kind === 'global') ||
        (!!scope.upper && isGlobalAugmentation(scope.upper))
      );
    }

`isThisParam(variable: TSESLint.Scope.Variable): boolean`¶

Check if variable is a this parameter.

Raw JSDoc

/**
     * Check if variable is a `this` parameter.
     */

Code

function isThisParam(variable: TSESLint.Scope.Variable): boolean {
      return (
        variable.defs[0].type === DefinitionType.Parameter &&
        variable.name === 'this'
      );
    }

`isTypeValueShadow(variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean`¶

Parameters:

variable TSESLint.Scope.Variable
shadowed TSESLint.Scope.Variable

Returns: boolean

Calls:

shadowed.defs.at
isTypeImport (from ../util/isTypeImport)

Internal Comments:

// this shouldn't happen...

Code

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.at(0);
      const isShadowedValue =
        !('isValueVariable' in shadowed) ||
        !firstDefinition ||
        (!isTypeImport(firstDefinition) && shadowed.isValueVariable);
      return variable.isValueVariable !== isShadowedValue;
    }

`isFunctionTypeParameterNameValueShadow(variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean`¶

Parameters:

variable TSESLint.Scope.Variable
shadowed TSESLint.Scope.Variable

Returns: boolean

Calls:

variable.defs.every
allowedFunctionVariableDefTypes.has

Internal Comments:

// this shouldn't happen...

Code

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 =>
        allowedFunctionVariableDefTypes.has(def.node.type),
      );
    }

`isGenericOfStaticMethod(variable: TSESLint.Scope.Variable): boolean`¶

Parameters:

variable TSESLint.Scope.Variable

Returns: boolean

Internal Comments:

// this shouldn't happen...

Code

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.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;
    }

`isGenericOfClass(variable: TSESLint.Scope.Variable): boolean`¶

Parameters:

variable TSESLint.Scope.Variable

Returns: boolean

Internal Comments:

// this shouldn't happen...

Code

function isGenericOfClass(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 ||
        classDecl.type === AST_NODE_TYPES.ClassExpression
      );
    }

`isGenericOfAStaticMethodShadow(variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean`¶

Parameters:

variable TSESLint.Scope.Variable
shadowed TSESLint.Scope.Variable

Returns: boolean

Calls:

isGenericOfStaticMethod
isGenericOfClass

Code

function isGenericOfAStaticMethodShadow(
      variable: TSESLint.Scope.Variable,
      shadowed: TSESLint.Scope.Variable,
    ): boolean {
      return isGenericOfStaticMethod(variable) && isGenericOfClass(shadowed);
    }

`isImportDeclaration(definition: TSESTree.ImportDeclaration | TSESTree.T…): definition is TSESTree.ImportDeclaration`¶

Parameters:

definition TSESTree.ImportDeclaration | TSESTree.TSImportEqualsDeclaration

Returns: definition is TSESTree.ImportDeclaration

Code

function isImportDeclaration(
      definition:
        TSESTree.ImportDeclaration | TSESTree.TSImportEqualsDeclaration,
    ): definition is TSESTree.ImportDeclaration {
      return definition.type === AST_NODE_TYPES.ImportDeclaration;
    }

`isExternalModuleDeclarationWithName(scope: TSESLint.Scope.Scope, name: string): boolean`¶

Parameters:

scope TSESLint.Scope.Scope
name string

Returns: boolean

Code

function isExternalModuleDeclarationWithName(
      scope: TSESLint.Scope.Scope,
      name: string,
    ): boolean {
      return (
        scope.type === ScopeType.tsModule &&
        scope.block.id.type === AST_NODE_TYPES.Literal &&
        scope.block.id.value === name
      );
    }

`isExternalDeclarationMerging(scope: TSESLint.Scope.Scope, variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean`¶

Parameters:

scope TSESLint.Scope.Scope
variable TSESLint.Scope.Variable
shadowed TSESLint.Scope.Variable

Returns: boolean

Calls:

isTypeImport (from ../util/isTypeImport)
isImportDeclaration
isExternalModuleDeclarationWithName

Code

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.type === AST_NODE_TYPES.TSTypeAliasDeclaration)
      );
    }

`isAllowed(variable: TSESLint.Scope.Variable): boolean`¶

Check if variable name is allowed.

Parameters:

variable any: The variable to check.

Returns: undefined Whether or not the variable name is allowed.

Raw JSDoc

/**
     * Check if variable name is allowed.
     * @param variable The variable to check.
     * @returns Whether or not the variable name is allowed.
     */

Calls:

options.allow!.includes

Internal Comments:

// eslint-disable-next-line @typescript-eslint/no-non-null-assertion

Code

function isAllowed(variable: TSESLint.Scope.Variable): boolean {
      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
      return options.allow!.includes(variable.name);
    }

`isDuplicatedClassNameVariable(variable: TSESLint.Scope.Variable): boolean`¶

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.

Parameters:

variable any: The variable to check.

Returns: undefined Whether or not the variable of the class name in the class scope of ClassDeclaration.

Raw JSDoc

/**
     * 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.
     */

Code

function isDuplicatedClassNameVariable(
      variable: TSESLint.Scope.Variable,
    ): boolean {
      const block = variable.scope.block;

      return (
        block.type === AST_NODE_TYPES.ClassDeclaration &&
        block.id === variable.identifiers[0]
      );
    }

`isDuplicatedEnumNameVariable(variable: TSESLint.Scope.Variable): boolean`¶

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.

Parameters:

variable any: The variable to check.

Returns: undefined Whether or not the variable of the class name in the class scope of TSEnumDeclaration.

Raw JSDoc

/**
     * 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.
     */

Code

function isDuplicatedEnumNameVariable(
      variable: TSESLint.Scope.Variable,
    ): boolean {
      const block = variable.scope.block;

      return (
        block.type === AST_NODE_TYPES.TSEnumDeclaration &&
        block.id === variable.identifiers[0]
      );
    }

`isInRange(node: TSESTree.Node | null, location: number): boolean | null`¶

Checks whether or not a given location is inside of the range of a given node.

Parameters:

node any: An node to check.
location any: A location to check.

Returns: undefined true if the location is inside of the range of the node.

Raw JSDoc

/**
     * 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.
     */

Code

function isInRange(
      node: TSESTree.Node | null,
      location: number,
    ): boolean | null {
      return node && node.range[0] <= location && location <= node.range[1];
    }

`findSelfOrAncestor(node: TSESTree.Node | undefined, match: (node: TSESTree.Node) => boolean): TSESTree.Node | undefined`¶

Searches from the current node through its ancestry to find a matching node.

Parameters:

node any: a node to get.
match any: a callback that checks whether or not the node verifies its condition or not.

Returns: undefined the matching node.

Raw JSDoc

/**
     * 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.
     */

Calls:

match

Code

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;
    }

`getOuterScope(scope: TSESLint.Scope.Scope): TSESLint.Scope.Scope | null`¶

Finds function's outer scope.

Parameters:

scope any: Function's own scope.

Returns: undefined Function's outer scope.

Raw JSDoc

/**
     * Finds function's outer scope.
     * @param scope Function's own scope.
     * @returns Function's outer scope.
     */

Code

function getOuterScope(
      scope: TSESLint.Scope.Scope,
    ): TSESLint.Scope.Scope | null {
      const upper = scope.upper;

      if (upper?.type === ScopeType.functionExpressionName) {
        return upper.upper;
      }
      return upper;
    }

`isInitPatternNode(variable: TSESLint.Scope.Variable, shadowedVariable: TSESLint.Scope.Variable): boolean`¶

Checks if a variable and a shadowedVariable have the same init pattern ancestor.

Parameters:

variable any: a variable to check.
shadowedVariable any: a shadowedVariable to check.

Returns: undefined Whether or not the variable and the shadowedVariable have the same init pattern ancestor.

Raw JSDoc

/**
     * 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.
     */

Calls:

shadowedVariable.defs.at
getOuterScope
findSelfOrAncestor
isInRange
[ AST_NODE_TYPES.ArrowFunctionExpression, AST_NODE_TYPES.CatchClause, AST_NODE_TYPES.ClassDeclaration, AST_NODE_TYPES.ClassExpression, AST_NODE_TYPES.ExportNamedDeclaration, AST_NODE_TYPES.FunctionDeclaration, AST_NODE_TYPES.FunctionExpression, AST_NODE_TYPES.ImportDeclaration, ].includes

Code

function isInitPatternNode(
      variable: TSESLint.Scope.Variable,
      shadowedVariable: TSESLint.Scope.Variable,
    ): boolean {
      const outerDef = shadowedVariable.defs.at(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 = outerDef.name as TSESTree.Node | undefined;
      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.ArrowFunctionExpression,
            AST_NODE_TYPES.CatchClause,
            AST_NODE_TYPES.ClassDeclaration,
            AST_NODE_TYPES.ClassExpression,
            AST_NODE_TYPES.ExportNamedDeclaration,
            AST_NODE_TYPES.FunctionDeclaration,
            AST_NODE_TYPES.FunctionExpression,
            AST_NODE_TYPES.ImportDeclaration,
          ].includes(node.type)
        ) {
          break;
        }

        node = node.parent;
      }

      return false;
    }

`unwrapExpression(node: TSESTree.Node): TSESTree.Node`¶

Finds the uppermost expression node that can evaluate to the given one, unwrapping through LogicalExpression and non-test ConditionalExpression branches.

Parameters:

node any: The node to unwrap.

Returns: undefined The topmost unwrapped node.

Raw JSDoc

/**
     * Finds the uppermost expression node that can evaluate to the given one,
     * unwrapping through LogicalExpression and non-test ConditionalExpression branches.
     * @param node The node to unwrap.
     * @returns The topmost unwrapped node.
     */

Calls:

unwrapExpression

Code

function unwrapExpression(node: TSESTree.Node): TSESTree.Node {
      const { parent } = node;
      if (
        parent?.type === AST_NODE_TYPES.LogicalExpression ||
        (parent?.type === AST_NODE_TYPES.ConditionalExpression &&
          parent.test !== node)
      ) {
        return unwrapExpression(parent);
      }
      return node;
    }

`isOnInitializer(variable: TSESLint.Scope.Variable, scopeVar: TSESLint.Scope.Variable): boolean`¶

Checks if a variable is the name of a function or class expression that is directly assigned (or transparently through ||/?:) as the initializer of scopeVar.

Allows var a = function a() {} but reports var a = wrap(function a() {}).

Parameters:

variable any: The variable to check.
scopeVar any: The scope variable to look for.

Returns: undefined Whether or not the variable is the direct initializer name of scopeVar.

Raw JSDoc

/**
     * Checks if a variable is the name of a function or class expression that is
     * directly assigned (or transparently through `||`/`?:`) as the initializer
     * of scopeVar.
     *
     * Allows `var a = function a() {}` but reports `var a = wrap(function a() {})`.
     * @param variable The variable to check.
     * @param scopeVar The scope variable to look for.
     * @returns Whether or not the variable is the direct initializer name of scopeVar.
     */

Calls:

scopeVar.defs.at
variable.defs.at
unwrapExpression

Code

function isOnInitializer(
      variable: TSESLint.Scope.Variable,
      scopeVar: TSESLint.Scope.Variable,
    ): boolean {
      const outerDef = scopeVar.defs.at(0);
      const innerDef = variable.defs.at(0);

      if (!outerDef || !innerDef) {
        return false;
      }

      if (!(
        (innerDef.type === DefinitionType.FunctionName &&
          innerDef.node.type === AST_NODE_TYPES.FunctionExpression) ||
        (innerDef.type === DefinitionType.ClassName &&
          innerDef.node.type === AST_NODE_TYPES.ClassExpression)
      )) {
        return false;
      }

      const outerIdentifier = outerDef.name;
      let initializerNode: TSESTree.Node | null | undefined;

      if (outerIdentifier.parent.type === AST_NODE_TYPES.VariableDeclarator) {
        initializerNode = outerIdentifier.parent.init;
      } else if (
        outerIdentifier.parent.type === AST_NODE_TYPES.AssignmentPattern
      ) {
        initializerNode = outerIdentifier.parent.right;
      }

      if (!initializerNode) {
        return false;
      }

      const nodeToCheck = innerDef.node;

      if (!(
        initializerNode.range[0] <= nodeToCheck.range[0] &&
        nodeToCheck.range[1] <= initializerNode.range[1]
      )) {
        return false;
      }

      return initializerNode === unwrapExpression(nodeToCheck);
    }

`getNameRange(variable: TSESLint.Scope.Variable): TSESTree.Range | undefined`¶

Get a range of a variable's identifier node.

Parameters:

variable any: The variable to get.

Returns: undefined The range of the variable's identifier node.

Raw JSDoc

/**
     * Get a range of a variable's identifier node.
     * @param variable The variable to get.
     * @returns The range of the variable's identifier node.
     */

Calls:

variable.defs.at

Code

function getNameRange(
      variable: TSESLint.Scope.Variable,
    ): TSESTree.Range | undefined {
      const def = variable.defs.at(0);
      return def?.name.range;
    }

`isInTdz(variable: TSESLint.Scope.Variable, scopeVar: TSESLint.Scope.Variable): boolean`¶

Checks if a variable is in TDZ of scopeVar.

Parameters:

variable any: The variable to check.
scopeVar any: The variable of TDZ.

Returns: undefined Whether or not the variable is in TDZ of scopeVar.

Raw JSDoc

/**
     * 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.
     */

Calls:

scopeVar.defs.at
getNameRange
functionsHoistedNodes.has
typesHoistedNodes.has

Code

function isInTdz(
      variable: TSESLint.Scope.Variable,
      scopeVar: TSESLint.Scope.Variable,
    ): boolean {
      const outerDef = scopeVar.defs.at(0);
      const inner = getNameRange(variable);
      const outer = getNameRange(scopeVar);

      if (!inner || !outer || inner[1] >= outer[0]) {
        return false;
      }

      if (!outerDef) {
        return true;
      }

      if (options.hoist === 'functions') {
        return !functionsHoistedNodes.has(outerDef.node.type);
      }

      if (options.hoist === 'types') {
        return !typesHoistedNodes.has(outerDef.node.type);
      }

      if (options.hoist === 'functions-and-types') {
        return (
          !functionsHoistedNodes.has(outerDef.node.type) &&
          !typesHoistedNodes.has(outerDef.node.type)
        );
      }

      return true;
    }

`getDeclaredLocation(variable: TSESLint.Scope.Variable): { column: number; global: false; line: number } | { global:…`¶

Get declared line and column of a variable.

Parameters:

variable any: The variable to get.

Returns: undefined The declared line and column of the variable.

Raw JSDoc

/**
     * Get declared line and column of a variable.
     * @param  variable The variable to get.
     * @returns The declared line and column of the variable.
     */

Calls:

variable.identifiers.at

Code

function getDeclaredLocation(
      variable: TSESLint.Scope.Variable,
    ): { column: number; global: false; line: number } | { global: true } {
      const identifier = variable.identifiers.at(0);
      if (identifier) {
        return {
          column: identifier.loc.start.column + 1,
          global: false,
          line: identifier.loc.start.line,
        };
      }
      return {
        global: true,
      };
    }

`isDeclareInDTSFile(variable: TSESLint.Scope.Variable): boolean`¶

Checks if the initialization of a variable has the declare modifier in a definition file.

Raw JSDoc

/**
     * Checks if the initialization of a variable has the declare modifier in a
     * definition file.
     */

Calls:

isDefinitionFile (from ../util)
variable.defs.some

Code

function isDeclareInDTSFile(variable: TSESLint.Scope.Variable): boolean {
      const fileName = context.filename;
      if (!isDefinitionFile(fileName)) {
        return false;
      }
      return variable.defs.some(def => {
        return (
          (def.type === DefinitionType.Variable && def.parent.declare) ||
          (def.type === DefinitionType.ClassName && def.node.declare) ||
          (def.type === DefinitionType.TSEnumName && def.node.declare) ||
          (def.type === DefinitionType.TSModuleName && def.node.declare)
        );
      });
    }

`checkForShadows(scope: TSESLint.Scope.Scope): void`¶

Checks the current context for shadowed variables.

Parameters:

scope any: Fixme

Raw JSDoc

/**
     * Checks the current context for shadowed variables.
     * @param scope Fixme
     */

Calls:

isGlobalAugmentation
isThisParam
isDuplicatedClassNameVariable
isDuplicatedEnumNameVariable
isAllowed
isDeclareInDTSFile
ASTUtils.findVariable
isTypeValueShadow
isFunctionTypeParameterNameValueShadow
isGenericOfAStaticMethodShadow
isExternalDeclarationMerging
isOnInitializer
isInitPatternNode
isInTdz
getDeclaredLocation
shadowed.defs.some
context.report

Internal Comments:

// ignore global augmentation
// ignore "arguments"
// this params are pseudo-params that cannot be shadowed
// ignore variables of a class name in the class scope of ClassDeclaration (x2)
// ignore configured allowed names
// ignore variables with the declare keyword in .d.ts files
// Gets shadowed variable. (x2)
// ignore type value variable shadowing if configured
// ignore function type parameter name shadowing if configured
// 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

Code

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;
        }

        // ignore variables with the declare keyword in .d.ts files
        if (isDeclareInDTSFile(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);

          const isEnumDeclaration = shadowed.defs.some(
            def => def.type === DefinitionType.TSEnumName,
          );

          context.report({
            node: variable.identifiers[0],
            ...(location.global
              ? {
                  messageId: 'noShadowGlobal',
                  data: {
                    name: variable.name,
                  },
                }
              : {
                  messageId: isEnumDeclaration ? 'noEnumShadow' : 'noShadow',
                  data: {
                    name: variable.name,
                    shadowedColumn: location.column,
                    shadowedLine: location.line,
                  },
                }),
          });
        }
      }
    }

Type Aliases¶

`MessageIds`¶

type MessageIds = 'noEnumShadow' | 'noShadow' | 'noShadowGlobal';

`Options`¶

type Options = [
  {
    allow?: string[];
    builtinGlobals?: boolean;
    hoist?: 'all' | 'functions' | 'functions-and-types' | 'never' | 'types';
    ignoreFunctionTypeParameterNameValueShadow?: boolean;
    ignoreOnInitialization?: boolean;
    ignoreTypeValueShadow?: boolean;
  },
];

Generated by Syntax Scribe

📄 no-shadow¶

📊 Analysis Summary¶

📚 Table of Contents¶

🛠️ File Location:¶

📤 Default Export¶

📦 Imports¶

Variables & Constants¶

Functions¶

create(context: any, [options]: any): { 'Program:exit'(node: any): void; }¶

Internal helpers¶

isGlobalAugmentation(scope: TSESLint.Scope.Scope): boolean¶

isThisParam(variable: TSESLint.Scope.Variable): boolean¶

isTypeValueShadow(variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean¶

isFunctionTypeParameterNameValueShadow(variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean¶

isGenericOfStaticMethod(variable: TSESLint.Scope.Variable): boolean¶

isGenericOfClass(variable: TSESLint.Scope.Variable): boolean¶

isGenericOfAStaticMethodShadow(variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean¶

isImportDeclaration(definition: TSESTree.ImportDeclaration | TSESTree.T…): definition is TSESTree.ImportDeclaration¶

isExternalModuleDeclarationWithName(scope: TSESLint.Scope.Scope, name: string): boolean¶

isExternalDeclarationMerging(scope: TSESLint.Scope.Scope, variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean¶

isAllowed(variable: TSESLint.Scope.Variable): boolean¶

isDuplicatedClassNameVariable(variable: TSESLint.Scope.Variable): boolean¶

isDuplicatedEnumNameVariable(variable: TSESLint.Scope.Variable): boolean¶

isInRange(node: TSESTree.Node | null, location: number): boolean | null¶

findSelfOrAncestor(node: TSESTree.Node | undefined, match: (node: TSESTree.Node) => boolean): TSESTree.Node | undefined¶

getOuterScope(scope: TSESLint.Scope.Scope): TSESLint.Scope.Scope | null¶

isInitPatternNode(variable: TSESLint.Scope.Variable, shadowedVariable: TSESLint.Scope.Variable): boolean¶

unwrapExpression(node: TSESTree.Node): TSESTree.Node¶

isOnInitializer(variable: TSESLint.Scope.Variable, scopeVar: TSESLint.Scope.Variable): boolean¶

getNameRange(variable: TSESLint.Scope.Variable): TSESTree.Range | undefined¶

isInTdz(variable: TSESLint.Scope.Variable, scopeVar: TSESLint.Scope.Variable): boolean¶

getDeclaredLocation(variable: TSESLint.Scope.Variable): { column: number; global: false; line: number } | { global:…¶

isDeclareInDTSFile(variable: TSESLint.Scope.Variable): boolean¶

checkForShadows(scope: TSESLint.Scope.Scope): void¶

Type Aliases¶

MessageIds¶

Options¶

📄 `no-shadow`¶

`create(context: any, [options]: any): { 'Program:exit'(node: any): void; }`¶

`isGlobalAugmentation(scope: TSESLint.Scope.Scope): boolean`¶

`isThisParam(variable: TSESLint.Scope.Variable): boolean`¶

`isTypeValueShadow(variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean`¶

`isFunctionTypeParameterNameValueShadow(variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean`¶

`isGenericOfStaticMethod(variable: TSESLint.Scope.Variable): boolean`¶

`isGenericOfClass(variable: TSESLint.Scope.Variable): boolean`¶

`isGenericOfAStaticMethodShadow(variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean`¶

`isImportDeclaration(definition: TSESTree.ImportDeclaration | TSESTree.T…): definition is TSESTree.ImportDeclaration`¶

`isExternalModuleDeclarationWithName(scope: TSESLint.Scope.Scope, name: string): boolean`¶

`isExternalDeclarationMerging(scope: TSESLint.Scope.Scope, variable: TSESLint.Scope.Variable, shadowed: TSESLint.Scope.Variable): boolean`¶

`isAllowed(variable: TSESLint.Scope.Variable): boolean`¶

`isDuplicatedClassNameVariable(variable: TSESLint.Scope.Variable): boolean`¶

`isDuplicatedEnumNameVariable(variable: TSESLint.Scope.Variable): boolean`¶

`isInRange(node: TSESTree.Node | null, location: number): boolean | null`¶

`findSelfOrAncestor(node: TSESTree.Node | undefined, match: (node: TSESTree.Node) => boolean): TSESTree.Node | undefined`¶

`getOuterScope(scope: TSESLint.Scope.Scope): TSESLint.Scope.Scope | null`¶

`isInitPatternNode(variable: TSESLint.Scope.Variable, shadowedVariable: TSESLint.Scope.Variable): boolean`¶

`unwrapExpression(node: TSESTree.Node): TSESTree.Node`¶

`isOnInitializer(variable: TSESLint.Scope.Variable, scopeVar: TSESLint.Scope.Variable): boolean`¶

`getNameRange(variable: TSESLint.Scope.Variable): TSESTree.Range | undefined`¶

`isInTdz(variable: TSESLint.Scope.Variable, scopeVar: TSESLint.Scope.Variable): boolean`¶

`getDeclaredLocation(variable: TSESLint.Scope.Variable): { column: number; global: false; line: number } | { global:…`¶

`isDeclareInDTSFile(variable: TSESLint.Scope.Variable): boolean`¶

`checkForShadows(scope: TSESLint.Scope.Scope): void`¶

`MessageIds`¶

`Options`¶