forked from typescript-eslint/typescript-eslint
/
no-invalid-void-type.ts
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/
no-invalid-void-type.ts
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import type { TSESTree } from '@typescript-eslint/utils';
import { AST_NODE_TYPES } from '@typescript-eslint/utils';
import * as util from '../util';
interface Options {
allowInGenericTypeArguments?: boolean | string[];
allowAsThisParameter?: boolean;
}
type MessageIds =
| 'invalidVoidForGeneric'
| 'invalidVoidNotReturnOrGeneric'
| 'invalidVoidNotReturn'
| 'invalidVoidNotReturnOrThisParam'
| 'invalidVoidNotReturnOrThisParamOrGeneric';
export default util.createRule<[Options], MessageIds>({
name: 'no-invalid-void-type',
meta: {
type: 'problem',
docs: {
description: 'Disallow `void` type outside of generic or return types',
recommended: 'strict',
},
messages: {
invalidVoidForGeneric:
'{{ generic }} may not have void as a type variable.',
invalidVoidNotReturnOrGeneric:
'void is only valid as a return type or generic type variable.',
invalidVoidNotReturn: 'void is only valid as a return type.',
invalidVoidNotReturnOrThisParam:
'void is only valid as return type or type of `this` parameter.',
invalidVoidNotReturnOrThisParamOrGeneric:
'void is only valid as a return type or generic type variable or the type of a `this` parameter.',
},
schema: [
{
type: 'object',
properties: {
allowInGenericTypeArguments: {
oneOf: [
{ type: 'boolean' },
{
type: 'array',
items: { type: 'string' },
minLength: 1,
},
],
},
allowAsThisParameter: {
type: 'boolean',
},
},
additionalProperties: false,
},
],
},
defaultOptions: [
{ allowInGenericTypeArguments: true, allowAsThisParameter: false },
],
create(context, [{ allowInGenericTypeArguments, allowAsThisParameter }]) {
const validParents: AST_NODE_TYPES[] = [
AST_NODE_TYPES.TSTypeAnnotation, //
];
const invalidGrandParents: AST_NODE_TYPES[] = [
AST_NODE_TYPES.TSPropertySignature,
AST_NODE_TYPES.CallExpression,
AST_NODE_TYPES.PropertyDefinition,
AST_NODE_TYPES.Identifier,
];
const validUnionMembers: AST_NODE_TYPES[] = [
AST_NODE_TYPES.TSVoidKeyword,
AST_NODE_TYPES.TSNeverKeyword,
];
if (allowInGenericTypeArguments === true) {
validParents.push(AST_NODE_TYPES.TSTypeParameterInstantiation);
}
/**
* @brief check if the given void keyword is used as a valid generic type
*
* reports if the type parametrized by void is not in the whitelist, or
* allowInGenericTypeArguments is false.
* no-op if the given void keyword is not used as generic type
*/
function checkGenericTypeArgument(node: TSESTree.TSVoidKeyword): void {
// only matches T<..., void, ...>
// extra check for precaution
/* istanbul ignore next */
if (
node.parent?.type !== AST_NODE_TYPES.TSTypeParameterInstantiation ||
node.parent.parent?.type !== AST_NODE_TYPES.TSTypeReference
) {
return;
}
// check whitelist
if (Array.isArray(allowInGenericTypeArguments)) {
const sourceCode = context.getSourceCode();
const fullyQualifiedName = sourceCode
.getText(node.parent.parent.typeName)
.replace(/ /gu, '');
if (
!allowInGenericTypeArguments
.map(s => s.replace(/ /gu, ''))
.includes(fullyQualifiedName)
) {
context.report({
messageId: 'invalidVoidForGeneric',
data: { generic: fullyQualifiedName },
node,
});
}
return;
}
if (!allowInGenericTypeArguments) {
context.report({
messageId: allowAsThisParameter
? 'invalidVoidNotReturnOrThisParam'
: 'invalidVoidNotReturn',
node,
});
}
}
/**
* @brief checks if the generic type parameter extends void
*/
function checkExtendedVoid(
node: TSESTree.TSVoidKeyword,
parentNode: TSESTree.TSTypeParameter,
): void {
if (
parentNode.constraint?.type !== AST_NODE_TYPES.TSVoidKeyword ||
JSON.stringify(parentNode.default?.range) !== JSON.stringify(node.range)
) {
return;
}
context.report({
messageId: 'invalidVoidNotReturnOrGeneric',
node: parentNode.constraint,
});
}
/**
* @brief checks if the type of given argument is TSESTree.TSTypeParameter
*/
function isTSTypeParameter(
node: TSESTree.Node,
): node is TSESTree.TSTypeParameter {
return node.type === AST_NODE_TYPES.TSTypeParameter;
}
/**
* @brief checks that a union containing void is valid
* @return true if every member of the union is specified as a valid type in
* validUnionMembers, or is a valid generic type parametrized by void
*/
function isValidUnionType(node: TSESTree.TSUnionType): boolean {
return node.types.every(
member =>
validUnionMembers.includes(member.type) ||
// allows any T<..., void, ...> here, checked by checkGenericTypeArgument
(member.type === AST_NODE_TYPES.TSTypeReference &&
member.typeParameters?.type ===
AST_NODE_TYPES.TSTypeParameterInstantiation &&
member.typeParameters?.params
.map(param => param.type)
.includes(AST_NODE_TYPES.TSVoidKeyword)),
);
}
return {
TSVoidKeyword(node: TSESTree.TSVoidKeyword): void {
/* istanbul ignore next */
if (!node.parent?.parent) {
return;
}
// checks T<..., void, ...> against specification of allowInGenericArguments option
if (
node.parent.type === AST_NODE_TYPES.TSTypeParameterInstantiation &&
node.parent.parent.type === AST_NODE_TYPES.TSTypeReference
) {
checkGenericTypeArgument(node);
return;
}
// allow <T = void> if allowInGenericTypeArguments is specified, and report if the generic type parameter extends void
if (
allowInGenericTypeArguments &&
isTSTypeParameter(node.parent) &&
node.parent.default?.type === AST_NODE_TYPES.TSVoidKeyword
) {
checkExtendedVoid(node, node.parent);
return;
}
// union w/ void must contain types from validUnionMembers, or a valid generic void type
if (
node.parent.type === AST_NODE_TYPES.TSUnionType &&
isValidUnionType(node.parent)
) {
return;
}
// this parameter is ok to be void.
if (
allowAsThisParameter &&
node.parent.type === AST_NODE_TYPES.TSTypeAnnotation &&
node.parent.parent.type === AST_NODE_TYPES.Identifier &&
node.parent.parent.name === 'this'
) {
return;
}
// default cases
if (
validParents.includes(node.parent.type) &&
!invalidGrandParents.includes(node.parent.parent.type)
) {
return;
}
context.report({
messageId:
allowInGenericTypeArguments && allowAsThisParameter
? 'invalidVoidNotReturnOrThisParamOrGeneric'
: allowInGenericTypeArguments
? 'invalidVoidNotReturnOrGeneric'
: allowAsThisParameter
? 'invalidVoidNotReturnOrThisParam'
: 'invalidVoidNotReturn',
node,
});
},
};
},
});