@typescript-eslint/eslint-plugin
Version:
TypeScript plugin for ESLint
198 lines (197 loc) • 8.21 kB
JavaScript
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Object.defineProperty(exports, "__esModule", { value: true });
const utils_1 = require("@typescript-eslint/utils");
const tsutils = __importStar(require("ts-api-utils"));
const ts = __importStar(require("typescript"));
const util_1 = require("../util");
exports.default = (0, util_1.createRule)({
name: 'no-unnecessary-type-arguments',
meta: {
type: 'suggestion',
docs: {
description: 'Disallow type arguments that are equal to the default',
recommended: 'strict',
requiresTypeChecking: true,
},
fixable: 'code',
messages: {
unnecessaryTypeParameter: 'This is the default value for this type parameter, so it can be omitted.',
},
schema: [],
},
defaultOptions: [],
create(context) {
const services = (0, util_1.getParserServices)(context);
const checker = services.program.getTypeChecker();
function getTypeForComparison(type) {
if ((0, util_1.isTypeReferenceType)(type)) {
return {
type: type.target,
typeArguments: checker.getTypeArguments(type),
};
}
return {
type,
typeArguments: [],
};
}
function checkTSArgsAndParameters(esParameters, typeParameters) {
// Just check the last one. Must specify previous type parameters if the last one is specified.
const i = esParameters.params.length - 1;
const arg = esParameters.params[i];
const param = typeParameters.at(i);
if (!param?.default) {
return;
}
// TODO: would like checker.areTypesEquivalent. https://github.com/Microsoft/TypeScript/issues/13502
const defaultType = checker.getTypeAtLocation(param.default);
const argType = services.getTypeAtLocation(arg);
// this check should handle some of the most simple cases of like strings, numbers, etc
if (defaultType !== argType) {
// For more complex types (like aliases to generic object types) - TS won't always create a
// global shared type object for the type - so we need to resort to manually comparing the
// reference type and the passed type arguments.
// Also - in case there are aliases - we need to resolve them before we do checks
const defaultTypeResolved = getTypeForComparison(defaultType);
const argTypeResolved = getTypeForComparison(argType);
if (
// ensure the resolved type AND all the parameters are the same
defaultTypeResolved.type !== argTypeResolved.type ||
defaultTypeResolved.typeArguments.length !==
argTypeResolved.typeArguments.length ||
defaultTypeResolved.typeArguments.some((t, i) => t !== argTypeResolved.typeArguments[i])) {
return;
}
}
context.report({
node: arg,
messageId: 'unnecessaryTypeParameter',
fix: fixer => fixer.removeRange(i === 0
? esParameters.range
: [esParameters.params[i - 1].range[1], arg.range[1]]),
});
}
return {
TSTypeParameterInstantiation(node) {
const expression = services.esTreeNodeToTSNodeMap.get(node);
const typeParameters = getTypeParametersFromNode(node, expression, checker);
if (typeParameters) {
checkTSArgsAndParameters(node, typeParameters);
}
},
};
},
});
function getTypeParametersFromNode(node, tsNode, checker) {
if (ts.isExpressionWithTypeArguments(tsNode)) {
return getTypeParametersFromType(node, tsNode.expression, checker);
}
if (ts.isTypeReferenceNode(tsNode)) {
return getTypeParametersFromType(node, tsNode.typeName, checker);
}
if (ts.isCallExpression(tsNode) ||
ts.isNewExpression(tsNode) ||
ts.isTaggedTemplateExpression(tsNode) ||
ts.isJsxOpeningElement(tsNode) ||
ts.isJsxSelfClosingElement(tsNode)) {
return getTypeParametersFromCall(node, tsNode, checker);
}
return undefined;
}
function getTypeParametersFromType(node, type, checker) {
const symAtLocation = checker.getSymbolAtLocation(type);
if (!symAtLocation) {
return undefined;
}
const sym = getAliasedSymbol(symAtLocation, checker);
const declarations = sym.getDeclarations();
if (!declarations) {
return undefined;
}
const sortedDeclaraions = sortDeclarationsByTypeValueContext(node, declarations);
return (0, util_1.findFirstResult)(sortedDeclaraions, decl => {
if (ts.isTypeAliasDeclaration(decl) ||
ts.isInterfaceDeclaration(decl) ||
ts.isClassLike(decl)) {
return decl.typeParameters;
}
if (ts.isVariableDeclaration(decl)) {
return getConstructSignatureDeclaration(symAtLocation, checker)
?.typeParameters;
}
return undefined;
});
}
function getTypeParametersFromCall(node, tsNode, checker) {
const sig = checker.getResolvedSignature(tsNode);
const sigDecl = sig?.getDeclaration();
if (!sigDecl) {
return ts.isNewExpression(tsNode)
? getTypeParametersFromType(node, tsNode.expression, checker)
: undefined;
}
return sigDecl.typeParameters;
}
function getAliasedSymbol(symbol, checker) {
return tsutils.isSymbolFlagSet(symbol, ts.SymbolFlags.Alias)
? checker.getAliasedSymbol(symbol)
: symbol;
}
function isInTypeContext(node) {
return (node.parent.type === utils_1.AST_NODE_TYPES.TSInterfaceHeritage ||
node.parent.type === utils_1.AST_NODE_TYPES.TSTypeReference ||
node.parent.type === utils_1.AST_NODE_TYPES.TSClassImplements);
}
function isTypeContextDeclaration(decl) {
return ts.isTypeAliasDeclaration(decl) || ts.isInterfaceDeclaration(decl);
}
function typeFirstCompare(declA, declB) {
const aIsType = isTypeContextDeclaration(declA);
const bIsType = isTypeContextDeclaration(declB);
return Number(bIsType) - Number(aIsType);
}
function sortDeclarationsByTypeValueContext(node, declarations) {
const sorted = [...declarations].sort(typeFirstCompare);
if (isInTypeContext(node)) {
return sorted;
}
return sorted.reverse();
}
function getConstructSignatureDeclaration(symbol, checker) {
const type = checker.getTypeOfSymbol(symbol);
const sig = type.getConstructSignatures();
return sig.at(0)?.getDeclaration();
}