eslint-plugin-sonarjs
Version:
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JavaScript
;
/*
* SonarQube JavaScript Plugin
* Copyright (C) SonarSource Sàrl
* mailto:info AT sonarsource DOT com
*
* You can redistribute and/or modify this program under the terms of
* the Sonar Source-Available License Version 1, as published by SonarSource Sàrl.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the Sonar Source-Available License for more details.
*
* You should have received a copy of the Sonar Source-Available License
* along with this program; if not, see https://sonarsource.com/license/ssal/
*/
// https://sonarsource.github.io/rspec/#/rspec/S3801/javascript
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
var desc = Object.getOwnPropertyDescriptor(m, k);
if (!desc || ("get" in desc ? !m.__esModule : desc.writable || desc.configurable)) {
desc = { enumerable: true, get: function() { return m[k]; } };
}
Object.defineProperty(o, k2, desc);
}) : (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
o[k2] = m[k];
}));
var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
o["default"] = v;
});
var __importStar = (this && this.__importStar) || (function () {
var ownKeys = function(o) {
ownKeys = Object.getOwnPropertyNames || function (o) {
var ar = [];
for (var k in o) if (Object.prototype.hasOwnProperty.call(o, k)) ar[ar.length] = k;
return ar;
};
return ownKeys(o);
};
return function (mod) {
if (mod && mod.__esModule) return mod;
var result = {};
if (mod != null) for (var k = ownKeys(mod), i = 0; i < k.length; i++) if (k[i] !== "default") __createBinding(result, mod, k[i]);
__setModuleDefault(result, mod);
return result;
};
})();
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.rule = void 0;
const typescript_1 = __importDefault(require("typescript"));
const parser_services_js_1 = require("../helpers/parser-services.js");
const type_js_1 = require("../helpers/type.js");
const generate_meta_js_1 = require("../helpers/generate-meta.js");
const location_js_1 = require("../helpers/location.js");
const ancestor_js_1 = require("../helpers/ancestor.js");
const meta = __importStar(require("./generated-meta.js"));
exports.rule = {
meta: (0, generate_meta_js_1.generateMeta)(meta),
create(context) {
const sourceCode = context.sourceCode;
const services = sourceCode.parserServices;
const hasTypeInformation = (0, parser_services_js_1.isRequiredParserServices)(services);
const functionContextStack = [];
const checkOnFunctionExit = (node) => checkFunctionLikeDeclaration(node, functionContextStack.at(-1), hasTypeInformation ? services : undefined);
// tracks the segments we've traversed in the current code path
let currentSegments;
// tracks all current segments for all open paths
const allCurrentSegments = [];
function checkFunctionLikeDeclaration(node, functionContext, services) {
if (!functionContext ||
(!!node.returnType &&
declaredReturnTypeContainsVoidOrNeverTypes(node.returnType.typeAnnotation))) {
return;
}
checkFunctionForImplicitReturn(functionContext, services);
if (hasInconsistentReturns(functionContext)) {
const secondaryLocations = getSecondaryLocations(functionContext, node);
(0, location_js_1.report)(context, {
message: `Refactor this function to use "return" consistently.`,
loc: (0, location_js_1.getMainFunctionTokenLocation)(node, (0, ancestor_js_1.getParent)(context, node), context),
}, secondaryLocations);
}
}
function checkFunctionForImplicitReturn(functionContext, services) {
// As this method is called at the exit point of a function definition, the current
// segments are the ones leading to the exit point at the end of the function. If they
// are reachable, it means there is an implicit return.
const hasReachableSegment = Array.from(currentSegments).some(segment => segment.reachable);
if (hasReachableSegment && services) {
// Check if any exhaustive switch makes the implicit return unreachable.
// A switch eliminates the implicit return if:
// 1. It's exhaustive (covers all possible values)
// 2. Its last case doesn't have a reachable exit (all paths return/throw)
const hasExhaustiveSwitch = functionContext.switchStatements.some(switchStmt => isExhaustiveSwitch(switchStmt, services) &&
!functionContext.switchLastCaseReachable.get(switchStmt));
// Check if the last call expression returns 'never' (e.g., a throwing function)
// If so, the implicit return is unreachable
const lastCallReturnsNever = functionContext.lastCallExpression &&
isNeverReturningCall(functionContext.lastCallExpression, services);
functionContext.containsImplicitReturn = !hasExhaustiveSwitch && !lastCallReturnsNever;
}
else {
functionContext.containsImplicitReturn = hasReachableSegment;
}
}
function getSecondaryLocations(functionContext, node) {
const secondaryLocations = functionContext.returnStatements
.slice()
.map(returnStatement => (0, location_js_1.toSecondaryLocation)(returnStatement, returnStatement.argument ? 'Return with value' : 'Return without value'));
if (functionContext.containsImplicitReturn) {
const closeCurlyBraceToken = sourceCode.getLastToken(node, token => token.value === '}');
if (!!closeCurlyBraceToken) {
secondaryLocations.push((0, location_js_1.toSecondaryLocation)(closeCurlyBraceToken, 'Implicit return without value'));
}
}
return secondaryLocations;
}
return {
onCodePathStart(codePath) {
functionContextStack.push({
codePath,
containsReturnWithValue: false,
containsReturnWithoutValue: false,
containsImplicitReturn: false,
returnStatements: [],
switchStatements: [],
switchLastCaseReachable: new Map(),
lastCallExpression: null,
});
allCurrentSegments.push(currentSegments);
currentSegments = new Set();
},
onCodePathEnd() {
functionContextStack.pop();
currentSegments = allCurrentSegments.pop();
},
onCodePathSegmentStart(segment) {
currentSegments.add(segment);
},
onCodePathSegmentEnd(segment) {
currentSegments.delete(segment);
},
onUnreachableCodePathSegmentStart(segment) {
currentSegments.add(segment);
},
onUnreachableCodePathSegmentEnd(segment) {
currentSegments.delete(segment);
},
ReturnStatement(node) {
const currentContext = functionContextStack.at(-1);
if (!!currentContext) {
const returnStatement = node;
currentContext.containsReturnWithValue =
currentContext.containsReturnWithValue || !!returnStatement.argument;
currentContext.containsReturnWithoutValue =
currentContext.containsReturnWithoutValue || !returnStatement.argument;
currentContext.returnStatements.push(returnStatement);
}
},
SwitchStatement(node) {
const currentContext = functionContextStack.at(-1);
if (currentContext) {
currentContext.switchStatements.push(node);
}
},
'SwitchCase:exit'(node) {
const currentContext = functionContextStack.at(-1);
if (!currentContext) {
return;
}
const switchStmt = (0, ancestor_js_1.getParent)(context, node);
const lastCase = switchStmt.cases.at(-1);
// Only track the last case - all fall-throughs eventually reach it
if (node === lastCase) {
const hasReachableExit = Array.from(currentSegments).some(s => s.reachable);
currentContext.switchLastCaseReachable.set(switchStmt, hasReachableExit);
}
},
ExpressionStatement(node) {
const currentContext = functionContextStack.at(-1);
if (currentContext) {
const expr = node.expression;
if (expr.type === 'CallExpression') {
// Track any call expression - we'll check if it returns 'never' later
currentContext.lastCallExpression = expr;
}
}
},
'FunctionDeclaration:exit': checkOnFunctionExit,
'FunctionExpression:exit': checkOnFunctionExit,
'ArrowFunctionExpression:exit': checkOnFunctionExit,
};
},
};
function hasInconsistentReturns(functionContext) {
return (functionContext.containsReturnWithValue &&
(functionContext.containsReturnWithoutValue || functionContext.containsImplicitReturn));
}
function declaredReturnTypeContainsVoidOrNeverTypes(returnTypeNode) {
return (isVoidType(returnTypeNode) ||
(returnTypeNode.type === 'TSUnionType' &&
returnTypeNode.types.some(declaredReturnTypeContainsVoidOrNeverTypes)));
}
function isVoidType(typeNode) {
return (typeNode.type === 'TSUndefinedKeyword' ||
typeNode.type === 'TSVoidKeyword' ||
typeNode.type === 'TSNeverKeyword');
}
/**
* Checks if a switch statement is exhaustive (covers all possible values).
* If exhaustive, ESLint's "implicit return" detection is a false positive
* because the "no case matches" path doesn't actually exist.
*/
function isExhaustiveSwitch(switchStmt, services) {
if (switchStmt.cases.length === 0) {
return false;
}
// If there's a default case, the switch handles all possible values
if (switchStmt.cases.some(c => c.test === null)) {
return true;
}
// Without a default, verify all union/enum members are covered
const discriminantType = (0, type_js_1.getTypeFromTreeNode)(switchStmt.discriminant, services);
const types = discriminantType.isUnion() ? discriminantType.types : [discriminantType];
// Must be a union or enum type to be exhaustive without a default
if (types.length <= 1 && !isEnumType(discriminantType)) {
return false;
}
// Collect all case test values
const coveredTypes = new Set();
for (const caseClause of switchStmt.cases) {
if (caseClause.test) {
const testType = (0, type_js_1.getTypeFromTreeNode)(caseClause.test, services);
if (testType.isUnion()) {
testType.types.forEach(t => coveredTypes.add(t));
}
else {
coveredTypes.add(testType);
}
}
}
// Check if all types are covered
const checker = services.program.getTypeChecker();
return types.every(type => Array.from(coveredTypes).some(covered => checker.isTypeAssignableTo(type, covered)));
}
function isEnumType(type) {
return ((type.flags & typescript_1.default.TypeFlags.EnumLike) !== 0 ||
(type.flags & typescript_1.default.TypeFlags.EnumLiteral) !== 0 ||
type.symbol?.flags === typescript_1.default.SymbolFlags.EnumMember);
}
/**
* Checks if a call expression returns 'never' (e.g., a function that always throws).
* This helps detect when an implicit return is actually unreachable because the
* last statement calls a function that never returns.
*/
function isNeverReturningCall(callExpr, services) {
const signature = (0, type_js_1.getSignatureFromCallee)(callExpr, services);
if (!signature) {
return false;
}
const returnType = signature.getReturnType();
return (returnType.flags & typescript_1.default.TypeFlags.Never) !== 0;
}