@typescript-eslint/eslint-plugin/dist/rules/no-unnecessary-type-arguments.js

"use strict";
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    if (k2 === undefined) k2 = k;
    Object.defineProperty(o, k2, { enumerable: true, get: function() { return m[k]; } });
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    if (k2 === undefined) k2 = k;
    o[k2] = m[k];
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    o["default"] = v;
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    if (mod && mod.__esModule) return mod;
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Object.defineProperty(exports, "__esModule", { value: true });
const tsutils = __importStar(require("tsutils"));
const ts = __importStar(require("typescript"));
const util = __importStar(require("../util"));
const util_1 = require("../util");
exports.default = util.createRule({
    name: 'no-unnecessary-type-arguments',
    meta: {
        docs: {
            description: 'Enforces that type arguments will not be used if not required',
            recommended: false,
            requiresTypeChecking: true,
        },
        fixable: 'code',
        messages: {
            unnecessaryTypeParameter: 'This is the default value for this type parameter, so it can be omitted.',
        },
        schema: [],
        type: 'suggestion',
    },
    defaultOptions: [],
    create(context) {
        const parserServices = util.getParserServices(context);
        const checker = parserServices.program.getTypeChecker();
        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[i];
            if (!(param === null || param === void 0 ? void 0 : param.default)) {
                return;
            }
            // TODO: would like checker.areTypesEquivalent. https://github.com/Microsoft/TypeScript/issues/13502
            const defaultType = checker.getTypeAtLocation(param.default);
            const argTsNode = parserServices.esTreeNodeToTSNodeMap.get(arg);
            const argType = checker.getTypeAtLocation(argTsNode);
            if (!argType.aliasSymbol && !defaultType.aliasSymbol) {
                if (argType.flags !== defaultType.flags) {
                    return;
                }
            }
            else if (argType.aliasSymbol !== defaultType.aliasSymbol ||
                argType.aliasTypeArguments !== defaultType.aliasTypeArguments) {
                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 = parserServices.esTreeNodeToTSNodeMap.get(node);
                const typeParameters = getTypeParametersFromNode(expression, checker);
                if (typeParameters) {
                    checkTSArgsAndParameters(node, typeParameters);
                }
            },
        };
    },
});
function getTypeParametersFromNode(node, checker) {
    if (ts.isExpressionWithTypeArguments(node)) {
        return getTypeParametersFromType(node.expression, checker);
    }
    if (ts.isTypeReferenceNode(node)) {
        return getTypeParametersFromType(node.typeName, checker);
    }
    if (ts.isCallExpression(node) || ts.isNewExpression(node)) {
        return getTypeParametersFromCall(node, checker);
    }
    return undefined;
}
function getTypeParametersFromType(type, checker) {
    const symAtLocation = checker.getSymbolAtLocation(type);
    if (!symAtLocation) {
        return undefined;
    }
    const sym = getAliasedSymbol(symAtLocation, checker);
    const declarations = sym.getDeclarations();
    if (!declarations) {
        return undefined;
    }
    return (0, util_1.findFirstResult)(declarations, decl => ts.isClassLike(decl) ||
        ts.isTypeAliasDeclaration(decl) ||
        ts.isInterfaceDeclaration(decl)
        ? decl.typeParameters
        : undefined);
}
function getTypeParametersFromCall(node, checker) {
    const sig = checker.getResolvedSignature(node);
    const sigDecl = sig === null || sig === void 0 ? void 0 : sig.getDeclaration();
    if (!sigDecl) {
        return ts.isNewExpression(node)
            ? getTypeParametersFromType(node.expression, checker)
            : undefined;
    }
    return sigDecl.typeParameters;
}
function getAliasedSymbol(symbol, checker) {
    return tsutils.isSymbolFlagSet(symbol, ts.SymbolFlags.Alias)
        ? checker.getAliasedSymbol(symbol)
        : symbol;
}
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