Function getIterationTypesOfMethod

test/fixtures/snapshot/typescript.js:83488–83574

* Gets the *yield*, *return*, and *next* types of a the `next()`, `return()`, or * `throw()` method of an `Iterator`-like or `AsyncIterator`-like type. * * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` * record is returned.

(type, resolver, methodName, errorNode)

         * record is returned. Otherwise, we return `undefined`.
         */
        function getIterationTypesOfMethod(type, resolver, methodName, errorNode) {
            var _a, _b, _c, _d;
            var method = getPropertyOfType(type, methodName);
            // Ignore 'return' or 'throw' if they are missing.
            if (!method && methodName !== "next") {
                return undefined;
            }
            var methodType = method && !(methodName === "next" && (method.flags & 16777216 /* SymbolFlags.Optional */))
                ? methodName === "next" ? getTypeOfSymbol(method) : getTypeWithFacts(getTypeOfSymbol(method), 2097152 /* TypeFacts.NEUndefinedOrNull */)
                : undefined;
            if (isTypeAny(methodType)) {
                // `return()` and `throw()` don't provide a *next* type.
                return methodName === "next" ? anyIterationTypes : anyIterationTypesExceptNext;
            }
            // Both async and non-async iterators *must* have a `next` method.
            var methodSignatures = methodType ? getSignaturesOfType(methodType, 0 /* SignatureKind.Call */) : ts.emptyArray;
            if (methodSignatures.length === 0) {
                if (errorNode) {
                    var diagnostic = methodName === "next"
                        ? resolver.mustHaveANextMethodDiagnostic
                        : resolver.mustBeAMethodDiagnostic;
                    error(errorNode, diagnostic, methodName);
                }
                return methodName === "next" ? anyIterationTypes : undefined;
            }
            // If the method signature comes exclusively from the global iterator or generator type,
            // create iteration types from its type arguments like `getIterationTypesOfIteratorFast`
            // does (so as to remove `undefined` from the next and return types). We arrive here when
            // a contextual type for a generator was not a direct reference to one of those global types,
            // but looking up `methodType` referred to one of them (and nothing else). E.g., in
            // `interface SpecialIterator extends Iterator<number> {}`, `SpecialIterator` is not a
            // reference to `Iterator`, but its `next` member derives exclusively from `Iterator`.
            if ((methodType === null || methodType === void 0 ? void 0 : methodType.symbol) && methodSignatures.length === 1) {
                var globalGeneratorType = resolver.getGlobalGeneratorType(/*reportErrors*/ false);
                var globalIteratorType = resolver.getGlobalIteratorType(/*reportErrors*/ false);
                var isGeneratorMethod = ((_b = (_a = globalGeneratorType.symbol) === null || _a === void 0 ? void 0 : _a.members) === null || _b === void 0 ? void 0 : _b.get(methodName)) === methodType.symbol;
                var isIteratorMethod = !isGeneratorMethod && ((_d = (_c = globalIteratorType.symbol) === null || _c === void 0 ? void 0 : _c.members) === null || _d === void 0 ? void 0 : _d.get(methodName)) === methodType.symbol;
                if (isGeneratorMethod || isIteratorMethod) {
                    var globalType = isGeneratorMethod ? globalGeneratorType : globalIteratorType;
                    var mapper = methodType.mapper;
                    return createIterationTypes(getMappedType(globalType.typeParameters[0], mapper), getMappedType(globalType.typeParameters[1], mapper), methodName === "next" ? getMappedType(globalType.typeParameters[2], mapper) : undefined);
                }
            }
            // Extract the first parameter and return type of each signature.
            var methodParameterTypes;
            var methodReturnTypes;
            for (var _i = 0, methodSignatures_1 = methodSignatures; _i < methodSignatures_1.length; _i++) {
                var signature = methodSignatures_1[_i];
                if (methodName !== "throw" && ts.some(signature.parameters)) {
                    methodParameterTypes = ts.append(methodParameterTypes, getTypeAtPosition(signature, 0));
                }
                methodReturnTypes = ts.append(methodReturnTypes, getReturnTypeOfSignature(signature));
            }
            // Resolve the *next* or *return* type from the first parameter of a `next()` or
            // `return()` method, respectively.
            var returnTypes;
            var nextType;
            if (methodName !== "throw") {