```
SELECT toStartOfDay(yesterday())


Received exception from server (version 20.10.1):
Code: 43. DB::Exception: Received from localhost:9000. DB::Exception: Function toStartOfDay supports a 2nd argument (optional) that must be non-empty and be a valid time zone.


SELECT toStartOfDay(today())


Received exception from server (version 20.10.1):
Code: 43. DB::Exception: Received from localhost:9000. DB::Exception: Function toStartOfDay supports a 2nd argument (optional) that must be non-empty and be a valid time zone.

```
because of https://github.com/ClickHouse/ClickHouse/pull/14509
ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; }
    void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) const override
    {
        const IDataType * from_type = block.getByPosition(arguments[0]).type.get();
        WhichDataType which(from_type);
        if (which.isDate())
            DateTimeTransformImpl<DataTypeDate, ToDataType, Transform>::execute(block, arguments, result, input_rows_count);
        else if (which.isDateTime())
            DateTimeTransformImpl<DataTypeDateTime, ToDataType, Transform>::execute(block, arguments, result, input_rows_count);
        else if (which.isDateTime64())
        {
            const auto scale = static_cast<const DataTypeDateTime64 *>(from_type)->getScale();
            const TransformDateTime64<Transform> transformer(scale);
            DateTimeTransformImpl<DataTypeDateTime64, ToDataType, decltype(transformer)>::execute(block, arguments, result, input_rows_count, transformer);
        }
        else
            throw Exception("Illegal type " + block.getByPosition(arguments[0]).type->getName() + " of argument of function " + getName(),
                ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
    }
    bool hasInformationAboutMonotonicity() const override
    {
        return true;
    }
    Monotonicity getMonotonicityForRange(const IDataType & type, const Field & left, const Field & right) const override