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**Describe the bug**

Interval data type is not passed correctly from subquery

**Does it reproduce on recent release?**

Yes, tested on 21.6.5.37.

**How to reproduce**

```sql
SELECT
    toIntervalDay(5) AS interval,
    now() + interval AS res

┌─interval─┬─────────────────res─┐
│        5 │ 2021-07-03 13:11:45 │
└──────────┴─────────────────────┘
```

But if I wrap interval calculation in subquery:

```sql
SELECT
    (SELECT toIntervalDay(5)) AS interval,
    now() + interval AS res

Received exception from server (version 21.6.5):
Code: 70. DB::Exception: Received from localhost:9000. DB::Exception: Conversion from Int8 to IntervalDay is not supported: While processing CAST(5, 'IntervalDay') AS interval, now() + interval AS res.
```

**Expected behavior**

Both queries should work the same way.
static FunctionPtr create() { return std::make_shared<FunctionConvertFromString>(); }
    String getName() const override
    {
        return name;
    }
    bool isVariadic() const override { return true; }
    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & ) const override { return true; }
    size_t getNumberOfArguments() const override { return 0; }
    bool useDefaultImplementationForConstants() const override { return true; }
    bool canBeExecutedOnDefaultArguments() const override { return false; }
    ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; }
    DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
    {
        DataTypePtr res;
        if (isDateTime64<Name, ToDataType>(arguments))
        {
            validateFunctionArgumentTypes(*this, arguments,
                FunctionArgumentDescriptors{{"string", &isStringOrFixedString<IDataType>, nullptr, "String or FixedString"}},
                
                FunctionArgumentDescriptors{
                    {"precision", &isUInt8<IDataType>, isColumnConst, "const UInt8"},
                    {"timezone", &isStringOrFixedString<IDataType>, isColumnConst, "const String or FixedString"},
                });
            UInt64 scale = to_datetime64 ? DataTypeDateTime64::default_scale : 0;
            if (arguments.size() > 1)
                scale = extractToDecimalScale(arguments[1]);
            const auto timezone = extractTimeZoneNameFromFunctionArguments(arguments, 2, 0);
            res = scale == 0 ? res = std::make_shared<DataTypeDateTime>(timezone) : std::make_shared<DataTypeDateTime64>(scale, timezone);
        }