For example, if I use UInt8 constant for if condition then only one branch is evaluated:
```sql
SELECT if(1, 'success', throwIf(1, 'Executing FALSE branch'))

┌─'success'─┐
│ success   │
└───────────┘

1 rows in set. Elapsed: 0.003 sec.
```

But if I use some constant expression, then both branches are evaluated:
```sql
SELECT if(empty(''), 'success', throwIf(1, 'Executing FALSE branch'))

0 rows in set. Elapsed: 0.003 sec.

Received exception from server (version 21.12.2):
Code: 395. DB::Exception: Received from localhost:9000. DB::Exception: Executing FALSE branch: While processing if(empty(''), 'success', throwIf(1, 'Executing FALSE branch')). (FUNCTION_THROW_IF_VALUE_IS_NON_ZERO)
```
ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; }
    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t ) const override
    {
        std::optional<String> custom_message;
        if (arguments.size() == 2)
        {
            const auto * msg_column = checkAndGetColumnConst<ColumnString>(arguments[1].column.get());
            if (!msg_column)
                throw Exception{"Second argument for function " + getName() + " must be constant String", ErrorCodes::ILLEGAL_COLUMN};
            custom_message = msg_column->getValue<String>();
        }
        const auto * in = arguments.front().column.get();
        ColumnPtr res;
        if (!((res = execute<UInt8>(in, custom_message))
            || (res = execute<UInt16>(in, custom_message))
            || (res = execute<UInt32>(in, custom_message))
            || (res = execute<UInt64>(in, custom_message))
            || (res = execute<Int8>(in, custom_message))
            || (res = execute<Int16>(in, custom_message))
            || (res = execute<Int32>(in, custom_message))
            || (res = execute<Int64>(in, custom_message))
            || (res = execute<Float32>(in, custom_message))
            || (res = execute<Float64>(in, custom_message))))
            throw Exception{"Illegal column " + in->getName() + " of first argument of function " + getName(), ErrorCodes::ILLEGAL_COLUMN};
        return res;
    }
    template <typename T>
    ColumnPtr execute(const IColumn * in_untyped, const std::optional<String> & message) const