Re: [Boost-users] [Spirit] Qi int_parser rejecting a negative signed std::intmax_t

Subject: Re: [Boost-users] [Spirit] Qi int_parser rejecting a negative signed std::intmax_t
From: Gavin Lambert (boost_at_[hidden])
Date: 2018-11-12 22:54:16

On 13/11/2018 11:47, Michael Powell wrote:
>> Hex and octal literals produce unsigned values.  You need to put those
>> into a uintmax_t, not an intmax_t.
>>
>> FWIW, you can still use an intmax_t in your AST if you want, as the
>> automatic attribute conversion will permit the twos-complement
>> conversion (though it might annoy some sanitisers).
>>
>>           hex_val %= no_case["0x"] >> uint_parser<std::uintmax_t, 16>{};
>>           oct_val %= "0" >> uint_parser<std::uintmax_t, 8>{};
>>           dec_val %= int_parser<ast::int_t, 10>{};
> 
> Hmm, I see... Maybe this is rinsing out in the conversion wash, then,
> because the decimal phrase seems to handle negative values just fine,
> whereas the hex and octal parsers fall flag on their face.

Decimal values can be negative.  Octal and hex values can't.