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Re: Throwing std::ios_base::failure on formatted input with gcc 6.2
- From: Jonathan Wakely <jwakely dot gcc at gmail dot com>
- To: Edward Diener <eldlistmailingz at tropicsoft dot com>
- Cc: gcc-help <gcc-help at gcc dot gnu dot org>
- Date: Wed, 26 Oct 2016 12:51:07 +0100
- Subject: Re: Throwing std::ios_base::failure on formatted input with gcc 6.2
- Authentication-results: sourceware.org; auth=none
- References: <nuq4vs$4c5$1@blaine.gmane.org> <CAH6eHdRAhZ0Vsmt1VrpUH_RTFTtgZNYmPOoAMmxA0epQZVGdPw@mail.gmail.com>
On 26 October 2016 at 12:48, Jonathan Wakely wrote:
> On 26 October 2016 at 12:45, Edward Diener wrote:
>> If I have code asuch as:
>>
>> std::stringstream ss;
>> ss.exceptions(std::ios_base::failbit | std::ios_base::badbit);
>> char c;
>> ss >> c;
>>
>> I would except an exception of std::ios_base::failure to be thrown yet gcc
>> 6.2 is throwing some other exception. Is there a reason for this ?
>
> There are two versions of std::ios::failure, one using the old ABI
> (called std::ios_base::failure) and one using the new ABI (called
> std::ios_base::[abi:__cxx11]failure).
>
> You're trying to catch the new one, but the library throws the old
> one. I'm probably going to change the library to throw the new one for
> GCC 7.
I forgot to say, the reason for the two versions is that C++11
required an ABI break for that type, adding a new std::system_error
base class, with extra data members. That base class wasn't present in
C++98 (because the type didn't exist) and so we've been shipping a
library for years that throws the old type.
They both have a base class of std::runtime_error so you can still
catch it as that, or std::exception.