Re: [boost] [program_options] PATCH: fix VC8 runtime assertionerror in options_description.cpp

From: Vladimir Prus (ghost_at_[hidden])
Date: 2006-04-24 04:04:44

Trent Nelson wrote:

>> I'd prefer to have a testcase for this bug before fixing it.
> 
> The following option triggered the assertion error for me every time:
> 
> desc.add_options()
>     ("type,t",
>      po::value<string>()->default_value("manual"),
>      "startup type (\"auto\" or \"manual\") (--install only)"));
> 
> If I reduced the description length such that it fit on a single line,
> the error went away for that particular option (only to crash on a
> different multiline option down the track).

Thank you. I've comitted a new test that catches this problem, and a fix
along the lines of what you've suggested. Thanks, and sorry for being slow
with this issue.

> Was being caught by the following macro on line 166 of 'C:\Program
> Files\Microsoft Visual Studio 8\VC\include\xstring':
> 
> _Myt& __CLR_OR_THIS_CALL operator+=(difference_type _Off)
>     {   // increment by integer
>     if (this->_Mycont != _IGNORE_MYCONT)
>     {
>         _SCL_SECURE_VALIDATE(this->_Mycont != NULL);
>         _SCL_SECURE_VALIDATE_RANGE(
>             _Myptr + _Off <= (((_Mystring *)this->_Mycont)->_Myptr() +
> ((_Mystring *)this->_Mycont)->_Mysize) &&
>             _Myptr + _Off >= ((_Mystring *)this->_Mycont)->_Myptr());
>     }
>     _Myptr += _Off;
>     return (*this);
>     }
> 
> Which makes sense, as it's checking we don't assign past the end of our
> underlying string, which is exactly what line 395 of
> options_descriptions.cpp does in multiline conditions.  

I'd still consider this check broken, since we never *access* via the
invalid iterator, we immediately check if it's past the end and reset it
back.

Anyway, this is fixed now, both on trunk and release branch.

- Volodya