Re: [Patch] Fix libstdc++/9507

[Paolo Carlini <pcarlini at unitus dot it>]

Pétur Runólfsson wrote:

> > P.S. The original testcase is really involved compared to the
> > underlying issue and I would rather prefer not adding it.
> It might be easier to test this by deriving a class from std::filebuf
> and override seekoff to always return pos_type(off_type(-1)).
Yes, thanks, like this:

class c_fbuf : public basic_filebuf<char>
{
 pos_type
 seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode 
__mode)
 {
   return pos_type(off_type(-1));
 }
};

int main()
{
 c_fbuf fbuf;
 c_fbuf* r = static_cast<c_fbuf*>(fbuf.open("xxx", ios_base::out | 
ios_base::ate));
 assert(!fbuf.is_open());
 assert(r == NULL);
}

however, I didn't notice that all the necessary includes were already
present in filebuf_members.cc and another testcase used the very same
functions. I'm going to post a revised patch including your original 
testcase.

Ciao, Paolo.