mbstate_t vs. __mbstate_t?

[Craig Rodrigues <rodrigc at mediaone dot net>]

Hi,

I posted the following message to the libstdc++ mailing list:
http://gcc.gnu.org/ml/libstdc++/2001-02/msg00100.html

If libstdc++-v3 is compiled on a glibc 2.1 system, there are a lot
of symbols stored in the library which reference "mbstate_t", eg.
00053288 W std::istream::seekg(std::fpos<mbstate_t>)

However, if you use this libstdc++.so on a system which has
been upgraded to glibc 2.2.1, you will obtain link errors because
mbstate_t is now a typedef for __mbstate_t:

#include <iostream>
using namespace std;

void seek(istream& i)
{
     unsigned long pos = 35;
     i.seekg(pos);
}

int main(int, char **) { return 0; }


% g++ d.cc
/tmp/ccx9JhBd.o: In function `seek(std::istream&)':
/tmp/ccx9JhBd.o(.text+0x3c): undefined reference to `std::istream::seekg(std::fpos<__mbstate_t>)'
collect2: ld returned 1 exit status

Is this a known difference between glibc 2.1 and glibc 2.2?
Should the libstdc++ people do something to prevent this binary
incompatibility in their libstdc++.so.3 library between glibc 2.1 and
glibc 2.2?

I apologize if this is not relevant to this list, but it does concern
glibc, and I did not get a response on the libstdc++ mailing list.

Thank you.
-- 
Craig Rodrigues        
http://www.gis.net/~craigr    
rodrigc@mediaone.net