Hello,

std::bitset cannot be instantiated with an extremely big number of bits like ULONG_MAX.
e.g.
--------- >% --------------
#include <iostream>
#include <bitset>

int main()
{
    std::cout << sizeof (std::bitset<0xffffffff>) << std::endl;
}
--------- >% --------------
outputs 1 with g++ 3.4.4 and 4.3.4 on cygwin, and with gcc 3.4.? on Solaris.

It seems related to the macro _GLIBCXX_BITSET_WORDS that overflows. With a simple division + modulo formula, the bug vanishes.
i.e.

#define _GLIBCXX_BITSET_WORDS(__n) \
 ((__n) < 1 ? 0 : (((__n)/_GLIBCXX_BITSET_BITS_PER_WORD) + (((__n)%_GLIBCXX_BITSET_BITS_PER_WORD==0)?0:1)))

HTH,

--Luc Hermitte