You can also use "apt-file search 64/bits/c++config.h" in a i386 installation. You will see that nothing shows up. "apt-file search 32/bits/c++config.h" on a amd64 installation will turn up the libstdc++6-4.{5,6}-dev packages. Also, looking at http://packages.ubuntu.com/oneiric/i386/libstdc++6-4.6-dev/filelist only shows the 32-bit versions of bits/c++config.h.
You can also use "apt-file search 64/bits/ c++config. h" in a i386 installation. You will see that nothing shows up. "apt-file search 32/bits/ c++config. h" on a amd64 installation will turn up the libstdc+ +6-4.{5, 6}-dev packages. Also, looking at http:// packages. ubuntu. com/oneiric/ i386/libstdc+ +6-4.6- dev/filelist only shows the 32-bit versions of bits/c++config.h.