Isn't the C++ standard library backward-compatible?
- by Chris Metzler
Hi. I'm working on a 64-bit Linux system, trying to build some code that depends on third-party libraries for which I have binaries. During linking, I get a stream of undefined reference errors for one of the libraries, indicating that the linker couldn't resolve references to standard C++ functions/classes, e.g.:
librxio.a(EphReader.o): In function `gpstk::EphReader::read_fic_data(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
EphReader.cpp:(.text+0x27c): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long)'
EphReader.cpp:(.text+0x4e8): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long)'
I'm not really a C++ programmer, but this looks to me like it can't find the standard library. Doing some more research, I got the following when I looked at librxio's dependency for the standard library:
$ ldd librxio.so.16.0
./librxio.so.16.0: /usr/lib64/libstdc++.so.6: version `GLIBCXX_3.4.9' not found (required by ./librxio.so.16.0)
libm.so.6 => /lib64/libm.so.6 (0x00002aaaaad45000)
libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00002aaaaafc8000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00002aaaab2c8000)
libc.so.6 => /lib64/libc.so.6 (0x00002aaaab4d7000)
/lib64/ld-linux-x86-64.so.2 (0x0000555555554000)
So I read that as saying that librxio (one of the third-party libraries) requires at least v3.4.9 of the standard library. But the version I have installed is 4.1.2:
$ rpm -qa | grep libstdc
compat-libstdc++-33-3.2.3-61.x86_64
libstdc++-devel-4.1.2-14.el5.i386
libstdc++-devel-4.1.2-14.el5.x86_64
libstdc++-4.1.2-14.el5.x86_64
libstdc++-4.1.2-14.el5.i386
Shouldn't this work? The shared object major number is 6, same as for v3.4.9. At this level, shouldn't this be backward compatible? It seems like the third-party library is looking for an earlier version of the standard library than what I have installed; but isn't there backward compatibility between versions with the same major number for the shared library? Again, I'm not really a C++ programmer; but I don't see what the problem is.
Any advice greatly appreciated. Thanks.
