Builds on 32bit systems fail due to violation of C++ one definition rule (ODR)

[badshah400]

Hi,
When building version the python modules for version 5.5.5 for openSUSE¹ on 32-bit systems (i586 specifically), we see builds failing due to multiple violation of the C++ ODR. These are reported thus:

[  114s]   [ 99%] Linking CXX shared library /home/abuild/rpmbuild/BUILD/xrootd-5.5.5/build/lib.linux-i686-cpython-39/pyxrootd/libXrdPosixPreload.so
[  114s]   /home/abuild/rpmbuild/BUILD/xrootd-5.5.5/src/./XrdPosix/XrdPosixLinkage.hh:347:7: error: type ‘struct XrdPosixLinkage’ violates the C++ One Definition Rule [-Werror=odr]
[  114s]     347 | class XrdPosixLinkage
[  114s]         |       ^
[  114s]   /home/abuild/rpmbuild/BUILD/xrootd-5.5.5/src/./XrdPosix/XrdPosixLinkage.hh:347:7: note: a different type is defined in another translation unit
[  114s]     347 | class XrdPosixLinkage
[  114s]         |       ^
[  114s]   /home/abuild/rpmbuild/BUILD/xrootd-5.5.5/src/./XrdPosix/XrdPosixLinkage.hh:365:26: note: the first difference of corresponding definitions is field ‘Fseeko’
[  114s]     365 |       Retv_Fseeko      (*Fseeko)(Args_Fseeko);
[  114s]         |                          ^
[  114s]   /home/abuild/rpmbuild/BUILD/xrootd-5.5.5/src/./XrdPosix/XrdPosixLinkage.hh:365:26: note: a field of same name but different type is defined in another translation unit
[  114s]     365 |       Retv_Fseeko      (*Fseeko)(Args_Fseeko);
[  114s]         |                          ^
[  114s]   /home/abuild/rpmbuild/BUILD/xrootd-5.5.5/src/./XrdPosix/XrdPosixLinkage.hh:347:7: note: type mismatch in parameter 2
[  114s]     347 | class XrdPosixLinkage
[  114s]         |       ^
[  114s]   /home/abuild/rpmbuild/BUILD/xrootd-5.5.5/src/XrdPosix/XrdPosixPreload32.cc:76:24: error: ‘Xunix’ violates the C++ One Definition Rule [-Werror=odr]
[  114s]      76 | extern XrdPosixLinkage Xunix;
[  114s]         |                        ^
[  114s]   /home/abuild/rpmbuild/BUILD/xrootd-5.5.5/src/./XrdPosix/XrdPosixLinkage.hh:347:7: note: type ‘struct XrdPosixLinkage’ itself violates the C++ One Definition Rule
[  114s]     347 | class XrdPosixLinkage
[  114s]         |       ^
[  114s]   /home/abuild/rpmbuild/BUILD/xrootd-5.5.5/src/XrdPosix/XrdPosixLinkage.cc:56:17: note: ‘Xunix’ was previously declared here
[  114s]      56 | XrdPosixLinkage Xunix;
[  114s]         |                 ^
[  114s]   lto1: all warnings being treated as errors

We see no such problems with 64 bit builds however.

Our build uses the following libraries/compilers:

• cmake 3.26
• GCC 13.1.1
• Python 3.9, 3.10, 3.11

Happy to supply any more information, if needed, to help debug and fix the issue. In the meanwhile, here is the full build log:
xrootd_i586_build_log.zip

Thanks in advance.

¹ We include commit 2401509 as a patch (lightly rebased to apply against 5.5.5) to get the python modules building. You may have a detailed look at our patches and build status here temporarily.

[amadio]

Thank you for the report, I will take a look at fixing this for 5.6, which will be released in the coming week or two.

[StefanBruens]

Removing LTO just makes it impossible for the linker to see the ODR violation, it still exists. Please reopen.

[StefanBruens]

The correct fix is to have distinct names for the XrdPosixLinkage struct/class, dependent on the XRDPOSIXPRELOAD32 define.

i.e. in XrdPosixLinkage.hh:

#if defined XRDPOSIXPRELOAD32
class XrdPosixLinkage32
#else
class XrdPosixLinkage
#endif
{...

and then use XrdPosixLinkage32 everywhere in XrdPosixPreload32.{hh,cc}

[amadio]

That makes sense. I'm reopening.