Re: [PATCH] Fix gnu-versioned-namespace build

[Jonathan Wakely <jwakely@redhat.com>]

On 11/12/19 08:29 +0100, François Dumont wrote:
>I plan to commit this tomorrow.
>
>Note that rather than just adding the missing 
>_GLIBCXX_[BEGIN,END]_VERSION_NAMESPACE I also move anonymous namespace 
>usage outside std namespace. Let me know if it was intentional.
>
>    * src/c++11/random.cc: Add _GLIBCXX_BEGIN_NAMESPACE_VERSION and
>    _GLIBCXX_END_NAMESPACE_VERSION. Move anonymous namespace outside std
>    namespace.
>
>Tested under Linux x86_64 normal/debug/versioned namespace modes.
>
>There are still tests failing in versioned namespace, more patches to come.

One of them fails like this:

/home/jwakely/src/gcc/buildso8/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/locale_classes.tcc:134: undefined reference to `_ZNSt3__87codecvtIDsDu11__mbstate_tE2idE'

For some reason some of the char8_t instantiations are not exported
from the libstdc++.so.8.0.0 shared library:

00000000000aaad0 t _ZNKSt3__87codecvtIDiDu11__mbstate_tE10do_unshiftERS1_PDuS4_RS4_
00000000000aaa80 t _ZNKSt3__87codecvtIDiDu11__mbstate_tE11do_encodingEv
00000000000aaaa0 t _ZNKSt3__87codecvtIDiDu11__mbstate_tE13do_max_lengthEv
00000000000aaa90 t _ZNKSt3__87codecvtIDiDu11__mbstate_tE16do_always_noconvEv
00000000000ab870 t _ZNKSt3__87codecvtIDiDu11__mbstate_tE5do_inERS1_PKDuS5_RS5_PDiS7_RS7_
00000000000abc50 t _ZNKSt3__87codecvtIDiDu11__mbstate_tE6do_outERS1_PKDiS5_RS5_PDuS7_RS7_
00000000000ab810 t _ZNKSt3__87codecvtIDiDu11__mbstate_tE9do_lengthERS1_PKDuS5_m
00000000000aaac0 t _ZNKSt3__87codecvtIDsDu11__mbstate_tE10do_unshiftERS1_PDuS4_RS4_
00000000000aaa80 t _ZNKSt3__87codecvtIDsDu11__mbstate_tE11do_encodingEv
00000000000aaaa0 t _ZNKSt3__87codecvtIDsDu11__mbstate_tE13do_max_lengthEv
00000000000aaa90 t _ZNKSt3__87codecvtIDsDu11__mbstate_tE16do_always_noconvEv
00000000000abd40 t _ZNKSt3__87codecvtIDsDu11__mbstate_tE5do_inERS1_PKDuS5_RS5_PDsS7_RS7_
00000000000ab990 t _ZNKSt3__87codecvtIDsDu11__mbstate_tE6do_outERS1_PKDsS5_RS5_PDuS7_RS7_
00000000000ab900 t _ZNKSt3__87codecvtIDsDu11__mbstate_tE9do_lengthERS1_PKDuS5_m
0000000000157a00 b _ZNSt3__87codecvtIDiDu11__mbstate_tE2idE
00000000000ab270 t _ZNSt3__87codecvtIDiDu11__mbstate_tED0Ev
00000000000ab130 t _ZNSt3__87codecvtIDiDu11__mbstate_tED1Ev
00000000000ab130 t _ZNSt3__87codecvtIDiDu11__mbstate_tED2Ev
0000000000157a08 b _ZNSt3__87codecvtIDsDu11__mbstate_tE2idE
00000000000ab250 t _ZNSt3__87codecvtIDsDu11__mbstate_tED0Ev
00000000000ab110 t _ZNSt3__87codecvtIDsDu11__mbstate_tED1Ev
00000000000ab110 t _ZNSt3__87codecvtIDsDu11__mbstate_tED2Ev

We should be able to add them manually to the
config/abi/pre/gnu-versioned-namespace.ver script, but that shouldn't
be necessary.

I think the problem is that the binutils demangler doesn't know how to
demangle char8_t symbols, so this fails to match them:

GLIBCXX_8.0 {

  global:

    # Names inside the 'extern' block are demangled names.
    extern "C++"
    {
      std::*;
      std::__8::*;
      std::random_device::*
    };

I'm using binutils-2.31.1-36.fc30.x86_64 but it looks like
binutils-2.32-30.fc31.x86_64 also can't demangle those symbols.