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Date: Sun, 02 Apr 2006 05:27:00 -0000
Subject: [Bug c++/26984]  New: link error with &(typeid(int)) in anonymous namespace
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From: "rjpeters at klab dot caltech dot edu" <gcc-bugzilla@gcc.gnu.org>
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Using g++ from 4.2.0 daily snapshot 20060401:

$ ~/local/gcc-4.2-20060401/bin/g++  -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: /lab/rjpeters/build/gcc-4.2-20060401/configure
--enable-languages=c,c++ --prefix=/lab/rjpeters/local/gcc-4.2-20060401
--enable-shared --enable-threads=posix --with-system-zlib --enable-__cxa_atexit
Thread model: posix
gcc version 4.2.0 20060401 (experimental)

I get a linker error when I try to compile and link the following into a shared
library. The link error only happens when I use -fpic, and it happens only when
I take the address of typeid(int) inside an anonymous namespace; no linker
error if I take the address in the global namespace or in a named namespace.

$ cat test.C

#include <typeinfo>

void g(const std::type_info&);

namespace { // <--- change to 'namespace X' and the error disappears
  const std::type_info* t = &(typeid(int));
}

template <class T>
struct C
{
  virtual void foo() const {
    g(typeid(int));
  }
};

C<void> c;

$ ~/local/gcc-4.2-20060401/bin/g++ -c test.C -fpic -o test.o

$ ~/local/gcc-4.2-20060401/bin/g++ -shared test.o -o test.so
/usr/bin/ld: test.o(.gnu.linkonce.t._ZNK1CIvE3fooEv+0x14): unresolvable
relocation against symbol `typeinfo for int@@CXXABI_1.3'
/usr/bin/ld: final link failed: Nonrepresentable section on output
collect2: ld returned 1 exit status

Not entirely sure which part of the toolchain this relates to, but I don't see
the error with g++ 3.4.4 or 4.1.0 so I'm guessing there's a chance it's
compiler-related.

If I compile test.C->test.o both with 3.4.4 and 4.2.0 (20060401), then diff the
outputs of 'nm test.o | c++filt', I get this:

$ diff nm-3.4.4 nm-4.2
3c3
< 0000003a t global constructors keyed to
_ZN35_GLOBAL__N_test.C_DFF67DD7_A20029871tE
---
> 0000003c t global constructors keyed to _ZN35_GLOBAL__N_test.C_00000000_CD2145311tE
14a15,16
> 00000000 T __i686.get_pc_thunk.bx
> 00000000 T __i686.get_pc_thunk.cx

Thanks,
Rob


-- 
           Summary: link error with &(typeid(int)) in anonymous namespace
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rjpeters at klab dot caltech dot edu
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26984