[Bug lto/67357] New: -Wodr warnings from types in anonymous namespace

[rogero at howzatt dot demon.co.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67357

            Bug ID: 67357
           Summary: -Wodr warnings from types in anonymous namespace
           Product: gcc
           Version: 5.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rogero at howzatt dot demon.co.uk
  Target Milestone: ---

The following code generates -Wodr warnings wih gcc 5.2.0

$ cat common.hxx
template <typename T>
struct values{
    typedef T const CT;
};

$ cat test1.cxx
#include "common.hxx"

extern void test2();

namespace {
    struct P {
        bool One;
    };
}

values<P> test1;

int main() { }

$ cat test2.cxx
#include "common.hxx"

namespace {
    struct P {
        int Two;
    };
}

values<P> test2;

$ /opt/gcc-5.2.0/bin/g++ -flto -Wodr test1.cxx test2.cxx
common.hxx:3:21: warning: type 'const struct CT' violates one definition rule
[-Wodr]
     typedef T const CT;
                     ^
common.hxx:3:21: note: a different type is defined in another translation unit
     typedef T const CT;
                     ^
test1.cxx:7:14: note: the first difference of corresponding definitions is
field 'One'
         bool One;
              ^
test2.cxx:5:13: note: a field with different name is defined in another
translation unit
         int Two;

Where

$ /opt/gcc-5.2.0/bin/g++ -v
Using built-in specs.
COLLECT_GCC=/opt/gcc-5.2.0/bin/g++
COLLECT_LTO_WRAPPER=/opt/gcc-5.2.0/libexec/gcc/x86_64-unknown-linux-gnu/5.2.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-5.2.0/configure --prefix=/opt/gcc-5.2.0
--enable-cloog-backend --enable-lto --enable-languages=c,c++
--enable-libstdcxx-time --enable-gold --enable-plugins --disable-multilib
Thread model: posix
gcc version 5.2.0 (GCC)

Note: this maybe related to 66180 although (a) this is a gcc 5.2.0 problem and
(b) the sample code in comment 5 of that ticket does compile and link cleanly
with gcc 5.2.0