[Bug pch/26895] New: Bug mangling function name inside unnamed namespace, with pch

["rodolfo at rodsoft dot org" <gcc-bugzilla at gcc dot gnu dot org>]

There seems to be a bug in the name mangling of a function inside a unnamed
namespace (using g++ 4.1.0), when the compilation unit uses a precompiled
header which contains another unnamed namespace. This is better demonstrated
with the following setup:

pch.h:
namespace { void inside_pch(){} }

test1.cpp:
#include "pch.h"
namespace { void test(){} }
int main() {}

test2.cpp:
#include "pch.h"
namespace { void test(){} }

Showing the bug:
g++ pch.h
g++ -o test1.o -c test1.cpp
g++ -o test2.o -c test2.cpp
g++ -o test test1.o test2.o
test2.o: In function `(anonymous namespace)::inside_pch()':
test2.cpp:(.text+0x0): multiple definition of `(anonymous
namespace)::inside_pch()'
test1.o:test1.cpp:(.text+0x0): first defined here
test2.o: In function `(anonymous namespace)::test()':
test2.cpp:(.text+0x6): multiple definition of `(anonymous namespace)::test()'
test1.o:test1.cpp:(.text+0x6): first defined here
collect2: ld returned 1 exit status

nm test1.o shows:
         U __gxx_personality_v0
0000000c T main
00000000 T _ZN34_GLOBAL__N_pch.h_00000000_ECAA0BAE10inside_pchEv
00000006 T _ZN34_GLOBAL__N_pch.h_00000000_ECAA0BAE4testEv

nm test2.o shows:
         U __gxx_personality_v0
00000000 T _ZN34_GLOBAL__N_pch.h_00000000_ECAA0BAE10inside_pchEv
00000006 T _ZN34_GLOBAL__N_pch.h_00000000_ECAA0BAE4testEv

While the incorrect mangling of unnamed namespace inside a pch is a 
longstanding bug, function test, both in test1.cpp and test2.cpp used to be
mangled correctly, at least with g++ 3.4.5.

Doing the same with g++ 3.4.5, we have as result the following error message:
test2.o: In function `(anonymous namespace)::inside_pch()':
test2.cpp:(.text+0x0): multiple definition of `(anonymous
namespace)::inside_pch()'
test1.o:test1.cpp:(.text+0x0): first defined here
collect2: ld returned 1 exit status

This time, nm test1.o returns:
0000000c T main
00000000 T _ZN34_GLOBAL__N_pch.h_00000000_7F4453F410inside_pchEv
00000006 T _ZN38_GLOBAL__N_test1.cpp_00000000_6EC548D94testEv

and nm test2.o
00000000 T _ZN34_GLOBAL__N_pch.h_00000000_7F4453F410inside_pchEv
00000006 T _ZN38_GLOBAL__N_test2.cpp_00000000_D5E9623F4testEv:

I hope this information helps.


-- 
           Summary: Bug mangling function name inside unnamed namespace,
                    with pch
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: pch
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rodolfo at rodsoft dot org
 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=26895