Bug#608029: typeinfo for armel is not weak when templates are explicitly instantiated

[Ron <ron@debian.org>]

Package: g++-4.4
Version: 4.4.5-10
Severity: normal

Hi,

I ran into this porting some existing code to armel, but a minimal example
follows.  Shown here using a cross compiler, but I've confirmed that it can
be reproduced on native armel with both gcc-4.4 from squeeze and gcc-4.5
from experimental (4.5.2-1).


$ cat Makefile 
out: b.o c.o
	$(CXX) $^ -o d

$ cat a.h
template <typename T> struct A { T a; virtual ~A() {} };
template struct A<int>;

$ cat b.cpp 
#include "a.h"
void use_A() { A<int> b; }

$ cat c.cpp 
#include "a.h"
int main() { A<int> c; return 0; }


$ make CXX=arm-linux-gnueabi-g++
arm-linux-gnueabi-g++    -c -o b.o b.cpp
arm-linux-gnueabi-g++    -c -o c.o c.cpp
arm-linux-gnueabi-g++ b.o c.o -o d
c.o:(.rodata+0x0): multiple definition of `typeinfo for A<int>'
b.o:(.rodata+0x0): first defined here
c.o:(.rodata+0x8): multiple definition of `typeinfo name for A<int>'
b.o:(.rodata+0x8): first defined here
collect2: ld returned 1 exit status


This works fine on amd64 though.  The interesting difference seems to be
that amd64 produces:

0000000000000000 V _ZTI1AIiE
0000000000000000 V _ZTS1AIiE
0000000000000000 V _ZTV1AIiE

While armel gives us:

00000000 R _ZTI1AIiE
00000008 R _ZTS1AIiE
00000000 V _ZTV1AIiE


If the template is left to be implicitly instantiated, then armel also
produces weak symbols for the typeinfo (but that causes other trouble
in the original example).


I found some hints of an earlier report upstream here:
http://gcc.gnu.org/ml/gcc-help/2010-02/msg00361.html
http://gcc.gnu.org/ml/gcc-help/2010-03/msg00007.html

But that didn't seem to end with any real conclusion as to what the
original problem was, which I think this example does demonstrate now.

Cheers,
Ron


-- System Information:
Debian Release: squeeze/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.32-5-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages g++-4.4 depends on:
ii  gcc-4.4                   4.4.5-10       The GNU C compiler
ii  gcc-4.4-base              4.4.5-10       The GNU Compiler Collection (base 
ii  libc6                     2.11.2-7       Embedded GNU C Library: Shared lib
ii  libgmp3c2                 2:4.3.2+dfsg-1 Multiprecision arithmetic library
ii  libmpfr4                  3.0.0-2        multiple precision floating-point 
ii  libstdc++6-4.4-dev        4.4.5-10       The GNU Standard C++ Library v3 (d

g++-4.4 recommends no packages.

Versions of packages g++-4.4 suggests:
pn  g++-4.4-multilib             <none>      (no description available)
ii  gcc-4.4-doc                  4.4.4.nf1-1 documentation for the GNU compiler
pn  libstdc++6-4.4-dbg           <none>      (no description available)

-- no debconf information