[Bug c++/31187] New: [4.2 regression] extern declaration of variable in anonymous namespace prevents use of its address as template argument

["zak at transversal dot com" <gcc-bugzilla at gcc dot gnu dot org>]

The following code, which compiles fine on gcc 4.1.2 and I believe is valid,
fails on an up-to-date checkout from the 4.2 branch:

--------------------------------------
class foo { };

namespace
{
        extern foo foo1;
        foo foo1;
}

template< foo * >
class bar { };

bar< &foo1 > bar1;
---------------------------------------

giving the error:

test.cc:12: error: '&<unnamed>::foo1' is not a valid template argument of type
'foo*' because '<unnamed>::foo1' does not have external linkage
test.cc:12: error: invalid type in declaration before ';' token


... which I would only expect if "foo1" were declared "static".


If I remove the line with the "extern" declaration, the code compiles again on
4.2.


-- 
           Summary: [4.2 regression] extern declaration of variable in
                    anonymous namespace prevents use of its address as
                    template argument
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zak at transversal dot com
 GCC build triplet: x86_64-pc-linux-gnu
  GCC host triplet: x86_64-pc-linux-gnu
GCC target triplet: x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31187