[Bug c++/33150] New: frend functions of template get new diagnostic

["igodard at pacbell dot net" <gcc-bugzilla at gcc dot gnu dot org>]

The following code received no diagnostic in 4.0.1, but on 4.2.1 gets:
~/ootbc/personal/ivan$ g++ foo.cc
foo.cc: In instantiation of 'foo2<int>':
foo.cc:16:   instantiated from here
foo.cc:12: error: redefinition of 'void bar(int)'
foo.cc:5: error: 'void bar(int)' previously defined here

Test case:

template<typename T>
class foo1 {
public:
    friend
    void    bar(T t) {};
    };

template<typename T>
class foo2 {
public:
    friend
    void    bar(T t) {};
    };

foo1<int>   f1;
foo2<int>   f2;

int main() {}

This may just be a result of tightening up gcc to the standard and the code
always was wrong, but I submit the report in case it is actually a regression
in a rarely-used part of the language.

As I understand it, every function defined in a template is considered to
itself be a template, and hence having a template function that is also a
definition does not count as a duplicate definition no matter how many times
the template is instantiated. However, that seems to no longer apply for
friends declared and defined in templates. Note that both friends refer to the
same function, which is textually declared identically.

Incidentally, declaring the friends "inline" makes no difference to the
diagnostic, whereas it would for a plain function. Possibly the construction
does in fact reflect the standard, but the inline keyword is mishandled? I
leave to the language lawyers whether this is valid or a regression, but in any
case you might want to add this code to your regression suite.


-- 
           Summary: frend functions of template get new diagnostic
           Product: gcc
           Version: 4.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: igodard at pacbell dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33150