[Bug c++/25927] New: Spurious offsetof warnings with private members

["rcbilson at plg dot uwaterloo dot ca" <gcc-bugzilla at gcc dot gnu dot org>]

Consider:

#include <iostream>
#include <cstddef>

class xxx {
    friend int main();
    void *q;
  public:
    void *r;
};

int main() {
    std::cout << "offset of xxx::q is " << offsetof( xxx, q ) << "\n";
    std::cout << "offset of xxx::r is " << offsetof( xxx, r ) << "\n";
    return 0;
}

The class xxx is POD, and the two applications of offsetof should be ok (per
18.1p5). However, g++ warns:

offsetof.cc: In function 'int main()':
offsetof.cc:12: warning: invalid access to non-static data member 'xxx::q' of
NULL object
offsetof.cc:12: warning: (perhaps the 'offsetof' macro was used incorrectly)
offsetof.cc:13: warning: invalid access to non-static data member 'xxx::r' of
NULL object
offsetof.cc:13: warning: (perhaps the 'offsetof' macro was used incorrectly)

Stranger still, if *both* q and r are made public g++ accepts the code without
complaint.


-- 
           Summary: Spurious offsetof warnings with private members
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rcbilson at plg dot uwaterloo dot ca
 GCC build triplet: sparc-sun-solaris2.8
  GCC host triplet: sparc-sun-solaris2.8
GCC target triplet: sparc-sun-solaris2.8


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25927