Re: c++/5338: -pedantic reports ambiguous base

[rodrigc@gcc.gnu.org]

Synopsis: -pedantic reports ambiguous base

State-Changed-From-To: open->analyzed
State-Changed-By: rodrigc
State-Changed-When: Wed Jan  9 22:48:37 2002
State-Changed-Why:
    Information submitted by martin@v.loewis.de
    
    > Without -pedantic there is not even a warning (even with -W -Wall).
    
    > 10.2.1 says "for a qualified-id, name lookup begins in the scope of
    > 10.2.the nested-name-specifier".  In which scope, I don't think the
    > 10.2.reference to pop() or HWQueue, for that matter, is ambiguous.
    
    This is caused by the fragment in cp/init.c
    
       /* Convert 'this' to the specified type to disambiguate conversion
          to the function's context.  Apparently Standard C++ says that we
          shouldn't do this.  */
       if (decl == current_class_ref
           && ! pedantic
           && ACCESSIBLY_UNIQUELY_DERIVED_P (type, current_class_type))
    
    It seems there are several interpretations of 10.2/1. GCC's
    interpretation is that, indeed, lookup starts in ISPmq, and finds
    HwQueue::pop. So the call you have written is equivalent to
    
       this->HwQueue::pop();
    
    which is ambiguous.
    
    It would be good if you could achieve independent clarification,
    e.g. through comp.std.c++. If people are of different opinion there as
    well, consider filing a Defect Report. Notice that variations of this
    have been discussed repeatedly in comp.stdc.c++; you may want to read
    the archives.
    
    Regards,
    Martin

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5338