[Bug c++/41958] New: [c++0x] bogus variadic partial ordering code

[jason at gcc dot gnu dot org]

more_specialized_fn contains

  /* All things being equal, if the next argument is a pack expansion
     for one function but not for the other, prefer the
     non-variadic function.  */
  if ((better1 > 0) - (better2 > 0) == 0
      && args1 && TREE_VALUE (args1)
      && args2 && TREE_VALUE (args2))
    {
      if (TREE_CODE (TREE_VALUE (args1)) == TYPE_PACK_EXPANSION)
        return TREE_CODE (TREE_VALUE (args2)) == TYPE_PACK_EXPANSION ? 0 : -1;
      else if (TREE_CODE (TREE_VALUE (args2)) == TYPE_PACK_EXPANSION)
        return 1;
    }

which makes us prefer a non-variadic option even when deduction failed in both
directions, which makes variadic-crash1.C pass purely by accident.  This also
makes us prefer an unused default argument to a function parameter pack.


-- 
           Summary: [c++0x] bogus variadic partial ordering code
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jason at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41958