Re: [PATCH] c++: wrong ambiguity in accessing static field [PR112744]

[Marek Polacek <polacek@redhat.com>]

On Wed, Nov 29, 2023 at 01:58:31PM -0500, Jason Merrill wrote:
> On 11/29/23 10:45, Marek Polacek wrote:
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > 
> > Now that I'm posting this patch, I think you'll probably want me to use
> > ba_any unconditionally.  That works too; g++.dg/tc1/dr52.C just needs
> > a trivial testsuite tweak:
> >    'C' is not an accessible base of 'X'
> > v.
> >    'C' is an inaccessible base of 'X'
> > We should probably unify those messages...
> 
> Hmm, won't using ba_any unconditionally break ambiguous base checking for
> non-static data members?

Yes.  I thought not but that's only because we weren't properly testing
that case (added scoped14.C, patch to follow).  So that settles that.
 
> > @@ -3493,9 +3493,24 @@ finish_class_member_access_expr (cp_expr object, tree name, bool template_p,
> >   	      return error_mark_node;
> >   	    }
> > +	  /* NAME may refer to a static data member, in which case there is
> > +	     one copy of the data member that is shared by all the objects of
> > +	     the class.  So NAME can be unambiguously referred to even if
> > +	     there are multiple indirect base classes containing NAME.  */
> > +	  const base_access ba = [scope, name] ()
> 
> Why a lambda?

Only so that I can set 'ba' once and make it const.  I don't believe it
deserves a named function.  It seems more readable than using a ?:.

> > +	    {
> > +	      if (identifier_p (name))
> > +		{
> > +		  tree m = lookup_member (scope, name, /*protect=*/0,
> > +					  /*want_type=*/false, tf_none);
> > +		  if (!m || VAR_P (m))
> 
> Do you want shared_member_p here?

That looks like the right thing to use, thanks.

Marek