On Wed, Oct 09, 2019 at 11:01:39AM +0100, Jonathan Wakely wrote:
> On 07/10/19 14:56 -0400, Jason Merrill wrote:
> > On 10/7/19 1:42 PM, Marek Polacek wrote:
> > > @@ -7401,8 +7432,20 @@ convert_like_real (conversion *convs, tree expr,
> > > tree fn, int argnum,
> > > error_at (loc, "cannot bind non-const lvalue reference of "
> > > "type %qH to an rvalue of type %qI", totype, extype);
> > > else if (!reference_compatible_p (TREE_TYPE (totype), extype))
> > > - error_at (loc, "binding reference of type %qH to %qI "
> > > - "discards qualifiers", totype, extype);
> > > + {
> > > + /* If we're converting from T[] to T[N], don't talk
> > > + about discarding qualifiers. (Converting from T[N] to
> > > + T[] is allowed by P0388R4.) */
> > > + if (TREE_CODE (extype) == ARRAY_TYPE
> > > + && TYPE_DOMAIN (extype) == NULL_TREE
> > > + && TREE_CODE (TREE_TYPE (totype)) == ARRAY_TYPE
> > > + && TYPE_DOMAIN (TREE_TYPE (totype)) != NULL_TREE)
> > > + error_at (loc, "binding reference of type %qH to %qI "
> > > + "discards array bounds", totype, extype);
> >
> > If we're converting to T[N], that would be adding, not discarding, array
> > bounds?
>
> I don't think the diagnostic would be very good if we say "adds array
> bounds" though. How about being consistent with the existing error for
> similar cases?
>
> a.cc:4:17: error: invalid initialization of reference of type ‘int (&)[3]’
> from expression of type ‘int []’
> int (&b)[3] = a;
> ^
In my latest patch the error message reads "cannot bind reference of type T to
U due to different array bounds".
It'd be trivial to adjust it if anyone hates that.
Marek
