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Re: [C++ PATCH] Fix xvalue COND_EXPR handling (PR c++/88103)


On Mon, Dec 3, 2018 at 4:36 PM Jakub Jelinek <jakub@redhat.com> wrote:
>
> On Mon, Dec 03, 2018 at 02:44:32PM -0500, Jason Merrill wrote:
> > > > Is there a reason not to use the 'move' function here?
> > >
> > > That doesn't work at all.  move doesn't call cp_convert, but
> > > build_static_cast (though for the same reference && type).
> > > But while cp_convert only adds NOP_EXPR around it, build_static_cast adds
> > > a target_expr, addr_expr around that, nop_expr cast to the reference && type
> > > and finally indirect_ref that the caller doesn't expect, because it adds it
> > > by itself, e.g. in
> > > 2424            if (temp)
> > > 2425              object = cp_build_fold_indirect_ref (temp);
> >
> > So the caller is trying to take the address of the COND_EXPR, which should
> > have POINTER_TYPE.  And then indirecting that gives an lvalue, as it should.
> > The bug is in the caller, build_class_member_access_expr.
>
> So like this then (if it passes bootstrap/regtest)?  Seems to fix the
> testcase.
>
> 2018-12-03  Jakub Jelinek  <jakub@redhat.com>
>
>         PR c++/88103
>         * typeck.c (build_class_member_access_expr): If unary_complex_lvalue
>         turned xvalue_p into non-xvalue_p, call move on it.
>
>         * g++.dg/cpp0x/rv-cond3.C: New test.

OK, thanks.

Jason


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