[Bug c++/101118] coroutines: unexpected ODR warning for coroutine frame type in LTO builds

["iains at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101118

--- Comment #7 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Jan Hubicka from comment #6)

from me there has been no progress on anything co-routines related, for a while
- I of not have any resources to work on it.

> I am not really expert on coroutines. But this seems to be a type (not a
> declaration we globalize during LTO) generated internally by the front-end. 
> The name __D.9984.3.4 looks like it has a global counter in it.
> ODR types are supposed to be literaly the same across units.
> 
> One way to silence this would be to not make these types ODR types since
> they are not the usual C++ types anyway.
> I wonder if  this is a part of the cross-unit API that is supposed to be
> same? I.e. is the coroutine in one compilation unit visible from the other?
> 
> If so, perhaps the only problem is hte global counter 9984 and if the counts
> were generated internally for each such type, the ODR handling wlll be happy.

the synthesised functions (actor, destroy) are intended to be TU-local.
the ramp function is what remains of the user's original function after the
coroutine body is outlined - so that has the original signature of the user's
function.

We do use counters to generate local symbol names for frame-promoted
temporaries, so I suppose that there is a possibility that the name(s) that are
intended to be TU-local become visible across TUs in LTO; but those should be
the names of coroutine frame entries (i.e. fields in a structure, not
themselves global symbols).