Re: Test with an lto-build of libgfortran.

[Jakub Jelinek <jakub@redhat.com>]

On Thu, Sep 28, 2023 at 01:00:41PM +0200, Tobias Burnus wrote:
> I am not aware of any logigal/integer/real(+comples)/character kind > 16,
> except for this PPC one. And complex numbers are pairs of BT_REAL.
> 
> Thus, I think that patch should be fine - except:
> 
> > Does anything error earlier if it is larger?  I mean, say user calling
> > _gfortan_transfer_integer by hand with kind 1024?
> 
> I think this will fail. We have various ways to deal with this in libgfortran;
> I see some cases where the switch "default:" sets the length to 0; we have
> other places where we use an "assert", I think we have other places were
> we run into UB.
> 
> Thus, one option would be to either 'assert(len <= 16)' or
> 'assert((size_t)len < GFC_OTOA_BUF_SIZE - 1)' instead.
> 
> Or we could handle it as len=0 and silently ignore the output or ...
> 
> I am fine with either of the many options - except that I like something
> explicit involving 'len' and a comparison (unreachable, assert, regarding as len = 0)
> better than the existing warning suppression which is too indirect for
> me. (Besides: it does not work for LTO.) Preferences? Tobias

Let's go with the __builtin_unreachable, ok for trunk.

	Jakub