Re: Deprecating -fgnu-tm support for GCC 14 and removing it for GCC 15

[Richard Biener <richard.guenther@gmail.com>]

On Mon, Dec 18, 2023 at 2:35 AM Andrew Pinski via Gcc <gcc@gcc.gnu.org> wrote:
>
> On Sun, Dec 17, 2023 at 1:20 PM Eric Gallager <egall@gwmail.gwu.edu> wrote:
> >
> > On Sat, Dec 16, 2023 at 3:16 PM Andrew Pinski via Gcc <gcc@gcc.gnu.org> wrote:
> > >
> > > -fgnu-tm support has not been improved since GCC 5 or earlier. It is
> > > not even supported with LTO. Does it make sense to deprecate the
> > > support for GCC 14 and remove it in GCC 15?
> > >
> > > Thanks,
> > > Andrew Pinski
> >
> > Personally, since GCC is in stage 3 now, I would push that schedule
> > back a release and move deprecation to GCC 15, and then only remove it
> > for GCC 16 if no one objects, but then again I don't actually use
> > -fgnu-tm myself, so I wouldn't be too upset if the faster schedule is
> > chosen instead.
>
> Considering -fgnu-tm has been broken for LTO ever since LTO was
> introduced, and broken with -fsanitize=undefined and broken with many
> code that might use internal functions (known since 2015), I suspect
> nobody is using this option in production nor even trying it out. If
> this was stage1, I might even just recommend removing the support. But
> deprecating it during stage 3 seems like a fair compromise.

Btw, I'm OK with deprecating it for GCC 14.  Can you please propose a
patch for changes.html and add a diagnostic message when -fgnu-tm is used
(disabled with -Wno-deprecated)?

Thanks,
Richard.

> > Eric Gallager