Re: [PATCH 2/2] ctype: use less short names in public header

On Tue, 30 Nov 2021 at 17:12, Jonathan Wakely <[email protected]> wrote:
>
> On Tue, 30 Nov 2021 at 15:14, Corinna Vinschen <[email protected]> wrote:
> >
> > On Nov 30 12:01, Jonathan Wakely wrote:
> > > On 23/11/21 23:15 -0500, Mike Frysinger wrote:
> > > > On 23 Nov 2021 15:09, Richard Earnshaw wrote:
> > > > > This is wrong and breaks all old versions of C++.
> > > >
> > > > this is a bit vague.  it would help if you provided details as to what broke.
> > > > i doubt this broke all old versions of C++ everywhere.
> > > >
> > > > i'm guessing you're referring to the GNU C++ (libstdc++) library specifically
> > > > and its hardcoding of newlib's internal ctype define names.
> > > > https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libstdc%2B%2B-v3/config/os/newlib/ctype_base.h;hb=releases/gcc-11.2.0
> > >
> > > Yes, you were CC'd on the GCC bug slightly before Richard sent his
> > > email to this list:
> > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103305#c16
> > >
> > > > if you're talking about something else, please state so clearly.
> > > >
> > > > > The GNU sim code should not be using reserved names (those starting _)
> > > > > in normal source code.  Such names are reserved to the implementation.
> > > >
> > > > that's not really a good reason to go pooping all over the namespace.
> > > >
> > > > we can maintain backwards compat here for C++ code fairly easily:
> > >
> > > Yes, or only do that for GCC < 12, as I suggested in
> > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103305#c19
> > >
> > > #if defined(__GNUC__) && defined(__cplusplus)
> > > # if __GNUC__ < 12
> > >
> > > The libstdc++ code on trunk uses the new _ISupper names.
> > >
> > > I have no opinion on how long you should keep such backwards
> > > compatibility around. Whatever time limit you set, at some point it
> > > will make a new newlib release unusable with past G++ versions.
> >
> > Is there a good reason to revert these patches in newlib?  I see the
> > problem but I'm unclear on how problematic the change is in real life.
>
> You cannot use newlib from Git to build any released version of GCC.
>
> Is building newlib from Git only supported when using GCC trunk, or is

Oops, I mean building *against* newlib from Git, not building newlib
itself. You can still build newlib itself, because it doesn't use C++.
But you can't build a GCC 11.2.0 compiler that uses the latest newlib
from Git as its libc.

> it supposed to build with e.g. GCC 11.2.0 from July this year? If yes,
> then newlib needs changes (whether reverting the change entirely, or
> just making another change to restore the old names in addition to the
> new ones).