Re: [PATCH] meson.build: Refuse XCode versions < v15.0

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Nov 26, 2024 at 12:11:43PM +0100, Philippe Mathieu-Daudé wrote:
> On 26/11/24 10:23, Daniel P. Berrangé wrote:
> > On Tue, Nov 26, 2024 at 09:57:15AM +0100, Philippe Mathieu-Daudé wrote:
> > > On 26/11/24 09:10, Thomas Huth wrote:
> > > > According to our support policy, we only support the two latest
> > > > major versions of macOS, and we already removed compatibility code
> > > > for older versions. However, it's still possible that people install
> > > > an older version of XCode on a recent version of macOS - which won't
> > > > be able to compile QEMU anymore, see for example the ticket here:
> > > > 
> > > >    https://gitlab.com/qemu-project/qemu/-/issues/2694
> > > 
> > > Wondering about this issue, it is possible to install concurrent
> > > XCode versions, which is useful i.e. when you build an application
> > > targeting multiple (and older) App Store releases. See:
> > > https://xcodereleases.com/
> > 
> > That's true of any platform. You can get many GCC versions for Debian
> > and Fedora too.
> > 
> > > Maybe we need to clarify our support policy that we only support
> > > the XCode released with the 2 latest major macOS versions?
> > 
> > We implicitly support the XCode versions that are the "default" with
> > the latest 2 macOS versions.
> 
> Implicit might not be sufficient for users, see #2694.

Well I'm not convinced the persno in that bug report would have
read the docs regardless. 

This patch takes care of making it explicit in a way that can't
be missed though.

> 
> > > > @@ -315,8 +315,8 @@ foreach lang : all_languages
> > > >        # ok
> > > >      elif compiler.get_id() == 'clang' and compiler.compiles('''
> > > >          #ifdef __apple_build_version__
> > > > -      # if __clang_major__ < 12 || (__clang_major__ == 12 && __clang_minor__ < 0)
> > > > -      #  error You need at least XCode Clang v12.0 to compile QEMU
> > > > +      # if __clang_major__ < 15 || (__clang_major__ == 15 && __clang_minor__ < 0)
> > > > +      #  error You need at least XCode Clang v15.0 to compile QEMU
> > > >          # endif
> > > >          #else
> > > >          # if __clang_major__ < 10 || (__clang_major__ == 10 && __clang_minor__ < 0)
> > > > @@ -325,7 +325,7 @@ foreach lang : all_languages
> > > >          #endif''')
> > > >        # ok
> > > >      else
> > > > -    error('You either need GCC v7.4 or Clang v10.0 (or XCode Clang v12.0) to compile QEMU')
> > > > +    error('You either need GCC v7.4 or Clang v10.0 (or XCode Clang v15.0) to compile QEMU')
> > > 
> > > BTW apparently CentOS 8 (which we don't support anymore IIRC)
> > > provides Clang 12.0.1, and also Ubuntu 22.04, Alpine 3.16.
> > > 
> > > I wonder if the relation with XCode __apple_build_version__ is
> > > always __clang_major__ + 3...
> > 
> > No, it isn't. It varies all over the place -
> > 
> > eg
> > 
> >  From xcode 11.3 to 11.4 they bump from llvm 8.0.0 to 9.0.0, while the
> > clang version goes from 11.0.0 to 11.0.3.
> > 
> >  From xcode 15.4 to 16.0 they from llmvm 16.0.0 to 17.0.6, while the
> > clang version goes from 15.0.0 to 16.0.0.
> > 
> > I can just about interpret a rule they're following, but relating that
> > to the upstream clang versions algorithmically is impossible.
> > 
> >    https://en.wikipedia.org/wiki/Xcode#Toolchain_versions
> 
> Doh...
> 
> Anyway, for this patch:
> 
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> 

With regards,
Daniel
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