Re: [PATCH 17/41] doc/build-platforms: document supported compilers

[Daniel P . Berrangé]

On Wed, Apr 20, 2022 at 08:47:25PM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Wed, Apr 20, 2022 at 7:55 PM Daniel P. Berrangé <berrange@redhat.com> 
> wrote:
> >
> > On Wed, Apr 20, 2022 at 07:32:38PM +0400, Marc-André Lureau wrote:
> > > Hi
> > >
> > > On Wed, Apr 20, 2022 at 7:24 PM Daniel P. Berrangé <berrange@redhat.com> 
> > > wrote:
> > > >
> > > > On Wed, Apr 20, 2022 at 06:50:12PM +0400, Marc-André Lureau wrote:
> > > > > Hi
> > > > >
> > > > > On Wed, Apr 20, 2022 at 6:46 PM Marc-André Lureau
> > > > > <marcandre.lureau@redhat.com> wrote:
> > > > > >
> > > > > > Hi
> > > > > >
> > > > > > On Wed, Apr 20, 2022 at 6:37 PM Thomas Huth <thuth@redhat.com> 
> > > > > > wrote:
> > > > > > >
> > > > > > > On 20/04/2022 16.10, Daniel P. Berrangé wrote:
> > > > > > > > On Wed, Apr 20, 2022 at 05:26:00PM +0400, 
> > > > > > > > marcandre.lureau@redhat.com wrote:
> > > > > > > >> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> > > > > > > >>
> > > > > > > >> According to our configure checks, this is the list of 
> > > > > > > >> supported
> > > > > > > >> compilers.
> > > > > > > >>
> > > > > > > >> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> > > > > > > >> Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
> > > > > > > >> ---
> > > > > > > >>   docs/about/build-platforms.rst | 10 ++++++++++
> > > > > > > >>   1 file changed, 10 insertions(+)
> > > > > > > >>
> > > > > > > >> diff --git a/docs/about/build-platforms.rst 
> > > > > > > >> b/docs/about/build-platforms.rst
> > > > > > > >> index c29a4b8fe649..1980c5d2476f 100644
> > > > > > > >> --- a/docs/about/build-platforms.rst
> > > > > > > >> +++ b/docs/about/build-platforms.rst
> > > > > > > >> @@ -92,6 +92,16 @@ hosted on Linux (Debian/Fedora).
> > > > > > > >>   The version of the Windows API that's currently targeted is 
> > > > > > > >> Vista / Server
> > > > > > > >>   2008.
> > > > > > > >>
> > > > > > > >> +Supported compilers
> > > > > > > >> +-------------------
> > > > > > > >> +
> > > > > > > >> +To compile, QEMU requires either:
> > > > > > > >> +
> > > > > > > >> +- GCC >= 7.4.0
> > > > > > > >> +- Clang >= 6.0
> > > > > > > >> +- XCode Clang >= 10.0
> > > > > > > >
> > > > > > > > Do we need to spell out the versions explicitly ? These 
> > > > > > > > versions are
> > > > > > > > all derived from what's available in the repos of the supported 
> > > > > > > > build
> > > > > > > > platforms, similar to any other build deps we have. I don't 
> > > > > > > > think we
> > > > > > > > want to start a precedent of duplicating versions in this doc 
> > > > > > > > for
> > > > > > > > build deps we have, and there's nothing particularly special 
> > > > > > > > about
> > > > > > > > compilers in this respect.
> > > > > > >
> > > > > > > I agree with Daniel - when I saw this patch, the first thought 
> > > > > > > that I had
> > > > > > > was: "This will be getting out of sync quickly" ...
> > > > > >
> > > > > > I don't have the impression we bump our compiler requirement 
> > > > > > regularly
> > > > > > or lightly.
> > > > > >
> > > > > > > so I'd also recommend to rather not add this here.
> > > > > >
> > > > > > Outdated documentation is still better than no documentation. YMMV.
> > > > >
> > > > > Another question that is difficult to answer without being familiar
> > > > > with QEMU details is whether it can compile with MSVC. This
> > > > > documentation would, since it is explicit about the requirement.
> > > >
> > > > Documenting that we mandate GCC or Clang is reasonable. Ideally we could
> > > > have a list of all 3rd party deps we have in fact, I'm just not a fan of
> > > > copying the version numbers across from configure/meson.
> > > >
> > >
> > > I agree, duplicating the version information is not optimal... Yet it
> > > is better than not having it, or having to read or run configure imho.
> > >
> > > Sorry (or not) to insist, but it would help having an explicit list of
> > > supported compilers in the human doc (because configure/meson doesn't
> > > rule others out, afaik, nor it really can or should)
> >
> > Perhaps I'm misunderstanding what you mean, but configure certainly
> > does rules out other compilers, giving a clear message:
> >
> > if ! compile_prog "" "" ; then
> >     error_exit "You need at least GCC v7.4 or Clang v6.0 (or XCode Clang 
> > v10.0)"
> > fi
> >
> 
> How can this test fail with other compilers?

This is just the error reporting, look at the code above it for the
full compiler check....

With regards,
Daniel
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