On Wed, Jan 20, 2021 at 2:48 AM Thierry Reding [off-list ref] wrote:

On Fri, Dec 18, 2020 at 08:33:37PM +0000, Jon Hunter wrote:

quoted

On 18/12/2020 17:54, Linus Torvalds wrote:

quoted

On Fri, Dec 18, 2020 at 7:33 AM Jon Hunter [off-list ref] wrote:

quoted

However, if you are saying that this is a problem/bug with our builders,
then of course we will have to get this fixed.

This seems to be a package dependency problem with the gcc plugins -
they clearly want libgmp, but apparently the package hasn't specified
that dependency.

If this turns out to be a big problem, I guess we can't simplify the
plugin check after all.

We historically just disabled gcc-plugins if that header didn't build,
which obviously meant that it "worked" for people, but it also means
that clearly the coverage can't have been as good as it could/should
be.

So if it's as simple as just installing the GNU multiprecision
libraries ("gmp-devel" on most rpm-based systems, "libgmp-dev" on most
debian systems), then I think that's the right thing to do. You'll get
a working build again, and equally importantly, your build servers
will actually do a better job of covering the different build options.

Thanks. I have reported this issue to the team that administers the
builders. So hopefully, they will install the necessary packages for us
now.

Just to close the loop on this, the builders now have libgmp-dev and
libmpc-dev packages installed and the builds are passing without the
workaround we had used.

Thierry

I was slightly concerned about your question:

"In case where CC != HOSTCC, it's possible that CC was not built against
the same version of GMP/MPC as HOSTCC. And even HOSTCC might not
necessarily have been built against the versions provided by libgmp-dev
or libmpc-dev. I'm not overly familiar with GMP/MPC, so perhaps if these
headers are reasonably stable, this is not all that important. But if it
is, then which version of GMP/MPC do we need? The version that CC was
built against, or the version that HOSTCC was built against?"



I do not have a good insight about this.

I am not sure if it is perfectly OK to
use gmp.h from HOSTCC when it was not bundled with CC.

The version difference might not be a significant issue, though...





-- 
Best Regards
Masahiro Yamada