Re: Improving GNUstep tooling with Clang

[Johannes Brakensiek]

On 29 Nov 2019, at 11:43, Frederik Seiffert wrote:

> Am 28.11.2019 um 22:06 schrieb Niels Grewe 
> <niels.grewe@halbordnung.de>:
> > On 28.11.19 17:15, Frederik Seiffert wrote:
> > > - Set up CI testing for the 2.0 runtime version, which currently 
> > > doesn’t seem to be tested with libs-base.
> > > I have submitted a pull request for this 
> > > (https://github.com/gnustep/libs-base/pull/88).

Thanks to the work of Patryk we have a working build setup with CI here 
now: https://github.com/plaurent/gnustep-build/

Would it be helpful to you if we’d run the tests on the runtime as 
well?

> > Unfortunately, when I tried to integrate that into my libdispatch 
> > stuff,
> > I discovered that this doesn't actually test the 2.0 runtime. The CI
> > script is still using a Ubuntu 14.04 builder, which ships with a 
> > clang
> > version that is too old to know about the 2.0 runtime version
> > (defaulting to something else, presumably). Once run under 18.04 
> > (baby
> > steps…), with clang 7, we're getting failures in the configure 
> > script
> > because the new objc_init struct references non-existent sections in 
> > the
> > binary (those conftest things don't declare any classes and such).
>
> Oh, good catch! How did you find out that the Clang version didn’t 
> support the 2.0 runtime? Is there a warning or similar that I can 
> watch out for in the future?
>
> > Upgrading to clang 9 fixes that, but now I'm seeing a load of test
> > failures that I haven't had the time to investigate further:
> >
> > https://travis-ci.org/gnustep/libs-base/builds/618352009

The output there looks as if you are still using clang 7?

> Ok wow – to be honest, based on our experience with the 2.0 runtime, 
> I was kind of surprised when all the tests were previously passing. It 
> sounds like something fundamental is broken here though and you’re 
> onto it (https://github.com/gnustep/libobjc2/issues/136). Let me know 
> if I can give a hand with this in any way.

I don’t know if there is anything fundamental broken, but clang 7 is 
known to not work with the 2.0 runtime as well as the lld linker (you 
have to use ld.gold). Did you notice Andreas’ paper describing this?

http://wiki.gnustep.org/index.php/Building_GNUstep_under_Debian_FreeBSD

His (and our) build experiences have been collected at the scripts 
mentioned at the repository above.

Johannes