svn commit: r365889 - head/share/mk

[Mark Johnston]

On Fri, Sep 18, 2020 at 01:27:23PM -0600, Ian Lepore wrote:
> On Fri, 2020-09-18 at 19:03 +0000, Mark Johnston wrote:
> > Author: markj
> > Date: Fri Sep 18 19:03:34 2020
> > New Revision: 365889
> > URL: https://svnweb.freebsd.org/changeset/base/365889
> > 
> > Log:
> >   Install library symlinks atomically.
> >   
> >   As we do for shared library binaries, pass -S to install(1) when
> >   installing symlinks.  Doing so helps avoid transient failures when
> >   libraries are being reinstalled, which seems to be the root cause
> > of
> >   spurious libgcc_s.so link failures during CI builds.
> >   
> 
> Actually, I believe this will just paper over the real problem, which
> is the fact that we're building and installing the same library
> multiple times during early build steps.  Nobody has yet been able to
> explain why we do that, and I haven't been able to figure out why by
> analyzing any differences in the generated files, but I'm not done
> trying.

Sorry, this deserved more commentary in the commit log.

Indeed, we install libgcc_s.so multiple times during buildworld.  As far
as I can see, it's intentional insofar as libgcc_s.so is listed in
multiple library targets: it's in both _prereq_libs and _startup_libs in
Makefile.inc1.  In particular, from scanning the log from a recent
instance of the failure, libgcc_s gets built once but installed multiple
times.

Why that's the case, or whether it's still necessary, is not clear to
me.  But adding -S seemed like a desirable change in general, so I went
forward with it.