It was failing to build with the GCC/binutils on the CentOS-based docker
image, but it doesn't with the Debian-based one, so we can remove the
dependency on the gcc toolchain task. This allows sccache to remain
untouched when we change the gcc build scripts, and more importantly,
this allows it to depend on no toolchain that requires building things.
This makes it now possible to use sccache as a dependency for all other
toolchains jobs that compile, if that's beneficial (which might not be
the case, given the current sccache retention time, but at least it's a
viable option, now)
When adding sccache toolchain jobs in bug 1381772, building with gcc
failed, and building with clang worked, so I just went with the path of
least resistance. That's however a suboptimal position in the dependency
graph, so it's still preferable to use gcc if possible.
Looking exactly how it fails, it turns out it's because without CC being
set, ring wants to build with "cc", which ends up being the system gcc
instead of ours (our gcc archive doesn't provide "cc", only "gcc"), and
it is too old to support the compiler flags ring uses.
So setting CC does the trick.
Our current sccache build links in openssl's libraries dynamically. The
sonames of the dynamic libraries linked in are specific to the
CentOS/Fedora-ish systems that we build on; attempting to run the
generated sccache binaries on different systems (e.g. Debian-ish) will
result in failure. All of our current automation images are
CentOS-based, but for various reasons, Debian-based images may be used
in the future, and it would be great to have an sccache binary to run on
such systems as well. (It might also be interesting to distribute the
sccache binary we use to local developers as well, but that's a bit
further off.)
Therefore, this patch alters the sccache build on Linux to use static
linking for openssl. We cannot use the system openssl we build on
because the system openssl links to libkrb5, and the distribution we use
for the system images does not provide static libraries of libkrb5.
Building openssl ourself enables us to eliminate the libkrb5 dependency.
An sccache binary from builds with this patch depends on the following
libraries:
froydnj@hawkeye:~$ ldd sccache2/sccache
linux-vdso.so.1 => (0x00007ffe02b39000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ff0e7403000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007ff0e71fb000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007ff0e6fdd000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007ff0e6dc6000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ff0e69fc000)
/lib64/ld-linux-x86-64.so.2 (0x0000557c8540b000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007ff0e66f2000)
which are standard on any Linux distribution.
