Try this patch to correctly link compiler-rt.

2018-02-13 15:15 GMT+01:00 Szabolcs Nagy <nsz@port70.net>:
* Dmitry Golovin <dima@golovin.in> [2018-02-13 15:34:34 +0200]:
> I'm trying to compile compiler-rt with musl and it used to be fine, but I can't succeed with recent versions of compiler-rt.
>
> The compilation fails because of the lack of real_shmctl while musl clearly has shmctl: http://git.musl-libc.org/cgit/musl/tree/src/ipc/shmctl.c
>
> Here is the complete output:
>
>     llvm/projects/compiler-rt/lib/msan/msan_interceptors.cc:1446:15: error: no member named 'real_shmctl' in namespace '__interception'; did you mean 'real_ioctl'?
>         int res = REAL(shmctl)(shmid, shmctl_ipc_stat, &ds);
>                   ^~~~~~~~~~~~

there should be a

DECLARE_REAL(int, shmctl, int shmid, int cmd, void *buf)

in that file which defines __interception::real_shmctl.

> To compile without glibc on linux using this patch:
> https://github.com/tpimh/ngtc/blob/alpine/patch/compiler-rt-01-sanitizer-nongnu.patch
>
> Regards,
> Dmitry