[Bug bootstrap/87231] New: stdatomic.h: No such file or directory on OpenBSD 6.3

[shane@time-travellers.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87231

            Bug ID: 87231
           Summary: stdatomic.h: No such file or directory on OpenBSD 6.3
           Product: gcc
           Version: 8.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shane@time-travellers.org
  Target Milestone: ---

Trying to build gcc 8.2.0 on OpenBSD 6.3 fails in stage 3.

(Note that the patch in bug 87225 is required to get to this failure.)

The error message:

/bin/sh ./libtool --tag=CC   --mode=compile
/home/shane/gcc-8.2.0/host-i386-unknown-openbsd6.3/gcc/xgcc
-B/home/shane/gcc-8.2.0/host-i386-unknown-openbsd6.3/gcc/
-B/opt/gcc-8.2.0/i386-unknown-openbsd6.3/bin/
-B/opt/gcc-8.2.0/i386-unknown-openbsd6.3/lib/ -isystem
/opt/gcc-8.2.0/i386-unknown-openbsd6.3/include -isystem
/opt/gcc-8.2.0/i386-unknown-openbsd6.3/sys-include    -DHAVE_CONFIG_H
-I../.././libatomic/config/x86 -I../.././libatomic/config/posix
-I../.././libatomic -I.    -march=i486 -mtune=i386 -fomit-frame-pointer -Wall
-Werror   -pthread -g -O2 -MT fence.lo -MD -MP -MF .deps/fence.Tpo -c -o
fence.lo ../.././libatomic/fence.c
libtool: compile:  /home/shane/gcc-8.2.0/host-i386-unknown-openbsd6.3/gcc/xgcc
-B/home/shane/gcc-8.2.0/host-i386-unknown-openbsd6.3/gcc/
-B/opt/gcc-8.2.0/i386-unknown-openbsd6.3/bin/
-B/opt/gcc-8.2.0/i386-unknown-openbsd6.3/lib/ -isystem
/opt/gcc-8.2.0/i386-unknown-openbsd6.3/include -isystem
/opt/gcc-8.2.0/i386-unknown-openbsd6.3/sys-include -DHAVE_CONFIG_H
-I../.././libatomic/config/x86 -I../.././libatomic/config/posix
-I../.././libatomic -I. -march=i486 -mtune=i386 -fomit-frame-pointer -Wall
-Werror -pthread -g -O2 -MT fence.lo -MD -MP -MF .deps/fence.Tpo -c
../.././libatomic/fence.c  -fPIC -DPIC -o .libs/fence.o
../.././libatomic/fence.c:26:10: fatal error: stdatomic.h: No such file or
directory
 #include <stdatomic.h>
          ^~~~~~~~~~~~~
compilation terminated.

My build process is:

* Install OpenBSD (all defaults).
* Run syspatch
* Install packages:
    # pkg_add wget
    # pkg_add gmp mpfr libmpc
    # pkg_add gmake
* Get latest source and unpack:
    $ wget
ftp://ftp.nluug.nl/mirror/languages/gcc/releases/gcc-8.2.0/gcc-8.2.0.tar.gz
    $ tar xzf gcc-8.2.0.tar.gz
    $ cd gcc-8.2.0
* Patch the code from here:
https://gcc.gnu.org/viewcvs/gcc/branches/gcc-8-branch/gcc/tree-vect-stmts.c?r1=264117&r2=264116&pathrev=264117
* Build:
    $ ./configure --prefix=/opt/gcc-8.2.0 --with-gmp=/usr/local
--enable-languages=c,c++
    $ gmake