GCC8 fails to build on 10.14.4

[PovlAbrahamsen]

GCC 8 isn't building for me, on 14.4.4 with command line tools 10.2. I have tried on two different computers, but on both it fails on stage 2 with the following error:

/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir/./prev-gcc/xg++ -B/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir/./prev-gcc/ -B/sw/lib/gcc8/x86_64-apple-darwin18.5.0/bin/ -nostdinc++ -B/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir/prev-x86_64-apple-darwin18.5.0/libstdc++-v3/src/.libs -B/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir/prev-x86_64-apple-darwin18.5.0/libstdc++-v3/libsupc++/.libs  -I/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir/prev-x86_64-apple-darwin18.5.0/libstdc++-v3/include/x86_64-apple-darwin18.5.0  -I/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir/prev-x86_64-apple-darwin18.5.0/libstdc++-v3/include  -I/sw/src/fink.build/gcc8-8.3.0-100/gcc-8.3.0/libstdc++-v3/libsupc++ -L/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir/prev-x86_64-apple-darwin18.5.0/libstdc++-v3/src/.libs -L/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir/prev-x86_64-apple-darwin18.5.0/libstdc++-v3/libsupc++/.libs -B/sw/lib/gcc8/x86_64-apple-darwin18.5.0/bin/ -B/sw/lib/gcc8/x86_64-apple-darwin18.5.0/lib/ -isystem /sw/lib/gcc8/x86_64-apple-darwin18.5.0/include -isystem /sw/lib/gcc8/x86_64-apple-darwin18.5.0/sys-include     -fno-PIE -c   -g -O2   -gtoggle -DIN_GCC     -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings   -DHAVE_CONFIG_H -I. -I. -I../../gcc-8.3.0/gcc -I../../gcc-8.3.0/gcc/. -I../../gcc-8.3.0/gcc/../include -I../../gcc-8.3.0/gcc/../libcpp/include -I/sw/include -I/sw/include  -I../../gcc-8.3.0/gcc/../libdecnumber -I../../gcc-8.3.0/gcc/../libdecnumber/dpd -I../libdecnumber -I../../gcc-8.3.0/gcc/../libbacktrace -I/sw/include -I/sw/include -o darwin-driver.o -MT darwin-driver.o -MMD -MP -MF ./.deps/darwin-driver.TPo ../../gcc-8.3.0/gcc/config/darwin-driver.c
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/sys/sysctl.h:83,
                 from ../../gcc-8.3.0/gcc/config/darwin-driver.c:30:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/sys/ucred.h:94:2: error: '_Atomic' does not name a type
  _Atomic u_long          cr_ref;  /* reference count */
  ^~~~~~~
make[3]: *** [../../gcc-8.3.0/gcc/config/t-darwin:35: darwin-driver.o] Error 1
make[3]: *** Waiting for unfinished jobs....
rm gfortran.pod gcc.pod
make[3]: Leaving directory '/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir/gcc'
make[2]: *** [Makefile:4690: all-stage2-gcc] Error 2
make[2]: Leaving directory '/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir'
make[1]: *** [Makefile:22034: stage2-bubble] Error 2
make[1]: Leaving directory '/sw/src/fink.build/gcc8-8.3.0-100/darwin_objdir'
make: *** [Makefile:22230: bootstrap] Error 2
### execution of /tmp/fink.GZejy failed, exit code 2
### execution of /tmp/fink.ecclM failed, exit code 2
Removing runtime build-lock...
Removing build-lock package...
/sw/bin/dpkg-lockwait -r fink-buildlock-gcc8-8.3.0-100
(Reading database ... 81980 files and directories currently installed.)
Removing fink-buildlock-gcc8-8.3.0-100 ...
Failed: phase compiling: gcc8-8.3.0-100 failed

I'm not sure if this is a new problem with the latest dev tools?

[PovlAbrahamsen]

More info about my system:

Distribution version: selfupdate-git Thu Mar 28 12:02:34 2019, 10.14, x86_64
Trees: local/main stable/main stable/crypto local/injected
Xcode.app: 10.2
Xcode command-line tools: 10.2.0.0.1.1552586384
Max. Fink build jobs:  4

[nieder]

I also see it on 10.14.4/10.2 (and was dumb enough to not try to build before I updated from 10.1).

It's not just us, either:
https://apple.stackexchange.com/questions/355049/compilation-error-with-mojave-error-atomic-does-not-name-a-type

[nieder]

This error applies to all gccX packages with Xcode 10.2.

[PovlAbrahamsen]

Also reported at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89864 (for GCC 9).

[akhansen]

We got a report of a fix:

https://gist.github.com/eschnett/f912c6b791e29c83477575017271db16#file-headers-10-14-4-fix-patch

[akhansen]

And I just saw that @nieder is aware of this.