cpp building error on arm64/ubuntu/gcc

[dpmabo]

Because stdatomic.h is not compatible with cpp on g++, please change the related testcase from cpp to c.

arch: aarch64
system: aws t4g.large
os: Ubuntu 18.04.6 LTS
gcc: 7.5.0
command: ./cppbuild/cppbuild

[ 53%] Building CXX object aeron-client/src/test/c/CMakeFiles/spsc_rb_test.dir/concurrent/aeron_spsc_rb_test.cpp.o
In file included from aeron/aeron-client/src/main/c/concurrent/aeron_atomic64_c11.h:22,
                 from aeron/aeron-client/src/main/c/concurrent/aeron_atomic.h:25,
                 from aeron/aeron-client/src/main/c/concurrent/aeron_rb.h:22,
                 from aeron/aeron-client/src/main/c/concurrent/aeron_spsc_rb.h:20,
                 from aeron/aeron-client/src/test/c/concurrent/aeron_spsc_rb_test.cpp:26:
/usr/lib/gcc/aarch64-linux-gnu/9/include/stdatomic.h:40:9: error: ‘_Atomic’ does not name a type
   40 | typedef _Atomic _Bool atomic_bool;
      |         ^~~~~~~
/usr/lib/gcc/aarch64-linux-gnu/9/include/stdatomic.h:41:9: error: ‘_Atomic’ does not name a type
   41 | typedef _Atomic char atomic_char;
      |         ^~~~~~~
/usr/lib/gcc/aarch64-linux-gnu/9/include/stdatomic.h:42:9: error: ‘_Atomic’ does not name a type
   42 | typedef _Atomic signed char atomic_schar;
      |         ^~~~~~~

[alextibbles]

Following comments on a GCC bug report, I was able to workaround this compilation problem by building with clang/clang++. It appears clang is either more permissive wrt _Atomic C keyword, more aware of C++20 stdatomic.h standardization?

#1291 fixes ARM clang link.

cmake -DCMAKE_C_COMPILER=clang-14 -DCMAKE_CXX_COMPILER=clang++-14 ../..

Jakub Jelinek 2021-08-11 09:58:13 UTC

Note, stdatomic.h is now in C++20.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60932#c14

[dpmabo]

waiting for a gcc fix.