(base) profile@names-laptop Troubleshooting % conda activate moose
(moose) profile@x86_64-apple-darwin13 Troubleshooting % cd /tmp
cat << EOF > hello.C
#include <mpi.h>
#include <stdio.h>

int main(int argc, char** argv) {
  // Initialize the MPI environment
  MPI_Init(NULL, NULL);

  // Get the number of processes
  int world_size;
  MPI_Comm_size(MPI_COMM_WORLD, &world_size);

  // Get the rank of the process
  int world_rank;
  MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);

  // Get the name of the processor
  char processor_name[MPI_MAX_PROCESSOR_NAME];
  int name_len;
  MPI_Get_processor_name(processor_name, &name_len);

  // Print off a hello world message
  printf("Hello world from processor %s, rank %d out of %d processors\n",
         processor_name, world_rank, world_size);

  // Finalize the MPI environment.
  MPI_Finalize();
}
EOF

mpicxx -fopenmp hello.C
In file included from hello.C:1:
In file included from /Users/profile/opt/anaconda3/envs/moose/include/mpi.h:50:
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:152:8: error: no member named 'int8_t' in the global namespace
using::int8_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:153:8: error: no member named 'int16_t' in the global namespace
using::int16_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:154:8: error: no member named 'int32_t' in the global namespace
using::int32_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:155:8: error: no member named 'int64_t' in the global namespace
using::int64_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:157:8: error: no member named 'uint8_t' in the global namespace
using::uint8_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:158:8: error: no member named 'uint16_t' in the global namespace
using::uint16_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:159:8: error: no member named 'uint32_t' in the global namespace
using::uint32_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:160:8: error: no member named 'uint64_t' in the global namespace
using::uint64_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:162:8: error: no member named 'int_least8_t' in the global namespace
using::int_least8_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:163:8: error: no member named 'int_least16_t' in the global namespace
using::int_least16_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:164:8: error: no member named 'int_least32_t' in the global namespace
using::int_least32_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:165:8: error: no member named 'int_least64_t' in the global namespace
using::int_least64_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:167:8: error: no member named 'uint_least8_t' in the global namespace
using::uint_least8_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:168:8: error: no member named 'uint_least16_t' in the global namespace
using::uint_least16_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:169:8: error: no member named 'uint_least32_t' in the global namespace
using::uint_least32_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:170:8: error: no member named 'uint_least64_t' in the global namespace
using::uint_least64_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:172:8: error: no member named 'int_fast8_t' in the global namespace
using::int_fast8_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:173:8: error: no member named 'int_fast16_t' in the global namespace
using::int_fast16_t;
     ~~^
/Users/profile/opt/anaconda3/envs/moose/bin/../include/c++/v1/cstdint:174:8: error: no member named 'int_fast32_t' in the global namespace
using::int_fast32_t;
     ~~^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.