External Issue: Build failure in third-party/libfabric with Apple Xcode 12.x

16759, “PHHargrove”, “Build failure in third-party/libfabric with Apple Xcode 12.x”, “2020-11-20T04:03:06Z”

In Xcode 12.x, Apple has decided to default to -Werror=implicit-function-declaration, making the C compiler behave as strictly a C++ compiler would when calling an unprototyped function. This behavior is contributing to the following build failure on master at e27061cf

/[path redacted]/chapel/third-party/libfabric/libfabric-src/prov/util/src/util_shm.c:81:8: error: implicit declaration of function 'ofi_process_vm_writev' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        ret = ofi_process_vm_writev(peer_smr->pid, &local_iov, 1,
              ^
1 error generated.
make[7]: *** [prov/util/src/src_libfabric_la-util_shm.lo] Error 1

See this page for more details about the failing build.