Hello everyone I know this issue is closed but I'm hitting a issue that is related.

In Node.js I have PR that updates the compiler to Clang: nodejs/node#62656

AIX header files don't ship declarations for sendmmsg and related functions, despite documentation showing they should be included. This appears to be a bug in AIX header files.

GCC tolerates implicit function declarations, but Clang 16+ treats them as errors:
https://www.redhat.com/en/blog/new-warnings-and-errors-clang-16

For now, we claim to not have these functions. The actual functions are available in libc, so an alternative would be to declare them ourselves for AIX 7.2+.

I agree with @Enc-EE comment in #23751 (comment)

I looked into this a bit more and want to share some information.
The sendmmsg and recvmmsg are defined in net/proto_uipc.h
Doesn't look like this file will be included when including sys/socket.h so I included it manually.

Shouldn't the fix really be adding #include <net/proto_uipc.h> in this conditional?

makr73@e40a810#diff-a818fa04807217bec0c2885bab4598ec7658fb32eac750f1525e2653ef925cc7R71-R75

Otherwise these functions won't be found and implict declaration would be used.

16:55:13 ../deps/openssl/openssl/crypto/bio/bss_dgram.c: In function 'dgram_sendmmsg':
16:55:13 ../deps/openssl/openssl/crypto/bio/bss_dgram.c:1416:11: warning: implicit declaration of function 'sendmmsg'; did you mean 'sendmsg'? [-Wimplicit-function-declaration]
16:55:14  1416 |     ret = sendmmsg(b->num, mh, num_msg, sysflags);
16:55:14       |           ^~~~~~~~
16:55:14       |           sendmsg
16:55:14 ../deps/openssl/openssl/crypto/bio/bss_dgram.c: In function 'dgram_recvmmsg':
16:55:14 ../deps/openssl/openssl/crypto/bio/bss_dgram.c:1609:11: warning: implicit declaration of function 'recvmmsg'; did you mean 'recvmsg'? [-Wimplicit-function-declaration]
16:55:14  1609 |     ret = recvmmsg(b->num, mh, num_msg, sysflags, NULL);
16:55:14       |           ^~~~~~~~
16:55:14       |           recvmsg

ref: https://ci.nodejs.org/job/node-test-commit-aix/nodes=aix72-power9/62022/consoleFull

Originally posted by @abmusse in #23751