Issue #21704: Merge.

Misc/ACKS

@@ -52,6 +52,7 @@ Ankur Ankan
 Jon Anglin
 Heidi Annexstad
 Ramchandra Apte
+Arfrever Frehtes Taifersar Arahesis
 Éric Araujo
 Alicia Arlen
 Jeffrey Armstrong

Misc/NEWS

@@ -113,6 +113,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #21704: Fix build error for _multiprocessing when semaphores
+  are not available.  Patch by Arfrever Frehtes Taifersar Arahesis.
+
 - Issue #20173: Convert sha1, sha256, sha512 and md5 to ArgumentClinic.
   Patch by Vajrasky Kok.
 

Modules/_multiprocessing/multiprocessing.c

@@ -128,7 +128,9 @@ static PyMethodDef module_methods[] = {
     {"recv", multiprocessing_recv, METH_VARARGS, ""},
     {"send", multiprocessing_send, METH_VARARGS, ""},
 #endif
+#ifndef POSIX_SEMAPHORES_NOT_ENABLED
     {"sem_unlink", _PyMp_sem_unlink, METH_VARARGS, ""},
+#endif
     {NULL}
 };