standards/57806: #include <arpa/inet.h> fails to define htonl/htons/ntohl/ntohs under _POSIX_C_SOURCE=200809L

[campbell+netbsd%mumble.net@localhost]

>Number:         57806
>Category:       standards
>Synopsis:       #include <arpa/inet.h> fails to define htonl/htons/ntohl/ntohs under _POSIX_C_SOURCE=200809L
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    standards-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jan 01 19:30:00 +0000 2024
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The <arpa/inet.h> Foundation
>Environment:
>Description:
POSIX and NetBSD both document htonl/htons/ntohl/ntohs as being provided by #include <arpa/inet.h>, but this doesn't provide them when _POSIX_C_SOURCE is defined to be 200809L.
>How-To-Repeat:
$ cat pr.c
#define	_POSIX_C_SOURCE	200809L
#include <arpa/inet.h>
int myntohl(int x) { return ntohl(x); }
$ make pr.o
cc -O2   -c pr.c
pr.c: In function ?myntohl?:
pr.c:3:29: warning: implicit declaration of function ?ntohl?; did you mean ?myntohl?? [-Wimplicit-function-declaration]
 int myntohl(int x) { return ntohl(x); }
                             ^~~~~
                             myntohl
>Fix:
Yes, please!