commit 84732a8849a08d42a9a95dcbee9005116be78eb8
Author: Khem Raj <raj.khem@gmail.com>
Date:   Sun Aug 7 14:39:19 2022 -0700

    check for sys/pidfd.h
    
    This header in newer glibc defines the signatures of functions
    pidfd_send_signal() and pidfd_open() and when these functions are
    defined by libc then we need to include the relevant header to get
    the definitions. Clang 15+ has started to error out when function
    signatures are missing.
    
    Fixes errors like
    misc-utils/kill.c:402:6: error: call to undeclared function 'pidfd_send_signal'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
            if (pidfd_send_signal(pfd, ctl->numsig, &info, 0) < 0)
    
    Signed-off-by: Khem Raj <raj.khem@gmail.com>

diff --git a/configure.ac b/configure.ac
index d8b4d475103c2bab..4a35d17f81375c29 100644
--- a/configure.ac
+++ b/configure.ac
@@ -339,6 +339,7 @@ AC_CHECK_HEADERS([ \
 	sys/mkdev.h \
 	sys/mount.h \
 	sys/param.h \
+	sys/pidfd.h \
 	sys/prctl.h \
 	sys/resource.h \
 	sys/sendfile.h \
diff --git a/include/pidfd-utils.h b/include/pidfd-utils.h
index eddede9767478be2..d9e33cbc57ae38c8 100644
--- a/include/pidfd-utils.h
+++ b/include/pidfd-utils.h
@@ -4,8 +4,10 @@
 #ifdef HAVE_SYS_SYSCALL_H
 # include <sys/syscall.h>
 # if defined(SYS_pidfd_send_signal) && defined(SYS_pidfd_open)
+#  ifdef HAVE_SYS_PIDFD_H
+#   include <sys/pidfd.h>
+#  endif
 #  include <sys/types.h>
-
 #  ifndef HAVE_PIDFD_SEND_SIGNAL
 static inline int pidfd_send_signal(int pidfd, int sig, siginfo_t *info,
 				    unsigned int flags)