/*

136 kamil@chieftec /tmp $ /usr/local/bin/clang -O0 null_plus_x-ub.c                                                                              
137 kamil@chieftec /tmp $ ./a.out                                                                                                                
1
138 kamil@chieftec /tmp $ /usr/local/bin/clang -O2 null_plus_x-ub.c 
139 kamil@chieftec /tmp $ ./a.out                                   
0
151 kamil@chieftec /tmp $ /usr/local/bin/clang -O3 -fwrapv null_plus_x-ub.c 
152 kamil@chieftec /tmp $ ./a.out                                                                                                                
1


$ ls -lh /usr/local/bin/clang  
lrwxr-xr-x  1 root  wheel    8B Nov  2 21:49 /usr/local/bin/clang -> clang-10

$ /usr/local/bin/clang --version                                                                                         
clang version 10.0.0 (git@github.com:krytarowski/llvm-project.git ed83942bc02501c62b55f77cba688263ea35221a)
Target: x86_64-unknown-netbsd9.99.24
Thread model: posix
InstalledDir: /usr/local/bin


$ uname -a
NetBSD chieftec 9.99.48 NetBSD 9.99.48 (GENERIC) #0: Fri Mar  6 20:46:53 CET 2020  root@chieftec:/public/netbsd-root/sys/arch/amd64/compile/GENERIC amd64
*/

#include <string.h>
#include <stddef.h>
#include <stdio.h>

int
statu(char *a)
{
	a -= 1;
	return a == NULL;
}

int
main(int argc, char **argv)
{
	char *ptr = (char *)(long)(argc);
	printf("%d\n", statu(ptr));
	return 0;
}