// Clause: 7.13.2.1 — If setjmp/longjmp used after stack unwound, UB.
#include <setjmp.h>
#include <stdio.h>
jmp_buf env;
void f(void){
    longjmp(env, 1); // UB: longjmp from function not active
}
int main(void){
    if (setjmp(env)==0){
        f();
    } else {
        puts("after longjmp");
    }
    return 0;
}