// Clause: 7.13 — If longjmp is invoked with an environment not set by the most recent setjmp in the current invocation chain, UB.
// Here we longjmp using an uninitialized jmp_buf.
#include <setjmp.h>
int main(void){
    jmp_buf jb; // uninitialized
    longjmp(jb, 1); // UB
    return 0;
}