#include <stdlib.h>

typedef struct node {
  int x;
  struct node * nxt;
} * node_t;

node_t head_create() {
  return (node_t)malloc(sizeof(struct node));
}

node_t node_create() {
  return (node_t)malloc(sizeof(struct node));
}

void f(node_t l) {
  node_t z = l->nxt;
  z->x = 1;
}

void g(node_t l) {
  node_t y = l->nxt;
  y->x = 0;
  // f should intervene here but doesn't because...
  y->x *= 2;
}

int main() {
  node_t head = node_create();  // head_create violates, node_create not
  head->nxt =  node_create();
  $parfor (int i:1..2) {
    if (i==1) {
      $atomic {f(head);}
    } else {
      g(head);
    }
  }
  $assert(head->nxt->x != 2);
}