merge.c: (in function f2)
merge.c:33:4: Variable y used in inconsistent state
   merge.c:30:28: Storage y becomes inconsistent (released on one branch)
merge.c:33:4: Dereference of possibly null pointer y: *y
   merge.c:21:12: Storage y may become null
merge.c: (in function f3)
merge.c:51:4: Dereference of possibly null pointer y: *y
   merge.c:50:7: Storage y may become null

Finished checking --- 3 code warnings, as expected