What is a pointer type’s region when it’s omitted?
Every pointer type has a region; if you omit it, the compiler chooses a region name you implicitly. The name chosen depends on where the pointer type occurs. In function arguments, a fresh region variable is used. In function results and type definitions (including typedef), the heap region (`H) is used. In function bodies, the compiler looks at the uses (using unification) to try to determine a region. See Regions and ][Memory Management Via Regions]] for more information.
