the memory occupied by the field, not the entire struct. When passing a
pointer to an element in an array or slice, the Go memory in question is
the entire array or the entire backing array of the slice.

C code may keep a copy of a Go pointer only as long as the memory it
points to is pinned.

C code may not keep a copy of a Go pointer after the call returns,

//	specify a different capacity; it must be no smaller than the
//	length. For example, make([]int, 0, 10) allocates an underlying array
//	of size 10 and returns a slice of length 0 and capacity 10 that is
//	backed by this underlying array.
//	Map: An empty map is allocated with enough space to hold the
//	specified number of elements. The size may be omitted, in which case
//	a small starting size is allocated.