+ In Go 1.15.3 and later, cgo will not permit Go code to allocate an
+ undefined struct type (a C struct defined as just struct
+ S; or similar) on the stack or heap.
+ Go code will only be permitted to use pointers to those types.
+ Allocating an instance of such a struct and passing a pointer, or a
+ full struct value, to C code was always unsafe and unlikely to work
+ correctly; it is now forbidden.
+ The fix is to either rewrite the Go code to use only pointers, or to
+ ensure that the Go code sees the full definition of the struct by
+ including the appropriate C header file.
+