fp_st type is incompatible with cgo FFI

[FiloSottile]

cggo can't see through "fp_st and fp_t are both different fancy typedefs for dig_t*", and gets particularly confused by the array type.

relic/relic.go:189: cannot use ep.st.y (type C.fp_st) as type *C.dig_t in argument to _Cfunc__fp_neg
relic/relic.go:189: cannot use ep.st.y (type C.fp_st) as type C.fp_t in argument to _Cfunc__fp_neg

[conradoplg]

Yep, turns out RELIC really isn't wrapper-friendly 😬

A proper solution will have to wait for the refactoring that @dfaranha is planning. But in the meantime, I was able to run this unholy mess:

package main

// #cgo CFLAGS: -I/home/conrado/workspace/relic/build/include  -I/home/conrado/workspace/relic/include
// #cgo LDFLAGS: -lrelic -L/home/conrado/workspace/relic/build/lib/
// #include <relic.h>
import "C"
import "fmt"

func main() {
	C.core_init()
	C.fp_param_set_any()
	x := make([]C.dig_t, 4)
	px := &x[0]

	x[0] = 1
	fmt.Println(x)
	C.fp_neg_basic(px, px)
	fmt.Println(x)

	var p C.ep_t
	p[0].x[0] = 1
	fmt.Println(p[0].x)
	px = &p[0].x[0]
	C.fp_neg_basic(px, px)
	fmt.Println(p[0].x)
}