t.Run("struct{}", func(t *testing.T) {
			arena := NewUserArena()
			var x any
			x = (*struct{})(nil)
			arena.New(&x)
			if v := unsafe.Pointer(x.(*struct{})); v != ZeroBase {
				t.Errorf("expected zero-sized type to be allocated as zerobase: got %x, want %x", v, ZeroBase)
			}
			arena.Free()
		})
		t.Run("[]struct{}", func(t *testing.T) {
			arena := NewUserArena()
			var sl []struct{}
			arena.Slice(&sl, 10)

//
// The underlying arena and its resources are managed through an opaque unsafe.Pointer.

// arena_newArena is a wrapper around newUserArena.
//
//go:linkname arena_newArena arena.runtime_arena_newArena
func arena_newArena() unsafe.Pointer {
	return unsafe.Pointer(newUserArena())
}

// arena_arena_New is a wrapper around (*userArena).new, except that typ

var ZeroBase = unsafe.Pointer(&zerobase)

const UserArenaChunkBytes = userArenaChunkBytes

type UserArena struct {
	arena *userArena
}

func NewUserArena() *UserArena {
	return &UserArena{newUserArena()}
}

func (a *UserArena) New(out *any) {
	i := efaceOf(out)
	typ := i._type
	if typ.Kind_&abi.KindMask != abi.Pointer {
		panic("new result of non-ptr type")
	}