What does 'go version' print?
go version default darwin/amd64

What steps reproduce the problem?

run the following program (go run main.go)
http://play.golang.org/p/WOFiz3zeyb

What happened?

I get warnings of the form

./main.go:35:3: warning: plain '_Complex' requires a type specifier; assuming '_Complex
double'
/usr/include/complex.h:37:17: note: expanded from macro 'complex'

and in main.cgo2.c the following definition

void
_cgo_7d1638001027_Cfunc_add(void *v)
{
 struct {
 complex p0;
 complex p1;
 complex r;
 } __attribute__((__packed__)) *a = v;
 a->r = add(a->p0, a->p1);
}

What should have happened instead?

On linux I get 'complex float' for the arguments instead and no warnings.