cxx, err := exec.Command("go", "env", "CXX").CombinedOutput()
	if err != nil {
		t.Fatalf("go env CXX failed: %s", err)
	}
	args, err := quoted.Split(string(cxx))
	if err != nil {
		t.Skipf("could not parse 'go env CXX' output %q: %s", string(cxx), err)
	}
	if len(args) == 0 {
		t.Skip("no C++ compiler")
	}
	testenv.MustHaveExecPath(t, string(args[0]))
}

var (
	swigOnce sync.Once