t := n.Chan.Type()
	if t == nil {
		return n
	}
	if !t.IsChan() {
		base.Errorf("invalid operation: %v (send to non-chan type %v)", n, t)
		return n
	}

	if !t.ChanDir().CanSend() {
		base.Errorf("invalid operation: %v (send to receive-only type %v)", n, t)
		return n
	}

	n.Value = AssignConv(n.Value, t.Elem(), "send")
	if n.Value.Type() == nil {
		return n
	}
	return n

	if t == nil {
		n.SetType(nil)
		return n
	}
	if !t.IsChan() {
		base.Errorf("invalid operation: %v (non-chan type %v)", n, t)
		n.SetType(nil)
		return n
	}

	if !t.ChanDir().CanSend() {
		base.Errorf("invalid operation: %v (cannot close receive-only channel)", n)
		n.SetType(nil)
		return n
	}
	return n
}

// tcComplex typechecks an OCOMPLEX node.

	}

	switch wantEnd {
	case trace.EventBad:
		if region.End != nil {
			t.Errorf("expected nil region end event, got\n%s", region.End.String())
		}
	case trace.EventStateTransition, trace.EventRegionEnd:
		if region.End == nil {
			t.Error("expected non-nil region end event, got nil")
		}
		kind := region.End.Kind()
		if kind != wantEnd {

	// Ensure start and end are correct.
	wantStart, wantEnd := want.Bounds()
	gotStart, gotEnd := got.Bounds()
	if gotStart != wantStart {
		t.Fatalf("start values not equal: got %d, want %d", gotStart, wantStart)
	}
	if gotEnd != wantEnd {
		t.Fatalf("end values not equal: got %d, want %d", gotEnd, wantEnd)
	}

	for i := gotStart; i < gotEnd; i++ {