return ir.OXXX, why
	}

	// 4. src is a bidirectional channel value, dst is a channel type,
	// src and dst have identical element types, and
	// either src or dst is not a named type.
	if src.IsChan() && src.ChanDir() == types.Cboth && dst.IsChan() {
		if types.Identical(src.Elem(), dst.Elem()) && (src.Sym() == nil || dst.Sym() == nil) {
			return ir.OCONVNOP, ""
		}
	}

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

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

	n.SetType(t.Elem())
	return n
}

// tcSPtr typechecks an OSPTR node.

	t := l.Type()
	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.

			break
		}
		om := fmtsort.Sort(val)
		for _, m := range om {
			oneIteration(m.Key, m.Value)
		}
		return
	case reflect.Chan:
		if val.IsNil() {
			break
		}
		if val.Type().ChanDir() == reflect.SendDir {
			s.errorf("range over send-only channel %v", val)
			break
		}
		i := 0
		for ; ; i++ {
			elem, ok := val.Recv()
			if !ok {
				break
			}

	checkSameType(t, ChanOf(SendDir, TypeOf(T1(1))), (chan<- T1)(nil))

	// check String form of ChanDir
	if crt.ChanDir().String() != "<-chan" {
		t.Errorf("chan dir: have %q, want %q", crt.ChanDir().String(), "<-chan")
	}
	if cst.ChanDir().String() != "chan<-" {
		t.Errorf("chan dir: have %q, want %q", cst.ChanDir().String(), "chan<-")
	}
}

func TestChanOfGC(t *testing.T) {
	done := make(chan bool, 1)

		{"CallExpr.Rparen", Field, 0},
		{"CaseClause", Type, 0},
		{"CaseClause.Body", Field, 0},
		{"CaseClause.Case", Field, 0},
		{"CaseClause.Colon", Field, 0},
		{"CaseClause.List", Field, 0},
		{"ChanDir", Type, 0},
		{"ChanType", Type, 0},
		{"ChanType.Arrow", Field, 1},
		{"ChanType.Begin", Field, 0},
		{"ChanType.Dir", Field, 0},
		{"ChanType.Value", Field, 0},
		{"CommClause", Type, 0},

pkg go/ast, const FilterUnassociatedComments MergeMode
pkg go/ast, const Fun ObjKind
pkg go/ast, const Lbl ObjKind
pkg go/ast, const Pkg ObjKind
pkg go/ast, const RECV ChanDir
pkg go/ast, const SEND ChanDir
pkg go/ast, const Typ ObjKind
pkg go/ast, const Var ObjKind
pkg go/ast, func FileExports(*File) bool
pkg go/ast, func FilterDecl(Decl, Filter) bool
pkg go/ast, func FilterFile(*File, Filter) bool

pkg reflect, const Uint32 = 10
pkg reflect, const Uint64 = 11
pkg reflect, const Uint8 = 8
pkg reflect, const Uintptr = 12
pkg reflect, const UnsafePointer = 26
pkg reflect, func ChanOf(ChanDir, Type) Type
pkg reflect, func MakeFunc(Type, func([]Value) []Value) Value
pkg reflect, func MapOf(Type, Type) Type
pkg reflect, func Select([]SelectCase) (int, Value, bool)
pkg reflect, func SliceOf(Type) Type