return &Union{terms}
		}

	case *Interface:
		methods, mcopied := subst.funcList(t.methods)
		embeddeds, ecopied := subst.typeList(t.embeddeds)
		if mcopied || ecopied {
			iface := subst.check.newInterface()
			iface.embeddeds = embeddeds
			iface.embedPos = t.embedPos
			iface.implicit = t.implicit
			assert(t.complete) // otherwise we are copying incomplete data
			iface.complete = t.complete

			return &Union{terms}
		}

	case *Interface:
		methods, mcopied := subst.funcList(t.methods)
		embeddeds, ecopied := subst.typeList(t.embeddeds)
		if mcopied || ecopied {
			iface := subst.check.newInterface()
			iface.embeddeds = embeddeds
			iface.embedPos = t.embedPos
			iface.implicit = t.implicit
			assert(t.complete) // otherwise we are copying incomplete data
			iface.complete = t.complete

	nullary := types.NewSignature(nil, nil, nil, false) // func()
	methods := []*types.Func{
		types.NewFunc(token.NoPos, nil, "Lock", nullary),
		types.NewFunc(token.NoPos, nil, "Unlock", nullary),
	}
	lockerType = types.NewInterface(methods, nil).Complete()

			// possible that it wasn't substituted. In this case we need to create
			// a new *Interface before modifying receivers.
			if iface == orig.underlying {
				old := iface
				iface = check.newInterface()
				iface.embeddeds = old.embeddeds
				assert(old.complete) // otherwise we are copying incomplete data
				iface.complete = old.complete
				iface.implicit = old.implicit // should be false but be conservative

			// possible that it wasn't substituted. In this case we need to create
			// a new *Interface before modifying receivers.
			if iface == orig.underlying {
				old := iface
				iface = check.newInterface()
				iface.embeddeds = old.embeddeds
				assert(old.complete) // otherwise we are copying incomplete data
				iface.complete = old.complete
				iface.implicit = old.implicit // should be false but be conservative

	fldt := mkFuncType(types.FakeRecvType(), []*types.Type{},
		[]*types.Type{types.Types[types.TSTRING]})
	field := types.NewField(src.NoXPos, typecheck.Lookup("F"), fldt)
	nei := types.NewInterface([]*types.Field{field})
	i16 := types.Types[types.TINT16]
	tb := types.Types[types.TBOOL]
	s1 := mkstruct(i16, i16, tb)
	ft := mkFuncType(nil, []*types.Type{s1, ei, ei, nei, pei, nei, i16},

		return typ

	case *ast.FuncType:
		typ := new(Signature)
		setDefType(def, typ)
		check.funcType(typ, nil, e)
		return typ

	case *ast.InterfaceType:
		typ := check.newInterface()
		setDefType(def, typ)
		check.interfaceType(typ, e, def)
		return typ

	case *ast.MapType:
		typ := new(Map)
		setDefType(def, typ)

		typ.key = check.varType(e.Key)

		check.use(e0)

	case *syntax.FuncType:
		typ := new(Signature)
		setDefType(def, typ)
		check.funcType(typ, nil, nil, e)
		return typ

	case *syntax.InterfaceType:
		typ := check.newInterface()
		setDefType(def, typ)
		check.interfaceType(typ, e, def)
		return typ

	case *syntax.MapType:
		typ := new(Map)
		setDefType(def, typ)

		typ.key = check.varType(e.Key)

pkg go/types, func NewField(token.Pos, *Package, string, Type, bool) *Var
pkg go/types, func NewFunc(token.Pos, *Package, string, *Signature) *Func
pkg go/types, func NewInterface([]*Func, []*Named) *Interface
pkg go/types, func NewLabel(token.Pos, *Package, string) *Label
pkg go/types, func NewMap(Type, Type) *Map
pkg go/types, func NewMethodSet(Type) *MethodSet