return &emptyInterface
	}

	// set method receivers if necessary
	typ := (*Checker)(nil).newInterface()
	for _, m := range methods {
		if sig := m.typ.(*Signature); sig.recv == nil {
			sig.recv = NewVar(m.pos, m.pkg, "", typ)
		}
	}

	// sort for API stability
	sortMethods(methods)

	typ.methods = methods
	typ.embeddeds = embeddeds
	typ.complete = true

	return typ
}

// check may be nil

		return &emptyInterface
	}

	// set method receivers if necessary
	typ := (*Checker)(nil).newInterface()
	for _, m := range methods {
		if sig := m.typ.(*Signature); sig.recv == nil {
			sig.recv = NewVar(m.pos, m.pkg, "", typ)
		}
	}

	// sort for API stability
	sortMethods(methods)

	typ.methods = methods
	typ.embeddeds = embeddeds
	typ.complete = true

	return typ
}

// check may be nil

		nullaryQ = NewSignatureType(nil, nil, []*TypeParam{tparam}, nil, nil, false)
	}
	{
		// type unaryP = func[P any](_ P)
		tparam := NewTypeParam(NewTypeName(nopos, nil, "P", nil), &emptyInterface)
		params := NewTuple(NewVar(nopos, nil, "_", tparam))
		unaryP = NewSignatureType(nil, nil, []*TypeParam{tparam}, params, nil, false)
	}

	ctxt := NewContext()

	// Update the context with an instantiation of nullaryP.

		nullaryQ = NewSignatureType(nil, nil, []*TypeParam{tparam}, nil, nil, false)
	}
	{
		// type unaryP = func[P any](_ P)
		tparam := NewTypeParam(NewTypeName(nopos, nil, "P", nil), &emptyInterface)
		params := NewTuple(NewVar(nopos, nil, "_", tparam))
		unaryP = NewSignatureType(nil, nil, []*TypeParam{tparam}, params, nil, false)
	}

	ctxt := NewContext()

	// Update the context with an instantiation of nullaryP.

	// type error interface{ Error() string }
	{
		obj := NewTypeName(nopos, nil, "error", nil)
		obj.setColor(black)
		typ := NewNamed(obj, nil, nil)

		// error.Error() string
		recv := NewVar(nopos, nil, "", typ)
		res := NewVar(nopos, nil, "", Typ[String])
		sig := NewSignatureType(recv, nil, nil, nil, NewTuple(res), false)
		err := NewFunc(nopos, nil, "Error", sig)

		// interface{ Error() string }

	// type error interface{ Error() string }
	{
		obj := NewTypeName(nopos, nil, "error", nil)
		obj.setColor(black)
		typ := NewNamed(obj, nil, nil)

		// error.Error() string
		recv := NewVar(nopos, nil, "", typ)
		res := NewVar(nopos, nil, "", Typ[String])
		sig := NewSignatureType(recv, nil, nil, nil, NewTuple(res), false)
		err := NewFunc(nopos, nil, "Error", sig)

		// interface{ Error() string }

					fn.Pkg().Path(), fn.Name())
			}
		}
	})
	return nil, nil
}

// func() string
var sigNoArgsStringResult = types.NewSignature(nil, nil,
	types.NewTuple(types.NewVar(token.NoPos, nil, "", types.Typ[types.String])),
	false)

type stringSetFlag map[string]bool

func (ss *stringSetFlag) String() string {
	var items []string
	for item := range *ss {

	if m := check.Types; m != nil {
		for {
			tv := m[x]
			assert(tv.Type != nil) // should have been recorded already
			pos := x.Pos()
			tv.Type = NewTuple(
				NewVar(pos, check.pkg, "", t0),
				NewVar(pos, check.pkg, "", t1),
			)
			m[x] = tv
			// if x is a parenthesized expression (p.X), update p.X
			p, _ := x.(*syntax.ParenExpr)
			if p == nil {
				break
			}
			x = p.X

		// completely set up all types in ImportData.
		r.p.later = append(r.p.later, setConstraintArgs{t: t, constraint: constraint})

	case 'V':
		typ := r.typ()

		r.declare(types.NewVar(pos, r.currPkg, name, typ))

	default:
		errorf("unexpected tag: %v", tag)
	}
}

func (r *importReader) declare(obj types.Object) {
	obj.Pkg().Scope().Insert(obj)
}

				// declare new variable
				name := identName(ident)
				obj = NewVar(ident.Pos(), check.pkg, name, nil)
				check.recordDef(ident, obj)
				// _ variables don't count as new variables
				if name != "_" {
					vars = append(vars, obj)
				}
			} else {
				check.errorf(lhs, InvalidSyntaxTree, "cannot declare %s", lhs)
				obj = NewVar(lhs.Pos(), check.pkg, "_", nil) // dummy variable
			}
			assert(obj.typ == nil)