qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-26 04:17:59 -07:00
Code Releases Activity

[dev.typeparams] go/types: accept embedded interface elements

Browse Source 
This is a port of CL 321689 to go/types. It differs from that CL in the
uses of the position, AST and error APIs, and in not factoring out an
unimplemented() helper (this helper didn't already exist in go/types, so
it seemed cleaner to defer adding it).

Change-Id: I577a57297caf35eb7a23f63f3f52037a7bb528ea
Reviewed-on: https://go-review.googlesource.com/c/go/+/326069
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Rob Findley 2021-06-08 10:21:51 -04:00 committed by Robert Findley
parent 54f854fb41
commit e7451f6616
23 changed files with 316 additions and 161 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/go/types/builtins.go
View File

@ -783,7 +783,7 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
tpar := NewTypeName(token.NoPos, nil /* = Universe pkg */, "<type parameter>", nil)
ptyp := check.newTypeParam(tpar, 0, &emptyInterface) // assigns type to tpar as a side-effect
tsum := _NewSum(rtypes)
ptyp.bound = &Interface{types: tsum, allMethods: markComplete, allTypes: tsum}
ptyp.bound = &Interface{allMethods: markComplete, allTypes: tsum}
return ptyp
}

11
src/go/types/errorcodes.go
View File

@ -281,16 +281,7 @@ const (
_IncomparableMapKey
// _InvalidIfaceEmbed occurs when a non-interface type is embedded in an
// interface.
//
// Example:
// type T struct {}
//
// func (T) m()
//
// type I interface {
// T
// }
// interface (for go 1.17 or earlier).
_InvalidIfaceEmbed
// _InvalidPtrEmbed occurs when an embedded field is of the pointer form *T,

5
src/go/types/infer.go
View File

@ -315,6 +315,9 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
// Thus, we only need to look at the input and result parameters.
return w.isParameterized(t.params) || w.isParameterized(t.results)
case *Union:
panic("unimplemented")
case *Interface:
if t.allMethods != nil {
// TODO(rFindley) at some point we should enforce completeness here
@ -332,7 +335,7 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
return true
}
}
return w.isParameterizedList(unpackType(t.types))
return w.isParameterizedList(t.embeddeds)
}, nil)
case *Map:

224
src/go/types/interface.go
View File

@ -13,74 +13,84 @@ import (
)
func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, def *Named) {
var tlist *ast.Ident // "type" name of first entry in a type list declaration
var types []ast.Expr
var tlist []ast.Expr
var tname *ast.Ident // "type" name of first entry in a type list declaration
for _, f := range iface.Methods.List {
if len(f.Names) > 0 {
// We have a method with name f.Names[0], or a type
// of a type list (name.Name == "type").
// (The parser ensures that there's only one method
// and we don't care if a constructed AST has more.)
name := f.Names[0]
if name.Name == "_" {
check.errorf(name, _BlankIfaceMethod, "invalid method name _")
continue // ignore
}
if name.Name == "type" {
// Always collect all type list entries, even from
// different type lists, under the assumption that
// the author intended to include all types.
types = append(types, f.Type)
if tlist != nil && tlist != name {
check.errorf(name, _Todo, "cannot have multiple type lists in an interface")
}
tlist = name
continue
}
typ := check.typ(f.Type)
sig, _ := typ.(*Signature)
if sig == nil {
if typ != Typ[Invalid] {
check.invalidAST(f.Type, "%s is not a method signature", typ)
}
continue // ignore
}
// Always type-check method type parameters but complain if they are not enabled.
// (This extra check is needed here because interface method signatures don't have
// a receiver specification.)
if sig.tparams != nil {
var at positioner = f.Type
if tparams := typeparams.Get(f.Type); tparams != nil {
at = tparams
}
check.errorf(at, _Todo, "methods cannot have type parameters")
}
// use named receiver type if available (for better error messages)
var recvTyp Type = ityp
if def != nil {
recvTyp = def
}
sig.recv = NewVar(name.Pos(), check.pkg, "", recvTyp)
m := NewFunc(name.Pos(), check.pkg, name.Name, sig)
check.recordDef(name, m)
ityp.methods = append(ityp.methods, m)
} else {
// We have an embedded type. completeInterface will
// eventually verify that we have an interface.
ityp.embeddeds = append(ityp.embeddeds, check.typ(f.Type))
if len(f.Names) == 0 {
// We have an embedded type; possibly a union of types.
ityp.embeddeds = append(ityp.embeddeds, parseUnion(check, flattenUnion(nil, f.Type)))
check.posMap[ityp] = append(check.posMap[ityp], f.Type.Pos())
continue
}
// We have a method with name f.Names[0], or a type
// of a type list (name.Name == "type").
// (The parser ensures that there's only one method
// and we don't care if a constructed AST has more.)
name := f.Names[0]
if name.Name == "_" {
check.errorf(name, _BlankIfaceMethod, "invalid method name _")
continue // ignore
}
if name.Name == "type" {
// For now, collect all type list entries as if it
// were a single union, where each union element is
// of the form ~T.
// TODO(rfindley) remove once we disallow type lists
op := new(ast.UnaryExpr)
op.Op = token.TILDE
op.X = f.Type
tlist = append(tlist, op)
if tname != nil && tname != name {
check.errorf(name, _Todo, "cannot have multiple type lists in an interface")
}
tname = name
continue
}
typ := check.typ(f.Type)
sig, _ := typ.(*Signature)
if sig == nil {
if typ != Typ[Invalid] {
check.invalidAST(f.Type, "%s is not a method signature", typ)
}
continue // ignore
}
// Always type-check method type parameters but complain if they are not enabled.
// (This extra check is needed here because interface method signatures don't have
// a receiver specification.)
if sig.tparams != nil {
var at positioner = f.Type
if tparams := typeparams.Get(f.Type); tparams != nil {
at = tparams
}
check.errorf(at, _Todo, "methods cannot have type parameters")
}
// use named receiver type if available (for better error messages)
var recvTyp Type = ityp
if def != nil {
recvTyp = def
}
sig.recv = NewVar(name.Pos(), check.pkg, "", recvTyp)
m := NewFunc(name.Pos(), check.pkg, name.Name, sig)
check.recordDef(name, m)
ityp.methods = append(ityp.methods, m)
}
// type constraints
ityp.types = _NewSum(check.collectTypeConstraints(iface.Pos(), types))
if tlist != nil {
ityp.embeddeds = append(ityp.embeddeds, parseUnion(check, tlist))
// Types T in a type list are added as ~T expressions but we don't
// have the position of the '~'. Use the first type position instead.
check.posMap[ityp] = append(check.posMap[ityp], tlist[0].(*ast.UnaryExpr).X.Pos())
}
if len(ityp.methods) == 0 && ityp.types == nil && len(ityp.embeddeds) == 0 {
if len(ityp.methods) == 0 && len(ityp.embeddeds) == 0 {
// empty interface
ityp.allMethods = markComplete
return
@ -93,32 +103,12 @@ func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, d
check.later(func() { check.completeInterface(iface.Pos(), ityp) })
}
func (check *Checker) collectTypeConstraints(pos token.Pos, types []ast.Expr) []Type {
list := make([]Type, 0, len(types)) // assume all types are correct
for _, texpr := range types {
if texpr == nil {
check.invalidAST(atPos(pos), "missing type constraint")
continue
}
list = append(list, check.varType(texpr))
func flattenUnion(list []ast.Expr, x ast.Expr) []ast.Expr {
if o, _ := x.(*ast.BinaryExpr); o != nil && o.Op == token.OR {
list = flattenUnion(list, o.X)
x = o.Y
}
// Ensure that each type is only present once in the type list. Types may be
// interfaces, which may not be complete yet. It's ok to do this check at the
// end because it's not a requirement for correctness of the code.
// Note: This is a quadratic algorithm, but type lists tend to be short.
check.later(func() {
for i, t := range list {
if t := asInterface(t); t != nil {
check.completeInterface(types[i].Pos(), t)
}
if includes(list[:i], t) {
check.softErrorf(types[i], _Todo, "duplicate type %s in type list", t)
}
}
})
return list
return append(list, x)
}
// includes reports whether typ is in list.
@ -146,6 +136,7 @@ func (check *Checker) completeInterface(pos token.Pos, ityp *Interface) {
completeInterface(check, pos, ityp)
}
// completeInterface may be called with check == nil.
func completeInterface(check *Checker, pos token.Pos, ityp *Interface) {
assert(ityp.allMethods == nil)
@ -198,6 +189,7 @@ func completeInterface(check *Checker, pos token.Pos, ityp *Interface) {
if check == nil {
panic(fmt.Sprintf("%v: duplicate method %s", m.pos, m.name))
}
// check != nil
check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
default:
@ -211,6 +203,7 @@ func completeInterface(check *Checker, pos token.Pos, ityp *Interface) {
todo = append(todo, m, other.(*Func))
break
}
// check != nil
check.later(func() {
if !check.allowVersion(m.pkg, 1, 14) || !check.identical(m.typ, other.Type()) {
check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
@ -224,9 +217,8 @@ func completeInterface(check *Checker, pos token.Pos, ityp *Interface) {
addMethod(m.pos, m, true)
}
// collect types
allTypes := ityp.types
// collect embedded elements
var allTypes Type
var posList []token.Pos
if check != nil {
posList = check.posMap[ityp]
@ -236,32 +228,36 @@ func completeInterface(check *Checker, pos token.Pos, ityp *Interface) {
if posList != nil {
pos = posList[i]
}
utyp := under(typ)
etyp := asInterface(utyp)
if etyp == nil {
if utyp != Typ[Invalid] {
var format string
if _, ok := utyp.(*_TypeParam); ok {
format = "%s is a type parameter, not an interface"
} else {
format = "%s is not an interface"
}
if check != nil {
// TODO: correct error code.
check.errorf(atPos(pos), _InvalidIfaceEmbed, format, typ)
} else {
panic(fmt.Sprintf(format, typ))
}
var types Type
switch t := under(typ).(type) {
case *Interface:
if t.allMethods == nil {
completeInterface(check, pos, t)
}
continue
for _, m := range t.allMethods {
addMethod(pos, m, false) // use embedding position pos rather than m.pos
}
types = t.allTypes
case *Union:
types = NewSum(t.terms)
case *TypeParam:
if check != nil && !check.allowVersion(check.pkg, 1, 18) {
check.errorf(atPos(pos), _InvalidIfaceEmbed, "%s is a type parameter, not an interface", typ)
continue
}
types = t
default:
if t == Typ[Invalid] {
continue
}
if check != nil && !check.allowVersion(check.pkg, 1, 18) {
check.errorf(atPos(pos), _InvalidIfaceEmbed, "%s is not an interface", typ)
continue
}
types = t
}
if etyp.allMethods == nil {
completeInterface(check, pos, etyp)
}
for _, m := range etyp.allMethods {
addMethod(pos, m, false) // use embedding position pos rather than m.pos
}
allTypes = intersect(allTypes, etyp.allTypes)
allTypes = intersect(allTypes, types)
}
// process todo's (this only happens if check == nil)
@ -281,7 +277,7 @@ func completeInterface(check *Checker, pos token.Pos, ityp *Interface) {
}
// intersect computes the intersection of the types x and y.
// Note: A incomming nil type stands for the top type. A top
// Note: An incomming nil type stands for the top type. A top
// type result is returned as nil.
func intersect(x, y Type) (r Type) {
defer func() {

3
src/go/types/predicates.go
View File

@ -288,6 +288,9 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
return true
}
case *Union:
panic("identical0 not implemented for union types")
case *Interface:
// Two interface types are identical if they have the same set of methods with
// the same names and identical function types. Lower-case method names from

6
src/go/types/sanitize.go
View File

@ -110,11 +110,11 @@ func (s sanitizer) typ(typ Type) Type {
case *_Sum:
s.typeList(t.types)
case *Union:
s.typeList(t.terms)
case *Interface:
s.funcList(t.methods)
if types := s.typ(t.types); types != t.types {
t.types = types
}
s.typeList(t.embeddeds)
s.funcList(t.allMethods)
if allTypes := s.typ(t.allTypes); allTypes != t.allTypes {

3
src/go/types/sizeof_test.go
View File

@ -27,7 +27,8 @@ func TestSizeof(t *testing.T) {
{Tuple{}, 12, 24},
{Signature{}, 44, 88},
{_Sum{}, 12, 24},
{Interface{}, 60, 120},
{Union{}, 24, 48},
{Interface{}, 52, 104},
{Map{}, 16, 32},
{Chan{}, 12, 24},
{Named{}, 68, 136},

2
src/go/types/sizes.go
View File

@ -150,6 +150,8 @@ func (s *StdSizes) Sizeof(T Type) int64 {
return offsets[n-1] + s.Sizeof(t.fields[n-1].typ)
case *_Sum:
panic("Sizeof unimplemented for type sum")
case *Union:
panic("Sizeof unimplemented for type union")
case *Interface:
return s.WordSize * 2
}

16
src/go/types/subst.go
View File

@ -311,15 +311,19 @@ func (subst *subster) typ(typ Type) Type {
return _NewSum(types)
}
case *Union:
terms, copied := subst.typeList(t.terms)
if copied {
// TODO(gri) Do we need to remove duplicates that may have
// crept in after substitution? It may not matter.
return newUnion(terms, t.tilde)
}
case *Interface:
methods, mcopied := subst.funcList(t.methods)
types := t.types
if t.types != nil {
types = subst.typ(t.types)
}
embeddeds, ecopied := subst.typeList(t.embeddeds)
if mcopied || types != t.types || ecopied {
iface := &Interface{methods: methods, types: types, embeddeds: embeddeds}
if mcopied || ecopied {
iface := &Interface{methods: methods, embeddeds: embeddeds}
if subst.check == nil {
panic("internal error: cannot instantiate interfaces yet")
}

2
src/go/types/testdata/check/decls0.src vendored
View File

@ -4,7 +4,7 @@
// type declarations
package decls0
package go1_17 // don't permit non-interface elements in interfaces
import "unsafe"

2
src/go/types/testdata/check/issues.src vendored
View File

@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package issues
package go1_17 // don't permit non-interface elements in interfaces
import (
"fmt"

6
src/go/types/testdata/check/typeinst2.go2 vendored
View File

@ -164,12 +164,12 @@ type _ interface {
// for them to be all in a single list, and we report the error
// as well.)
type _ interface {
type int, int /* ERROR duplicate type int */
type /* ERROR multiple type lists */ int /* ERROR duplicate type int */
type int, int /* ERROR duplicate term int */
type /* ERROR multiple type lists */ int /* ERROR duplicate term int */
}
type _ interface {
type struct{f int}, struct{g int}, struct /* ERROR duplicate type */ {f int}
type struct{f int}, struct{g int}, struct /* ERROR duplicate term */ {f int}
}
// Interface type lists can contain any type, incl. *Named types.

25
src/go/types/testdata/examples/constraints.go2 vendored Normal file
View File

@ -0,0 +1,25 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file shows some examples of generic constraint interfaces.
package p
type (
// Arbitrary types may be embedded like interfaces.
_ interface{int}
_ interface{~int}
// Types may be combined into a union.
_ interface{int|~string}
// Union terms must be unique independent of whether they are ~ or not.
_ interface{int|int /* ERROR duplicate term int */ }
_ interface{int|~ /* ERROR duplicate term int */ int }
_ interface{~int|~ /* ERROR duplicate term int */ int }
// For now we do not permit interfaces with ~ or in unions.
_ interface{~ /* ERROR cannot use interface */ interface{}}
_ interface{int|interface /* ERROR cannot use interface */ {}}
)

2
src/go/types/testdata/fixedbugs/issue39634.go2 vendored
View File

@ -36,7 +36,7 @@ func bar8[A foo8[A]](a A) {}
func main8() {}
// crash 9
type foo9[A any] interface { type foo9 /* ERROR interface contains type constraints */ [A] }
type foo9[A any] interface { type foo9 /* ERROR cannot use interface */ [A] }
func _() { var _ = new(foo9 /* ERROR interface contains type constraints */ [int]) }
// crash 12

17
src/go/types/testdata/fixedbugs/issue39693.go2 vendored
View File

@ -4,11 +4,20 @@
package p
type Number interface {
int /* ERROR int is not an interface */
float64 /* ERROR float64 is not an interface */
type Number1 interface {
// embedding non-interface types is permitted
int
float64
}
func Add[T Number](a, b T) T {
func Add[T Number1](a, b T) T {
return a /* ERROR not defined */ + b
}
type Number2 interface {
int|float64
}
func Add2[T Number2](a, b T) T {
return a + b
}

4
src/go/types/testdata/fixedbugs/issue39711.go2 vendored
View File

@ -7,5 +7,7 @@ package p
// Do not report a duplicate type error for this type list.
// (Check types after interfaces have been completed.)
type _ interface {
type interface{ Error() string }, interface{ String() string }
// TODO(rfindley) Once we have full type sets we can enable this again.
// Fow now we don't permit interfaces in type lists.
// type interface{ Error() string }, interface{ String() string }
}

2
src/go/types/testdata/fixedbugs/issue39723.go2 vendored
View File

@ -6,4 +6,4 @@ package p
// A constraint must be an interface; it cannot
// be a type parameter, for instance.
func _[A interface{ type interface{} }, B A /* ERROR not an interface */ ]()
func _[A interface{ type int }, B A /* ERROR not an interface */ ]()

8
src/go/types/testdata/fixedbugs/issue39948.go2 vendored
View File

@ -2,7 +2,13 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package p
// TODO(rfindley) Eventually, once we disallow type lists, we need to
// adjust this code: for 1.17 we don't accept type parameters,
// and for 1.18 this code is valid.
// Leaving for now so we can see that existing errors
// are being reported.
package go1_17 // don't permit non-interface elements in interfaces
type T[P any] interface{
P // ERROR P is a type parameter, not an interface

1
src/go/types/type.go
View File

@ -305,7 +305,6 @@ func (s *_Sum) is(pred func(Type) bool) bool {
// An Interface represents an interface type.
type Interface struct {
methods []*Func // ordered list of explicitly declared methods
types Type // (possibly a Sum) type declared with a type list (TODO(gri) need better field name)
embeddeds []Type // ordered list of explicitly embedded types
allMethods []*Func // ordered list of methods declared with or embedded in this interface (TODO(gri): replace with mset)

21
src/go/types/typestring.go
View File

@ -159,11 +159,17 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
writeSignature(buf, t, qf, visited)
case *_Sum:
for i, t := range t.types {
writeTypeList(buf, t.types, qf, visited)
case *Union:
for i, e := range t.terms {
if i > 0 {
buf.WriteString(", ")
buf.WriteString("|")
}
writeType(buf, t, qf, visited)
if t.tilde[i] {
buf.WriteByte('~')
}
writeType(buf, e, qf, visited)
}
case *Interface:
@ -208,14 +214,6 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
writeSignature(buf, m.typ.(*Signature), qf, visited)
empty = false
}
if !empty && t.types != nil {
buf.WriteString("; ")
}
if t.types != nil {
buf.WriteString("type ")
writeType(buf, t.types, qf, visited)
empty = false
}
if !empty && len(t.embeddeds) > 0 {
buf.WriteString("; ")
}
@ -301,6 +299,7 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
default:
// For externally defined implementations of Type.
// Note: In this case cycles won't be caught.
buf.WriteString(t.String())
}
}

3
src/go/types/typestring_test.go
View File

@ -95,6 +95,9 @@ var independentTestTypes = []testEntry{
dup("interface{}"),
dup("interface{m()}"),
dup(`interface{String() string; m(int) float32}`),
{"interface{type int, float32, complex128}", "interface{~int|~float32|~complex128}"},
dup("interface{int|float32|complex128}"),
dup("interface{int|~float32|~complex128}"),
// TODO(rFindley) uncomment this once this AST is accepted, and add more test
// cases.

4
src/go/types/unify.go
View File

@ -356,6 +356,10 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool {
// This should not happen with the current internal use of sum types.
panic("type inference across sum types not implemented")
case *Union:
// This should not happen with the current internal use of union types.
panic("type inference across union types not implemented")
case *Interface:
// Two interface types are identical if they have the same set of methods with
// the same names and identical function types. Lower-case method names from

108
src/go/types/union.go Normal file
View File

@ -0,0 +1,108 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package types
import (
"go/ast"
"go/token"
)
// ----------------------------------------------------------------------------
// API
// A Union represents a union of terms.
// A term is a type, possibly with a ~ (tilde) indication.
type Union struct {
terms []Type // terms are unique
tilde []bool // if tilde[i] is set, terms[i] is of the form ~T
}
func NewUnion(terms []Type, tilde []bool) Type { return newUnion(terms, tilde) }
func (u *Union) NumTerms() int { return len(u.terms) }
func (u *Union) Term(i int) (Type, bool) { return u.terms[i], u.tilde[i] }
func (u *Union) Underlying() Type { return u }
func (u *Union) String() string { return TypeString(u, nil) }
// ----------------------------------------------------------------------------
// Implementation
func newUnion(terms []Type, tilde []bool) Type {
assert(len(terms) == len(tilde))
if terms == nil {
return nil
}
t := new(Union)
t.terms = terms
t.tilde = tilde
return t
}
func parseUnion(check *Checker, tlist []ast.Expr) Type {
var terms []Type
var tilde []bool
for _, x := range tlist {
t, d := parseTilde(check, x)
if len(tlist) == 1 && !d {
return t // single type
}
terms = append(terms, t)
tilde = append(tilde, d)
}
// Ensure that each type is only present once in the type list.
// It's ok to do this check at the end because it's not a requirement
// for correctness of the code.
// Note: This is a quadratic algorithm, but unions tend to be short.
check.later(func() {
for i, t := range terms {
t := expand(t)
if t == Typ[Invalid] {
continue
}
x := tlist[i]
pos := x.Pos()
// We may not know the position of x if it was a typechecker-
// introduced ~T type of a type list entry T. Use the position
// of T instead.
// TODO(rfindley) remove this test once we don't support type lists anymore
if !pos.IsValid() {
if op, _ := x.(*ast.UnaryExpr); op != nil {
pos = op.X.Pos()
}
}
u := under(t)
if tilde[i] {
// TODO(rfindley) enable this check once we have converted tests
// if !Identical(u, t) {
// check.errorf(x, "invalid use of ~ (underlying type of %s is %s)", t, u)
// }
}
if _, ok := u.(*Interface); ok {
check.errorf(atPos(pos), _Todo, "cannot use interface %s with ~ or inside a union (implementation restriction)", t)
}
// Complain about duplicate entries a|a, but also a|~a, and ~a|~a.
if includes(terms[:i], t) {
// TODO(rfindley) this currently doesn't print the ~ if present
check.softErrorf(atPos(pos), _Todo, "duplicate term %s in union element", t)
}
}
})
return newUnion(terms, tilde)
}
func parseTilde(check *Checker, x ast.Expr) (Type, bool) {
tilde := false
if op, _ := x.(*ast.UnaryExpr); op != nil && op.Op == token.TILDE {
x = op.X
tilde = true
}
return check.anyType(x), tilde
}