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[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
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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
}