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go/types: consider structural restrictions in Implements

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Fixes #49786

Change-Id: I4559d013399deda48bcb97aef3427ecf87a3ef26
Reviewed-on: https://go-review.googlesource.com/c/go/+/367515
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Robert Findley 2021-11-29 12:21:46 -05:00
parent ebd0b778c9
commit c402d64f37
4 changed files with 227 additions and 4 deletions
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12
src/cmd/compile/internal/types2/api.go
View File

@ -440,8 +440,16 @@ func ConvertibleTo(V, T Type) bool {
// Implements reports whether type V implements interface T.
func Implements(V Type, T *Interface) bool {
f, _ := MissingMethod(V, T, true)
return f == nil
if T.Empty() {
// All types (even Typ[Invalid]) implement the empty interface.
return true
}
// Checker.implements suppresses errors for invalid types, so we need special
// handling here.
if V.Underlying() == Typ[Invalid] {
return false
}
return (*Checker)(nil).implements(V, T, nil) == nil
}
// Identical reports whether x and y are identical types.

103
src/cmd/compile/internal/types2/api_test.go
View File

@ -2102,3 +2102,106 @@ func TestInstanceIdentity(t *testing.T) {
t.Errorf("mismatching types: a.A: %s, b.B: %s", a.Type(), b.Type())
}
}
func TestImplements(t *testing.T) {
const src = `
package p
type EmptyIface interface{}
type I interface {
m()
}
type C interface {
m()
~int
}
type Integer interface{
int8 | int16 | int32 | int64
}
type EmptyTypeSet interface{
Integer
~string
}
type N1 int
func (N1) m() {}
type N2 int
func (*N2) m() {}
type N3 int
func (N3) m(int) {}
type N4 string
func (N4) m()
type Bad Bad // invalid type
`
f, err := parseSrc("p.go", src)
if err != nil {
t.Fatal(err)
}
conf := Config{Error: func(error) {}}
pkg, _ := conf.Check(f.PkgName.Value, []*syntax.File{f}, nil)
scope := pkg.Scope()
var (
EmptyIface = scope.Lookup("EmptyIface").Type().Underlying().(*Interface)
I = scope.Lookup("I").Type().(*Named)
II = I.Underlying().(*Interface)
C = scope.Lookup("C").Type().(*Named)
CI = C.Underlying().(*Interface)
Integer = scope.Lookup("Integer").Type().Underlying().(*Interface)
EmptyTypeSet = scope.Lookup("EmptyTypeSet").Type().Underlying().(*Interface)
N1 = scope.Lookup("N1").Type()
N1p = NewPointer(N1)
N2 = scope.Lookup("N2").Type()
N2p = NewPointer(N2)
N3 = scope.Lookup("N3").Type()
N4 = scope.Lookup("N4").Type()
Bad = scope.Lookup("Bad").Type()
)
tests := []struct {
t Type
i *Interface
want bool
}{
{I, II, true},
{I, CI, false},
{C, II, true},
{C, CI, true},
{Typ[Int8], Integer, true},
{Typ[Int64], Integer, true},
{Typ[String], Integer, false},
{EmptyTypeSet, II, true},
{EmptyTypeSet, EmptyTypeSet, true},
{Typ[Int], EmptyTypeSet, false},
{N1, II, true},
{N1, CI, true},
{N1p, II, true},
{N1p, CI, false},
{N2, II, false},
{N2, CI, false},
{N2p, II, true},
{N2p, CI, false},
{N3, II, false},
{N3, CI, false},
{N4, II, true},
{N4, CI, false},
{Bad, II, false},
{Bad, CI, false},
{Bad, EmptyIface, true},
}
for _, test := range tests {
if got := Implements(test.t, test.i); got != test.want {
t.Errorf("Implements(%s, %s) = %t, want %t", test.t, test.i, got, test.want)
}
}
}

12
src/go/types/api.go
View File

@ -436,8 +436,16 @@ func ConvertibleTo(V, T Type) bool {
// Implements reports whether type V implements interface T.
func Implements(V Type, T *Interface) bool {
f, _ := MissingMethod(V, T, true)
return f == nil
if T.Empty() {
// All types (even Typ[Invalid]) implement the empty interface.
return true
}
// Checker.implements suppresses errors for invalid types, so we need special
// handling here.
if V.Underlying() == Typ[Invalid] {
return false
}
return (*Checker)(nil).implements(V, T, nil) == nil
}
// Identical reports whether x and y are identical types.

104
src/go/types/api_test.go
View File

@ -2093,3 +2093,107 @@ func TestInstanceIdentity(t *testing.T) {
t.Errorf("mismatching types: a.A: %s, b.B: %s", a.Type(), b.Type())
}
}
func TestImplements(t *testing.T) {
const src = `
package p
type EmptyIface interface{}
type I interface {
m()
}
type C interface {
m()
~int
}
type Integer interface{
int8 | int16 | int32 | int64
}
type EmptyTypeSet interface{
Integer
~string
}
type N1 int
func (N1) m() {}
type N2 int
func (*N2) m() {}
type N3 int
func (N3) m(int) {}
type N4 string
func (N4) m()
type Bad Bad // invalid type
`
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "p.go", src, 0)
if err != nil {
t.Fatal(err)
}
conf := Config{Error: func(error) {}}
pkg, _ := conf.Check(f.Name.Name, fset, []*ast.File{f}, nil)
scope := pkg.Scope()
var (
EmptyIface = scope.Lookup("EmptyIface").Type().Underlying().(*Interface)
I = scope.Lookup("I").Type().(*Named)
II = I.Underlying().(*Interface)
C = scope.Lookup("C").Type().(*Named)
CI = C.Underlying().(*Interface)
Integer = scope.Lookup("Integer").Type().Underlying().(*Interface)
EmptyTypeSet = scope.Lookup("EmptyTypeSet").Type().Underlying().(*Interface)
N1 = scope.Lookup("N1").Type()
N1p = NewPointer(N1)
N2 = scope.Lookup("N2").Type()
N2p = NewPointer(N2)
N3 = scope.Lookup("N3").Type()
N4 = scope.Lookup("N4").Type()
Bad = scope.Lookup("Bad").Type()
)
tests := []struct {
t Type
i *Interface
want bool
}{
{I, II, true},
{I, CI, false},
{C, II, true},
{C, CI, true},
{Typ[Int8], Integer, true},
{Typ[Int64], Integer, true},
{Typ[String], Integer, false},
{EmptyTypeSet, II, true},
{EmptyTypeSet, EmptyTypeSet, true},
{Typ[Int], EmptyTypeSet, false},
{N1, II, true},
{N1, CI, true},
{N1p, II, true},
{N1p, CI, false},
{N2, II, false},
{N2, CI, false},
{N2p, II, true},
{N2p, CI, false},
{N3, II, false},
{N3, CI, false},
{N4, II, true},
{N4, CI, false},
{Bad, II, false},
{Bad, CI, false},
{Bad, EmptyIface, true},
}
for _, test := range tests {
if got := Implements(test.t, test.i); got != test.want {
t.Errorf("Implements(%s, %s) = %t, want %t", test.t, test.i, got, test.want)
}
}
}