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go/types, types2: use exact unification when comparing interface methods

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Irrespective of whether unification is exact or inexact, method
signatures of interfaces must always match exactly: a type never
satisfies/implements an interface if relevant method signatures
are different (i.e., not identical, possibly after substitution).

Fixes #61879.

Change-Id: I20c0aa28ac86e2edec615b40f2269938e4a96938
Reviewed-on: https://go-review.googlesource.com/c/go/+/519435
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
This commit is contained in:
Robert Griesemer 2023-08-14 14:07:56 -07:00 committed by Gopher Robot
parent dd307f193b
commit 197522d3ae
3 changed files with 63 additions and 6 deletions
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6
src/cmd/compile/internal/types2/unify.go
View file

@ -500,7 +500,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
}
// All xmethods must exist in ymethods and corresponding signatures must unify.
for _, xm := range xmethods {
if ym := ymap[xm.Id()]; ym == nil || !u.nify(xm.typ, ym.typ, emode, p) {
if ym := ymap[xm.Id()]; ym == nil || !u.nify(xm.typ, ym.typ, exact, p) {
return false
}
}
@ -521,7 +521,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
xmethods := xi.typeSet().methods
for _, xm := range xmethods {
obj, _, _ := LookupFieldOrMethod(y, false, xm.pkg, xm.name)
if ym, _ := obj.(*Func); ym == nil || !u.nify(xm.typ, ym.typ, emode, p) {
if ym, _ := obj.(*Func); ym == nil || !u.nify(xm.typ, ym.typ, exact, p) {
return false
}
}
@ -680,7 +680,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
}
for i, f := range a {
g := b[i]
if f.Id() != g.Id() || !u.nify(f.typ, g.typ, emode, q) {
if f.Id() != g.Id() || !u.nify(f.typ, g.typ, exact, q) {
return false
}
}

6
src/go/types/unify.go
View file

@ -502,7 +502,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
}
// All xmethods must exist in ymethods and corresponding signatures must unify.
for _, xm := range xmethods {
if ym := ymap[xm.Id()]; ym == nil || !u.nify(xm.typ, ym.typ, emode, p) {
if ym := ymap[xm.Id()]; ym == nil || !u.nify(xm.typ, ym.typ, exact, p) {
return false
}
}
@ -523,7 +523,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
xmethods := xi.typeSet().methods
for _, xm := range xmethods {
obj, _, _ := LookupFieldOrMethod(y, false, xm.pkg, xm.name)
if ym, _ := obj.(*Func); ym == nil || !u.nify(xm.typ, ym.typ, emode, p) {
if ym, _ := obj.(*Func); ym == nil || !u.nify(xm.typ, ym.typ, exact, p) {
return false
}
}
@ -682,7 +682,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
}
for i, f := range a {
g := b[i]
if f.Id() != g.Id() || !u.nify(f.typ, g.typ, emode, q) {
if f.Id() != g.Id() || !u.nify(f.typ, g.typ, exact, q) {
return false
}
}

57
src/internal/types/testdata/fixedbugs/issue61879.go vendored Normal file
View file

@ -0,0 +1,57 @@
// Copyright 2023 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 p
import "fmt"
type Interface[T any] interface {
m(Interface[T])
}
func f[S []Interface[T], T any](S) {}
func _() {
var s []Interface[int]
f(s) // panic here
}
// Larger example from issue
type InterfaceA[T comparable] interface {
setData(string) InterfaceA[T]
}
type ImplA[T comparable] struct {
data string
args []any
}
func NewInterfaceA[T comparable](args ...any) InterfaceA[T] {
return &ImplA[T]{
data: fmt.Sprintf("%v", args...),
args: args,
}
}
func (k *ImplA[T]) setData(data string) InterfaceA[T] {
k.data = data
return k
}
func Foo[M ~map[InterfaceA[T]]V, T comparable, V any](m M) {
// DO SOMETHING HERE
return
}
func Bar() {
keys := make([]InterfaceA[int], 0, 10)
m := make(map[InterfaceA[int]]int)
for i := 0; i < 10; i++ {
keys = append(keys, NewInterfaceA[int](i))
m[keys[i]] = i
}
Foo(m) // panic here
}