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go/types, types2: better error message when missing method is unexported

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Change lookupMethod such that "foldCase" means "ignore case
and package" and analyze a lookup result further to determine
if a method name was not exported, and report a better error
message in that case.

Fixes #59831.

Change-Id: Ice6222e1fc00dba13caeda6c48971e8473d12da5
Reviewed-on: https://go-review.googlesource.com/c/go/+/549298
Run-TryBot: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
This commit is contained in:
Robert Griesemer 2023-12-12 17:52:36 -08:00 committed by Gopher Robot
parent f2d243db8f
commit 0b3dd75f6c
4 changed files with 172 additions and 10 deletions
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73
src/cmd/compile/internal/types2/issues_test.go
View File

@ -1003,3 +1003,76 @@ type S struct{ A }
t.Fatalf("got %q; want %q", got, want)
}
}
func TestIssue59831(t *testing.T) {
// Package a exports a type S with an unexported method m;
// the tests check the error messages when m is not found.
const asrc = `package a; type S struct{}; func (S) m() {}`
apkg := mustTypecheck(asrc, nil, nil)
// Package b exports a type S with an exported method m;
// the tests check the error messages when M is not found.
const bsrc = `package b; type S struct{}; func (S) M() {}`
bpkg := mustTypecheck(bsrc, nil, nil)
tests := []struct {
imported *Package
src, err string
}{
// tests importing a (or nothing)
{apkg, `package a1; import "a"; var _ interface { M() } = a.S{}`,
"a.S does not implement interface{M()} (missing method M) have m() want M()"},
{apkg, `package a2; import "a"; var _ interface { m() } = a.S{}`,
"a.S does not implement interface{m()} (unexported method m)"}, // test for issue
{nil, `package a3; type S struct{}; func (S) m(); var _ interface { M() } = S{}`,
"S does not implement interface{M()} (missing method M) have m() want M()"},
{nil, `package a4; type S struct{}; func (S) m(); var _ interface { m() } = S{}`,
""}, // no error expected
{nil, `package a5; type S struct{}; func (S) m(); var _ interface { n() } = S{}`,
"S does not implement interface{n()} (missing method n)"},
// tests importing b (or nothing)
{bpkg, `package b1; import "b"; var _ interface { m() } = b.S{}`,
"b.S does not implement interface{m()} (missing method m) have M() want m()"},
{bpkg, `package b2; import "b"; var _ interface { M() } = b.S{}`,
""}, // no error expected
{nil, `package b3; type S struct{}; func (S) M(); var _ interface { M() } = S{}`,
""}, // no error expected
{nil, `package b4; type S struct{}; func (S) M(); var _ interface { m() } = S{}`,
"S does not implement interface{m()} (missing method m) have M() want m()"},
{nil, `package b5; type S struct{}; func (S) M(); var _ interface { n() } = S{}`,
"S does not implement interface{n()} (missing method n)"},
}
for _, test := range tests {
// typecheck test source
conf := Config{Importer: importHelper{pkg: test.imported}}
pkg, err := typecheck(test.src, &conf, nil)
if err == nil {
if test.err != "" {
t.Errorf("package %s: got no error, want %q", pkg.Name(), test.err)
}
continue
}
if test.err == "" {
t.Errorf("package %s: got %q, want not error", pkg.Name(), err.Error())
}
// flatten reported error message
errmsg := strings.ReplaceAll(err.Error(), "\n", " ")
errmsg = strings.ReplaceAll(errmsg, "\t", "")
// verify error message
if !strings.Contains(errmsg, test.err) {
t.Errorf("package %s: got %q, want %q", pkg.Name(), errmsg, test.err)
}
}
}

18
src/cmd/compile/internal/types2/lookup.go
View File

@ -96,7 +96,7 @@ func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
// and missingMethod (the latter doesn't care about struct fields).
//
// If foldCase is true, method names are considered equal if they are equal
// with case folding.
// with case folding, irrespective of which package they are in.
//
// The resulting object may not be fully type-checked.
func lookupFieldOrMethodImpl(T Type, addressable bool, pkg *Package, name string, foldCase bool) (obj Object, index []int, indirect bool) {
@ -343,6 +343,7 @@ func (check *Checker) missingMethod(V, T Type, static bool, equivalent func(x, y
ok = iota
notFound
wrongName
unexported
wrongSig
ambigSel
ptrRecv
@ -388,6 +389,11 @@ func (check *Checker) missingMethod(V, T Type, static bool, equivalent func(x, y
f, _ = obj.(*Func)
if f != nil {
state = wrongName
if f.name == m.name {
// If the names are equal, f must be unexported
// (otherwise the package wouldn't matter).
state = unexported
}
}
}
break
@ -436,8 +442,9 @@ func (check *Checker) missingMethod(V, T Type, static bool, equivalent func(x, y
}
case wrongName:
fs, ms := check.funcString(f, false), check.funcString(m, false)
*cause = check.sprintf("(missing method %s)\n\t\thave %s\n\t\twant %s",
m.Name(), fs, ms)
*cause = check.sprintf("(missing method %s)\n\t\thave %s\n\t\twant %s", m.Name(), fs, ms)
case unexported:
*cause = check.sprintf("(unexported method %s)", m.Name())
case wrongSig:
fs, ms := check.funcString(f, false), check.funcString(m, false)
if fs == ms {
@ -582,11 +589,12 @@ func fieldIndex(fields []*Var, pkg *Package, name string) int {
}
// lookupMethod returns the index of and method with matching package and name, or (-1, nil).
// If foldCase is true, method names are considered equal if they are equal with case folding.
// If foldCase is true, method names are considered equal if they are equal with case folding
// and their packages are ignored (e.g., pkg1.m, pkg1.M, pkg2.m, and pkg2.M are all equal).
func lookupMethod(methods []*Func, pkg *Package, name string, foldCase bool) (int, *Func) {
if name != "_" {
for i, m := range methods {
if (m.name == name || foldCase && strings.EqualFold(m.name, name)) && m.sameId(pkg, m.name) {
if m.sameId(pkg, name) || foldCase && strings.EqualFold(m.name, name) {
return i, m
}
}

73
src/go/types/issues_test.go
View File

@ -1013,3 +1013,76 @@ type S struct{ A }
t.Fatalf("got %q; want %q", got, want)
}
}
func TestIssue59831(t *testing.T) {
// Package a exports a type S with an unexported method m;
// the tests check the error messages when m is not found.
const asrc = `package a; type S struct{}; func (S) m() {}`
apkg := mustTypecheck(asrc, nil, nil)
// Package b exports a type S with an exported method m;
// the tests check the error messages when M is not found.
const bsrc = `package b; type S struct{}; func (S) M() {}`
bpkg := mustTypecheck(bsrc, nil, nil)
tests := []struct {
imported *Package
src, err string
}{
// tests importing a (or nothing)
{apkg, `package a1; import "a"; var _ interface { M() } = a.S{}`,
"a.S does not implement interface{M()} (missing method M) have m() want M()"},
{apkg, `package a2; import "a"; var _ interface { m() } = a.S{}`,
"a.S does not implement interface{m()} (unexported method m)"}, // test for issue
{nil, `package a3; type S struct{}; func (S) m(); var _ interface { M() } = S{}`,
"S does not implement interface{M()} (missing method M) have m() want M()"},
{nil, `package a4; type S struct{}; func (S) m(); var _ interface { m() } = S{}`,
""}, // no error expected
{nil, `package a5; type S struct{}; func (S) m(); var _ interface { n() } = S{}`,
"S does not implement interface{n()} (missing method n)"},
// tests importing b (or nothing)
{bpkg, `package b1; import "b"; var _ interface { m() } = b.S{}`,
"b.S does not implement interface{m()} (missing method m) have M() want m()"},
{bpkg, `package b2; import "b"; var _ interface { M() } = b.S{}`,
""}, // no error expected
{nil, `package b3; type S struct{}; func (S) M(); var _ interface { M() } = S{}`,
""}, // no error expected
{nil, `package b4; type S struct{}; func (S) M(); var _ interface { m() } = S{}`,
"S does not implement interface{m()} (missing method m) have M() want m()"},
{nil, `package b5; type S struct{}; func (S) M(); var _ interface { n() } = S{}`,
"S does not implement interface{n()} (missing method n)"},
}
for _, test := range tests {
// typecheck test source
conf := Config{Importer: importHelper{pkg: test.imported}}
pkg, err := typecheck(test.src, &conf, nil)
if err == nil {
if test.err != "" {
t.Errorf("package %s: got no error, want %q", pkg.Name(), test.err)
}
continue
}
if test.err == "" {
t.Errorf("package %s: got %q, want not error", pkg.Name(), err.Error())
}
// flatten reported error message
errmsg := strings.ReplaceAll(err.Error(), "\n", " ")
errmsg = strings.ReplaceAll(errmsg, "\t", "")
// verify error message
if !strings.Contains(errmsg, test.err) {
t.Errorf("package %s: got %q, want %q", pkg.Name(), errmsg, test.err)
}
}
}

18
src/go/types/lookup.go
View File

@ -98,7 +98,7 @@ func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
// and missingMethod (the latter doesn't care about struct fields).
//
// If foldCase is true, method names are considered equal if they are equal
// with case folding.
// with case folding, irrespective of which package they are in.
//
// The resulting object may not be fully type-checked.
func lookupFieldOrMethodImpl(T Type, addressable bool, pkg *Package, name string, foldCase bool) (obj Object, index []int, indirect bool) {
@ -345,6 +345,7 @@ func (check *Checker) missingMethod(V, T Type, static bool, equivalent func(x, y
ok = iota
notFound
wrongName
unexported
wrongSig
ambigSel
ptrRecv
@ -390,6 +391,11 @@ func (check *Checker) missingMethod(V, T Type, static bool, equivalent func(x, y
f, _ = obj.(*Func)
if f != nil {
state = wrongName
if f.name == m.name {
// If the names are equal, f must be unexported
// (otherwise the package wouldn't matter).
state = unexported
}
}
}
break
@ -438,8 +444,9 @@ func (check *Checker) missingMethod(V, T Type, static bool, equivalent func(x, y
}
case wrongName:
fs, ms := check.funcString(f, false), check.funcString(m, false)
*cause = check.sprintf("(missing method %s)\n\t\thave %s\n\t\twant %s",
m.Name(), fs, ms)
*cause = check.sprintf("(missing method %s)\n\t\thave %s\n\t\twant %s", m.Name(), fs, ms)
case unexported:
*cause = check.sprintf("(unexported method %s)", m.Name())
case wrongSig:
fs, ms := check.funcString(f, false), check.funcString(m, false)
if fs == ms {
@ -584,11 +591,12 @@ func fieldIndex(fields []*Var, pkg *Package, name string) int {
}
// lookupMethod returns the index of and method with matching package and name, or (-1, nil).
// If foldCase is true, method names are considered equal if they are equal with case folding.
// If foldCase is true, method names are considered equal if they are equal with case folding
// and their packages are ignored (e.g., pkg1.m, pkg1.M, pkg2.m, and pkg2.M are all equal).
func lookupMethod(methods []*Func, pkg *Package, name string, foldCase bool) (int, *Func) {
if name != "_" {
for i, m := range methods {
if (m.name == name || foldCase && strings.EqualFold(m.name, name)) && m.sameId(pkg, m.name) {
if m.sameId(pkg, name) || foldCase && strings.EqualFold(m.name, name) {
return i, m
}
}