cmd/compile: improve error when setting unexported fields

Improve the error user experience when users try to set/refer
to unexported fields and methods of struct literals, by directly saying

    "cannot refer to unexported field or method"

Fixes #31053

Change-Id: I6fd3caf64b7ca9f9d8ea60b7756875e340792d59
Reviewed-on: https://go-review.googlesource.com/c/go/+/201657
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Emmanuel T Odeke 2019-10-16 23:13:25 -07:00 committed by Emmanuel Odeke
parent 65126c588e
commit 7cbee12444
5 changed files with 78 additions and 4 deletions

View File

@ -2967,6 +2967,8 @@ func typecheckcomplit(n *Node) (res *Node) {
if ci := lookdot1(nil, l.Sym, t, t.Fields(), 2); ci != nil { // Case-insensitive lookup.
if visible(ci.Sym) {
yyerror("unknown field '%v' in struct literal of type %v (but does have %v)", l.Sym, t, ci.Sym)
} else if nonexported(l.Sym) && l.Sym.Name == ci.Sym.Name { // Ensure exactness before the suggestion.
yyerror("cannot refer to unexported field '%v' in struct literal of type %v", l.Sym, t)
} else {
yyerror("unknown field '%v' in struct literal of type %v", l.Sym, t)
}
@ -3070,6 +3072,11 @@ func visible(sym *types.Sym) bool {
return sym != nil && (types.IsExported(sym.Name) || sym.Pkg == localpkg)
}
// nonexported reports whether sym is an unexported field.
func nonexported(sym *types.Sym) bool {
return sym != nil && !types.IsExported(sym.Name)
}
// lvalue etc
func islvalue(n *Node) bool {
switch n.Op {

View File

@ -9,13 +9,13 @@ package main
import "net/http"
var s = http.Server{}
var _ = s.doneChan // ERROR "s.doneChan undefined .cannot refer to unexported field or method doneChan.$"
var _ = s.DoneChan // ERROR "s.DoneChan undefined .type http.Server has no field or method DoneChan.$"
var _ = s.doneChan // ERROR "s.doneChan undefined .cannot refer to unexported field or method doneChan.$"
var _ = s.DoneChan // ERROR "s.DoneChan undefined .type http.Server has no field or method DoneChan.$"
var _ = http.Server{tlsConfig: nil} // ERROR "unknown field 'tlsConfig' in struct literal.+ .but does have TLSConfig.$"
var _ = http.Server{DoneChan: nil} // ERROR "unknown field 'DoneChan' in struct literal of type http.Server$"
var _ = http.Server{DoneChan: nil} // ERROR "unknown field 'DoneChan' in struct literal of type http.Server$"
type foo struct {
bar int
bar int
}
var _ = &foo{bAr: 10} // ERROR "unknown field 'bAr' in struct literal.+ .but does have bar.$"

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@ -0,0 +1,18 @@
// Copyright 2019 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 f1
type Foo struct {
doneChan chan bool
Name string
fOO int
hook func()
}
func (f *Foo) Exported() {
}
func (f *Foo) unexported() {
}

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@ -0,0 +1,42 @@
// errorcheck
// Copyright 2019 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 "./f1"
func main() {
f := f1.Foo{
doneChan: nil, // ERROR "cannot refer to unexported field 'doneChan' in struct literal of type f1.Foo"
DoneChan: nil, // ERROR "unknown field 'DoneChan' in struct literal of type f1.Foo"
Name: "hey",
name: "there", // ERROR "unknown field 'name' in struct literal of type f1.Foo .but does have Name."
noSuchPrivate: true, // ERROR "unknown field 'noSuchPrivate' in struct literal of type f1.Foo"
NoSuchPublic: true, // ERROR "unknown field 'NoSuchPublic' in struct literal of type f1.Foo"
foo: true, // ERROR "unknown field 'foo' in struct literal of type f1.Foo"
hook: func() {}, // ERROR "cannot refer to unexported field 'hook' in struct literal of type f1.Foo"
unexported: func() {}, // ERROR "unknown field 'unexported' in struct literal of type f1.Foo"
Exported: func() {}, // ERROR "unknown field 'Exported' in struct literal of type f1.Foo"
}
f.doneChan = nil // ERROR "f.doneChan undefined .cannot refer to unexported field or method doneChan."
f.DoneChan = nil // ERROR "f.DoneChan undefined .type f1.Foo has no field or method DoneChan."
f.name = nil // ERROR "f.name undefined .type f1.Foo has no field or method name, but does have Name."
_ = f.doneChan // ERROR "f.doneChan undefined .cannot refer to unexported field or method doneChan."
_ = f.DoneChan // ERROR "f.DoneChan undefined .type f1.Foo has no field or method DoneChan."
_ = f.Name
_ = f.name // ERROR "f.name undefined .type f1.Foo has no field or method name, but does have Name."
_ = f.noSuchPrivate // ERROR "f.noSuchPrivate undefined .type f1.Foo has no field or method noSuchPrivate."
_ = f.NoSuchPublic // ERROR "f.NoSuchPublic undefined .type f1.Foo has no field or method NoSuchPublic."
_ = f.foo // ERROR "f.foo undefined .type f1.Foo has no field or method foo."
_ = f.Exported
_ = f.exported // ERROR "f.exported undefined .type f1.Foo has no field or method exported, but does have Exported."
_ = f.Unexported // ERROR "f.Unexported undefined .type f1.Foo has no field or method Unexported."
_ = f.unexported // ERROR "f.unexported undefined .cannot refer to unexported field or method f1..\*Foo..unexported."
f.unexported = 10 // ERROR "f.unexported undefined .cannot refer to unexported field or method f1..\*Foo..unexported."
f.unexported() // ERROR "f.unexported undefined .cannot refer to unexported field or method f1..\*Foo..unexported."
_ = f.hook // ERROR "f.hook undefined .cannot refer to unexported field or method hook."
}

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@ -0,0 +1,7 @@
// errorcheckdir
// Copyright 2019 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 ignored