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[dev.regabi] cmd/compile: fix defined-pointer method call check

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The compiler has logic to check whether we implicitly dereferenced a
defined pointer while trying to select a method. However, rather than
checking whether there were any implicit dereferences of a defined
pointer, it was finding the innermost dereference/selector expression
and checking whether that was dereferencing a named pointer. Moreover,
it was only checking defined pointer declared in the package block.

This CL restructures the code to match go/types and gccgo's behavior.

Fixes #43384.

Change-Id: I7bddfe2515776d9480eb2c7286023d4c15423888
Reviewed-on: https://go-review.googlesource.com/c/go/+/280392
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Trust: Robert Griesemer <gri@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Matthew Dempsky 2020-12-26 01:06:03 -08:00
parent f9b67f76a5
commit 0c1a899a6c
2 changed files with 144 additions and 11 deletions
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27
src/cmd/compile/internal/typecheck/typecheck.go
View File

@ -1328,6 +1328,7 @@ func lookdot(n *ir.SelectorExpr, t *types.Type, dostrcmp int) *types.Field {
// Already in the process of diagnosing an error.
return f2
}
orig := n.X
tt := n.X.Type()
types.CalcSize(tt)
rcvr := f2.Type.Recv().Type
@ -1358,21 +1359,29 @@ func lookdot(n *ir.SelectorExpr, t *types.Type, dostrcmp int) *types.Field {
}
}
implicit, ll := n.Implicit(), n.X
for ll != nil && (ll.Op() == ir.ODOT || ll.Op() == ir.ODOTPTR || ll.Op() == ir.ODEREF) {
switch l := ll.(type) {
// Check that we haven't implicitly dereferenced any defined pointer types.
for x := n.X; ; {
var inner ir.Node
implicit := false
switch x := x.(type) {
case *ir.AddrExpr:
inner, implicit = x.X, x.Implicit()
case *ir.SelectorExpr:
implicit, ll = l.Implicit(), l.X
inner, implicit = x.X, x.Implicit()
case *ir.StarExpr:
implicit, ll = l.Implicit(), l.X
inner, implicit = x.X, x.Implicit()
}
if !implicit {
break
}
if implicit && ll.Type().IsPtr() && ll.Type().Sym() != nil && ll.Type().Sym().Def != nil && ir.AsNode(ll.Type().Sym().Def).Op() == ir.OTYPE {
// It is invalid to automatically dereference a named pointer type when selecting a method.
// Make n.Left == ll to clarify error message.
n.X = ll
if inner.Type().Sym() != nil && (x.Op() == ir.ODEREF || x.Op() == ir.ODOTPTR) {
// Found an implicit dereference of a defined pointer type.
// Restore n.X for better error message.
n.X = orig
return nil
}
x = inner
}
n.Selection = f2
n.SetType(f2.Type)

124
test/fixedbugs/issue43384.go Normal file
View File

@ -0,0 +1,124 @@
// errorcheck
// Copyright 2020 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
type T int
func (T) Mv() {}
func (*T) Mp() {}
type P1 struct{ T }
type P2 struct{ *T }
type P3 *struct{ T }
type P4 *struct{ *T }
func _() {
{
var p P1
p.Mv()
(&p).Mv()
(*&p).Mv()
p.Mp()
(&p).Mp()
(*&p).Mp()
}
{
var p P2
p.Mv()
(&p).Mv()
(*&p).Mv()
p.Mp()
(&p).Mp()
(*&p).Mp()
}
{
var p P3
p.Mv() // ERROR "undefined"
(&p).Mv() // ERROR "undefined"
(*&p).Mv() // ERROR "undefined"
(**&p).Mv()
(*p).Mv()
(&*p).Mv()
p.Mp() // ERROR "undefined"
(&p).Mp() // ERROR "undefined"
(*&p).Mp() // ERROR "undefined"
(**&p).Mp()
(*p).Mp()
(&*p).Mp()
}
{
var p P4
p.Mv() // ERROR "undefined"
(&p).Mv() // ERROR "undefined"
(*&p).Mv() // ERROR "undefined"
(**&p).Mv()
(*p).Mv()
(&*p).Mv()
p.Mp() // ERROR "undefined"
(&p).Mp() // ERROR "undefined"
(*&p).Mp() // ERROR "undefined"
(**&p).Mp()
(*p).Mp()
(&*p).Mp()
}
}
func _() {
type P5 struct{ T }
type P6 struct{ *T }
type P7 *struct{ T }
type P8 *struct{ *T }
{
var p P5
p.Mv()
(&p).Mv()
(*&p).Mv()
p.Mp()
(&p).Mp()
(*&p).Mp()
}
{
var p P6
p.Mv()
(&p).Mv()
(*&p).Mv()
p.Mp()
(&p).Mp()
(*&p).Mp()
}
{
var p P7
p.Mv() // ERROR "undefined"
(&p).Mv() // ERROR "undefined"
(*&p).Mv() // ERROR "undefined"
(**&p).Mv()
(*p).Mv()
(&*p).Mv()
p.Mp() // ERROR "undefined"
(&p).Mp() // ERROR "undefined"
(*&p).Mp() // ERROR "undefined"
(**&p).Mp()
(*p).Mp()
(&*p).Mp()
}
{
var p P8
p.Mv() // ERROR "undefined"
(&p).Mv() // ERROR "undefined"
(*&p).Mv() // ERROR "undefined"
(**&p).Mv()
(*p).Mv()
(&*p).Mv()
p.Mp() // ERROR "undefined"
(&p).Mp() // ERROR "undefined"
(*&p).Mp() // ERROR "undefined"
(**&p).Mp()
(*p).Mp()
(&*p).Mp()
}
}