qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-11 19:51:37 -07:00
Code Releases Activity

cmd/compile: fix order-of-assignment issue w/ defers

Browse Source 
CL 261677 fixed a logic issue in walk's alias detection, where it was
checking the RHS expression instead of the LHS expression when trying
to determine the kind of assignment. However, correcting this exposed
a latent issue with assigning to result parameters in functions with
defers, where an assignment could become visible earlier than intended
if a later expression could panic.

Fixes #43835.

Change-Id: I061ced125e3896e26d65f45b28c99db2c8a74a8c
Reviewed-on: https://go-review.googlesource.com/c/go/+/285633
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Matthew Dempsky 2021-01-21 19:27:12 -08:00
parent ad2ca26a52
commit deaf29a8a8
2 changed files with 43 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
src/cmd/compile/internal/gc/walk.go
View File

@ -267,7 +267,7 @@ func walkstmt(n *Node) *Node {
if n.List.Len() == 0 {
break
}
if (Curfn.Type.FuncType().Outnamed && n.List.Len() > 1) || paramoutheap(Curfn) {
if (Curfn.Type.FuncType().Outnamed && n.List.Len() > 1) || paramoutheap(Curfn) || Curfn.Func.HasDefer() {
// assign to the function out parameters,
// so that reorder3 can fix up conflicts
var rl []*Node
@ -2233,7 +2233,15 @@ func aliased(r *Node, all []*Node) bool {
memwrite = true
continue
case PAUTO, PPARAM, PPARAMOUT:
case PPARAMOUT:
// Assignments to a result parameter in a function with defers
// becomes visible early if evaluation of any later expression
// panics (#43835).
if Curfn.Func.HasDefer() {
return true
}
fallthrough
case PAUTO, PPARAM:
if l.Name.Addrtaken() {
memwrite = true
continue

33
test/fixedbugs/issue43835.go Normal file
View File

@ -0,0 +1,33 @@
// run
// Copyright 2021 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 main
func main() {
if f() {
panic("FAIL")
}
if bad, _ := g(); bad {
panic("FAIL")
}
}
func f() (bad bool) {
defer func() {
recover()
}()
var p *int
bad, _ = true, *p
return
}
func g() (bool, int) {
defer func() {
recover()
}()
var p *int
return true, *p
}