mirror of
https://github.com/golang/go
synced 2024-11-13 18:40:22 -07:00
34db5f0c4d
Currently, we handle "x op= y" by rewriting as "x = x op y", while ensuring that any calls or receive operations in 'x' are only evaluated once. Notably, pointer indirection, indexing operations, etc. are left alone as it's typically safe to re-evaluate those. However, those operations were interleaved with evaluating 'y', which could include function calls that might cause re-evaluation to yield different memory addresses. As a fix, simply ensure that we order side-effecting operations in 'y' before either evaluation of 'x'. Fixes #21687. Change-Id: Ib14e77760fda9c828e394e8e362dc9e5319a84b2 Reviewed-on: https://go-review.googlesource.com/60091 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com>
69 lines
940 B
Go
69 lines
940 B
Go
// run
|
|
|
|
// Copyright 2017 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.
|
|
|
|
// Issue 21687: cmd/compile evaluates x twice in "x op= y", which was
|
|
// detectable if evaluating y affects x.
|
|
|
|
package main
|
|
|
|
func ptrs() (int, int) {
|
|
one := 1
|
|
two := 2
|
|
|
|
x := &one
|
|
*x += func() int {
|
|
x = &two
|
|
return 0
|
|
}()
|
|
|
|
return one, two
|
|
}
|
|
|
|
func slices() (int, int) {
|
|
one := []int{1}
|
|
two := []int{2}
|
|
|
|
x := one
|
|
x[0] += func() int {
|
|
x = two
|
|
return 0
|
|
}()
|
|
|
|
return one[0], two[0]
|
|
}
|
|
|
|
func maps() (int, int) {
|
|
one := map[int]int{0: 1}
|
|
two := map[int]int{0: 2}
|
|
|
|
x := one
|
|
x[0] += func() int {
|
|
x = two
|
|
return 0
|
|
}()
|
|
|
|
return one[0], two[0]
|
|
}
|
|
|
|
var tests = [...]func() (int, int){
|
|
ptrs,
|
|
slices,
|
|
maps,
|
|
}
|
|
|
|
func main() {
|
|
bad := 0
|
|
for i, f := range tests {
|
|
if a, b := f(); a+b != 3 {
|
|
println(i, a, b)
|
|
bad++
|
|
}
|
|
}
|
|
if bad != 0 {
|
|
panic(bad)
|
|
}
|
|
}
|