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-rw-r--r--test/fixedbugs/issue52612.go49
1 files changed, 49 insertions, 0 deletions
diff --git a/test/fixedbugs/issue52612.go b/test/fixedbugs/issue52612.go
new file mode 100644
index 0000000..d8be049
--- /dev/null
+++ b/test/fixedbugs/issue52612.go
@@ -0,0 +1,49 @@
+// run
+
+// Copyright 2022 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
+
+import (
+ "sync/atomic"
+ "unsafe"
+)
+
+var one interface{} = 1
+
+type eface struct {
+ typ unsafe.Pointer
+ data unsafe.Pointer
+}
+
+func f(c chan struct{}) {
+ var x atomic.Value
+
+ go func() {
+ x.Swap(one) // writing using the old marker
+ }()
+ for i := 0; i < 100000; i++ {
+ v := x.Load() // reading using the new marker
+
+ p := (*eface)(unsafe.Pointer(&v)).typ
+ if uintptr(p) == ^uintptr(0) {
+ // We read the old marker, which the new reader
+ // doesn't know is a case where it should retry
+ // instead of returning it.
+ panic("bad typ field")
+ }
+ }
+ c <- struct{}{}
+}
+
+func main() {
+ c := make(chan struct{}, 10)
+ for i := 0; i < 10; i++ {
+ go f(c)
+ }
+ for i := 0; i < 10; i++ {
+ <-c
+ }
+}