Adding upstream version 1.21.8.upstream/1.21.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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
+	}
+}