Initial commit: Go 1.23 release state

test/fixedbugs/issue66096.go

@@ -0,0 +1,17 @@
+// compile
+
+// Copyright 2024 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 Message struct {
+	Header map[string][]string
+}
+
+func f() {
+	m := Message{Header: map[string][]string{}}
+	m.Header[""] = append([]string(m.Header[""]), "")
+	_ = m
+}