From d01b4e94cc72abaae859d1fe739ca6b81e2cfa04 Mon Sep 17 00:00:00 2001
From: Braden Ganetsky <braden.ganetsky@gmail.com>
Date: Mon, 24 Jun 2024 13:15:05 -0500
Subject: [PATCH] Write test for empty_value private inheritance

---
 test/Jamfile.v2                           |  1 +
 test/empty_value_compile_fail_casting.cpp | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 test/empty_value_compile_fail_casting.cpp

diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 5df9242..e9a1d07 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -226,6 +226,7 @@ run empty_value_test.cpp ;
 run empty_value_size_test.cpp ;
 run empty_value_final_test.cpp ;
 run empty_value_constexpr_test.cpp ;
+compile-fail empty_value_compile_fail_casting.cpp ;
 
 run quick_exit_test.cpp ;
 run-fail quick_exit_fail.cpp ;
diff --git a/test/empty_value_compile_fail_casting.cpp b/test/empty_value_compile_fail_casting.cpp
new file mode 100644
index 0000000..e4cac42
--- /dev/null
+++ b/test/empty_value_compile_fail_casting.cpp
@@ -0,0 +1,20 @@
+// Copyright 2024 Braden Ganetsky
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/empty_value.hpp>
+
+struct empty {};
+
+// This test ensures private inheritance of `boost::empty_value<T>` for empty `T`.
+// With public inheritance, `boost::empty_value<empty>*` could cast to `empty*`.
+void test_empty_not_convertible_to_base()
+{
+    const boost::empty_value<empty> x(boost::empty_init);
+    const empty* x2 = static_cast<const empty*>(&x);
+    (void)x2;
+}
+
+int main()
+{
+}