From 8f503af08aec3e11871e312f3b8ec0a0f3ebd541 Mon Sep 17 00:00:00 2001
From: Julien Blanc <julien.blanc@tgcm.eu>
Date: Sun, 9 Nov 2025 07:13:57 +0000
Subject: [PATCH 1/3] Fix issue #58

Ensure we don't rely on an unknown return type in the context
of incomplete classes definitions

Signed-off-by: Julien Blanc <julien.blanc@tgcm.eu>
---
 include/boost/describe/enum.hpp        | 2 ++
 include/boost/describe/enumerators.hpp | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/include/boost/describe/enum.hpp b/include/boost/describe/enum.hpp
index dc0f473..cc3fcc3 100644
--- a/include/boost/describe/enum.hpp
+++ b/include/boost/describe/enum.hpp
@@ -66,6 +66,7 @@ template<class... T> auto enum_descriptor_fn_impl( int, T... )
 
 #define BOOST_DESCRIBE_NESTED_ENUM(E, ...) \
     static_assert(std::is_enum<E>::value, "BOOST_DESCRIBE_NESTED_ENUM should only be used with enums"); \
+    friend bool boost_has_nested_enum_descriptor_fn( E** ) { return true; } \
     friend BOOST_DESCRIBE_ENUM_BEGIN(E) \
     BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_ENUM_ENTRY, E, __VA_ARGS__) \
     BOOST_DESCRIBE_ENUM_END(E)
@@ -81,6 +82,7 @@ template<class... T> auto enum_descriptor_fn_impl( int, T... )
 
 #define BOOST_DESCRIBE_NESTED_ENUM(E, ...) \
     static_assert(std::is_enum<E>::value, "BOOST_DESCRIBE_NESTED_ENUM should only be used with enums"); \
+    friend bool boost_has_nested_enum_descriptor_fn( E** ) { return true; } \
     BOOST_DESCRIBE_MAYBE_UNUSED friend BOOST_DESCRIBE_ENUM_BEGIN(E) \
     BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_ENUM_ENTRY, E, ##__VA_ARGS__) \
     BOOST_DESCRIBE_ENUM_END(E)
diff --git a/include/boost/describe/enumerators.hpp b/include/boost/describe/enumerators.hpp
index f50c470..1a0afd1 100644
--- a/include/boost/describe/enumerators.hpp
+++ b/include/boost/describe/enumerators.hpp
@@ -20,6 +20,7 @@ namespace describe
 // describe_enumerators<E>
 
 template<class E> using describe_enumerators = decltype( boost_enum_descriptor_fn( static_cast<E**>(0) ) );
+template<class E> using nested_describe_enumerators = decltype (boost_has_nested_enum_descriptor_fn(static_cast<E**>(0) ) );
 
 // has_describe_enumerators<E>
 
@@ -34,6 +35,10 @@ template<class E> struct has_describe_enumerators<E, void_t<describe_enumerators
 {
 };
 
+template<class E> struct has_describe_enumerators<E, void_t<nested_describe_enumerators<E>>>: std::true_type
+{
+};
+
 } // namespace detail
 
 template<class E> using has_describe_enumerators = detail::has_describe_enumerators<E>;

From 9cdd1276f09e88fbea1a9b501211d147a7b2cc62 Mon Sep 17 00:00:00 2001
From: Julien Blanc <julien.blanc@tgcm.eu>
Date: Sun, 9 Nov 2025 07:18:46 +0000
Subject: [PATCH 2/3] Adds a test for #58

Signed-off-by: Julien Blanc <julien.blanc@tgcm.eu>
---
 test/nested_enum_test.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/test/nested_enum_test.cpp b/test/nested_enum_test.cpp
index 0ef5ecf..54a1600 100644
--- a/test/nested_enum_test.cpp
+++ b/test/nested_enum_test.cpp
@@ -27,6 +27,10 @@ class X2
 
     BOOST_DESCRIBE_NESTED_ENUM(E, v1, v2)
 
+#if defined(BOOST_DESCRIBE_CXX14)
+    static_assert(boost::describe::has_describe_enumerators<E>::value, "");
+#endif
+
 public:
 
     typedef E E2;

From 6e631fdb24499e4c38b157a3453ba9ebe709ae8a Mon Sep 17 00:00:00 2001
From: Julien Blanc <julien.blanc@tgcm.eu>
Date: Wed, 12 Nov 2025 10:58:41 +0000
Subject: [PATCH 3/3] Fix compilation for old msvc

---
 include/boost/describe/enumerators.hpp | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/boost/describe/enumerators.hpp b/include/boost/describe/enumerators.hpp
index 1a0afd1..e0fab3d 100644
--- a/include/boost/describe/enumerators.hpp
+++ b/include/boost/describe/enumerators.hpp
@@ -35,13 +35,21 @@ template<class E> struct has_describe_enumerators<E, void_t<describe_enumerators
 {
 };
 
-template<class E> struct has_describe_enumerators<E, void_t<nested_describe_enumerators<E>>>: std::true_type
+template<class E, class En = void> struct has_nested_describe_enumerators: std::false_type
 {
 };
 
+template<class E> struct has_nested_describe_enumerators<E, void_t<nested_describe_enumerators<E>>>: std::true_type
+{
+};
+
+template<class E> struct has_describe_enumerators_or_nested_describe_enumerators : std::integral_constant<bool, 
+    has_nested_describe_enumerators<E>::value || has_describe_enumerators<E>::value>
+{
+};
 } // namespace detail
 
-template<class E> using has_describe_enumerators = detail::has_describe_enumerators<E>;
+template<class E> using has_describe_enumerators = detail::has_describe_enumerators_or_nested_describe_enumerators<E>;
 
 } // namespace describe
 } // namespace boost