Merge branch 'maybe-unused' of https://github.com/ecatmur/describe into feature/pr-24

Suppresses Wunused-function / Wunneeded-internal-declaration (clang) on internal-linkage types

https://github.com/boostorg/describe/issues/23

include/boost/describe/class.hpp

@@ -54,17 +54,17 @@ namespace describe
 #define BOOST_DESCRIBE_PRIVATE_MEMBERS_(...) BOOST_DESCRIBE_PRIVATE_MEMBERS(__VA_ARGS__)
 
 #define BOOST_DESCRIBE_CLASS(C, Bases, Public, Protected, Private) \
-    friend BOOST_DESCRIBE_BASES_(C BOOST_DESCRIBE_PP_UNPACK Bases) \
-    friend BOOST_DESCRIBE_PUBLIC_MEMBERS_(C BOOST_DESCRIBE_PP_UNPACK Public) \
-    friend BOOST_DESCRIBE_PROTECTED_MEMBERS_(C BOOST_DESCRIBE_PP_UNPACK Protected) \
-    friend BOOST_DESCRIBE_PRIVATE_MEMBERS_(C BOOST_DESCRIBE_PP_UNPACK Private)
+    BOOST_DESCRIBE_MAYBE_UNUSED friend BOOST_DESCRIBE_BASES_(C BOOST_DESCRIBE_PP_UNPACK Bases) \
+    BOOST_DESCRIBE_MAYBE_UNUSED friend BOOST_DESCRIBE_PUBLIC_MEMBERS_(C BOOST_DESCRIBE_PP_UNPACK Public) \
+    BOOST_DESCRIBE_MAYBE_UNUSED friend BOOST_DESCRIBE_PROTECTED_MEMBERS_(C BOOST_DESCRIBE_PP_UNPACK Protected) \
+    BOOST_DESCRIBE_MAYBE_UNUSED friend BOOST_DESCRIBE_PRIVATE_MEMBERS_(C BOOST_DESCRIBE_PP_UNPACK Private)
 
 #define BOOST_DESCRIBE_STRUCT(C, Bases, Members) \
     static_assert(std::is_class<C>::value, "BOOST_DESCRIBE_STRUCT should only be used with class types"); \
-    BOOST_DESCRIBE_BASES_(C BOOST_DESCRIBE_PP_UNPACK Bases) \
-    BOOST_DESCRIBE_PUBLIC_MEMBERS_(C BOOST_DESCRIBE_PP_UNPACK Members) \
-    BOOST_DESCRIBE_PROTECTED_MEMBERS_(C) \
-    BOOST_DESCRIBE_PRIVATE_MEMBERS_(C)
+    BOOST_DESCRIBE_MAYBE_UNUSED BOOST_DESCRIBE_BASES_(C BOOST_DESCRIBE_PP_UNPACK Bases) \
+    BOOST_DESCRIBE_MAYBE_UNUSED BOOST_DESCRIBE_PUBLIC_MEMBERS_(C BOOST_DESCRIBE_PP_UNPACK Members) \
+    BOOST_DESCRIBE_MAYBE_UNUSED BOOST_DESCRIBE_PROTECTED_MEMBERS_(C) \
+    BOOST_DESCRIBE_MAYBE_UNUSED BOOST_DESCRIBE_PRIVATE_MEMBERS_(C)
 
 #endif
 

include/boost/describe/detail/config.hpp

@@ -27,4 +27,12 @@
 # define BOOST_DESCRIBE_CONSTEXPR_OR_CONST const
 #endif
 
+#define BOOST_DESCRIBE_MAYBE_UNUSED
+#if defined(__has_cpp_attribute)
+# if __has_cpp_attribute(maybe_unused)
+#  undef BOOST_DESCRIBE_MAYBE_UNUSED
+#  define BOOST_DESCRIBE_MAYBE_UNUSED [[maybe_unused]]
+# endif
+#endif
+
 #endif // #ifndef BOOST_DESCRIBE_DETAIL_CONFIG_HPP_INCLUDED

include/boost/describe/enum.hpp

@@ -71,13 +71,13 @@ template<class... T> auto enum_descriptor_fn_impl( int, T... )
 
 #define BOOST_DESCRIBE_ENUM(E, ...) \
     static_assert(std::is_enum<E>::value, "BOOST_DESCRIBE_ENUM should only be used with enums"); \
-    BOOST_DESCRIBE_ENUM_BEGIN(E) \
+    BOOST_DESCRIBE_MAYBE_UNUSED BOOST_DESCRIBE_ENUM_BEGIN(E) \
     BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_ENUM_ENTRY, E, ##__VA_ARGS__) \
     BOOST_DESCRIBE_ENUM_END(E)
 
 #define BOOST_DESCRIBE_NESTED_ENUM(E, ...) \
     static_assert(std::is_enum<E>::value, "BOOST_DESCRIBE_NESTED_ENUM should only be used with enums"); \
-    friend BOOST_DESCRIBE_ENUM_BEGIN(E) \
+    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)
 

meta/libraries.json

@@ -9,6 +9,7 @@
     ],
     "description": "A C++14 reflection library.",
     "category": [
+        "Emulation",
         "Metaprogramming"
     ]
 }

test/Jamfile

@@ -63,6 +63,9 @@ run operator_lt_test.cpp ;
 run descriptor_by_name_test.cpp ;
 run descriptor_by_pointer_test.cpp ;
 
+compile unnamed_namespace_test.cpp ;
+compile unnamed_namespace_test2.cpp ;
+
 # examples
 
 obj describe_cxx14 : describe_cxx14.cpp ;

test/unnamed_namespace_test.cpp

@@ -0,0 +1,35 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe.hpp>
+
+#if !defined(BOOST_DESCRIBE_CXX14)
+
+#include <boost/config/pragma_message.hpp>
+
+BOOST_PRAGMA_MESSAGE("Skipping test because C++14 is not available")
+
+#else
+
+namespace
+{
+
+enum E { v };
+
+BOOST_DESCRIBE_ENUM(E, v)
+
+struct S
+{
+};
+
+BOOST_DESCRIBE_STRUCT(S, (), ())
+
+class C
+{
+    BOOST_DESCRIBE_CLASS(C, (), (), (), ())
+};
+
+} // namespace
+
+#endif // !defined(BOOST_DESCRIBE_CXX14)

test/unnamed_namespace_test2.cpp

@@ -0,0 +1,45 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe.hpp>
+
+#if !defined(BOOST_DESCRIBE_CXX14)
+
+#include <boost/config/pragma_message.hpp>
+
+BOOST_PRAGMA_MESSAGE("Skipping test because C++14 is not available")
+
+#else
+
+namespace
+{
+
+enum E { v };
+
+BOOST_DESCRIBE_ENUM(E, v)
+
+struct X
+{
+};
+
+BOOST_DESCRIBE_STRUCT(X, (), ())
+
+class Y
+{
+    BOOST_DESCRIBE_CLASS(Y, (), (), (), ())
+};
+
+} // namespace
+
+using namespace boost::describe;
+
+using L1 = describe_enumerators<E>;
+
+using L2 = describe_bases<X, mod_any_access>;
+using L3 = describe_members<X, mod_any_access>;
+
+using L4 = describe_bases<Y, mod_any_access>;
+using L5 = describe_members<Y, mod_any_access>;
+
+#endif // !defined(BOOST_DESCRIBE_CXX14)