review

include/boost/pfr/config.hpp

@@ -98,8 +98,16 @@
 #   endif
 #endif
 
+#ifndef BOOST_PFR_FUNCTION_MACRO_SUPPORTED
+#   if defined(__clang__) || defined(__GNUC__) || defined(_MSC_VER)
+#       define BOOST_PFR_FUNCTION_MACRO_SUPPORTED 1
+#   else
+#       define BOOST_PFR_FUNCTION_MACRO_SUPPORTED 0
+#   endif
+#endif
+
 #ifndef BOOST_PFR_ENABLE_GETTING_NAMES
-#   if defined(__cpp_nontype_template_args) && __cpp_nontype_template_args >= 201911
+#   if defined(__cpp_nontype_template_args) && __cpp_nontype_template_args >= 201911 && BOOST_PFR_FUNCTION_MACRO_SUPPORTED
 #       define BOOST_PFR_ENABLE_GETTING_NAMES 1
 #   else
 #       define BOOST_PFR_ENABLE_GETTING_NAMES 0

include/boost/pfr/core_name.hpp

@@ -28,7 +28,7 @@ namespace boost { namespace pfr {
 
 template <std::size_t I, class T>
 constexpr auto get_name() noexcept {
-    return detail::sequence_tuple::get<I>( detail::tie_as_names_tuple<T>() );
+    return detail::get_name<T, I>();
 }
 
 // FIXME: implement this

include/boost/pfr/detail/core_name.hpp

@@ -14,8 +14,8 @@
 
 #include <boost/pfr/detail/config.hpp>
 
-// Each core_name provides `TODO:` and
-// `TODO:` functions.
+// Each core_name provides `boost::pfr::detail::get_name` and
+// `boost::pfr::detail::tie_as_names_tuple` functions.
 //
 // The whole functional of extracting field's names is build on top of those
 // two functions.

include/boost/pfr/detail/core_name14_disabled.hpp

@@ -23,12 +23,21 @@ constexpr auto make_sequence_tuple(Args... args) noexcept {
     return sequence_tuple::tuple<Args...>{ args... };
 }
 
+template <class T, std::size_t I>
+constexpr auto get_name() noexcept {
+    static_assert(
+        sizeof(T) && false,
+        "====================> Boost.PFR: Field's names extracting functionality requires C++20 and compiler that supports __PRETTY_FUNCTION__ or __FUNCSIG__ macro (GCC, Clang or MSVC)."
+    );
+    
+    return nullptr;
+}
 
 template <class T>
 constexpr auto tie_as_names_tuple() noexcept {
     static_assert(
         sizeof(T) && false,
-        "====================> Boost.PFR: Extraction of field's names is allowed only in C++20"
+        "====================> Boost.PFR: Field's names extracting functionality requires C++20 and compiler that supports __PRETTY_FUNCTION__ or __FUNCSIG__ macro (GCC, Clang or MSVC)."
     );
 
     return detail::make_sequence_tuple(); 

include/boost/pfr/detail/core_name20_static.hpp

@@ -20,6 +20,7 @@
 #include <type_traits>
 #include <string_view>
 #include <array>
+#include <algorithm> // for std::ranges::copy
 
 namespace boost { namespace pfr { namespace detail {
 
@@ -30,7 +31,7 @@ constexpr auto make_sequence_tuple(Args... args) noexcept {
 }
 
 template <auto& ptr> 
-constexpr auto name_of_field_impl() noexcept {
+consteval auto name_of_field_impl() noexcept {
 #ifdef _MSC_VER
     constexpr std::string_view sv = __FUNCSIG__;
     constexpr auto last = sv.find_last_not_of(" >(", sv.size() - 6);
@@ -38,11 +39,11 @@ constexpr auto name_of_field_impl() noexcept {
     constexpr std::string_view sv = __PRETTY_FUNCTION__;
     constexpr auto last = sv.find_last_not_of(" ])");
 #endif
-    constexpr auto first = sv.find_last_not_of("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_0123456789", last);
-    std::array<char, last - first + 1> res{};
-    auto it = res.data();
-    for (auto a = first+1; a <= last; ++a)
-        *it++ = sv[a];
+    constexpr auto first = sv.find_last_of(":", last);
+    auto res = std::array<char, last - first + 1>{};
+    std::ranges::copy(sv.begin()+first+1,
+                      sv.begin()+last+1,
+                      res.begin());
     return res;
 }
 
@@ -59,6 +60,20 @@ constexpr auto tie_as_names_tuple_impl(std::index_sequence<I...>) noexcept {
     return detail::make_sequence_tuple(std::string_view{stored_name_of_field<T, I>.data()}...);
 }
 
+template <class T, std::size_t I>
+constexpr std::string_view get_name() noexcept {
+    static_assert(
+        !std::is_union<T>::value,
+        "====================> Boost.PFR: For safety reasons it is forbidden to reflect unions. See `Reflection of unions` section in the docs for more info."
+    );
+    static_assert(
+        sizeof(T) && BOOST_PFR_USE_CPP17,
+        "====================> Boost.PFR: Extraction of field's names is allowed only when the BOOST_PFR_USE_CPP17 macro enabled."
+   );
+   
+   return stored_name_of_field<T, I>.data();  
+}
+
 template <class T>
 constexpr auto tie_as_names_tuple() noexcept {
     static_assert(

test/core_name/Jamfile.v2

@@ -51,6 +51,8 @@ test-suite pfr_tests
   :
     [ run fields_names.cpp : : : : ]
     [ run fields_names_constexpr.cpp : : : : ]
+    [ run fields_names_nonascii.cpp : : : : ]
+    [ run fields_names_unnamed_struct.cpp : : : <cxxflags>"-fpermissive" : ]
   ;
 
 

test/core_name/fields_names.cpp

@@ -58,6 +58,7 @@ void test_names_as_array() {
     }
 }
 
+
 } // anonymous namespace
 
 

test/core_name/fields_names_nonascii.cpp

@@ -0,0 +1,50 @@
+// Copyright (c) 2023 Bela Schaum, X-Ryl669, Denis Mikhailov.
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+
+// Initial implementation by Bela Schaum, https://github.com/schaumb
+// The way to make it union and UB free by X-Ryl669, https://github.com/X-Ryl669
+//
+
+#include <boost/pfr/core_name.hpp>
+
+#include <boost/core/lightweight_test.hpp>
+
+namespace testing {
+
+namespace {
+
+struct Aggregate {
+    int _π;
+};
+
+void test_get_name() {
+    BOOST_TEST_EQ( ((boost::pfr::get_name<0, Aggregate>())), "_π");
+}
+
+void test_names_as_array() {
+    const auto expected = std::array<std::string_view, 1>{
+        "_π"
+    };
+    const auto value = boost::pfr::names_as_array<Aggregate>();
+    BOOST_TEST_EQ(expected.size(), value.size());
+    for (std::size_t i=0;i<expected.size();++i) {
+        BOOST_TEST_EQ(value[i], expected[i]);
+    }
+}
+
+} // anonymous namespace
+
+
+} // namespace testing
+
+int main() {
+    testing::test_get_name();
+    testing::test_names_as_array();
+
+    return boost::report_errors();
+}
+
+

test/core_name/fields_names_unnamed_struct.cpp

@@ -0,0 +1,56 @@
+// Copyright (c) 2023 Bela Schaum, X-Ryl669, Denis Mikhailov.
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+
+// Initial implementation by Bela Schaum, https://github.com/schaumb
+// The way to make it union and UB free by X-Ryl669, https://github.com/X-Ryl669
+//
+
+#include <boost/pfr/core_name.hpp>
+
+#include <boost/core/lightweight_test.hpp>
+
+namespace testing {
+
+namespace {
+
+struct {
+    int field_of_unnamed_structure;
+} unnamed;
+
+void test_get_name() {
+    BOOST_TEST_EQ( ((boost::pfr::get_name<0, decltype(unnamed)>())), "field_of_unnamed_structure");
+}
+
+void test_names_as_array() {
+    const auto expected = std::array<std::string_view, 1>{
+        "field_of_unnamed_structure"
+    };
+    const auto value = boost::pfr::names_as_array<decltype(unnamed)>();
+    BOOST_TEST_EQ(expected.size(), value.size());
+    for (std::size_t i=0;i<expected.size();++i) {
+        BOOST_TEST_EQ(value[i], expected[i]);
+    }
+}
+
+void test_get_name_for_local_structure() {
+    struct A { int a_field_name; };
+    BOOST_TEST_EQ( ((boost::pfr::get_name<0, A>())), "a_field_name" );
+}
+
+} // anonymous namespace
+
+
+} // namespace testing
+
+int main() {
+    testing::test_get_name();
+    testing::test_names_as_array();
+    testing::test_get_name_for_local_structure();
+
+    return boost::report_errors();
+}
+
+