Replace macos-10.15 with macos-11 in ci.yml

Poison BOOST_DESCRIBE_ENUM in class scope

.github/workflows/ci.yml

@@ -47,6 +47,10 @@ jobs:
             cxxstd: "03,11,14,17,2a"
             os: ubuntu-20.04
             install: g++-11
+          - toolset: gcc-12
+            cxxstd: "03,11,14,17,20"
+            os: ubuntu-22.04
+            install: g++-12
           - toolset: clang
             compiler: clang++-3.9
             cxxstd: "03,11,14"
@@ -97,9 +101,19 @@ jobs:
             cxxstd: "03,11,14,17,2a"
             os: ubuntu-20.04
             install: clang-12
+          - toolset: clang
+            compiler: clang++-13
+            cxxstd: "03,11,14,17,20"
+            os: ubuntu-22.04
+            install: clang-13
+          - toolset: clang
+            compiler: clang++-14
+            cxxstd: "03,11,14,17,20"
+            os: ubuntu-22.04
+            install: clang-14
           - toolset: clang
             cxxstd: "03,11,14,17,2a"
-            os: macos-10.15
+            os: macos-11
 
     runs-on: ${{matrix.os}}
 
@@ -148,28 +162,32 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - toolset: msvc-14.1
-            cxxstd: "14,17,latest"
-            addrmd: 32,64
-            os: windows-2016
-          - toolset: msvc-14.2
-            cxxstd: "14,17,latest"
+          - toolset: msvc-14.0
+            cxxstd: "14,latest"
             addrmd: 32,64
             os: windows-2019
           - toolset: msvc-14.2
-            cxxstd: "14,17,latest"
+            cxxstd: "14,17,20,latest"
+            addrmd: 32,64
+            os: windows-2019
+          - toolset: msvc-14.2
+            cxxstd: "14,17,20,latest"
             addrmd: 32,64
             cxxflags: "-Zc:preprocessor"
             os: windows-2019
           - toolset: msvc-14.3
-            cxxstd: "14,17,latest"
+            cxxstd: "14,17,20,latest"
             addrmd: 32,64
             os: windows-2022
           - toolset: msvc-14.3
-            cxxstd: "14,17,latest"
+            cxxstd: "14,17,20,latest"
             addrmd: 32,64
             cxxflags: "-Zc:preprocessor"
             os: windows-2022
+          - toolset: clang-win
+            cxxstd: "14,17,latest"
+            addrmd: 32,64
+            os: windows-2022
           - toolset: gcc
             cxxstd: "03,11,14,17,2a"
             addrmd: 64
@@ -207,4 +225,163 @@ jobs:
         run: |
           cd ../boost-root
           if not "${{matrix.cxxflags}}" == "" set CXXFLAGS=cxxflags=${{matrix.cxxflags}}
-          b2 -j3 libs/%LIBRARY%/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} %CXXFLAGS% variant=debug,release
+          b2 -j3 libs/%LIBRARY%/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} %CXXFLAGS% variant=debug,release embed-manifest-via=linker
+
+  posix-cmake-subdir:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-18.04
+          - os: ubuntu-20.04
+          - os: ubuntu-22.04
+          - os: macos-11
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install packages
+        if: matrix.install
+        run: sudo apt install ${{matrix.install}}
+
+      - name: Setup Boost
+        run: |
+          echo GITHUB_REPOSITORY: $GITHUB_REPOSITORY
+          LIBRARY=${GITHUB_REPOSITORY#*/}
+          echo LIBRARY: $LIBRARY
+          echo "LIBRARY=$LIBRARY" >> $GITHUB_ENV
+          echo GITHUB_BASE_REF: $GITHUB_BASE_REF
+          echo GITHUB_REF: $GITHUB_REF
+          REF=${GITHUB_BASE_REF:-$GITHUB_REF}
+          REF=${REF#refs/heads/}
+          echo REF: $REF
+          BOOST_BRANCH=develop && [ "$REF" == "master" ] && BOOST_BRANCH=master || true
+          echo BOOST_BRANCH: $BOOST_BRANCH
+          cd ..
+          git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          cp -r $GITHUB_WORKSPACE/* libs/$LIBRARY
+          git submodule update --init tools/boostdep
+          python tools/boostdep/depinst/depinst.py --git_args "--jobs 3" $LIBRARY
+
+      - name: Use library with add_subdirectory
+        run: |
+          cd ../boost-root/libs/$LIBRARY/test/cmake_subdir_test
+          mkdir __build__ && cd __build__
+          cmake ..
+          cmake --build .
+          ctest --output-on-failure --no-tests=error
+
+  posix-cmake-install:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-18.04
+          - os: ubuntu-20.04
+          - os: ubuntu-22.04
+          - os: macos-11
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install packages
+        if: matrix.install
+        run: sudo apt install ${{matrix.install}}
+
+      - name: Setup Boost
+        run: |
+          echo GITHUB_REPOSITORY: $GITHUB_REPOSITORY
+          LIBRARY=${GITHUB_REPOSITORY#*/}
+          echo LIBRARY: $LIBRARY
+          echo "LIBRARY=$LIBRARY" >> $GITHUB_ENV
+          echo GITHUB_BASE_REF: $GITHUB_BASE_REF
+          echo GITHUB_REF: $GITHUB_REF
+          REF=${GITHUB_BASE_REF:-$GITHUB_REF}
+          REF=${REF#refs/heads/}
+          echo REF: $REF
+          BOOST_BRANCH=develop && [ "$REF" == "master" ] && BOOST_BRANCH=master || true
+          echo BOOST_BRANCH: $BOOST_BRANCH
+          cd ..
+          git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          cp -r $GITHUB_WORKSPACE/* libs/$LIBRARY
+          git submodule update --init tools/boostdep
+          python tools/boostdep/depinst/depinst.py --git_args "--jobs 3" $LIBRARY
+
+      - name: Configure
+        run: |
+          cd ../boost-root
+          mkdir __build__ && cd __build__
+          cmake -DBOOST_INCLUDE_LIBRARIES=$LIBRARY -DCMAKE_INSTALL_PREFIX=~/.local ..
+
+      - name: Install
+        run: |
+          cd ../boost-root/__build__
+          cmake --build . --target install
+
+      - name: Use the installed library
+        run: |
+          cd ../boost-root/libs/$LIBRARY/test/cmake_install_test && mkdir __build__ && cd __build__
+          cmake -DCMAKE_INSTALL_PREFIX=~/.local ..
+          cmake --build .
+          ctest --output-on-failure --no-tests=error
+
+  posix-cmake-test:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-18.04
+          - os: ubuntu-20.04
+          - os: ubuntu-22.04
+          - os: macos-11
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install packages
+        if: matrix.install
+        run: sudo apt install ${{matrix.install}}
+
+      - name: Setup Boost
+        run: |
+          echo GITHUB_REPOSITORY: $GITHUB_REPOSITORY
+          LIBRARY=${GITHUB_REPOSITORY#*/}
+          echo LIBRARY: $LIBRARY
+          echo "LIBRARY=$LIBRARY" >> $GITHUB_ENV
+          echo GITHUB_BASE_REF: $GITHUB_BASE_REF
+          echo GITHUB_REF: $GITHUB_REF
+          REF=${GITHUB_BASE_REF:-$GITHUB_REF}
+          REF=${REF#refs/heads/}
+          echo REF: $REF
+          BOOST_BRANCH=develop && [ "$REF" == "master" ] && BOOST_BRANCH=master || true
+          echo BOOST_BRANCH: $BOOST_BRANCH
+          cd ..
+          git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          cp -r $GITHUB_WORKSPACE/* libs/$LIBRARY
+          git submodule update --init tools/boostdep
+          python tools/boostdep/depinst/depinst.py --git_args "--jobs 3" $LIBRARY
+
+      - name: Configure
+        run: |
+          cd ../boost-root
+          mkdir __build__ && cd __build__
+          cmake -DBOOST_INCLUDE_LIBRARIES=$LIBRARY -DBUILD_TESTING=ON ..
+
+      - name: Build tests
+        run: |
+          cd ../boost-root/__build__
+          cmake --build . --target tests
+
+      - name: Run tests
+        run: |
+          cd ../boost-root/__build__
+          ctest --output-on-failure --no-tests=error

README.md

@@ -9,7 +9,7 @@ for more information and usage examples.
 
 * GCC 5 or later with `-std=c++14` or above
 * Clang 3.9 or later with `-std=c++14` or above
-* Visual Studio 2015, 2017, 2019
+* Visual Studio 2015 or later
 
 Tested on [Github Actions](https://github.com/boostorg/describe/actions) and
 [Appveyor](https://ci.appveyor.com/project/pdimov/describe).

appveyor.yml

@@ -1,4 +1,4 @@
-# Copyright 2016-2020 Peter Dimov
+# Copyright 2016-2021 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)
 
@@ -15,27 +15,19 @@ branches:
 environment:
   matrix:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      TOOLSET: msvc-14.0
+      TOOLSET: msvc-9.0,msvc-10.0,msvc-11.0
+      ADDRMD: 32
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      TOOLSET: msvc-12.0,msvc-14.0
       ADDRMD: 32,64
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       TOOLSET: msvc-14.1
-      CXXSTD: 14,17
-      ADDRMD: 32,64
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-      TOOLSET: clang-win
-      CXXSTD: 14,17,latest
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
-      TOOLSET: msvc-14.2
       CXXSTD: 14,17,latest
       ADDRMD: 32,64
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       TOOLSET: clang-win
       CXXSTD: 14,17,latest
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
-      TOOLSET: msvc-14.2
-      CXXSTD: 14,17,latest
       ADDRMD: 32,64
-      CXXFLAGS: -Zc:preprocessor
 
 install:
   - set BOOST_BRANCH=develop

doc/describe/changes.adoc

@@ -8,9 +8,17 @@ https://www.boost.org/LICENSE_1_0.txt
 # Revision History
 :idprefix:
 
+## Changes in Boost 1.79.0
+
+* Enabled unions in `BOOST_DESCRIBE_STRUCT` and updated examples to check `std::is_union<T>`.
+* Added example of defining a `fmtlib` class formatter.
+* Added example of defining a `fmtlib` enum formatter.
+* Added example of printing pointers to members.
+
 ## Changes in Boost 1.78.0
 
 * Added `has_describe_enumerators`, `has_describe_bases`, `has_describe_members`.
 * Added `enum_to_string`, `enum_from_string`.
 * Added relational and stream insertion operators.
 * Added `descriptor_by_name`, `descriptor_by_pointer`.
+* Added `struct_to_tuple` example.

doc/describe/examples.adoc

@@ -19,6 +19,15 @@ descriptors using `mp11::mp_for_each` and prints them.
 include::../../example/printing_enums_ct.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+v1: 11
+v2: 12
+v3: 5
+----
+
 [#example_printing_enums_rt]
 ## Printing Enumerators with a Run Time Loop
 
@@ -31,6 +40,18 @@ an ordinary `for` loop, instead of `mp_for_each`.
 include::../../example/printing_enums_rt.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+v1: 0
+v2: 1
+v3: 2
+v4: 3
+v5: 4
+v6: 5
+----
+
 [#example_enum_to_string]
 ## enum_to_string
 
@@ -43,6 +64,14 @@ to a named value, the function returns `"(unnamed)"`.
 include::../../example/enum_to_string.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+E(3): v1
+E(0): (unnamed)
+----
+
 Since release 1.78.0, the library provides `enum_to_string`.
 It differs from the one in the example by having a second
 parameter that determines what should be returned when the
@@ -60,6 +89,16 @@ does not correspond to any enumerator name, throws an exception.
 include::../../example/string_to_enum.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+v1: 0
+v2: 1
+v3: 2
+v4: Invalid enumerator name 'v4' for enum type 'enum E'
+----
+
 Since release 1.78.0, the library provides `enum_from_string`.
 It differs from the function in the example by signaling failure
 by a `bool` return value instead of using exceptions. The
@@ -85,6 +124,13 @@ change its state and hence cannot violate its invariant.)
 include::../../example/print_function.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+{{.m1 = 1}, {.m2 = 2}, .m1 = 3, .m2 = 4}
+----
+
 Since release 1.78.0, this universal `operator<<` is supplied
 by the library, in the `boost::describe::operators` namespace.
 It's enabled by means of a using declaration in the namespace
@@ -122,6 +168,13 @@ to all annotated classes also defined in `app`.
 include::../../example/hash_value.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+12526671134390370097
+----
+
 [#example_equality]
 ## Implementing operator==
 
@@ -137,6 +190,13 @@ to all annotated classes also defined in `app`.
 include::../../example/equality.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+true false
+----
+
 Since release 1.78.0, this universal `operator==` is supplied
 by the library, in the `boost::describe::operators` namespace.
 It's enabled by means of a using declaration in the namespace
@@ -161,6 +221,25 @@ using boost::describe::operators::operator==;
 The rest of the relational operators are also provided and can
 be enabled similarly.
 
+[#example_struct_to_tuple]
+## struct_to_tuple
+
+This example defines a function `struct_to_tuple` that takes
+a described class type as an argument and returns a tuple of
+all its public members.
+
+[source]
+----
+include::../../example/struct_to_tuple.cpp[lines=5..-1]
+----
+
+Sample output:
+
+[listing]
+----
+std::tuple<int, float>: 1, 3.14
+----
+
 [#example_to_json]
 ## Automatic Conversion to JSON
 
@@ -182,6 +261,13 @@ disabled in this case using `std::enable_if_t`.
 include::../../example/to_json.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+{"v":[{"x":1,"y":2},{"x":3,"y":4}],"m":{"k1":{"x":5,"y":6},"k2":{"x":7,"y":8}}}
+----
+
 [#example_from_json]
 ## Automatic Conversion from JSON
 
@@ -194,6 +280,14 @@ an annotated struct.
 include::../../example/from_json.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+jv: {"x":1,"y":2}
+a: { 1, 2 }
+----
+
 [#example_serialization]
 ## Automatic Serialization
 
@@ -206,6 +300,49 @@ support to annotated classes.
 include::../../example/serialization.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
+<!DOCTYPE boost_serialization>
+<boost_serialization signature="serialization::archive" version="19">
+<c1 class_id="0" tracking_level="0" version="0">
+        <v class_id="1" tracking_level="0" version="0">
+                <count>3</count>
+                <item_version>0</item_version>
+                <item class_id="2" tracking_level="0" version="0">
+                        <base.1 class_id="3" tracking_level="0" version="0">
+                                <x>1</x>
+                        </base.1>
+                        <base.2 class_id="4" tracking_level="0" version="0">
+                                <y>2</y>
+                        </base.2>
+                </item>
+                <item>
+                        <base.1>
+                                <x>3</x>
+                        </base.1>
+                        <base.2>
+                                <y>4</y>
+                        </base.2>
+                </item>
+                <item>
+                        <base.1>
+                                <x>5</x>
+                        </base.1>
+                        <base.2>
+                                <y>6</y>
+                        </base.2>
+                </item>
+        </v>
+</c1>
+</boost_serialization>
+
+
+22 serialization::archive 19 0 0 0 0 3 0 0 0 0 0 1 0 0 2 3 4 5 6
+----
+
 [#example_json_rpc]
 ## Automatic JSON RPC
 
@@ -219,6 +356,14 @@ in a `boost::json::value`.
 include::../../example/json_rpc.cpp[lines=5..-1]
 ----
 
+Sample output:
+
+[listing]
+----
+"Hello, world!"
+3
+----
+
 [#example_console]
 ## Interactive Variable Console
 
@@ -230,3 +375,120 @@ for converting the variables to and from a string form.
 ----
 include::../../example/console.cpp[lines=9..-1]
 ----
+
+Sample output:
+
+[listing]
+----
+
+> help
+"Enter a variable name ('x', 'y', 'v', or 'm') to print its value; enter variable=value to assign a new value to a variable. Values are in JSON format."
+
+> x
+1
+
+> y
+3.14E0
+
+> v
+[1,2,3]
+
+> m
+{"BTC":4.489868E4,"ETH":1.38657E3}
+
+> x="hello"
+Error: not a number [boost.json:15]
+
+> x=3.14
+Error: not exact [boost.json:16]
+
+> x=4
+
+> x
+4
+
+> y=6.28
+
+> y
+6.28E0
+
+> v=["hello", "world"]
+Error: not a number [boost.json:15]
+
+> v=[1.2, 3.4]
+Error: not exact [boost.json:16]
+
+> v=[11, 27]
+
+> c
+Error: 'c': no such variable
+
+> v
+[11,27]
+
+> m={"BTC": 42139.07, "ETH": 2912.00}
+
+> m
+{"BTC":4.213907E4,"ETH":2.912E3}
+----
+
+[#example_fmtlib_class_formatter]
+## `fmtlib` Class Formatter
+
+This example defines a universal https://github.com/fmtlib/fmt[`fmtlib`]
+formatter that works on any class or struct type that has been described
+with `BOOST_DESCRIBE_STRUCT` or `BOOST_DESCRIBE_CLASS`. It's similar to
+<<example_print_function,the universal print function shown above>>.
+
+[source]
+----
+include::../../example/fmtlib_class_formatter.cpp[lines=5..-1]
+----
+
+Sample output:
+
+[listing]
+----
+{ { .r=255, .g=192, .b=16 }, .first={ .x=1, .y=2 }, .last={ .x=3, .y=4 } }
+----
+
+[#example_fmtlib_enum_formatter]
+## `fmtlib` Enum Formatter
+
+This example defines a https://github.com/fmtlib/fmt[`fmtlib`] formatter
+for described enums.
+
+[source]
+----
+include::../../example/fmtlib_enum_formatter.cpp[lines=5..-1]
+----
+
+Sample output:
+
+[listing]
+----
+____v1____
+____7_____
+----
+
+[#example_pm_to_string]
+## Printing Pointers to Members
+
+This example defines an `operator<<` overload for pointers to members.
+
+[source]
+----
+include::../../example/pm_to_string.cpp[lines=9..-1]
+----
+
+Sample output:
+
+[listing]
+----
+&X::m [int]
+&X::f [int() const]
+&Y::m [int]
+&X::f [int() const]
+&Y::g [int() const]
+&Z::(unknown) [void()]
+----

doc/describe/implementation.adoc

@@ -16,7 +16,7 @@ https://boost.org/libs/mp11[Boost.Mp11].
 
 * GCC 5 or later with `-std=c++14` or above
 * Clang 3.9 or later with `-std=c++14` or above
-* Visual Studio 2015, 2017, 2019
+* Visual Studio 2015 or later
 
 Tested on https://github.com/boostorg/describe/actions[Github Actions]
 and https://ci.appveyor.com/project/pdimov/describe[Appveyor].

doc/describe/reference.adoc

@@ -88,7 +88,7 @@ enum class E: Base { v1, v2, ..., vN };
 BOOST_DESCRIBE_ENUM(E, v1, v2, ..., vN)
 ```
 
-## <boost/describe/enumerators.hpp>
+## <boost/describe/{zwsp}enumerators{zwsp}.hpp>
 
 ```
 namespace boost {
@@ -332,7 +332,7 @@ Since the library does not provide a way to describe bases and members separatel
 `has_describe_bases` and `has_describe_members` are, in practice, synonyms. They
 are provided separately for consistency.
 
-## <boost/describe/enum_to_string.hpp>
+## <boost/describe/{zwsp}enum_to_string{zwsp}.hpp>
 
 ```
 namespace boost {
@@ -349,7 +349,7 @@ The function `enum_to_string` returns the name of the enumerator `e`. `E` must
 be a described enumeration type. If `e` does not correspond to one of the described
 values, the function returns `def`.
 
-## <boost/describe/enum_from_string.hpp>
+## <boost/describe/{zwsp}enum_from_string{zwsp}.hpp>
 
 ```
 namespace boost {
@@ -440,7 +440,7 @@ Returns the negated result of `operator<`.
 Outputs a representation of `t` to `os` by recursively using `operator<<`
 to output all bases and then all members.
 
-## <boost/describe/descriptor_by_name.hpp>
+## <boost/describe/{zwsp}descriptor_by_name{zwsp}.hpp>
 
 ```
 namespace boost {
@@ -478,7 +478,7 @@ using N = BOOST_DESCRIBE_MAKE_NAME(some_member);
 using D = descriptor_by_name<L, N>; // descriptor for SomeType::some_member
 ```
 
-## <boost/describe/descriptor_by_pointer.hpp>
+## <boost/describe/{zwsp}descriptor_by_pointer{zwsp}.hpp>
 
 ```
 namespace boost {

example/equality.cpp

@@ -13,7 +13,8 @@ namespace app
 {
 template<class T,
     class Bd = describe_bases<T, mod_any_access>,
-    class Md = describe_members<T, mod_any_access>>
+    class Md = describe_members<T, mod_any_access>,
+    class En = std::enable_if_t<!std::is_union<T>::value> >
     bool operator==( T const& t1, T const& t2 )
 {
     bool r = true;

example/fmtlib_class_formatter.cpp

@@ -0,0 +1,101 @@
+// Copyright 2022 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe.hpp>
+#include <boost/mp11.hpp>
+#include <fmt/format.h>
+#include <type_traits>
+
+template<class T> struct fmt::formatter<T, char, std::enable_if_t<
+    boost::describe::has_describe_bases<T>::value &&
+    boost::describe::has_describe_members<T>::value &&
+    !std::is_union<T>::value>>
+{
+    constexpr auto parse( format_parse_context& ctx )
+    {
+        auto it = ctx.begin(), end = ctx.end();
+
+        if( it != end && *it != '}' )
+        {
+            ctx.error_handler().on_error( "invalid format" );
+        }
+
+        return it;
+    }
+
+    auto format( T const& t, format_context& ctx ) const
+    {
+        using namespace boost::describe;
+
+        using Bd = describe_bases<T, mod_any_access>;
+        using Md = describe_members<T, mod_any_access>;
+
+        auto out = ctx.out();
+
+        *out++ = '{';
+
+        bool first = true;
+
+        boost::mp11::mp_for_each<Bd>([&](auto D){
+
+            if( !first )
+            {
+                *out++ = ',';
+            }
+
+            first = false;
+
+            out = fmt::format_to( out, " {}",
+                (typename decltype(D)::type const&)t );
+        });
+
+        boost::mp11::mp_for_each<Md>([&](auto D){
+
+            if( !first )
+            {
+                *out++ = ',';
+            }
+
+            first = false;
+
+            out = fmt::format_to( out, " .{}={}",
+                D.name, t.*D.pointer );
+        });
+
+        if( !first )
+        {
+            *out++ = ' ';
+        }
+
+        *out++ = '}';
+
+        return out;
+    }
+};
+
+struct point
+{
+    int x, y;
+};
+
+BOOST_DESCRIBE_STRUCT( point, (), (x, y) )
+
+struct color
+{
+    unsigned char r, g, b;
+};
+
+BOOST_DESCRIBE_STRUCT( color, (), (r, g, b) )
+
+struct line: color
+{
+    point first, last;
+};
+
+BOOST_DESCRIBE_STRUCT( line, (color), (first, last) )
+
+int main()
+{
+    fmt::print( "{}\n", line{ { 255, 192, 16 }, { 1, 2 }, { 3, 4 } } );
+}

example/fmtlib_enum_formatter.cpp

@@ -0,0 +1,60 @@
+// Copyright 2022 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe.hpp>
+#include <fmt/format.h>
+#include <type_traits>
+
+template<class T> struct fmt::formatter<T, char, std::enable_if_t<
+    boost::describe::has_describe_enumerators<T>::value>>
+{
+private:
+
+    using U = std::underlying_type_t<T>;
+
+    fmt::formatter<fmt::string_view, char> sf_;
+    fmt::formatter<U, char> nf_;
+
+public:
+
+    constexpr auto parse( format_parse_context& ctx )
+    {
+        auto i1 = sf_.parse( ctx );
+        auto i2 = nf_.parse( ctx );
+
+        if( i1 != i2 )
+        {
+            ctx.error_handler().on_error( "invalid format" );
+        }
+
+        return i1;
+    }
+
+    auto format( T const& t, format_context& ctx ) const
+    {
+        char const * s = boost::describe::enum_to_string( t, 0 );
+
+        if( s )
+        {
+            return sf_.format( s, ctx );
+        }
+        else
+        {
+            return nf_.format( static_cast<U>( t ), ctx );
+        }
+    }
+};
+
+enum E1
+{
+    v1, v2, v3 = 11
+};
+
+BOOST_DESCRIBE_ENUM( E1, v1, v2, v3 )
+
+int main()
+{
+    fmt::print( "{:_^10}\n", E1::v1 );
+    fmt::print( "{:_^10}\n", (E1)7 );
+}

example/from_json.cpp

@@ -19,7 +19,7 @@ template<class T,
     class D1 = boost::describe::describe_members<T,
         boost::describe::mod_public | boost::describe::mod_protected>,
     class D2 = boost::describe::describe_members<T, boost::describe::mod_private>,
-    class En = std::enable_if_t<boost::mp11::mp_empty<D2>::value> >
+    class En = std::enable_if_t<boost::mp11::mp_empty<D2>::value && !std::is_union<T>::value> >
 
     T tag_invoke( boost::json::value_to_tag<T> const&, boost::json::value const& v )
 {

example/hash_value.cpp

@@ -15,7 +15,8 @@ namespace app
 
 template<class T,
     class Bd = describe_bases<T, mod_any_access>,
-    class Md = describe_members<T, mod_any_access>>
+    class Md = describe_members<T, mod_any_access>,
+    class En = std::enable_if_t<!std::is_union<T>::value> >
     std::size_t hash_value( T const & t )
 {
     std::size_t r = 0;

example/pm_to_string.cpp

@@ -0,0 +1,125 @@
+// Copyright 2022 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__GNUC__) && __GNUC__ == 12
+# pragma GCC diagnostic ignored "-Wrestrict" // false positive
+#endif
+
+#include <boost/describe.hpp>
+#include <boost/mp11.hpp>
+#include <boost/core/type_name.hpp>
+#include <string>
+#include <ostream>
+
+namespace detail
+{
+
+template<class T1, class T2>
+constexpr auto equals( T1 t1, T2 t2, int ) -> decltype( t1 == t2 )
+{
+    return t1 == t2;
+}
+
+template<class T1, class T2>
+constexpr bool equals( T1 /*t1*/, T2 /*t2*/, long )
+{
+    return false;
+}
+
+using namespace boost::describe;
+
+template<class T, class C,
+    class L = describe_members<C, mod_any_access | mod_any_member>>
+char const* get_member_name( T C::* pm, int )
+{
+    char const * name = nullptr;
+
+    boost::mp11::mp_for_each<L>([&](auto D){
+
+        if( equals( D.pointer, pm, 0 ) ) name = D.name;
+
+    });
+
+    return name;
+}
+
+template<class T, class C>
+char const* get_member_name( T C::* /*pm*/, long )
+{
+    return nullptr;
+}
+
+} // namespace detail
+
+template<class T, class C>
+std::string pm_to_string( T C::* pm )
+{
+    char const * name = ::detail::get_member_name( pm, 0 );
+
+    if( name == nullptr ) name = "(unknown)";
+
+    return "&" + boost::core::type_name<C>() + "::" + name
+        + " [" + boost::core::type_name<T>() + "]";
+}
+
+template<class T, class C>
+std::ostream& operator<<( std::ostream& os, T C::* pm )
+{
+    os << pm_to_string( pm );
+    return os;
+}
+
+struct X
+{
+    int m;
+    int f() const { return m; }
+};
+
+BOOST_DESCRIBE_STRUCT(X, (), (m, f))
+
+struct Y: public X
+{
+    int m;
+    int g() const { return -m; }
+};
+
+BOOST_DESCRIBE_STRUCT(Y, (X), (m, g))
+
+struct Z
+{
+    void h() {}
+};
+
+#if !defined(_MSC_VER) || defined(__clang__)
+
+// MSVC doesn't support BOOST_DESCRIBE_CLASS inside
+// templates until 2022 in C++20 mode
+
+template<class T1, class T2> struct pair
+{
+    T1 first;
+    T2 second;
+
+    BOOST_DESCRIBE_CLASS(pair, (), (first, second), (), ())
+};
+
+#endif
+
+#include <iostream>
+
+int main()
+{
+    std::cout << &X::m << std::endl;
+    std::cout << &X::f << std::endl;
+
+    std::cout << &Y::m << std::endl;
+    std::cout << &Y::f << std::endl;
+    std::cout << &Y::g << std::endl;
+
+    std::cout << &Z::h << std::endl;
+
+#if !defined(_MSC_VER) || defined(__clang__)
+    std::cout << &pair<int, float>::second << std::endl;
+#endif
+}

example/print_function.cpp

@@ -10,7 +10,8 @@ using namespace boost::describe;
 
 template<class T,
     class Bd = describe_bases<T, mod_any_access>,
-    class Md = describe_members<T, mod_any_access>>
+    class Md = describe_members<T, mod_any_access>,
+    class En = std::enable_if_t<!std::is_union<T>::value> >
     std::ostream& operator<<( std::ostream & os, T const & t )
 {
     os << "{";

example/serialization.cpp

@@ -24,8 +24,8 @@ template<class Archive, class T,
     class D3 = boost::describe::describe_members<T,
         boost::describe::mod_public | boost::describe::mod_protected>,
     class D4 = boost::describe::describe_members<T, boost::describe::mod_private>,
-    class En = std::enable_if_t<
-        boost::mp11::mp_empty<D2>::value && boost::mp11::mp_empty<D4>::value> >
+    class En = std::enable_if_t< boost::mp11::mp_empty<D2>::value &&
+        boost::mp11::mp_empty<D4>::value && !std::is_union<T>::value> >
 
     void serialize( Archive & ar, T & t, boost::serialization::version_type )
 {

example/struct_to_tuple.cpp

@@ -0,0 +1,57 @@
+// 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>
+#include <tuple>
+
+namespace desc = boost::describe;
+
+template<class T, template<class...> class L, class... D>
+auto struct_to_tuple_impl( T const& t, L<D...> )
+{
+    return std::make_tuple( t.*D::pointer... );
+}
+
+template<class T,
+    class Dm = desc::describe_members<T,
+        desc::mod_public | desc::mod_inherited>,
+    class En = std::enable_if_t<!std::is_union<T>::value> >
+auto struct_to_tuple( T const& t )
+{
+    return struct_to_tuple_impl( t, Dm() );
+}
+
+#include <boost/core/type_name.hpp>
+#include <iostream>
+
+struct X
+{
+    int a = 1;
+};
+
+BOOST_DESCRIBE_STRUCT(X, (), (a))
+
+struct Y
+{
+    float b = 3.14f;
+};
+
+BOOST_DESCRIBE_STRUCT(Y, (), (b))
+
+struct Z: X, Y
+{
+};
+
+BOOST_DESCRIBE_STRUCT(Z, (X, Y), ())
+
+int main()
+{
+    Z z;
+
+    auto tp = struct_to_tuple( z );
+
+    std::cout <<
+        boost::core::type_name<decltype(tp)>() << ": "
+        << std::get<0>(tp) << ", " << std::get<1>(tp);
+}

example/to_json.cpp

@@ -16,7 +16,7 @@ template<class T,
     class D1 = boost::describe::describe_members<T,
         boost::describe::mod_public | boost::describe::mod_protected>,
     class D2 = boost::describe::describe_members<T, boost::describe::mod_private>,
-    class En = std::enable_if_t<boost::mp11::mp_empty<D2>::value> >
+    class En = std::enable_if_t<boost::mp11::mp_empty<D2>::value && !std::is_union<T>::value> >
 
     void tag_invoke( boost::json::value_from_tag const&, boost::json::value& v, T const & t )
 {

include/boost/describe/bases.hpp

@@ -21,7 +21,7 @@ namespace describe
 namespace detail
 {
 
-template<class T> using _describe_bases = decltype( boost_base_descriptor_fn( static_cast<T*>(0) ) );
+template<class T> using _describe_bases = decltype( boost_base_descriptor_fn( static_cast<T**>(0) ) );
 
 template<unsigned M> struct base_filter
 {

include/boost/describe/class.hpp

@@ -34,7 +34,7 @@ namespace describe
     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"); \
+    static_assert(std::is_class<C>::value || std::is_union<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) \
@@ -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)
+    static_assert(std::is_class<C>::value || std::is_union<C>::value, "BOOST_DESCRIBE_STRUCT should only be used with class types"); \
+    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/bases.hpp

@@ -37,12 +37,12 @@ template<class... T> auto base_descriptor_fn_impl( int, T... )
 
 #if defined(_MSC_VER) && !defined(__clang__)
 
-#define BOOST_DESCRIBE_BASES(C, ...) inline auto boost_base_descriptor_fn( C * ) \
+#define BOOST_DESCRIBE_BASES(C, ...) inline auto boost_base_descriptor_fn( C** ) \
 { return boost::describe::detail::base_descriptor_fn_impl( 0 BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_BASE_IMPL, C, __VA_ARGS__) ); }
 
 #else
 
-#define BOOST_DESCRIBE_BASES(C, ...) inline auto boost_base_descriptor_fn( C * ) \
+#define BOOST_DESCRIBE_BASES(C, ...) inline auto boost_base_descriptor_fn( C** ) \
 { return boost::describe::detail::base_descriptor_fn_impl( 0 BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_BASE_IMPL, C, ##__VA_ARGS__) ); }
 
 #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/detail/members.hpp

@@ -53,24 +53,24 @@ template<class C, class F> constexpr auto mfn( F * p ) { return p; }
 
 #if defined(_MSC_VER) && !defined(__clang__)
 
-#define BOOST_DESCRIBE_PUBLIC_MEMBERS(C, ...) inline auto boost_public_member_descriptor_fn( C * ) \
+#define BOOST_DESCRIBE_PUBLIC_MEMBERS(C, ...) inline auto boost_public_member_descriptor_fn( C** ) \
 { return boost::describe::detail::member_descriptor_fn_impl<boost::describe::mod_public>( 0 BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_MEMBER_IMPL, C, __VA_ARGS__) ); }
 
-#define BOOST_DESCRIBE_PROTECTED_MEMBERS(C, ...) inline auto boost_protected_member_descriptor_fn( C * ) \
+#define BOOST_DESCRIBE_PROTECTED_MEMBERS(C, ...) inline auto boost_protected_member_descriptor_fn( C** ) \
 { return boost::describe::detail::member_descriptor_fn_impl<boost::describe::mod_protected>( 0 BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_MEMBER_IMPL, C, __VA_ARGS__) ); }
 
-#define BOOST_DESCRIBE_PRIVATE_MEMBERS(C, ...) inline auto boost_private_member_descriptor_fn( C * ) \
+#define BOOST_DESCRIBE_PRIVATE_MEMBERS(C, ...) inline auto boost_private_member_descriptor_fn( C** ) \
 { return boost::describe::detail::member_descriptor_fn_impl<boost::describe::mod_private>( 0 BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_MEMBER_IMPL, C, __VA_ARGS__) ); }
 
 #else
 
-#define BOOST_DESCRIBE_PUBLIC_MEMBERS(C, ...) inline auto boost_public_member_descriptor_fn( C * ) \
+#define BOOST_DESCRIBE_PUBLIC_MEMBERS(C, ...) inline auto boost_public_member_descriptor_fn( C** ) \
 { return boost::describe::detail::member_descriptor_fn_impl<boost::describe::mod_public>( 0 BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_MEMBER_IMPL, C, ##__VA_ARGS__) ); }
 
-#define BOOST_DESCRIBE_PROTECTED_MEMBERS(C, ...) inline auto boost_protected_member_descriptor_fn( C * ) \
+#define BOOST_DESCRIBE_PROTECTED_MEMBERS(C, ...) inline auto boost_protected_member_descriptor_fn( C** ) \
 { return boost::describe::detail::member_descriptor_fn_impl<boost::describe::mod_protected>( 0 BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_MEMBER_IMPL, C, ##__VA_ARGS__) ); }
 
-#define BOOST_DESCRIBE_PRIVATE_MEMBERS(C, ...) inline auto boost_private_member_descriptor_fn( C * ) \
+#define BOOST_DESCRIBE_PRIVATE_MEMBERS(C, ...) inline auto boost_private_member_descriptor_fn( C** ) \
 { return boost::describe::detail::member_descriptor_fn_impl<boost::describe::mod_private>( 0 BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_MEMBER_IMPL, C, ##__VA_ARGS__) ); }
 
 #endif

include/boost/describe/enum.hpp

@@ -42,7 +42,7 @@ template<class... T> auto enum_descriptor_fn_impl( int, T... )
 }
 
 #define BOOST_DESCRIBE_ENUM_BEGIN(E) \
-    inline auto boost_enum_descriptor_fn( E* ) \
+    inline auto boost_enum_descriptor_fn( E** ) \
     { return boost::describe::detail::enum_descriptor_fn_impl( 0
 
 #define BOOST_DESCRIBE_ENUM_ENTRY(E, e) , []{ struct _boost_desc { \
@@ -56,6 +56,7 @@ template<class... T> auto enum_descriptor_fn_impl( int, T... )
 #if defined(_MSC_VER) && !defined(__clang__)
 
 #define BOOST_DESCRIBE_ENUM(E, ...) \
+    namespace should_use_BOOST_DESCRIBE_NESTED_ENUM {} \
     static_assert(std::is_enum<E>::value, "BOOST_DESCRIBE_ENUM should only be used with enums"); \
     BOOST_DESCRIBE_ENUM_BEGIN(E) \
     BOOST_DESCRIBE_PP_FOR_EACH(BOOST_DESCRIBE_ENUM_ENTRY, E, __VA_ARGS__) \
@@ -70,14 +71,15 @@ template<class... T> auto enum_descriptor_fn_impl( int, T... )
 #else
 
 #define BOOST_DESCRIBE_ENUM(E, ...) \
+    namespace should_use_BOOST_DESCRIBE_NESTED_ENUM {} \
     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)
 

include/boost/describe/enumerators.hpp

@@ -19,7 +19,7 @@ namespace describe
 
 // describe_enumerators<E>
 
-template<class E> using describe_enumerators = decltype( boost_enum_descriptor_fn( static_cast<E*>(0) ) );
+template<class E> using describe_enumerators = decltype( boost_enum_descriptor_fn( static_cast<E**>(0) ) );
 
 // has_describe_enumerators<E>
 

include/boost/describe/members.hpp

@@ -29,9 +29,9 @@ namespace detail
 
 // _describe_members<T>
 
-template<class T> using _describe_public_members = decltype( boost_public_member_descriptor_fn( static_cast<T*>(0) ) );
-template<class T> using _describe_protected_members = decltype( boost_protected_member_descriptor_fn( static_cast<T*>(0) ) );
-template<class T> using _describe_private_members = decltype( boost_private_member_descriptor_fn( static_cast<T*>(0) ) );
+template<class T> using _describe_public_members = decltype( boost_public_member_descriptor_fn( static_cast<T**>(0) ) );
+template<class T> using _describe_protected_members = decltype( boost_protected_member_descriptor_fn( static_cast<T**>(0) ) );
+template<class T> using _describe_private_members = decltype( boost_private_member_descriptor_fn( static_cast<T**>(0) ) );
 
 template<class T> using _describe_members = mp11::mp_append<_describe_public_members<T>, _describe_protected_members<T>, _describe_private_members<T>>;
 

include/boost/describe/modifiers.hpp

@@ -34,7 +34,7 @@ BOOST_DESCRIBE_ENUM(modifiers,
     mod_function,
     mod_any_member,
     mod_inherited,
-    mod_hidden);
+    mod_hidden)
 
 BOOST_DESCRIBE_CONSTEXPR_OR_CONST modifiers mod_any_access = static_cast<modifiers>( mod_public | mod_protected | mod_private );
 

include/boost/describe/operators.hpp

@@ -25,8 +25,8 @@ namespace detail
 {
 
 template<class T,
-    class Bd = describe_bases<T, mod_any_access>,
-    class Md = describe_members<T, mod_any_access>>
+    class Bd = describe::describe_bases<T, mod_any_access>,
+    class Md = describe::describe_members<T, mod_any_access>>
 bool eq( T const& t1, T const& t2 )
 {
     bool r = true;
@@ -48,8 +48,8 @@ bool eq( T const& t1, T const& t2 )
 }
 
 template<class T,
-    class Bd = describe_bases<T, mod_any_access>,
-    class Md = describe_members<T, mod_any_access>>
+    class Bd = describe::describe_bases<T, mod_any_access>,
+    class Md = describe::describe_members<T, mod_any_access>>
 bool lt( T const& t1, T const& t2 )
 {
     int r = 0;
@@ -73,8 +73,8 @@ bool lt( T const& t1, T const& t2 )
 }
 
 template<class Os, class T,
-    class Bd = describe_bases<T, mod_any_access>,
-    class Md = describe_members<T, mod_any_access>>
+    class Bd = describe::describe_bases<T, mod_any_access>,
+    class Md = describe::describe_members<T, mod_any_access>>
 void print( Os& os, T const& t )
 {
     os << "{";
@@ -109,49 +109,49 @@ namespace operators
 {
 
 template<class T> std::enable_if_t<
-    has_describe_bases<T>::value && has_describe_members<T>::value, bool>
+    has_describe_bases<T>::value && has_describe_members<T>::value && !std::is_union<T>::value, bool>
     operator==( T const& t1, T const& t2 )
 {
     return detail::eq( t1, t2 );
 }
 
 template<class T> std::enable_if_t<
-    has_describe_bases<T>::value && has_describe_members<T>::value, bool>
+    has_describe_bases<T>::value && has_describe_members<T>::value && !std::is_union<T>::value, bool>
     operator!=( T const& t1, T const& t2 )
 {
     return !detail::eq( t1, t2 );
 }
 
 template<class T> std::enable_if_t<
-    has_describe_bases<T>::value && has_describe_members<T>::value, bool>
+    has_describe_bases<T>::value && has_describe_members<T>::value && !std::is_union<T>::value, bool>
     operator<( T const& t1, T const& t2 )
 {
     return detail::lt( t1, t2 );
 }
 
 template<class T> std::enable_if_t<
-    has_describe_bases<T>::value && has_describe_members<T>::value, bool>
+    has_describe_bases<T>::value && has_describe_members<T>::value && !std::is_union<T>::value, bool>
     operator>=( T const& t1, T const& t2 )
 {
     return !detail::lt( t1, t2 );
 }
 
 template<class T> std::enable_if_t<
-    has_describe_bases<T>::value && has_describe_members<T>::value, bool>
+    has_describe_bases<T>::value && has_describe_members<T>::value && !std::is_union<T>::value, bool>
     operator>( T const& t1, T const& t2 )
 {
     return detail::lt( t2, t1 );
 }
 
 template<class T> std::enable_if_t<
-    has_describe_bases<T>::value && has_describe_members<T>::value, bool>
+    has_describe_bases<T>::value && has_describe_members<T>::value && !std::is_union<T>::value, bool>
     operator<=( T const& t1, T const& t2 )
 {
     return !detail::lt( t2, t1 );
 }
 
 template<class T, class Ch, class Tr> std::enable_if_t<
-    has_describe_bases<T>::value && has_describe_members<T>::value,
+    has_describe_bases<T>::value && has_describe_members<T>::value && !std::is_union<T>::value,
     std::basic_ostream<Ch, Tr>&>
     operator<<( std::basic_ostream<Ch, Tr>& os, T const& t )
 {

meta/libraries.json

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

test/Jamfile

@@ -48,6 +48,9 @@ compile test_d_type.cpp ;
 compile-fail enum_struct_fail.cpp ;
 compile-fail struct_enum_fail.cpp ;
 
+compile-fail enum_nested_fail.cpp ;
+compile-fail nested_enum_fail.cpp ;
+
 run class_template_test.cpp ;
 
 run has_enumerators_test.cpp ;
@@ -63,6 +66,12 @@ 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 ;
+
+run union_test.cpp ;
+run union_test2.cpp ;
+
 # examples
 
 obj describe_cxx14 : describe_cxx14.cpp ;
@@ -85,3 +94,5 @@ run ../example/json_rpc.cpp : : : $(CXX14) $(JSON) ;
 run ../example/hash_value.cpp : : : $(CXX14) ;
 run ../example/equality.cpp : : : $(CXX14) ;
 link ../example/console.cpp : $(CXX14) $(JSON) ;
+run ../example/struct_to_tuple.cpp : : : $(CXX14) ;
+run ../example/pm_to_string.cpp : : : $(CXX14) ;

test/bases_test.cpp

@@ -7,6 +7,11 @@
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/lightweight_test_trait.hpp>
 
+#if defined(_MSC_VER) && _MSC_VER < 1900
+# pragma warning(disable: 4510) // default constructor could not be generated
+# pragma warning(disable: 4610) // struct can never be instantiated
+#endif
+
 struct X
 {
 };

test/cmake_install_test/CMakeLists.txt

@@ -0,0 +1,17 @@
+# Copyright 2018, 2019, 2022 Peter Dimov
+# 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
+
+cmake_minimum_required(VERSION 3.5...3.20)
+
+project(cmake_install_test LANGUAGES CXX)
+
+find_package(boost_describe REQUIRED)
+
+add_executable(main main.cpp)
+target_link_libraries(main Boost::describe)
+
+enable_testing()
+add_test(main main)
+
+add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)

test/cmake_install_test/main.cpp

@@ -0,0 +1,49 @@
+// Copyright 2017, 2020, 2021, 2022 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe.hpp>
+#include <cassert>
+
+#define BOOST_TEST(expr) assert(expr)
+#define BOOST_TEST_EQ(x1, x2) assert((x1)==(x2))
+
+struct X
+{
+    int m;
+};
+
+BOOST_DESCRIBE_STRUCT(X, (), (m))
+
+struct Y: public X
+{
+    void m() {}
+};
+
+BOOST_DESCRIBE_STRUCT(Y, (X), (m))
+
+#if !defined(BOOST_DESCRIBE_CXX14)
+
+#pragma message "Skipping test because C++14 is not available"
+
+int main()
+{
+}
+
+#else
+
+BOOST_DEFINE_ENUM(E, v1, v2, v3)
+
+#include <boost/mp11.hpp>
+
+int main()
+{
+    using namespace boost::describe;
+    using namespace boost::mp11;
+
+    BOOST_TEST_EQ( (mp_size< describe_enumerators<E> >::value), 3 );
+    BOOST_TEST_EQ( (mp_size< describe_bases<Y, mod_any_access> >::value), 1 );
+    BOOST_TEST_EQ( (mp_size< describe_members<Y, mod_any_access | mod_inherited | mod_hidden> >::value), 1 );
+}
+
+#endif // !defined(BOOST_DESCRIBE_CXX14)

test/cmake_subdir_test/CMakeLists.txt

@@ -0,0 +1,23 @@
+# Copyright 2018-2022 Peter Dimov
+# 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
+
+cmake_minimum_required(VERSION 3.5...3.20)
+
+project(cmake_subdir_test LANGUAGES CXX)
+
+add_subdirectory(../.. boostorg/describe)
+add_subdirectory(../../../assert boostorg/assert)
+add_subdirectory(../../../config boostorg/config)
+add_subdirectory(../../../core boostorg/core)
+add_subdirectory(../../../mp11 boostorg/mp11)
+add_subdirectory(../../../static_assert boostorg/static_assert)
+add_subdirectory(../../../throw_exception boostorg/throw_exception)
+
+add_executable(quick ../quick.cpp)
+target_link_libraries(quick Boost::describe Boost::core)
+
+enable_testing()
+add_test(quick quick)
+
+add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure --no-tests=error -C $<CONFIG>)

test/enum_from_string_test.cpp

@@ -21,7 +21,7 @@ BOOST_DESCRIBE_ENUM(E1, v101, v102)
 enum class E2 { v201 = 201, v202 = 202 };
 BOOST_DESCRIBE_ENUM(E2, v201, v202)
 
-BOOST_DEFINE_ENUM(E3, v301, v302);
+BOOST_DEFINE_ENUM(E3, v301, v302)
 BOOST_DEFINE_ENUM_CLASS(E4, v401, v402)
 
 int main()

test/enum_nested_fail.cpp

@@ -0,0 +1,18 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe/enum.hpp>
+
+#if !defined(BOOST_DESCRIBE_CXX14)
+
+#error "Skipping test because C++14 is not available"
+
+#else
+
+struct S1 {
+    enum E1 {};
+    BOOST_DESCRIBE_ENUM(E1)
+};
+
+#endif // !defined(BOOST_DESCRIBE_CXX14)

test/enum_to_string_test.cpp

@@ -21,7 +21,7 @@ BOOST_DESCRIBE_ENUM(E1, v1)
 enum class E2 { v2 };
 BOOST_DESCRIBE_ENUM(E2, v2)
 
-BOOST_DEFINE_ENUM(E3, v3);
+BOOST_DEFINE_ENUM(E3, v3)
 BOOST_DEFINE_ENUM_CLASS(E4, v4)
 
 int main()

test/enumerators_test.cpp

@@ -11,9 +11,9 @@ enum E1
     v1_1 = 5
 };
 
-BOOST_DESCRIBE_ENUM(E1, v1_1);
+BOOST_DESCRIBE_ENUM(E1, v1_1)
 
-BOOST_DEFINE_ENUM(E3, v3_1, v3_2, v3_3);
+BOOST_DEFINE_ENUM(E3, v3_1, v3_2, v3_3)
 
 #if !defined(BOOST_DESCRIBE_CXX11)
 
@@ -30,12 +30,12 @@ enum class E2
     v2_2 = 7
 };
 
-BOOST_DESCRIBE_ENUM(E2, v2_1, v2_2);
+BOOST_DESCRIBE_ENUM(E2, v2_1, v2_2)
 
-BOOST_DEFINE_FIXED_ENUM(E4, int, v4_1, v4_2, v4_3, v4_4);
+BOOST_DEFINE_FIXED_ENUM(E4, int, v4_1, v4_2, v4_3, v4_4)
 
-BOOST_DEFINE_ENUM_CLASS(E5, v5_1, v5_2, v5_3, v5_4, v5_5);
-BOOST_DEFINE_FIXED_ENUM_CLASS(E6, int, v6_1, v6_2, v6_3, v6_4, v6_5, v6_6);
+BOOST_DEFINE_ENUM_CLASS(E5, v5_1, v5_2, v5_3, v5_4, v5_5)
+BOOST_DEFINE_FIXED_ENUM_CLASS(E6, int, v6_1, v6_2, v6_3, v6_4, v6_5, v6_6)
 
 #if !defined(BOOST_DESCRIBE_CXX14)
 

test/has_bases_test.cpp

@@ -27,6 +27,9 @@ struct X3 {};
 class X4 {};
 union X5 {};
 
+struct X6: X1 {};
+struct X7: X2 {};
+
 int main()
 {
     using boost::describe::has_describe_bases;
@@ -46,6 +49,8 @@ int main()
     BOOST_TEST_TRAIT_FALSE((has_describe_bases<X3>));
     BOOST_TEST_TRAIT_FALSE((has_describe_bases<X4>));
     BOOST_TEST_TRAIT_FALSE((has_describe_bases<X5>));
+    BOOST_TEST_TRAIT_FALSE((has_describe_bases<X6>));
+    BOOST_TEST_TRAIT_FALSE((has_describe_bases<X7>));
     BOOST_TEST_TRAIT_FALSE((has_describe_bases<int>));
     BOOST_TEST_TRAIT_FALSE((has_describe_bases<void>));
 

test/has_enumerators_test.cpp

@@ -21,7 +21,7 @@ BOOST_DESCRIBE_ENUM(E1, v1)
 enum class E2 { v2 };
 BOOST_DESCRIBE_ENUM(E2, v2)
 
-BOOST_DEFINE_ENUM(E3, v3);
+BOOST_DEFINE_ENUM(E3, v3)
 BOOST_DEFINE_ENUM_CLASS(E4, v4)
 
 enum E5 { v5 };

test/has_members_test.cpp

@@ -27,6 +27,9 @@ struct X3 {};
 class X4 {};
 union X5 {};
 
+struct X6: X1 {};
+struct X7: X2 {};
+
 int main()
 {
     using boost::describe::has_describe_members;
@@ -46,6 +49,8 @@ int main()
     BOOST_TEST_TRAIT_FALSE((has_describe_members<X3>));
     BOOST_TEST_TRAIT_FALSE((has_describe_members<X4>));
     BOOST_TEST_TRAIT_FALSE((has_describe_members<X5>));
+    BOOST_TEST_TRAIT_FALSE((has_describe_members<X6>));
+    BOOST_TEST_TRAIT_FALSE((has_describe_members<X7>));
     BOOST_TEST_TRAIT_FALSE((has_describe_members<int>));
     BOOST_TEST_TRAIT_FALSE((has_describe_members<void>));
 

test/nested_enum_fail.cpp

@@ -0,0 +1,16 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe/enum.hpp>
+
+#if !defined(BOOST_DESCRIBE_CXX14)
+
+#error "Skipping test because C++14 is not available"
+
+#else
+
+enum E1 {};
+BOOST_DESCRIBE_NESTED_ENUM(E1);
+
+#endif // !defined(BOOST_DESCRIBE_CXX14)

test/operator_eq_test.cpp

@@ -20,9 +20,11 @@ namespace app
 
 struct X
 {
+    void f() const {}
+    static void g() {}
 };
 
-BOOST_DESCRIBE_STRUCT(X, (), ())
+BOOST_DESCRIBE_STRUCT(X, (), (f, g))
 
 using boost::describe::operators::operator==;
 using boost::describe::operators::operator<<;

test/operator_lt_test.cpp

@@ -20,9 +20,11 @@ namespace app
 
 struct X
 {
+    void f() const {}
+    static void g() {}
 };
 
-BOOST_DESCRIBE_STRUCT(X, (), ())
+BOOST_DESCRIBE_STRUCT(X, (), (f, g))
 
 using boost::describe::operators::operator<=;
 using boost::describe::operators::operator>=;

test/union_test.cpp

@@ -0,0 +1,79 @@
+// Copyright 2020, 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe/members.hpp>
+#include <boost/describe/class.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config/pragma_message.hpp>
+
+#if !defined(BOOST_DESCRIBE_CXX11)
+
+BOOST_PRAGMA_MESSAGE("Skipping test because C++11 is not available")
+int main() {}
+
+#elif defined(__GNUC__) && __GNUC__ < 5
+
+BOOST_PRAGMA_MESSAGE("Skipping test because g++ 4.8")
+int main() {}
+
+#else
+
+union A
+{
+    int m1;
+    static int m2;
+    int f1() const { return m1; }
+    static int f2() { return m2; }
+};
+
+BOOST_DESCRIBE_STRUCT(A, (), (m1, m2, f1, f2))
+
+int A::m2;
+
+#if !defined(BOOST_DESCRIBE_CXX14)
+
+BOOST_PRAGMA_MESSAGE("Skipping test because C++14 is not available")
+int main() {}
+
+#else
+
+#include <boost/mp11.hpp>
+
+int main()
+{
+    using namespace boost::describe;
+    using namespace boost::mp11;
+
+    {
+        using L = describe_members<A, mod_any_access | mod_any_member>;
+
+        BOOST_TEST_EQ( mp_size<L>::value, 4 );
+
+        using D1 = mp_at_c<L, 0>;
+        using D2 = mp_at_c<L, 1>;
+        using D3 = mp_at_c<L, 2>;
+        using D4 = mp_at_c<L, 3>;
+
+        BOOST_TEST( D1::pointer == &A::m1 );
+        BOOST_TEST_CSTR_EQ( D1::name, "m1" );
+        BOOST_TEST_EQ( D1::modifiers, mod_public );
+
+        BOOST_TEST( D2::pointer == &A::m2 );
+        BOOST_TEST_CSTR_EQ( D2::name, "m2" );
+        BOOST_TEST_EQ( D2::modifiers, mod_public | mod_static );
+
+        BOOST_TEST( D3::pointer == &A::f1 );
+        BOOST_TEST_CSTR_EQ( D3::name, "f1" );
+        BOOST_TEST_EQ( D3::modifiers, mod_public | mod_function );
+
+        BOOST_TEST( D4::pointer == &A::f2 );
+        BOOST_TEST_CSTR_EQ( D4::name, "f2" );
+        BOOST_TEST_EQ( D4::modifiers, mod_public | mod_static | mod_function );
+    }
+
+    return boost::report_errors();
+}
+
+#endif // !defined(BOOST_DESCRIBE_CXX14)
+#endif // !defined(BOOST_DESCRIBE_CXX11)

test/union_test2.cpp

@@ -0,0 +1,153 @@
+// Copyright 2020, 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe/members.hpp>
+#include <boost/describe/class.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config/pragma_message.hpp>
+
+#if !defined(BOOST_DESCRIBE_CXX11)
+
+BOOST_PRAGMA_MESSAGE("Skipping test because C++11 is not available")
+int main() {}
+
+#elif defined(__GNUC__) && __GNUC__ < 5
+
+BOOST_PRAGMA_MESSAGE("Skipping test because g++ 4.8")
+int main() {}
+
+#else
+
+union A
+{
+public:
+
+    int m1;
+    static int m2;
+    int f1() const { return m1; }
+    static int f2() { return m2; }
+
+protected:
+
+    int m3;
+    static int m4;
+    int f3() const { return m3; }
+    static int f4() { return m4; }
+
+private:
+
+    int m5;
+    static int m6;
+    int f5() const { return m5; }
+    static int f6() { return m6; }
+
+    BOOST_DESCRIBE_CLASS(A, (), (m1, m2, f1, f2), (m3, m4, f3, f4), (m5, m6, f5, f6))
+
+    friend int main();
+};
+
+int A::m2;
+int A::m4;
+int A::m6;
+
+#if !defined(BOOST_DESCRIBE_CXX14)
+
+BOOST_PRAGMA_MESSAGE("Skipping test because C++14 is not available")
+int main() {}
+
+#else
+
+#include <boost/mp11.hpp>
+
+int main()
+{
+    using namespace boost::describe;
+    using namespace boost::mp11;
+
+    {
+        using L = describe_members<A, mod_public | mod_any_member>;
+
+        BOOST_TEST_EQ( mp_size<L>::value, 4 );
+
+        using D1 = mp_at_c<L, 0>;
+        using D2 = mp_at_c<L, 1>;
+        using D3 = mp_at_c<L, 2>;
+        using D4 = mp_at_c<L, 3>;
+
+        BOOST_TEST( D1::pointer == &A::m1 );
+        BOOST_TEST_CSTR_EQ( D1::name, "m1" );
+        BOOST_TEST_EQ( D1::modifiers, mod_public );
+
+        BOOST_TEST( D2::pointer == &A::m2 );
+        BOOST_TEST_CSTR_EQ( D2::name, "m2" );
+        BOOST_TEST_EQ( D2::modifiers, mod_public | mod_static );
+
+        BOOST_TEST( D3::pointer == &A::f1 );
+        BOOST_TEST_CSTR_EQ( D3::name, "f1" );
+        BOOST_TEST_EQ( D3::modifiers, mod_public | mod_function );
+
+        BOOST_TEST( D4::pointer == &A::f2 );
+        BOOST_TEST_CSTR_EQ( D4::name, "f2" );
+        BOOST_TEST_EQ( D4::modifiers, mod_public | mod_static | mod_function );
+    }
+
+    {
+        using L = describe_members<A, mod_protected | mod_any_member>;
+
+        BOOST_TEST_EQ( mp_size<L>::value, 4 );
+
+        using D1 = mp_at_c<L, 0>;
+        using D2 = mp_at_c<L, 1>;
+        using D3 = mp_at_c<L, 2>;
+        using D4 = mp_at_c<L, 3>;
+
+        BOOST_TEST( D1::pointer == &A::m3 );
+        BOOST_TEST_CSTR_EQ( D1::name, "m3" );
+        BOOST_TEST_EQ( D1::modifiers, mod_protected );
+
+        BOOST_TEST( D2::pointer == &A::m4 );
+        BOOST_TEST_CSTR_EQ( D2::name, "m4" );
+        BOOST_TEST_EQ( D2::modifiers, mod_protected | mod_static );
+
+        BOOST_TEST( D3::pointer == &A::f3 );
+        BOOST_TEST_CSTR_EQ( D3::name, "f3" );
+        BOOST_TEST_EQ( D3::modifiers, mod_protected | mod_function );
+
+        BOOST_TEST( D4::pointer == &A::f4 );
+        BOOST_TEST_CSTR_EQ( D4::name, "f4" );
+        BOOST_TEST_EQ( D4::modifiers, mod_protected | mod_static | mod_function );
+    }
+
+    {
+        using L = describe_members<A, mod_private | mod_any_member>;
+
+        BOOST_TEST_EQ( mp_size<L>::value, 4 );
+
+        using D1 = mp_at_c<L, 0>;
+        using D2 = mp_at_c<L, 1>;
+        using D3 = mp_at_c<L, 2>;
+        using D4 = mp_at_c<L, 3>;
+
+        BOOST_TEST( D1::pointer == &A::m5 );
+        BOOST_TEST_CSTR_EQ( D1::name, "m5" );
+        BOOST_TEST_EQ( D1::modifiers, mod_private );
+
+        BOOST_TEST( D2::pointer == &A::m6 );
+        BOOST_TEST_CSTR_EQ( D2::name, "m6" );
+        BOOST_TEST_EQ( D2::modifiers, mod_private | mod_static );
+
+        BOOST_TEST( D3::pointer == &A::f5 );
+        BOOST_TEST_CSTR_EQ( D3::name, "f5" );
+        BOOST_TEST_EQ( D3::modifiers, mod_private | mod_function );
+
+        BOOST_TEST( D4::pointer == &A::f6 );
+        BOOST_TEST_CSTR_EQ( D4::name, "f6" );
+        BOOST_TEST_EQ( D4::modifiers, mod_private | mod_static | mod_function );
+    }
+
+    return boost::report_errors();
+}
+
+#endif // !defined(BOOST_DESCRIBE_CXX14)
+#endif // !defined(BOOST_DESCRIBE_CXX11)

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)