Add note about identity being moved from functional

.drone.jsonnet

@@ -344,6 +344,18 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
         { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,1z' } + asan,
     ),
 
+    macos_pipeline(
+        "MacOS 12.4 Xcode 13.4.1 UBSAN",
+        { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,17,20,2b' } + ubsan,
+        xcode_version = "13.4.1", osx_version = "monterey", arch = "arm64",
+    ),
+
+    macos_pipeline(
+        "MacOS 12.4 Xcode 13.4.1 ASAN",
+        { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,17,20,2b' } + asan,
+        xcode_version = "13.4.1", osx_version = "monterey", arch = "arm64",
+    ),
+
     windows_pipeline(
         "Windows VS2015 msvc-14.0",
         "cppalliance/dronevs2015",

.drone/drone.sh

@@ -5,6 +5,7 @@
 # https://www.boost.org/LICENSE_1_0.txt
 
 set -ex
+export PATH=~/.local/bin:/usr/local/bin:$PATH
 
 DRONE_BUILD_DIR=$(pwd)
 

.github/workflows/ci.yml

@@ -466,7 +466,7 @@ jobs:
             if [ -n "${{matrix.ubsan}}" ]
             then
                 export UBSAN_OPTIONS="print_stacktrace=1"
-                B2_ARGS+=("cxxflags=-fsanitize=undefined -fno-sanitize-recover=undefined" "linkflags=-fsanitize=undefined -fuse-ld=gold" "define=UBSAN=1" "debug-symbols=on" "visibility=global")
+                B2_ARGS+=("undefined-sanitizer=norecover" "linkflags=-fuse-ld=gold" "define=UBSAN=1" "debug-symbols=on" "visibility=global")
             fi
             if [ -n "${{matrix.cxxflags}}" ]
             then

doc/changes.qbk

@@ -22,6 +22,15 @@
   `boost::core::max_align`, the alignment of `max_align_t`.
 * Added [link core.memory_resource `boost::core::memory_resource`], a portable equivalent of `std::pmr::memory_resource`
   from C++17.
+* Added [link core.serialization `boost/core/serialization.hpp`], a collection of primitives allowing libraries to
+  implement Boost.Serialization support for their types without including a Serialization header and thereby making
+  their libraries depend on Serialization.
+* Added [link core.data `boost::data`], an implementation of `std::data`.
+* Added [link core.size `boost::size`], an implementation of `std::size`.
+* Updated `boost::span` to use `boost::data` which adds support for range
+  construction from an `std::initializer_list`.
+* Added [link core.identity `boost::identity`], an implementation of
+  `std::identity`. This facility has been moved from Boost.Functional.
 
 [endsect]
 

doc/core.qbk

@@ -55,6 +55,7 @@ criteria for inclusion is that the utility component be:
 [include exchange.qbk]
 [include explicit_operator_bool.qbk]
 [include first_scalar.qbk]
+[include identity.qbk]
 [include ignore_unused.qbk]
 [include is_same.qbk]
 [include launder.qbk]
@@ -72,6 +73,7 @@ criteria for inclusion is that the utility component be:
 [include quick_exit.qbk]
 [include ref.qbk]
 [include scoped_enum.qbk]
+[include serialization.qbk]
 [include size.qbk]
 [include span.qbk]
 [include swap.qbk]

doc/data.qbk

@@ -50,10 +50,10 @@ data(std::initializer_list<T> l) noexcept;
 [variablelist
 [[`template<class C> constexpr auto data(C& c) noexcept(noexcept(c.data())) ->
 decltype(c.data());`]
-[Returns `c.begin()`.]]
+[Returns `c.data()`.]]
 [[`template<class C> constexpr auto data(const C& c)
 noexcept(noexcept(c.data())) -> decltype(c.data());`]
-[Returns `c.begin()`.]]
+[Returns `c.data()`.]]
 [[`template<class T, std::size_t N> constexpr T* data(T(&a)[N]) noexcept;`]
 [Returns `a`.]]
 [[`template<class T> constexpr const T* data(std::initializer_list<T> l)

doc/identity.qbk

@@ -0,0 +1,61 @@
+[/
+Copyright 2021-2023 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+]
+
+[section:identity identity]
+
+[simplesect Authors]
+
+* Glen Fernandes
+
+[endsimplesect]
+
+[section Overview]
+
+The header <boost/functional/identity.hpp> provides the function object
+`boost::identity` whose `operator()` returns its argument. It is an
+implementation of C++20's `std::identity` that supports C++03 and above.
+
+[endsect]
+
+[section Example]
+
+It is commonly used as the default projection in constrained algorithms.
+
+```
+template<class Range, class Projection = boost::identity>
+void print(Range&& range, Projection projection = {});
+```
+
+[endsect]
+
+[section Reference]
+
+```
+namespace boost {
+
+struct identity {
+    using is_transparent = unspecified;
+
+    template<class T>
+    T&& operator()(T&& value) const noexcept;
+};
+
+} /* boost */
+```
+
+[section Operators]
+
+[variablelist
+[[`template<class T> T&& operator()(T&& value) const noexcept;`]
+[Returns `std::forward<T>(value)`.]]]
+
+[endsect]
+
+[endsect]
+
+[endsect]

doc/serialization.qbk

@@ -0,0 +1,145 @@
+[/
+  Copyright 2023 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:serialization serialization]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/serialization.hpp>]
+
+The header `<boost/core/serialization.hpp>` implements primitives
+that are necessary to implement Boost.Serialization support without
+including a Boost.Serialization header and thereby making a library
+dependent on Boost.Serialization.
+
+[section Synopsis]
+
+``
+#include <boost/core/nvp.hpp>
+
+namespace boost
+{
+namespace serialization
+{
+
+// forward declarations
+
+template<class T> struct version;
+class access;
+
+// core_version_type
+
+struct core_version_type;
+
+} // namespace serialization
+
+namespace core
+{
+
+// nvp
+
+using serialization::nvp;
+using serialization::make_nvp;
+
+// split_free
+
+template<class Ar, class T> void split_free( Ar& ar, T& t, unsigned int v );
+
+// split_member
+
+template<class Ar, class T> void split_member( Ar& ar, T& t, unsigned int v );
+
+// load_construct_data_adl
+
+template<class Ar, class T> void load_construct_data_adl( Ar& ar, T* t, unsigned int v );
+
+// save_construct_data_adl
+
+template<class Ar, class T> void save_construct_data_adl( Ar& ar, T const* t, unsigned int v );
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[section `core_version_type`]
+
+``
+struct core_version_type
+{
+    unsigned int version_;
+
+    core_version_type( unsigned int version ): version_( version ) {}
+    operator unsigned int () const { return version_; }
+};
+``
+
+`core_version_type` is a Core reimplementation of
+`boost::serialization::version_type`, needed to call ADL serialization
+primitives such as, for example, `load_construct_data` below.
+
+It's defined in the `serialization` namespace instead of the `core`
+namespace because its only purpose is to add `boost::serialization` to
+the list of the associated namespaces of the corresponding call.
+
+[endsect]
+
+[section `split_free`]
+
+`template<class Ar, class T> inline void split_free( Ar& ar, T& t, unsigned int v );`
+
+`boost::core::split_free` is a Core reimplementation of
+`boost::serialization::split_free`.
+
+* *Effects:*
+  * If `Ar::is_saving::value` is `true`, calls `save( ar, t, core_version_type( v ) )`;
+  * Otherwise, calls `load( ar, t, core_version_type( v ) )`.
+
+[endsect]
+
+[section `split_member`]
+
+`template<class Ar, class T> void split_member( Ar& ar, T& t, unsigned int v );`
+
+`boost::core::split_member` is a Core reimplementation of
+`boost::serialization::split_member`.
+
+* *Effects:*
+  * If `Ar::is_saving::value` is `true`, calls `t.save( ar, v )`;
+  * Otherwise, calls `t.load( ar, v )`.
+
+[endsect]
+
+[section `load_construct_data_adl`]
+
+`template<class Ar, class T> void load_construct_data_adl( Ar& ar, T* t, unsigned int v );`
+
+`boost::core::load_construct_data_adl` is a Core reimplementation of
+`boost::serialization::load_construct_data_adl`.
+
+* *Effects:* `load_construct_data( ar, t, serialization::core_version_type( v ) );`.
+
+[endsect]
+
+[section `save_construct_data_adl`]
+
+`template<class Ar, class T> void save_construct_data_adl( Ar& ar, T const* t, unsigned int v );`
+
+`boost::core::save_construct_data_adl` is a Core reimplementation of
+`boost::serialization::save_construct_data_adl`.
+
+* *Effects:* `save_construct_data( ar, t, serialization::core_version_type( v ) );`.
+
+[endsect]
+
+[endsect]
+
+[endsect]

doc/span.qbk

@@ -227,13 +227,13 @@ constexpr span(R&& r);`]
 [`remove_cvref_t<R>` is not a specialization of `span`,]
 [`remove_cvref_t<R>` is not a specialization of `array`,]
 [`is_array_v<remove_cvref_t<R>>` is `false`,]
-[`r.data()` is well-formed and
+[`data(r)` is well-formed and
 `is_convertible_v<remove_pointer_t<iterator_t<R> >(*)[],
 T(*)[]>` is `true`, and]
 [`r.size()` is well-formed and
 `is_convertible_v<decltype(declval<R&>().size()), size_t>` is `true`.]]]]
-[[Effects][Constructs a `span` with data `r.data()` and size `r.size()`.]]
-[[Throws][What and when r.data() and r.size() throw.]]]]]
+[[Effects][Constructs a `span` with data `data(r)` and size `r.size()`.]]
+[[Throws][What and when data(r) and r.size() throw.]]]]]
 [[`explicit(E != dynamic_extent && N == dynamic_extent)
 template<class U, std::size_t N>
 constexpr span(const span<U, N>& s) noexcept;`]

include/boost/core/identity.hpp

@@ -0,0 +1,61 @@
+/*
+Copyright 2021-2023 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#ifndef BOOST_CORE_IDENTITY_HPP
+#define BOOST_CORE_IDENTITY_HPP
+
+#include <boost/config.hpp>
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+#include <utility>
+#endif
+
+namespace boost {
+
+struct identity {
+    typedef void is_transparent;
+
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+    template<class T>
+    BOOST_CONSTEXPR T&& operator()(T&& value) const BOOST_NOEXCEPT {
+        return std::forward<T>(value);
+    }
+#else
+    template<class T>
+    BOOST_CONSTEXPR const T& operator()(const T& value) const BOOST_NOEXCEPT {
+        return value;
+    }
+
+    template<class T>
+    BOOST_CONSTEXPR T& operator()(T& value) const BOOST_NOEXCEPT {
+        return value;
+    }
+#endif
+
+    template<class>
+    struct result { };
+
+    template<class T>
+    struct result<identity(T&)> {
+        typedef T& type;
+    };
+
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+    template<class T>
+    struct result<identity(T)> {
+        typedef T&& type;
+    };
+
+    template<class T>
+    struct result<identity(T&&)> {
+        typedef T&& type;
+    };
+#endif
+};
+
+} /* boost */
+
+#endif

include/boost/core/span.hpp

@@ -8,11 +8,10 @@ Distributed under the Boost Software License, Version 1.0.
 #ifndef BOOST_CORE_SPAN_HPP
 #define BOOST_CORE_SPAN_HPP
 
+#include <boost/core/data.hpp>
 #include <array>
-#include <initializer_list>
 #include <iterator>
 #include <type_traits>
-#include <cstddef>
 
 namespace boost {
 
@@ -63,29 +62,8 @@ struct span_is_array<std::array<T, N> > {
     static constexpr bool value = true;
 };
 
-template<class C>
-inline constexpr auto
-span_begin(C& c) noexcept(noexcept(c.data())) -> decltype(c.data())
-{
-    return c.data();
-}
-
-template<class C>
-inline constexpr auto
-span_begin(const C& c) noexcept(noexcept(c.data())) -> decltype(c.data())
-{
-    return c.data();
-}
-
 template<class T>
-inline constexpr const T*
-span_begin(std::initializer_list<T> l) noexcept
-{
-    return l.begin();
-}
-
-template<class T>
-using span_ptr = decltype(boost::detail::span_begin(std::declval<T&>()));
+using span_ptr = decltype(boost::data(std::declval<T&>()));
 
 template<class, class = void>
 struct span_data { };
@@ -245,16 +223,16 @@ public:
     template<class R,
         typename std::enable_if<E == dynamic_extent &&
             detail::span_is_range<R, T>::value, int>::type = 0>
-    constexpr span(R&& r) noexcept(noexcept(detail::span_begin(r)) &&
+    constexpr span(R&& r) noexcept(noexcept(boost::data(r)) &&
         noexcept(r.size()))
-        : s_(detail::span_begin(r), r.size()) { }
+        : s_(boost::data(r), r.size()) { }
 
     template<class R,
         typename std::enable_if<E != dynamic_extent &&
             detail::span_is_range<R, T>::value, int>::type = 0>
-    explicit constexpr span(R&& r) noexcept(noexcept(detail::span_begin(r)) &&
+    explicit constexpr span(R&& r) noexcept(noexcept(boost::data(r)) &&
         noexcept(r.size()))
-        : s_(detail::span_begin(r), r.size()) { }
+        : s_(boost::data(r), r.size()) { }
 
     template<class U, std::size_t N,
         typename std::enable_if<detail::span_implicit<E, N>::value &&

test/Jamfile.v2

@@ -363,10 +363,13 @@ run memory_resource_test.cpp ;
 run data_test.cpp ;
 run size_test.cpp ;
 
-run serialization_nvp_test.cpp : : : <library>/boost//serialization/<warnings>off <toolset>clang,<undefined-sanitizer>norecover:<build>no ;
-run serialization_split_free_test.cpp : : : <library>/boost//serialization/<warnings>off ;
-run serialization_split_member_test.cpp : : : <library>/boost//serialization/<warnings>off ;
-run serialization_construct_data_test.cpp : : : <library>/boost//serialization/<warnings>off ;
+run serialization_nvp_test.cpp : : : <library>/boost//serialization/<warnings>off <undefined-sanitizer>norecover:<build>no ;
+run serialization_split_free_test.cpp : : : <library>/boost//serialization/<warnings>off <undefined-sanitizer>norecover:<link>static ;
+run serialization_split_member_test.cpp : : : <library>/boost//serialization/<warnings>off <undefined-sanitizer>norecover:<link>static ;
+run serialization_construct_data_test.cpp : : : <library>/boost//serialization/<warnings>off <undefined-sanitizer>norecover:<link>static ;
+
+run identity_test.cpp ;
+run identity_rvalue_test.cpp ;
 
 use-project /boost/core/swap : ./swap ;
 build-project ./swap ;

test/identity_rvalue_test.cpp

@@ -0,0 +1,69 @@
+/*
+Copyright 2021-2023 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#include <boost/config.hpp>
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+#include <boost/core/identity.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <algorithm>
+#include <iterator>
+#include <string>
+#include <vector>
+
+bool test(std::string&&)
+{
+    return true;
+}
+
+bool test(const std::string&&)
+{
+    return true;
+}
+
+template<class T>
+bool test(T&&)
+{
+    return false;
+}
+
+void simple_test()
+{
+    typedef std::string string;
+    BOOST_TEST(boost::identity()(string("a")) == string("a"));
+    BOOST_TEST(test(boost::identity()(string("a"))));
+    typedef const std::string cstring;
+    BOOST_TEST(boost::identity()(cstring("a")) == cstring("a"));
+    BOOST_TEST(test(boost::identity()(cstring("a"))));
+}
+
+void algorithm_test()
+{
+    std::vector<std::string> v1;
+    v1.push_back(std::string("a"));
+    v1.push_back(std::string("b"));
+    v1.push_back(std::string("c"));
+    std::vector<std::string> v2(v1);
+    std::vector<std::string> v3;
+    std::transform(std::make_move_iterator(v2.begin()),
+        std::make_move_iterator(v2.end()),
+        std::back_inserter(v3),
+        boost::identity());
+    BOOST_TEST(v3 == v1);
+}
+
+int main()
+{
+    simple_test();
+    algorithm_test();
+    return boost::report_errors();
+}
+#else
+int main()
+{
+    return 0;
+}
+#endif

test/identity_test.cpp

@@ -0,0 +1,66 @@
+/*
+Copyright 2021-2023 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#include <boost/core/identity.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <algorithm>
+#include <iterator>
+#include <string>
+#include <vector>
+
+bool test(std::string&)
+{
+    return true;
+}
+
+bool test(const std::string&)
+{
+    return true;
+}
+
+template<class T>
+bool test(T&)
+{
+    return false;
+}
+
+template<class T>
+bool test(const T&)
+{
+    return false;
+}
+
+void simple_test()
+{
+    std::string s1("a");
+    BOOST_TEST(boost::identity()(s1) == s1);
+    BOOST_TEST(&boost::identity()(s1) == &s1);
+    BOOST_TEST(test(boost::identity()(s1)));
+    const std::string s2("a");
+    BOOST_TEST(boost::identity()(s2) == s2);
+    BOOST_TEST(&boost::identity()(s2) == &s2);
+    BOOST_TEST(test(boost::identity()(s2)));
+}
+
+void algorithm_test()
+{
+    std::vector<std::string> v1;
+    v1.push_back(std::string("a"));
+    v1.push_back(std::string("b"));
+    v1.push_back(std::string("c"));
+    std::vector<std::string> v2;
+    std::transform(v1.begin(), v1.end(), std::back_inserter(v2),
+         boost::identity());
+    BOOST_TEST(v2 == v1);
+}
+
+int main()
+{
+    simple_test();
+    algorithm_test();
+    return boost::report_errors();
+}

test/max_align_test.cpp

@@ -54,16 +54,9 @@ int main()
     BOOST_TEST_GE( boost::core::max_align, boost::alignment_of<void (X::*)()>::value );
 
 #if !defined(BOOST_NO_CXX11_ALIGNOF) && !defined(BOOST_NO_STD_MAX_ALIGN_T)
-# if defined(BOOST_LIBSTDCXX_VERSION) && BOOST_LIBSTDCXX_VERSION < 70000
 
-    // libstdc++ 7 adds __float128 to std::max_align_t, but we always have it
     BOOST_TEST_GE( boost::core::max_align, alignof( std::max_align_t ) );
 
-# else
-
-    BOOST_TEST_EQ( boost::core::max_align, alignof( std::max_align_t ) );
-
-# endif
 #endif
 
     return boost::report_errors();