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

@@ -47,6 +47,7 @@ criteria for inclusion is that the utility component be:
 [include bit.qbk]
 [include checked_delete.qbk]
 [include cmath.qbk]
+[include data.qbk]
 [include default_allocator.qbk]
 [include demangle.qbk]
 [include empty_value.qbk]
@@ -54,10 +55,12 @@ 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]
 [include lightweight_test.qbk]
+[include make_span.qbk]
 [include max_align.qbk]
 [include memory_resource.qbk]
 [include no_exceptions_support.qbk]
@@ -70,6 +73,8 @@ 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]
 [include typeinfo.qbk]

doc/data.qbk

@@ -0,0 +1,67 @@
+[/
+Copyright 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:data data]
+
+[simplesect Authors]
+
+* Glen Fernandes
+
+[endsimplesect]
+
+[section Overview]
+
+The header <boost/core/data.hpp> provides function templates `data`
+to obtain the pointer to the first element in a range.
+
+[endsect]
+
+[section Reference]
+
+```
+namespace boost {
+
+template<class C>
+constexpr auto
+data(C& c) noexcept(noexcept(c.data())) -> decltype(c.data());
+
+template<class C>
+constexpr auto
+data(const C& c) noexcept(noexcept(c.data())) -> decltype(c.data());
+
+template<class T, std::size_t N>
+constexpr T*
+data(T(&a)[N]) noexcept;
+
+template<class T>
+constexpr const T*
+data(std::initializer_list<T> l) noexcept;
+
+} /* boost */
+```
+
+[section Functions]
+
+[variablelist
+[[`template<class C> constexpr auto data(C& c) noexcept(noexcept(c.data())) ->
+decltype(c.data());`]
+[Returns `c.data()`.]]
+[[`template<class C> constexpr auto data(const C& c)
+noexcept(noexcept(c.data())) -> decltype(c.data());`]
+[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)
+noexcept;`]
+[Returns `l.begin()`.]]]
+
+[endsect]
+
+[endsect]
+
+[endsect]

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/make_span.qbk

@@ -0,0 +1,81 @@
+[/
+Copyright 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:make_span make_span]
+
+[simplesect Authors]
+
+* Glen Fernandes
+
+[endsimplesect]
+
+[section Overview]
+
+The header <boost/core/make_span.hpp> provides function templates `make_span`
+to conveniently create `span` objects. They are useful before C++17 where Class
+Template Argument Deduction (CTAD) is not available.
+
+[endsect]
+
+[section Reference]
+
+```
+namespace boost {
+
+template<class I>
+constexpr span<I>
+make_span(I* d, std::size_t n) noexcept;
+
+template<class I>
+constexpr span<I>
+make_span(I* b, I* e) noexcept;
+
+template<class T, std::size_t N>
+constexpr span<T, N>
+make_span(T(&a)[N]) noexcept;
+
+template<class T, std::size_t N>
+constexpr span<T, N>
+make_span(std::array<T, N>& a) noexcept;
+
+template<class T, std::size_t N>
+constexpr span<const T, N>
+make_span(const std::array<T, N>& a) noexcept;
+
+template<class R>
+span<remove_pointer_t<iterator_t<R> > >
+make_span(R&& r);
+
+} /* boost */
+```
+
+[section Functions]
+
+[variablelist
+[[`template<class I> span<I> make_span(I* f, std::size_t c);`]
+[Returns `span<I>(f, c)`.]]
+[[`template<class I> span<I> make_span(I* f, I* l);`]
+[Returns `span<I>(f, l)`.]]
+[[`template<class T, std::size_t N> span<T, N> make_span(T(&a)[N]);`]
+[Returns `span<T, N>(a)`.]]
+[[`template<class T, std::size_t N> span<T, N>
+make_span(std::array<T, N>& a);`]
+[Returns `span<T, N>(a)`.]]
+[[`template<class T, std::size_t N> span<const T, N>
+make_span(const std::array<T, N>& a);`]
+[Returns `span<const T, N>(a)`.]]
+[[`template<class R>
+span<remove_pointer_t<iterator_t<R> > >
+make_span(R&& r);`]
+[Returns `span<remove_pointer_t<iterator_t<R> > >(std::forward<R>(r))`.]]]
+
+[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/size.qbk

@@ -0,0 +1,54 @@
+[/
+Copyright 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:size size]
+
+[simplesect Authors]
+
+* Glen Fernandes
+
+[endsimplesect]
+
+[section Overview]
+
+The header <boost/core/size.hpp> provides function templates `size` to obtain
+the number of elements in a range.
+
+[endsect]
+
+[section Reference]
+
+```
+namespace boost {
+
+template<class C>
+constexpr auto
+size(const C& c) noexcept(noexcept(c.size())) -> decltype(c.size());
+
+template<class T, std::size_t N>
+constexpr std::size_t
+size(T(&)[N]) noexcept;
+
+} /* boost */
+```
+
+[section Functions]
+
+[variablelist
+[[`template<class C> constexpr auto size(const C& c)
+noexcept(noexcept(c.size())) -> decltype(c.size());`]
+[Returns `c.size()`.]]
+[[`template<class T, std::size_t N> constexpr std::size_t size(T(&)[N])
+noexcept;`]
+[Returns `N`.]]]
+
+[endsect]
+
+[endsect]
+
+[endsect]

doc/span.qbk

@@ -149,7 +149,7 @@ template<class T, std::size_t N>
 span(const std::array<T, N>&) -> span<const T, N>;
 
 template<class R>
-span(R&&) -> span<std::remove_pointer_t<decltype(std::declval<R&>().data())> >;
+span(R&&) -> span<remove_pointer_t<iterator_t<R> > >;
 
 template<class T, std::size_t E>
 span<const std::byte, E == dynamic_extent ? dynamic_extent : sizeof(T) * E>
@@ -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
-`is_convertible_v<remove_pointer_t<decltype(declval<R&>().data())>(*)[],
+[`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/data.hpp

@@ -0,0 +1,46 @@
+/*
+Copyright 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_DATA_HPP
+#define BOOST_CORE_DATA_HPP
+
+#include <initializer_list>
+#include <cstddef>
+
+namespace boost {
+
+template<class C>
+inline constexpr auto
+data(C& c) noexcept(noexcept(c.data())) -> decltype(c.data())
+{
+    return c.data();
+}
+
+template<class C>
+inline constexpr auto
+data(const C& c) noexcept(noexcept(c.data())) -> decltype(c.data())
+{
+    return c.data();
+}
+
+template<class T, std::size_t N>
+inline constexpr T*
+data(T(&a)[N]) noexcept
+{
+    return a;
+}
+
+template<class T>
+inline constexpr const T*
+data(std::initializer_list<T> l) noexcept
+{
+    return l.begin();
+}
+
+} /* boost */
+
+#endif

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/make_span.hpp

@@ -0,0 +1,59 @@
+/*
+Copyright 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_MAKE_SPAN_HPP
+#define BOOST_CORE_MAKE_SPAN_HPP
+
+#include <boost/core/span.hpp>
+
+namespace boost {
+
+template<class I>
+inline constexpr span<I>
+make_span(I* f, std::size_t c) noexcept
+{
+    return span<I>(f, c);
+}
+
+template<class I>
+inline constexpr span<I>
+make_span(I* f, I* l) noexcept
+{
+    return span<I>(f, l);
+}
+
+template<class T, std::size_t N>
+inline constexpr span<T, N>
+make_span(T(&a)[N]) noexcept
+{
+    return span<T, N>(a);
+}
+
+template<class T, std::size_t N>
+inline constexpr span<T, N>
+make_span(std::array<T, N>& a) noexcept
+{
+    return span<T, N>(a);
+}
+
+template<class T, std::size_t N>
+inline constexpr span<const T, N>
+make_span(const std::array<T, N>& a) noexcept
+{
+    return span<const T, N>(a);
+}
+
+template<class R>
+inline span<typename detail::span_data<R>::type>
+make_span(R&& r)
+{
+    return span<typename detail::span_data<R>::type>(std::forward<R>(r));
+}
+
+} /* boost */
+
+#endif

include/boost/core/serialization.hpp

@@ -0,0 +1,131 @@
+#ifndef BOOST_CORE_SERIALIZATION_HPP_INCLUDED
+#define BOOST_CORE_SERIALIZATION_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+//
+// Utilities needed to implement serialization support
+// without including a Boost.Serialization header
+
+#include <boost/core/nvp.hpp>
+#include <cstddef>
+
+namespace boost
+{
+
+namespace serialization
+{
+
+// Forward declarations (needed for specializations)
+
+template<class T> struct version;
+
+class access;
+
+// Our own version_type replacement. This has to be in
+// the `serialization` namespace, because its only purpose
+// is to add `serialization` as an associated namespace.
+
+struct core_version_type
+{
+    unsigned int version_;
+
+    core_version_type( unsigned int version ): version_( version ) {}
+    operator unsigned int () const { return version_; }
+};
+
+} // namespace serialization
+
+namespace core
+{
+
+// nvp
+
+using serialization::nvp;
+using serialization::make_nvp;
+
+// split_free
+
+namespace detail
+{
+
+template<bool IsSaving> struct load_or_save_f;
+
+template<> struct load_or_save_f<true>
+{
+    template<class A, class T> void operator()( A& a, T& t, unsigned int v ) const
+    {
+        save( a, t, serialization::core_version_type( v ) );
+    }
+};
+
+template<> struct load_or_save_f<false>
+{
+    template<class A, class T> void operator()( A& a, T& t, unsigned int v ) const
+    {
+        load( a, t, serialization::core_version_type( v ) );
+    }
+};
+
+} // namespace detail
+
+template<class A, class T> inline void split_free( A& a, T& t, unsigned int v )
+{
+    detail::load_or_save_f< A::is_saving::value >()( a, t, v );
+}
+
+// split_member
+
+namespace detail
+{
+
+template<bool IsSaving, class Access = serialization::access> struct load_or_save_m;
+
+template<class Access> struct load_or_save_m<true, Access>
+{
+    template<class A, class T> void operator()( A& a, T const& t, unsigned int v ) const
+    {
+        Access::member_save( a, t, v );
+    }
+};
+
+template<class Access> struct load_or_save_m<false, Access>
+{
+    template<class A, class T> void operator()( A& a, T& t, unsigned int v ) const
+    {
+        Access::member_load( a, t, v );
+    }
+};
+
+} // namespace detail
+
+template<class A, class T> inline void split_member( A& a, T& t, unsigned int v )
+{
+    detail::load_or_save_m< A::is_saving::value >()( a, t, v );
+}
+
+// load_construct_data_adl
+
+template<class Ar, class T> void load_construct_data_adl( Ar& ar, T* t, unsigned int v )
+{
+    load_construct_data( ar, t, serialization::core_version_type( v ) );
+}
+
+// save_construct_data_adl
+
+template<class Ar, class T> void save_construct_data_adl( Ar& ar, T const* t, unsigned int v )
+{
+    save_construct_data( ar, t, serialization::core_version_type( v ) );
+}
+
+} // namespace core
+} // namespace boost
+
+#endif  // #ifndef BOOST_CORE_SERIALIZATION_HPP_INCLUDED

include/boost/core/size.hpp

@@ -0,0 +1,31 @@
+/*
+Copyright 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_SIZE_HPP
+#define BOOST_CORE_SIZE_HPP
+
+#include <cstddef>
+
+namespace boost {
+
+template<class C>
+inline constexpr auto
+size(const C& c) noexcept(noexcept(c.size())) -> decltype(c.size())
+{
+    return c.size();
+}
+
+template<class T, std::size_t N>
+inline constexpr std::size_t
+size(T(&)[N]) noexcept
+{
+    return N;
+}
+
+} /* boost */
+
+#endif

include/boost/core/span.hpp

@@ -1,5 +1,5 @@
 /*
-Copyright 2019 Glen Joseph Fernandes
+Copyright 2019-2023 Glen Joseph Fernandes
 (glenjofe@gmail.com)
 
 Distributed under the Boost Software License, Version 1.0.
@@ -8,10 +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 <iterator>
 #include <type_traits>
-#include <cstddef>
 
 namespace boost {
 
@@ -39,10 +39,8 @@ struct span_compatible {
 };
 
 template<class T>
-struct span_uncvref {
-    typedef typename std::remove_cv<typename
-        std::remove_reference<T>::type>::type type;
-};
+using span_uncvref = typename std::remove_cv<typename
+    std::remove_reference<T>::type>::type;
 
 template<class>
 struct span_is_span {
@@ -64,15 +62,16 @@ struct span_is_array<std::array<T, N> > {
     static constexpr bool value = true;
 };
 
+template<class T>
+using span_ptr = decltype(boost::data(std::declval<T&>()));
+
 template<class, class = void>
 struct span_data { };
 
 template<class T>
 struct span_data<T,
-    typename std::enable_if<std::is_pointer<decltype(std::declval<T
-        &>().data())>::value>::type> {
-    typedef typename std::remove_pointer<decltype(std::declval<T
-        &>().data())>::type type;
+    typename std::enable_if<std::is_pointer<span_ptr<T> >::value>::type> {
+    typedef typename std::remove_pointer<span_ptr<T> >::type type;
 };
 
 template<class, class, class = void>
@@ -102,9 +101,9 @@ template<class R, class T>
 struct span_is_range {
     static constexpr bool value = (std::is_const<T>::value ||
         std::is_lvalue_reference<R>::value) &&
-        !span_is_span<typename span_uncvref<R>::type>::value &&
-        !span_is_array<typename span_uncvref<R>::type>::value &&
-        !std::is_array<typename span_uncvref<R>::type>::value &&
+        !span_is_span<span_uncvref<R> >::value &&
+        !span_is_array<span_uncvref<R> >::value &&
+        !std::is_array<span_uncvref<R> >::value &&
         span_has_data<R, T>::value &&
         span_has_size<R>::value;
 };
@@ -224,15 +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(r.data()) && noexcept(r.size()))
-        : s_(r.data(), r.size()) { }
+    constexpr span(R&& r) noexcept(noexcept(boost::data(r)) &&
+        noexcept(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(r.data()) &&
+    explicit constexpr span(R&& r) noexcept(noexcept(boost::data(r)) &&
         noexcept(r.size()))
-        : s_(r.data(), 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/CMakeLists.txt

@@ -31,6 +31,13 @@ set(BOOST_TEST_LINK_LIBRARIES Boost::core Boost::config Boost::move Boost::smart
 
 boost_test(TYPE run SOURCES fclose_deleter_test.cpp)
 
+set(BOOST_TEST_LINK_LIBRARIES Boost::core Boost::serialization)
+
+boost_test(TYPE run SOURCES serialization_nvp_test.cpp)
+boost_test(TYPE run SOURCES serialization_split_free_test.cpp)
+boost_test(TYPE run SOURCES serialization_split_member_test.cpp)
+boost_test(TYPE run SOURCES serialization_construct_data_test.cpp)
+
 endif()
 
 add_subdirectory(swap)

test/Jamfile.v2

@@ -343,6 +343,7 @@ run span_deduction_guide_test.cpp ;
 run as_bytes_test.cpp ;
 run as_writable_bytes_test.cpp ;
 compile span_boost_begin_test.cpp ;
+run make_span_test.cpp ;
 
 run splitmix64_test.cpp
   : : : $(pedantic-errors) ;
@@ -359,5 +360,16 @@ run max_align_test.cpp ;
 
 run memory_resource_test.cpp ;
 
+run data_test.cpp ;
+run size_test.cpp ;
+
+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/data_test.cpp

@@ -0,0 +1,68 @@
+/*
+Copyright 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_CONSTEXPR) && !defined(BOOST_NO_CXX11_DECLTYPE)
+#include <boost/core/data.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+class range {
+public:
+    int* data() {
+        return &v_[0];
+    }
+
+    const int* data() const {
+        return &v_[0];
+    }
+
+    std::size_t size() const {
+        return 4;
+    }
+
+private:
+    int v_[4];
+};
+
+void test_range()
+{
+    range c;
+    BOOST_TEST_EQ(boost::data(c), c.data());
+}
+
+void test_const_range()
+{
+    const range c = range();
+    BOOST_TEST_EQ(boost::data(c), c.data());
+}
+
+void test_array()
+{
+    int a[4];
+    BOOST_TEST_EQ(boost::data(a), a);
+}
+
+void test_initializer_list()
+{
+    std::initializer_list<int> l{1, 2, 3, 4};
+    BOOST_TEST_EQ(boost::data(l), l.begin());
+}
+
+int main()
+{
+    test_range();
+    test_const_range();
+    test_array();
+    test_initializer_list();
+    return boost::report_errors();
+}
+#else
+int main()
+{
+    return 0;
+}
+#endif

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/make_span_test.cpp

@@ -0,0 +1,100 @@
+/*
+Copyright 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_CONSTEXPR) && !defined(BOOST_NO_CXX11_DECLTYPE)
+#include <boost/core/make_span.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+template<class T>
+class range {
+public:
+    T* data() {
+        return &v_[0];
+    }
+
+    std::size_t size() const {
+        return 4;
+    }
+
+private:
+    T v_[4];
+};
+
+void test_data_size()
+{
+    int a[4];
+    boost::span<int> s = boost::make_span(&a[0], 4);
+    BOOST_TEST_EQ(s.data(), &a[0]);
+    BOOST_TEST_EQ(s.size(), 4);
+}
+
+void test_first_last()
+{
+    int a[4];
+    boost::span<int> s = boost::make_span(&a[0], &a[4]);
+    BOOST_TEST_EQ(s.data(), &a[0]);
+    BOOST_TEST_EQ(s.size(), 4);
+}
+
+void test_array()
+{
+    int a[4];
+    boost::span<int, 4> s = boost::make_span(a);
+    BOOST_TEST_EQ(s.data(), &a[0]);
+    BOOST_TEST_EQ(s.size(), 4);
+}
+
+void test_std_array()
+{
+    std::array<int, 4> a;
+    boost::span<int, 4> s = boost::make_span(a);
+    BOOST_TEST_EQ(s.data(), a.data());
+    BOOST_TEST_EQ(s.size(), a.size());
+}
+
+void test_const_std_array()
+{
+    const std::array<int, 4> a = std::array<int, 4>();
+    boost::span<const int> s = boost::make_span(a);
+    BOOST_TEST_EQ(s.data(), a.data());
+    BOOST_TEST_EQ(s.size(), a.size());
+}
+
+void test_range()
+{
+    range<int> c;
+    boost::span<int> s = boost::make_span(c);
+    BOOST_TEST_EQ(s.data(), c.data());
+    BOOST_TEST_EQ(s.size(), c.size());
+}
+
+void test_initializer_list()
+{
+    std::initializer_list<int> l{1, 2};
+    boost::span<const int> s = boost::make_span(l);
+    BOOST_TEST_EQ(s.data(), l.begin());
+    BOOST_TEST_EQ(s.size(), l.size());
+}
+
+int main()
+{
+    test_data_size();
+    test_first_last();
+    test_array();
+    test_std_array();
+    test_const_std_array();
+    test_range();
+    test_initializer_list();
+    return boost::report_errors();
+}
+#else
+int main()
+{
+    return 0;
+}
+#endif

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();

test/serialization_construct_data_test.cpp

@@ -0,0 +1,102 @@
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__clang__) && defined(__has_warning)
+# if __has_warning( "-Wdeprecated-copy" )
+#  pragma clang diagnostic ignored "-Wdeprecated-copy"
+# endif
+#endif
+
+#include <boost/core/serialization.hpp>
+#include <new>
+
+struct X
+{
+    int v_;
+    explicit X( int v ): v_( v ) {}
+
+    template<class Ar> void serialize( Ar& /*ar*/, unsigned /*v*/ )
+    {
+    }
+};
+
+template<class Ar> void save_construct_data( Ar& ar, X const* t, unsigned /*v*/ )
+{
+    ar << t->v_;
+}
+
+template<class Ar> void load_construct_data( Ar& ar, X* t, unsigned /*v*/ )
+{
+    int v;
+    ar >> v;
+
+    ::new( t ) X( v );
+}
+
+struct Y
+{
+    X x1, x2;
+
+    explicit Y( int v1, int v2 ): x1( v1 ), x2( v2 ) {}
+
+private:
+
+    friend class boost::serialization::access;
+
+    template<class Ar> void load( Ar& ar, unsigned v )
+    {
+        boost::core::load_construct_data_adl( ar, &x1, v );
+        ar >> x1;
+
+        boost::core::load_construct_data_adl( ar, &x2, v );
+        ar >> x2;
+    }
+
+    template<class Ar> void save( Ar& ar, unsigned v ) const
+    {
+        boost::core::save_construct_data_adl( ar, &x1, v );
+        ar << x1;
+
+        boost::core::save_construct_data_adl( ar, &x2, v );
+        ar << x2;
+    }
+
+    template<class Ar> void serialize( Ar& ar, unsigned v )
+    {
+        boost::core::split_member( ar, *this, v );
+    }
+};
+
+#include <boost/archive/text_oarchive.hpp>
+#include <boost/archive/text_iarchive.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <sstream>
+#include <string>
+
+int main()
+{
+    std::ostringstream os;
+
+    Y y1( 7, 11 );
+
+    {
+        boost::archive::text_oarchive ar( os );
+        ar << y1;
+    }
+
+    std::string s = os.str();
+
+    Y y2( 0, 0 );
+
+    {
+        std::istringstream is( s );
+        boost::archive::text_iarchive ar( is );
+        ar >> y2;
+    }
+
+    BOOST_TEST_EQ( y1.x1.v_, y2.x1.v_ );
+    BOOST_TEST_EQ( y1.x2.v_, y2.x2.v_ );
+
+    return boost::report_errors();
+}

test/serialization_nvp_test.cpp

@@ -0,0 +1,55 @@
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__clang__) && defined(__has_warning)
+# if __has_warning( "-Wdeprecated-copy" )
+#  pragma clang diagnostic ignored "-Wdeprecated-copy"
+# endif
+#endif
+
+#include <boost/core/serialization.hpp>
+
+struct X
+{
+    int a, b;
+
+    template<class Ar> void serialize( Ar& ar, unsigned /*v*/ )
+    {
+        ar & boost::core::make_nvp( "a", a );
+        ar & boost::core::make_nvp( "b", b );
+    }
+};
+
+#include <boost/archive/xml_oarchive.hpp>
+#include <boost/archive/xml_iarchive.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <sstream>
+#include <string>
+
+int main()
+{
+    std::ostringstream os;
+
+    X x1 = { 7, 11 };
+
+    {
+        boost::archive::xml_oarchive ar( os );
+        ar << boost::core::make_nvp( "x1", x1 );
+    }
+
+    std::string s = os.str();
+
+    X x2 = { 0, 0 };
+
+    {
+        std::istringstream is( s );
+        boost::archive::xml_iarchive ar( is );
+        ar >> boost::make_nvp( "x2", x2 );
+    }
+
+    BOOST_TEST_EQ( x1.a, x2.a );
+    BOOST_TEST_EQ( x1.b, x2.b );
+
+    return boost::report_errors();
+}

test/serialization_split_free_test.cpp

@@ -0,0 +1,66 @@
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__clang__) && defined(__has_warning)
+# if __has_warning( "-Wdeprecated-copy" )
+#  pragma clang diagnostic ignored "-Wdeprecated-copy"
+# endif
+#endif
+
+#include <boost/core/serialization.hpp>
+
+struct X
+{
+    int a, b;
+};
+
+template<class Ar> void load( Ar& ar, X& x, unsigned /*v*/ )
+{
+    ar >> x.a;
+    ar >> x.b;
+}
+
+template<class Ar> void save( Ar& ar, X const& x, unsigned /*v*/ )
+{
+    ar << x.a;
+    ar << x.b;
+}
+
+template<class Ar> void serialize( Ar& ar, X& x, unsigned v )
+{
+    boost::core::split_free( ar, x, v );
+}
+
+#include <boost/archive/text_oarchive.hpp>
+#include <boost/archive/text_iarchive.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <sstream>
+#include <string>
+
+int main()
+{
+    std::ostringstream os;
+
+    X x1 = { 7, 11 };
+
+    {
+        boost::archive::text_oarchive ar( os );
+        ar << x1;
+    }
+
+    std::string s = os.str();
+
+    X x2 = { 0, 0 };
+
+    {
+        std::istringstream is( s );
+        boost::archive::text_iarchive ar( is );
+        ar >> x2;
+    }
+
+    BOOST_TEST_EQ( x1.a, x2.a );
+    BOOST_TEST_EQ( x1.b, x2.b );
+
+    return boost::report_errors();
+}

test/serialization_split_member_test.cpp

@@ -0,0 +1,70 @@
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__clang__) && defined(__has_warning)
+# if __has_warning( "-Wdeprecated-copy" )
+#  pragma clang diagnostic ignored "-Wdeprecated-copy"
+# endif
+#endif
+
+#include <boost/core/serialization.hpp>
+
+struct X
+{
+    int a, b;
+
+private:
+
+    friend class boost::serialization::access;
+
+    template<class Ar> void load( Ar& ar, unsigned /*v*/ )
+    {
+        ar >> a;
+        ar >> b;
+    }
+
+    template<class Ar> void save( Ar& ar, unsigned /*v*/ ) const
+    {
+        ar << a;
+        ar << b;
+    }
+
+    template<class Ar> void serialize( Ar& ar, unsigned v )
+    {
+        boost::core::split_member( ar, *this, v );
+    }
+};
+
+#include <boost/archive/text_oarchive.hpp>
+#include <boost/archive/text_iarchive.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <sstream>
+#include <string>
+
+int main()
+{
+    std::ostringstream os;
+
+    X x1 = { 7, 11 };
+
+    {
+        boost::archive::text_oarchive ar( os );
+        ar << x1;
+    }
+
+    std::string s = os.str();
+
+    X x2 = { 0, 0 };
+
+    {
+        std::istringstream is( s );
+        boost::archive::text_iarchive ar( is );
+        ar >> x2;
+    }
+
+    BOOST_TEST_EQ( x1.a, x2.a );
+    BOOST_TEST_EQ( x1.b, x2.b );
+
+    return boost::report_errors();
+}

test/size_test.cpp

@@ -0,0 +1,42 @@
+/*
+Copyright 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_CONSTEXPR) && !defined(BOOST_NO_CXX11_DECLTYPE)
+#include <boost/core/size.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+struct range {
+    std::size_t size() const {
+        return 4;
+    }
+};
+
+void test_range()
+{
+    range c;
+    BOOST_TEST_EQ(boost::size(c), 4);
+}
+
+void test_array()
+{
+    int a[4];
+    BOOST_TEST_EQ(boost::size(a), 4);
+}
+
+int main()
+{
+    test_range();
+    test_array();
+    return boost::report_errors();
+}
+#else
+int main()
+{
+    return 0;
+}
+#endif

test/span_constructible_test.cpp

@@ -1,5 +1,5 @@
 /*
-Copyright 2019 Glen Joseph Fernandes
+Copyright 2019-2023 Glen Joseph Fernandes
 (glenjofe@gmail.com)
 
 Distributed under the Boost Software License, Version 1.0.
@@ -140,6 +140,14 @@ void test_range()
         range<derived>&>));
 }
 
+void test_initializer_list()
+{
+    BOOST_TEST_TRAIT_TRUE((std::is_constructible<boost::span<const int>,
+        std::initializer_list<int> >));
+    BOOST_TEST_TRAIT_FALSE((std::is_constructible<boost::span<int>,
+        std::initializer_list<int> >));
+}
+
 void test_span()
 {
     BOOST_TEST_TRAIT_TRUE((std::is_constructible<boost::span<const int>,
@@ -187,6 +195,7 @@ int main()
     test_std_array();
     test_const_std_array();
     test_range();
+    test_initializer_list();
     test_span();
     test_copy();
     test_assign();

test/span_deduction_guide_test.cpp

@@ -1,5 +1,5 @@
 /*
-Copyright 2019 Glen Joseph Fernandes
+Copyright 2019-2023 Glen Joseph Fernandes
 (glenjofe@gmail.com)
 
 Distributed under the Boost Software License, Version 1.0.
@@ -78,6 +78,15 @@ void test_range()
     BOOST_TEST_EQ(s.size(), c.size());
 }
 
+void test_initializer_list()
+{
+    std::initializer_list<int> l{1, 2};
+    boost::span s(l);
+    BOOST_TEST_EQ(s.extent, boost::dynamic_extent);
+    BOOST_TEST_EQ(s.data(), l.begin());
+    BOOST_TEST_EQ(s.size(), l.size());
+}
+
 void test_span_dynamic()
 {
     int a[4];
@@ -104,6 +113,7 @@ int main()
     test_std_array();
     test_const_std_array();
     test_range();
+    test_initializer_list();
     test_span_dynamic();
     test_span_static();
     return boost::report_errors();

test/span_test.cpp

@@ -1,5 +1,5 @@
 /*
-Copyright 2019 Glen Joseph Fernandes
+Copyright 2019-2023 Glen Joseph Fernandes
 (glenjofe@gmail.com)
 
 Distributed under the Boost Software License, Version 1.0.
@@ -118,6 +118,14 @@ void test_construct_range()
     BOOST_TEST_EQ(s.size(), c.size());
 }
 
+void test_construct_initializer_list()
+{
+    std::initializer_list<int> l{1, 2};
+    boost::span<const int> s(l);
+    BOOST_TEST_EQ(s.data(), l.begin());
+    BOOST_TEST_EQ(s.size(), l.size());
+}
+
 void test_construct_span_dynamic()
 {
     int a[4];
@@ -376,6 +384,7 @@ int main()
     test_construct_const_std_array_dynamic();
     test_construct_const_std_array_static();
     test_construct_range();
+    test_construct_initializer_list();
     test_construct_span_dynamic();
     test_construct_span_dynamic_static();
     test_construct_span_static();