Remove hash_value overload for basic_string_view; it's no longer needed

Rename typedef `base` to `core_ev_base`

.drone.jsonnet

@@ -32,6 +32,8 @@ local linux_pipeline(name, image, environment, packages = "", sources = [], arch
             commands:
             [
                 'set -e',
+                'uname -a',
+                'echo $DRONE_STAGE_MACHINE',
                 'wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -',
             ] +
             (if sources != [] then [ ('apt-add-repository "' + source + '"') for source in sources ] else []) +
@@ -200,31 +202,37 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
     ),
 
     linux_pipeline(
-        "Linux 23.04 GCC 13 32 ASAN",
-        "cppalliance/droneubuntu2304:1",
-        { TOOLSET: 'gcc', COMPILER: 'g++-13', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '32' } + asan,
-        "g++-13-multilib",
+        "Linux 24.04 GCC 13* 32/64",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '32,64' },
     ),
 
     linux_pipeline(
-        "Linux 23.04 GCC 13 64 ASAN",
-        "cppalliance/droneubuntu2304:1",
-        { TOOLSET: 'gcc', COMPILER: 'g++-13', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '64' } + asan,
-        "g++-13-multilib",
+        "Linux 24.04 GCC 14 32 ASAN",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-14', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '32' } + asan,
+        "g++-14-multilib",
     ),
 
     linux_pipeline(
-        "Linux 23.04 GCC 13 32 UBSAN",
-        "cppalliance/droneubuntu2304:1",
-        { TOOLSET: 'gcc', COMPILER: 'g++-13', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '32' } + ubsan,
-        "g++-13-multilib",
+        "Linux 24.04 GCC 14 64 ASAN",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-14', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '64' } + asan,
+        "g++-14-multilib",
     ),
 
     linux_pipeline(
-        "Linux 23.04 GCC 13 64 UBSAN",
-        "cppalliance/droneubuntu2304:1",
-        { TOOLSET: 'gcc', COMPILER: 'g++-13', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '64' } + ubsan,
-        "g++-13-multilib",
+        "Linux 24.04 GCC 14 32 UBSAN",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-14', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '32' } + ubsan,
+        "g++-14-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 24.04 GCC 14 64 UBSAN",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-14', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '64' } + ubsan,
+        "g++-14-multilib",
     ),
 
     linux_pipeline(
@@ -347,24 +355,38 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
     ),
 
     linux_pipeline(
-        "Linux 23.04 Clang 16",
-        "cppalliance/droneubuntu2304:1",
+        "Linux 24.04 Clang 16",
+        "cppalliance/droneubuntu2404:1",
         { TOOLSET: 'clang', COMPILER: 'clang++-16', CXXSTD: '03,11,14,17,20,2b' },
         "clang-16",
     ),
 
     linux_pipeline(
-        "Linux 23.10 Clang 17 UBSAN",
-        "cppalliance/droneubuntu2310:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-17', CXXSTD: '03,11,14,17,20,2b' } + ubsan,
+        "Linux 24.04 Clang 17",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-17', CXXSTD: '03,11,14,17,20,2b' },
         "clang-17",
     ),
 
     linux_pipeline(
-        "Linux 23.10 Clang 17 ASAN",
-        "cppalliance/droneubuntu2310:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-17', CXXSTD: '03,11,14,17,20,2b' } + asan,
-        "clang-17",
+        "Linux 24.04 Clang 18 UBSAN",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-18', CXXSTD: '03,11,14,17,20,2b' } + ubsan,
+        "clang-18",
+    ),
+
+    linux_pipeline(
+        "Linux 24.04 Clang 18 ASAN",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-18', CXXSTD: '03,11,14,17,20,2b' } + asan,
+        "clang-18",
+    ),
+
+    linux_pipeline(
+        "Linux 24.10 Clang 19",
+        "cppalliance/droneubuntu2410:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-19', CXXSTD: '03,11,14,17,20,2b' },
+        "clang-19",
     ),
 
     macos_pipeline(

.github/workflows/ci.yml

@@ -128,6 +128,13 @@ jobs:
             container: ubuntu:23.04
             install:
               - g++-13-multilib
+          - toolset: gcc-14
+            cxxstd: "03,11,14,17,20,23"
+            address-model: 32,64
+            os: ubuntu-latest
+            container: ubuntu:24.04
+            install:
+              - g++-14-multilib
           - name: UBSAN
             toolset: gcc-12
             cxxstd: "03,11,14,17,20,23"
@@ -286,15 +293,23 @@ jobs:
           - toolset: clang
             compiler: clang++-17
             cxxstd: "03,11,14,17,20,2b"
-            os: ubuntu-22.04
+            os: ubuntu-latest
+            container: ubuntu:23.10
             install:
               - clang-17
               - libc++-17-dev
               - libc++abi-17-dev
-            sources:
-              - "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-17 main"
-            source_keys:
-              - "https://apt.llvm.org/llvm-snapshot.gpg.key"
+            cxxflags: -stdlib=libc++
+            linkflags: -stdlib=libc++
+          - toolset: clang
+            compiler: clang++-18
+            cxxstd: "03,11,14,17,20,2b"
+            os: ubuntu-latest
+            container: ubuntu:24.04
+            install:
+              - clang-18
+              - libc++-18-dev
+              - libc++abi-18-dev
             cxxflags: -stdlib=libc++
             linkflags: -stdlib=libc++
           - name: UBSAN
@@ -310,15 +325,15 @@ jobs:
               - libc++-15-dev
               - libc++abi-15-dev
 
-          - toolset: clang
-            cxxstd: "03,11,14,17,20,2b"
-            os: macos-12
           - toolset: clang
             cxxstd: "03,11,14,17,20,2b"
             os: macos-13
           - toolset: clang
             cxxstd: "03,11,14,17,20,2b"
             os: macos-14
+          - toolset: clang
+            cxxstd: "03,11,14,17,20,2b"
+            os: macos-15
 
     timeout-minutes: 45
     runs-on: ${{matrix.os}}
@@ -611,9 +626,10 @@ jobs:
         include:
           - os: ubuntu-20.04
           - os: ubuntu-22.04
-          - os: macos-12
+          - os: ubuntu-24.04
           - os: macos-13
           - os: macos-14
+          - os: macos-15
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 10
@@ -678,9 +694,10 @@ jobs:
         include:
           - os: ubuntu-20.04
           - os: ubuntu-22.04
-          - os: macos-12
+          - os: ubuntu-24.04
           - os: macos-13
           - os: macos-14
+          - os: macos-15
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 10
@@ -755,9 +772,10 @@ jobs:
         include:
           - os: ubuntu-20.04
           - os: ubuntu-22.04
-          - os: macos-12
+          - os: ubuntu-24.04
           - os: macos-13
           - os: macos-14
+          - os: macos-15
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 20

build.jam

@@ -0,0 +1,23 @@
+# Copyright 2023-2024 René Ferdinand Rivera Morell
+# Copyright 2024 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# https://www.boost.org/LICENSE_1_0.txt
+
+require-b2 5.2 ;
+
+constant boost_dependencies :
+    /boost/assert//boost_assert
+    /boost/config//boost_config
+    /boost/static_assert//boost_static_assert
+    /boost/throw_exception//boost_throw_exception
+    ;
+
+project /boost/core ;
+
+explicit
+    [ alias boost_core : : : : <include>include <library>$(boost_dependencies) ]
+    [ alias all : boost_core test ]
+    ;
+
+call-if : boost-library core
+    ;

doc/Jamfile.v2

@@ -9,7 +9,7 @@ import project ;
 import doxygen ;
 import quickbook ;
 
-path-constant INCLUDES : ../../.. ;
+path-constant INCLUDES : ../include ;
 
 doxygen ref_reference
   :

doc/changes.qbk

@@ -7,12 +7,24 @@
 
 [section Revision History]
 
+[section Changes in 1.86.0]
+
+* Added a [link core.pointer_in_range `boost/core/pointer_in_range.hpp`] header with a `pointer_in_range`
+  function template to check if a pointer is within a given range.
+* Fixed `type_name` for abstract classes. ([github_issue 172])
+* Fixed `boost/core/type_name.hpp` compilation error with MSVC with disabled native `wchar_t` type.
+  ([github_issue 173])
+* Added a workaround for an MSVC [@https://developercommunity.visualstudio.com/t/Compiler-bug:-Incorrect-C2247-and-C2248/10690025 bug]
+  causing `empty_value` compilation errors when it is used with a nested class. ([github_pr 175])
+
+[endsect]
+
 [section Changes in 1.85.0]
 
 * Added a new [link core.functor `boost/core/functor.hpp`] header with a `functor` class template
   for wrapping a raw function into a function object class.
 * Changed [link core.null_deleter `null_deleter`], [link core.fclose_deleter `fclose_deleter`]
-  and [link.checked_delete checked deleter] definitions so that they don't bring namespace `boost`
+  and [link core.checked_delete checked deleter] definitions so that they don't bring namespace `boost`
   into argument-dependent lookup in cases like this:
   ```
   std::unique_ptr< std::FILE, boost::fclose_deleter > p1, p2;

doc/core.qbk

@@ -20,6 +20,9 @@ or copy at http://boost.org/LICENSE_1_0.txt)
   ]
 ]
 
+[template github_issue[key]'''<ulink url="https://github.com/boostorg/core/issues/'''[key]'''">#'''[key]'''</ulink>''']
+[template github_pr[key]'''<ulink url="https://github.com/boostorg/core/pull/'''[key]'''">PR#'''[key]'''</ulink>''']
+
 [template simplesect[title]
 [block '''<simplesect><title>'''[title]'''</title>''']]
 

include/boost/core/detail/string_view.hpp

@@ -41,9 +41,6 @@ namespace boost
 // forward declaration of boost::basic_string_view from Utility
 template<class Ch, class Tr> class basic_string_view;
 
-// forward declaration of boost::hash_range from ContainerHash
-template<class It> std::size_t hash_range( It, It );
-
 namespace core
 {
 namespace detail
@@ -1181,11 +1178,6 @@ public:
     }
 
 #endif
-
-    inline friend std::size_t hash_value( basic_string_view const& sv )
-    {
-        return boost::hash_range( sv.begin(), sv.end() );
-    }
 };
 
 // stream inserter

include/boost/core/empty_value.hpp

@@ -95,9 +95,57 @@ private:
 };
 
 #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
+#if defined(BOOST_MSVC)
+/*
+This is a workaround to an MSVC bug when T is a nested class:
+https://developercommunity.visualstudio.com/t/Compiler-bug:-Incorrect-C2247-and-C2248/10690025
+*/
+namespace detail {
+
+template<class T>
+class empty_value_base
+    : public T {
+public:
+#if !defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS)
+    empty_value_base() = default;
+#else
+    BOOST_CONSTEXPR empty_value_base() { }
+#endif
+
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
+    template<class U, class... Args>
+    BOOST_CONSTEXPR empty_value_base(U&& value, Args&&... args)
+        : T(std::forward<U>(value), std::forward<Args>(args)...) { }
+#else
+    template<class U>
+    BOOST_CONSTEXPR empty_value_base(U&& value)
+        : T(std::forward<U>(value)) { }
+#endif
+#else
+    template<class U>
+    BOOST_CONSTEXPR empty_value_base(const U& value)
+        : T(value) { }
+
+    template<class U>
+    BOOST_CONSTEXPR empty_value_base(U& value)
+        : T(value) { }
+#endif
+};
+
+} /* detail */
+#endif
+
 template<class T, unsigned N>
 class empty_value<T, N, true>
+#if defined(BOOST_MSVC)
+    : detail::empty_value_base<T> {
+    typedef detail::empty_value_base<T> empty_base_;
+#else
     : T {
+    typedef T empty_base_;
+#endif
+
 public:
     typedef T type;
 
@@ -108,26 +156,26 @@ public:
 #endif
 
     BOOST_CONSTEXPR empty_value(boost::empty_init_t)
-        : T() { }
+        : empty_base_() { }
 
 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
 #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
     template<class U, class... Args>
     BOOST_CONSTEXPR empty_value(boost::empty_init_t, U&& value, Args&&... args)
-        : T(std::forward<U>(value), std::forward<Args>(args)...) { }
+        : empty_base_(std::forward<U>(value), std::forward<Args>(args)...) { }
 #else
     template<class U>
     BOOST_CONSTEXPR empty_value(boost::empty_init_t, U&& value)
-        : T(std::forward<U>(value)) { }
+        : empty_base_(std::forward<U>(value)) { }
 #endif
 #else
     template<class U>
     BOOST_CONSTEXPR empty_value(boost::empty_init_t, const U& value)
-        : T(value) { }
+        : empty_base_(value) { }
 
     template<class U>
     BOOST_CONSTEXPR empty_value(boost::empty_init_t, U& value)
-        : T(value) { }
+        : empty_base_(value) { }
 #endif
 
     BOOST_CONSTEXPR const T& get() const BOOST_NOEXCEPT {

test/CMakeLists.txt

@@ -8,17 +8,6 @@ if(HAVE_BOOST_TEST)
 
 boost_test_jamfile(FILE Jamfile.v2 LINK_LIBRARIES Boost::core Boost::static_assert Boost::type_traits)
 
-set(BOOST_TEST_LINK_LIBRARIES Boost::core Boost::type_traits)
-
-boost_test(TYPE run SOURCES eif_constructors.cpp)
-boost_test(TYPE run SOURCES eif_dummy_arg_disambiguation.cpp)
-boost_test(TYPE run SOURCES eif_lazy.cpp)
-boost_test(TYPE run SOURCES eif_lazy_test.cpp)
-boost_test(TYPE run SOURCES eif_member_templates.cpp)
-boost_test(TYPE run SOURCES eif_namespace_disambiguation.cpp)
-boost_test(TYPE run SOURCES eif_no_disambiguation.cpp)
-boost_test(TYPE run SOURCES eif_partial_specializations.cpp)
-
 set(BOOST_TEST_LINK_LIBRARIES Boost::core Boost::throw_exception)
 
 boost_test(TYPE run SOURCES no_exceptions_support_test.cpp)
@@ -27,6 +16,10 @@ set(BOOST_TEST_LINK_LIBRARIES Boost::core Boost::utility)
 
 boost_test(TYPE run SOURCES sv_conversion_test2.cpp)
 
+set(BOOST_TEST_LINK_LIBRARIES Boost::core Boost::container_hash)
+
+boost_test(TYPE run SOURCES sv_hash_test.cpp)
+
 set(BOOST_TEST_LINK_LIBRARIES Boost::core Boost::config Boost::move Boost::smart_ptr)
 
 boost_test(TYPE run SOURCES fclose_deleter_test.cpp)

test/Jamfile.v2

@@ -6,11 +6,15 @@
 #  See accompanying file LICENSE_1_0.txt or copy at
 #  http://www.boost.org/LICENSE_1_0.txt
 
+require-b2 5.0.1 ;
+import-search /boost/config/checks ;
+import config : requires ;
 import modules ;
 import testing ;
 
 project : requirements
-
+  <library>/boost/core//boost_core
+  <library>/boost/type_traits//boost_type_traits
   <warnings>extra
   <toolset>msvc:<warnings-as-errors>on
   <toolset>clang:<warnings-as-errors>on
@@ -31,6 +35,8 @@ local pedantic-errors = <warnings>pedantic
     <toolset>gcc:<warnings-as-errors>on
     <toolset>clang:<warnings-as-errors>on ;
 
+local CPP11 = [ requires cxx11_variadic_templates cxx11_template_aliases cxx11_decltype cxx11_constexpr cxx11_noexcept cxx11_ref_qualifiers ] ;
+
 # quick test (for CI)
 run quick.cpp ;
 
@@ -79,14 +85,14 @@ compile-fail ref_implicit_fail4.cpp
 run ref_cv_test.cpp ;
 run ref_conversion_test.cpp ;
 
-run eif_constructors.cpp : ;
-run eif_dummy_arg_disambiguation.cpp : ;
-run eif_lazy.cpp : ;
-run eif_lazy_test.cpp : ;
-run eif_member_templates.cpp : ;
-run eif_namespace_disambiguation.cpp : ;
-run eif_no_disambiguation.cpp : ;
-run eif_partial_specializations.cpp : ;
+run eif_constructors.cpp ;
+run eif_dummy_arg_disambiguation.cpp ;
+run eif_lazy.cpp ;
+run eif_lazy_test.cpp ;
+run eif_member_templates.cpp ;
+run eif_namespace_disambiguation.cpp ;
+run eif_no_disambiguation.cpp ;
+run eif_partial_specializations.cpp ;
 
 compile-fail noncopyable_compile_fail.cpp
   : $(warnings-as-errors-off) ;
@@ -197,7 +203,13 @@ run underlying_type.cpp ;
 compile-fail null_deleter_compile_fail_adl.cpp
   : $(warnings-as-errors-off) ;
 
-run fclose_deleter_test.cpp : : : <target-os>windows:<define>_CRT_SECURE_NO_WARNINGS <target-os>windows:<define>_CRT_SECURE_NO_DEPRECATE ;
+run fclose_deleter_test.cpp : : :
+  $(CPP11)
+  <library>/boost/move//boost_move
+  <library>/boost/smart_ptr//boost_smart_ptr
+  <target-os>windows:<define>_CRT_SECURE_NO_WARNINGS
+  <target-os>windows:<define>_CRT_SECURE_NO_DEPRECATE ;
+
 compile-fail fclose_deleter_compile_fail_adl.cpp
   : <target-os>windows:<define>_CRT_SECURE_NO_WARNINGS <target-os>windows:<define>_CRT_SECURE_NO_DEPRECATE $(warnings-as-errors-off) ;
 
@@ -205,7 +217,6 @@ run functor_test.cpp ;
 compile-fail functor_compile_fail_adl.cpp
   : $(warnings-as-errors-off) ;
 
-
 run pointer_traits_pointer_test.cpp ;
 run pointer_traits_element_type_test.cpp ;
 run pointer_traits_difference_type_test.cpp ;
@@ -226,6 +237,8 @@ run empty_value_test.cpp ;
 run empty_value_size_test.cpp ;
 run empty_value_final_test.cpp ;
 run empty_value_constexpr_test.cpp ;
+compile empty_value_nested_test.cpp ;
+compile-fail empty_value_compile_fail_casting.cpp ;
 
 run quick_exit_test.cpp ;
 run-fail quick_exit_fail.cpp ;
@@ -379,7 +392,7 @@ run sv_stream_insert_test.cpp
   : : : $(pedantic-errors) ;
 run sv_conversion_test.cpp
   : : : $(pedantic-errors) ;
-run sv_conversion_test2.cpp : ;
+run sv_conversion_test2.cpp : : : <library>/boost/utility//boost_utility ;
 run sv_common_reference_test.cpp
   : : : $(pedantic-errors) ;
 compile sv_common_reference_test2.cpp ;
@@ -390,6 +403,8 @@ compile-fail sv_nullptr_fail.cpp
 compile sv_construct_test_cx.cpp ;
 compile sv_construct_test_cx2.cpp ;
 
+run sv_hash_test.cpp : : : $(CPP11) <library>/boost/container_hash//boost_container_hash ;
+
 run span_test.cpp ;
 run span_types_test.cpp ;
 run span_constructible_test.cpp ;
@@ -417,11 +432,15 @@ run memory_resource_test.cpp ;
 run data_test.cpp ;
 run size_test.cpp ;
 
-import ../../config/checks/config : requires ;
-
-local CPP11 = [ requires cxx11_variadic_templates cxx11_template_aliases cxx11_decltype cxx11_constexpr cxx11_noexcept ] ;
-
-local with-serialization = <library>/boost//serialization/<warnings>off $(warnings-as-errors-off) <undefined-sanitizer>norecover:<link>static $(CPP11) ;
+local with-serialization =
+    <library>/boost/serialization//boost_serialization/<warnings>off
+    $(warnings-as-errors-off)
+    <undefined-sanitizer>norecover:<link>static
+    $(CPP11)
+    # Serialization no longer builds under classic MinGW
+    # and <toolset>gcc,<target-os>windows,<address-model>32 fails for some reason
+    <toolset>gcc,<target-os>windows:<build>no
+;
 
 run serialization_nvp_test.cpp : : : $(with-serialization) <undefined-sanitizer>norecover:<build>no ;
 run serialization_split_free_test.cpp : : : $(with-serialization) ;

test/cmake_install_test/CMakeLists.txt

@@ -14,4 +14,4 @@ target_link_libraries(quick Boost::core)
 enable_testing()
 add_test(quick quick)
 
-add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)
+add_custom_target(check VERBATIM COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)

test/cmake_subdir_test/CMakeLists.txt

@@ -18,4 +18,4 @@ target_link_libraries(quick Boost::core)
 enable_testing()
 add_test(quick quick)
 
-add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)
+add_custom_target(check VERBATIM COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)

test/empty_value_compile_fail_casting.cpp

@@ -0,0 +1,20 @@
+// Copyright 2024 Braden Ganetsky
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/empty_value.hpp>
+
+struct empty {};
+
+// This test ensures private inheritance of `boost::empty_value<T>` for empty `T`.
+// With public inheritance, `boost::empty_value<empty>*` could cast to `empty*`.
+void test_empty_not_convertible_to_base()
+{
+    const boost::empty_value<empty> x(boost::empty_init);
+    const empty* x2 = static_cast<const empty*>(&x);
+    (void)x2;
+}
+
+int main()
+{
+}

test/empty_value_nested_test.cpp

@@ -0,0 +1,45 @@
+/*
+Copyright 2024 Braden Ganetsky
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#include <boost/core/empty_value.hpp>
+
+/*
+Tests workaround for MSVC bug:
+https://developercommunity.visualstudio.com/t/Compiler-bug:-Incorrect-C2247-and-C2248/10690025
+*/
+template<class T>
+struct derived
+    : boost::empty_value<T> {
+    typedef typename boost::empty_value<T>::type type;
+    derived(boost::empty_init_t e)
+        : boost::empty_value<T>(e) { }
+};
+
+struct outer {
+    struct inner_empty { };
+    struct inner_non_empty {
+        inner_non_empty()
+            : value() { }
+        int value;
+    };
+};
+
+void test()
+{
+    const boost::empty_value<outer> x1(boost::empty_init);
+    (void)x1;
+    const boost::empty_value<outer::inner_empty> x2(boost::empty_init);
+    (void)x2;
+    const boost::empty_value<outer::inner_non_empty> x3(boost::empty_init);
+    (void)x3;
+    const derived<outer> x4(boost::empty_init);
+    (void)x4;
+    const derived<outer::inner_empty> x5(boost::empty_init);
+    (void)x5;
+    const derived<outer::inner_non_empty> x6(boost::empty_init);
+    (void)x6;
+}

test/sv_hash_test.cpp

@@ -0,0 +1,48 @@
+// Copyright 2021-2024 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/string_view.hpp>
+#include <boost/container_hash/hash.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+#include <string>
+
+template<class T> std::size_t hv( T const& t )
+{
+    return boost::hash<T>()( t );
+}
+
+template<class Ch> void test( Ch const* p )
+{
+    std::basic_string<Ch> s( p );
+    boost::core::basic_string_view<Ch> sv( s );
+
+    BOOST_TEST_EQ( hv( s ), hv( sv ) );
+}
+
+int main()
+{
+    test( "123" );
+    test( L"123" );
+
+#if !defined(BOOST_NO_CXX11_CHAR16_T)
+
+    test( u"123" );
+
+#endif
+
+#if !defined(BOOST_NO_CXX11_CHAR32_T)
+
+    test( U"123" );
+
+#endif
+
+#if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
+
+    test( u8"123" );
+
+#endif
+
+    return boost::report_errors();
+}