Remove dependencies on Boost.StaticAssert.

Boost.StaticAssert has been merged into Boost.Config, so replace the dependency accordingly.
Document is_placeholder
2026-05-06 16:36:28 +02:00 · 2026-01-22 15:21:40 +03:00 · 2026-01-02 13:40:47 +02:00 · 2026-01-02 13:22:31 +02:00 · 2025-12-25 16:31:01 +02:00 · 2025-12-25 15:05:02 +02:00
318 changed files with 24202 additions and 1879 deletions
@@ -0,0 +1,463 @@
+# Copyright 2022 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# https://www.boost.org/LICENSE_1_0.txt
+
+local library = "core";
+
+local triggers =
+{
+    branch: [ "master", "develop", "feature/*" ]
+};
+
+local ubsan = { UBSAN: '1', UBSAN_OPTIONS: 'print_stacktrace=1' };
+local asan = { ASAN: '1' };
+
+local linux_pipeline(name, image, environment, packages = "", sources = [], arch = "amd64") =
+{
+    name: name,
+    kind: "pipeline",
+    type: "docker",
+    trigger: triggers,
+    platform:
+    {
+        os: "linux",
+        arch: arch
+    },
+    steps:
+    [
+        {
+            name: "everything",
+            image: image,
+            environment: environment,
+            commands:
+            [
+                'set -e',
+                'uname -a',
+                'echo $DRONE_STAGE_MACHINE',
+            ] +
+            (if sources != [] then [ ('apt-add-repository "' + source + '"') for source in sources ] else []) +
+            (if packages != "" then [ 'apt-get update', 'apt-get -y install ' + packages ] else []) +
+            [
+                'export LIBRARY=' + library,
+                './.drone/drone.sh',
+            ]
+        }
+    ]
+};
+
+local macos_pipeline(name, environment, xcode_version = "12.2", osx_version = "catalina", arch = "amd64") =
+{
+    name: name,
+    kind: "pipeline",
+    type: "exec",
+    trigger: triggers,
+    platform: {
+        "os": "darwin",
+        "arch": arch
+    },
+    node: {
+        "os": osx_version
+    },
+    steps: [
+        {
+            name: "everything",
+            environment: environment + { "DEVELOPER_DIR": "/Applications/Xcode-" + xcode_version + ".app/Contents/Developer" },
+            commands:
+            [
+                'export LIBRARY=' + library,
+                './.drone/drone.sh',
+            ]
+        }
+    ]
+};
+
+local windows_pipeline(name, image, environment, arch = "amd64") =
+{
+    name: name,
+    kind: "pipeline",
+    type: "docker",
+    trigger: triggers,
+    platform:
+    {
+        os: "windows",
+        arch: arch
+    },
+    "steps":
+    [
+        {
+            name: "everything",
+            image: image,
+            environment: environment,
+            commands:
+            [
+                'cmd /C .drone\\\\drone.bat ' + library,
+            ]
+        }
+    ]
+};
+
+[
+    linux_pipeline(
+        "Linux 16.04 GCC 4.4",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-4.4', CXXSTD: '98,0x' },
+        "g++-4.4",
+        [ "ppa:ubuntu-toolchain-r/test" ],
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 GCC 4.6 32/64",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-4.6', CXXSTD: '98,0x', ADDRMD: '32,64' },
+        "g++-4.6-multilib",
+        [ "ppa:ubuntu-toolchain-r/test" ],
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 GCC 4.7 32/64",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-4.7', CXXSTD: '98,0x', ADDRMD: '32,64' },
+        "g++-4.7-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 GCC 4.8 32/64",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-4.8', CXXSTD: '03,11', ADDRMD: '32,64' },
+        "g++-4.8-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 GCC 4.9 32/64",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-4.9', CXXSTD: '03,11', ADDRMD: '32,64' },
+        "g++-4.9-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 GCC 5* 32/64",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14', ADDRMD: '32,64' },
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 GCC 6 32/64",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-6', CXXSTD: '03,11,14', ADDRMD: '32,64' },
+        "g++-6-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 GCC 7* 32/64",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17', ADDRMD: '32,64' },
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 GCC 8 32/64",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-8', CXXSTD: '03,11,14,17', ADDRMD: '32,64' },
+        "g++-8-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 GCC 9* 32/64",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17,2a', ADDRMD: '32,64' },
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 GCC 9* ARM64",
+        "cppalliance/droneubuntu2004:multiarch",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17,2a' },
+        arch="arm64",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 GCC 9* S390x",
+        "cppalliance/droneubuntu2004:multiarch",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17,2a' },
+        arch="s390x",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 GCC 10 32/64",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-10', CXXSTD: '03,11,14,17,20', ADDRMD: '32,64' },
+        "g++-10-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 GCC 11* 32/64",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17,2a', ADDRMD: '32,64' },
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 GCC 12 32/64",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-12', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '32,64' },
+        "g++-12-multilib",
+    ),
+
+    linux_pipeline(
+        "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 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 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 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(
+        "Linux 25.04 GCC 15 32/64",
+        "cppalliance/droneubuntu2504:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-15', CXXSTD: '03,11,14,17,20,23,2c', ADDRMD: '32,64' },
+        "g++-15-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 Clang 3.5",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.5', CXXSTD: '03,11' },
+        "clang-3.5",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 Clang 3.6",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.6', CXXSTD: '03,11,14' },
+        "clang-3.6",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 Clang 3.7",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.7', CXXSTD: '03,11,14' },
+        "clang-3.7",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 Clang 3.8",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.8', CXXSTD: '03,11,14' },
+        "clang-3.8",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 3.9",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.9', CXXSTD: '03,11,14' },
+        "clang-3.9",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 4.0",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-4.0', CXXSTD: '03,11,14' },
+        "clang-4.0",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 5.0",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-5.0', CXXSTD: '03,11,14,1z' },
+        "clang-5.0",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 6.0",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-6.0', CXXSTD: '03,11,14,17' },
+        "clang-6.0",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 7",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-7', CXXSTD: '03,11,14,17' },
+        "clang-7",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 8",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-8', CXXSTD: '03,11,14,17' },
+        "clang-8",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 9",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-9', CXXSTD: '03,11,14,17,2a' },
+        "clang-9",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 10",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-10', CXXSTD: '03,11,14,17,2a' },
+        "clang-10",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 11",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-11', CXXSTD: '03,11,14,17,2a' },
+        "clang-11",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 12",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-12', CXXSTD: '03,11,14,17,2a' },
+        "clang-12",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 Clang 13",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-13', CXXSTD: '03,11,14,17,20' },
+        "clang-13",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 Clang 14",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-14', CXXSTD: '03,11,14,17,20,2b' },
+        "clang-14",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 Clang 15",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-15', CXXSTD: '03,11,14,17,20,2b' },
+        "clang-15",
+    ),
+
+    linux_pipeline(
+        "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 24.04 Clang 17",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-17', CXXSTD: '03,11,14,17,20,2b' },
+        "clang-17",
+    ),
+
+    linux_pipeline(
+        "Linux 24.04 Clang 18",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-18', CXXSTD: '03,11,14,17,20,2b' },
+        "clang-18",
+    ),
+
+    linux_pipeline(
+        "Linux 24.04 Clang 19",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-19', CXXSTD: '03,11,14,17,20,2b' },
+        "clang-19",
+    ),
+
+    linux_pipeline(
+        "Linux 24.04 Clang 20 UBSAN",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-20', CXXSTD: '03,11,14,17,20,23,2c' } + ubsan,
+        "clang-20",
+    ),
+
+    linux_pipeline(
+        "Linux 24.04 Clang 20 ASAN",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-20', CXXSTD: '03,11,14,17,20,23,2c' } + asan,
+        "clang-20",
+    ),
+
+    linux_pipeline(
+        "Linux 25.10 Clang 21",
+        "cppalliance/droneubuntu2510:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-21', CXXSTD: '03,11,14,17,20,23,2c' },
+        "clang-21",
+    ),
+
+    macos_pipeline(
+        "MacOS 10.15 Xcode 12.2 UBSAN",
+        { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,1z' } + ubsan,
+    ),
+
+    macos_pipeline(
+        "MacOS 10.15 Xcode 12.2 ASAN",
+        { 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",
+        { TOOLSET: 'msvc-14.0', CXXSTD: '14,latest', B2_DONT_EMBED_MANIFEST: '1' },
+    ),
+
+    windows_pipeline(
+        "Windows VS2017 msvc-14.1",
+        "cppalliance/dronevs2017",
+        { TOOLSET: 'msvc-14.1', CXXSTD: '14,17,latest', ADDRMD: '32,64' },
+    ),
+
+    windows_pipeline(
+        "Windows VS2019 msvc-14.2",
+        "cppalliance/dronevs2019",
+        { TOOLSET: 'msvc-14.2', CXXSTD: '14,17,20,latest', ADDRMD: '32,64' },
+    ),
+
+    windows_pipeline(
+        "Windows VS2022 msvc-14.3",
+        "cppalliance/dronevs2022:1",
+        { TOOLSET: 'msvc-14.3', CXXSTD: '14,17,20,latest', ADDRMD: '32,64' },
+    ),
+
+    windows_pipeline(
+        "Windows VS2026 msvc-14.5",
+        "cppalliance/dronevs2026:1",
+        { TOOLSET: 'msvc-14.5', CXXSTD: '14,17,20,latest', ADDRMD: '32,64' },
+    ),
+]
@@ -0,0 +1,23 @@
+@REM Copyright 2022 Peter Dimov
+@REM Distributed under the Boost Software License, Version 1.0.
+@REM https://www.boost.org/LICENSE_1_0.txt
+
+@ECHO ON
+
+set LIBRARY=%1
+set DRONE_BUILD_DIR=%CD%
+
+set BOOST_BRANCH=develop
+if "%DRONE_BRANCH%" == "master" set BOOST_BRANCH=master
+cd ..
+git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule update --init tools/boostdep
+xcopy /s /e /q %DRONE_BUILD_DIR% libs\%LIBRARY%\
+python tools/boostdep/depinst/depinst.py -I examples %LIBRARY%
+cmd /c bootstrap
+b2 -d0 headers
+
+if not "%CXXSTD%" == "" set CXXSTD=cxxstd=%CXXSTD%
+if not "%ADDRMD%" == "" set ADDRMD=address-model=%ADDRMD%
+b2 -j3 libs/%LIBRARY%/test toolset=%TOOLSET% %CXXSTD% %ADDRMD% variant=debug,release embed-manifest-via=linker
@@ -0,0 +1,25 @@
+#!/bin/bash
+
+# Copyright 2022 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# https://www.boost.org/LICENSE_1_0.txt
+
+set -ex
+export PATH=~/.local/bin:/usr/local/bin:$PATH
+
+DRONE_BUILD_DIR=$(pwd)
+
+BOOST_BRANCH=develop
+if [ "$DRONE_BRANCH" = "master" ]; then BOOST_BRANCH=master; fi
+
+cd ..
+git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule update --init tools/boostdep
+cp -r $DRONE_BUILD_DIR/* libs/$LIBRARY
+python tools/boostdep/depinst/depinst.py -I examples $LIBRARY
+./bootstrap.sh
+./b2 -d0 headers
+
+echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
+./b2 -j3 libs/$LIBRARY/test toolset=$TOOLSET cxxstd=$CXXSTD variant=debug,release ${ADDRMD:+address-model=$ADDRMD} ${UBSAN:+undefined-sanitizer=norecover debug-symbols=on} ${ASAN:+address-sanitizer=norecover debug-symbols=on} ${LINKFLAGS:+linkflags=$LINKFLAGS}
@@ -1,412 +0,0 @@
-# Copyright 2016-2019 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)
-
-language: cpp
-
-dist: xenial
-
-branches:
-  only:
-    - master
-    - develop
-    - /feature\/.*/
-
-env:
-  matrix:
-    - BOGUS_JOB=true
-
-matrix:
-
-  exclude:
-    - env: BOGUS_JOB=true
-
-  include:
-    - os: linux
-      compiler: g++
-      env: TOOLSET=gcc COMPILER=g++ CXXSTD=03,11
-
-    - os: linux
-      compiler: g++-4.4
-      env: TOOLSET=gcc COMPILER=g++-4.4 CXXSTD=98,0x
-      addons:
-        apt:
-          packages:
-            - g++-4.4
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: g++-4.6
-      env: TOOLSET=gcc COMPILER=g++-4.6 CXXSTD=03,0x
-      addons:
-        apt:
-          packages:
-            - g++-4.6
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: g++-4.7
-      env: TOOLSET=gcc COMPILER=g++-4.7 CXXSTD=03,11
-      addons:
-        apt:
-          packages:
-            - g++-4.7
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: g++-4.8
-      env: TOOLSET=gcc COMPILER=g++-4.8 CXXSTD=03,11
-      addons:
-        apt:
-          packages:
-            - g++-4.8
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: g++-4.9
-      env: TOOLSET=gcc COMPILER=g++-4.9 CXXSTD=03,11
-      addons:
-        apt:
-          packages:
-            - g++-4.9
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: g++-5
-      env: TOOLSET=gcc COMPILER=g++-5 CXXSTD=03,11,14,1z
-      addons:
-        apt:
-          packages:
-            - g++-5
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: g++-6
-      env: TOOLSET=gcc COMPILER=g++-6 CXXSTD=03,11,14,1z
-      addons:
-        apt:
-          packages:
-            - g++-6
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: g++-7
-      env: TOOLSET=gcc COMPILER=g++-7 CXXSTD=03,11,14,17
-      addons:
-        apt:
-          packages:
-            - g++-7
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: g++-8
-      env: TOOLSET=gcc COMPILER=g++-8 CXXSTD=03,11,14,17
-      addons:
-        apt:
-          packages:
-            - g++-8
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: g++-9
-      env: TOOLSET=gcc COMPILER=g++-9 CXXSTD=03,11,14,17,2a
-      addons:
-        apt:
-          packages:
-            - g++-9
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      dist: bionic
-      compiler: g++-10
-      env: TOOLSET=gcc COMPILER=g++-10 CXXSTD=03,11,14,17,2a
-      addons:
-        apt:
-          packages:
-            - g++-10
-          sources:
-            - sourceline: "ppa:ubuntu-toolchain-r/test"
-
-    - os: linux
-      dist: bionic
-      compiler: g++-10
-      env: UBSAN=1 TOOLSET=gcc COMPILER=g++-10 CXXSTD=03,11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1 LINKFLAGS=-fuse-ld=gold
-      addons:
-        apt:
-          packages:
-            - g++-10
-          sources:
-            - sourceline: "ppa:ubuntu-toolchain-r/test"
-
-    - os: linux
-      compiler: clang++
-      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11
-
-    - os: linux
-      dist: trusty
-      compiler: /usr/bin/clang++
-      env: TOOLSET=clang COMPILER=/usr/bin/clang++ CXXSTD=03,11
-      addons:
-        apt:
-          packages:
-            - clang-3.3
-
-    - os: linux
-      dist: trusty
-      compiler: /usr/bin/clang++
-      env: TOOLSET=clang COMPILER=/usr/bin/clang++ CXXSTD=03,11
-      addons:
-        apt:
-          packages:
-            - clang-3.4
-
-    - os: linux
-      dist: trusty
-      compiler: clang++-3.5
-      env: TOOLSET=clang COMPILER=clang++-3.5 CXXSTD=03,11
-      addons:
-        apt:
-          packages:
-            - clang-3.5
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: clang++-3.6
-      env: TOOLSET=clang COMPILER=clang++-3.6 CXXSTD=03,11,14,1z
-      addons:
-        apt:
-          packages:
-            - clang-3.6
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: clang++-3.7
-      env: TOOLSET=clang COMPILER=clang++-3.7 CXXSTD=03,11,14,1z
-      addons:
-        apt:
-          packages:
-            - clang-3.7
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: clang++-3.8
-      env: TOOLSET=clang COMPILER=clang++-3.8 CXXSTD=03,11,14,1z
-      addons:
-        apt:
-          packages:
-            - clang-3.8
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: clang++-3.9
-      env: TOOLSET=clang COMPILER=clang++-3.9 CXXSTD=03,11,14,1z
-      addons:
-        apt:
-          packages:
-            - clang-3.9
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: clang++-4.0
-      env: TOOLSET=clang COMPILER=clang++-4.0 CXXSTD=03,11,14,1z
-      addons:
-        apt:
-          packages:
-            - clang-4.0
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: clang++-5.0
-      env: TOOLSET=clang COMPILER=clang++-5.0 CXXSTD=03,11,14,1z
-      addons:
-        apt:
-          packages:
-            - clang-5.0
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: clang++-6.0
-      env: TOOLSET=clang COMPILER=clang++-6.0 CXXSTD=03,11,14,17
-      addons:
-        apt:
-          packages:
-            - clang-6.0
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      compiler: clang++-7
-      env: TOOLSET=clang COMPILER=clang++-7 CXXSTD=03,11,14,17
-      addons:
-        apt:
-          packages:
-            - clang-7
-          sources:
-            - ubuntu-toolchain-r-test
-            - llvm-toolchain-xenial-7
-
-    - os: linux
-      compiler: clang++-8
-      env: TOOLSET=clang COMPILER=clang++-8 CXXSTD=03,11,14,17,2a
-      addons:
-        apt:
-          packages:
-            - clang-8
-          sources:
-            - ubuntu-toolchain-r-test
-            - llvm-toolchain-xenial-8
-
-    - os: linux
-      compiler: clang++-9
-      env: TOOLSET=clang COMPILER=clang++-9 CXXSTD=03,11,14,17,2a
-      addons:
-        apt:
-          packages:
-            - clang-9
-          sources:
-            - ubuntu-toolchain-r-test
-            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main'
-              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
-
-    - os: linux
-      compiler: clang++-10
-      env: TOOLSET=clang COMPILER=clang++-10 CXXSTD=03,11,14,17,2a
-      addons:
-        apt:
-          packages:
-            - clang-10
-          sources:
-            - ubuntu-toolchain-r-test
-            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-10 main'
-              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
-
-    - os: linux
-      compiler: clang++-10
-      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-10 CXXSTD=03,11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1
-      addons:
-        apt:
-          packages:
-            - clang-10
-          sources:
-            - ubuntu-toolchain-r-test
-            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-10 main'
-              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
-
-    - os: linux
-      dist: trusty
-      compiler: clang++-libc++
-      env: TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=03,11,14,1z
-      addons:
-        apt:
-          packages:
-            - libc++-dev
-            - libc++abi-dev
-
-    - os: linux
-      dist: trusty
-      compiler: clang++-libc++
-      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=03,11,14,1z UBSAN_OPTIONS=print_stacktrace=1
-      addons:
-        apt:
-          packages:
-            - libc++-dev
-            - libc++abi-dev
-
-    - os: osx
-      compiler: clang++
-      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
-      osx_image: xcode7.3
-
-    - os: osx
-      compiler: clang++
-      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
-      osx_image: xcode8.3
-
-    - os: osx
-      compiler: clang++
-      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
-      osx_image: xcode9.4
-
-    - os: osx
-      compiler: clang++
-      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
-      osx_image: xcode10.1
-
-    - os: linux
-      env: CMAKE_TEST=1
-      script:
-        - mkdir __build__ && cd __build__
-        - cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=core ..
-        - ctest --output-on-failure -R boost_core
-
-    - os: linux
-      env: CMAKE_SUBDIR_TEST=1
-      install:
-        - BOOST_BRANCH=develop
-        - if [ "$TRAVIS_BRANCH" = "master" ]; then BOOST_BRANCH=master; fi
-        - git clone -b $BOOST_BRANCH https://github.com/boostorg/config.git ../config
-        - git clone -b $BOOST_BRANCH https://github.com/boostorg/assert.git ../assert
-      script:
-      - cd test/cmake_subdir_test && mkdir __build__ && cd __build__
-      - cmake ..
-      - cmake --build .
-      - cmake --build . --target check
-
-    - os: linux
-      env: CMAKE_INSTALL_TEST=1
-      script:
-        - mkdir __build__ && cd __build__
-        - cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES="assert;config;core" -DCMAKE_INSTALL_PREFIX=~/.local ..
-        - cmake --build . --target install
-        - cd ../libs/core/test/cmake_install_test && mkdir __build__ && cd __build__
-        - cmake -DCMAKE_INSTALL_PREFIX=~/.local ..
-        - cmake --build .
-        - cmake --build . --target check
-
-install:
-  - BOOST_BRANCH=develop
-  - if [ "$TRAVIS_BRANCH" = "master" ]; then BOOST_BRANCH=master; fi
-  - cd ..
-  - git clone -b $BOOST_BRANCH https://github.com/boostorg/boost.git boost-root
-  - cd boost-root
-  - git submodule init libs/headers
-  - git submodule init libs/assert
-  - git submodule init libs/config
-  - git submodule init libs/predef
-  - git submodule init libs/static_assert
-  - git submodule init libs/throw_exception
-  - git submodule init libs/type_traits
-  - git submodule init tools/build
-  - git submodule init tools/boost_install
-  - git submodule init tools/cmake
-  - git submodule update --jobs 4
-  - cp -r $TRAVIS_BUILD_DIR/* libs/core
-  - ./bootstrap.sh
-  - ./b2 headers
-
-script:
-  - |-
-    echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
-  - BUILD_JOBS=`(nproc || sysctl -n hw.ncpu) 2> /dev/null`
-  - ./b2 -j $BUILD_JOBS libs/core/test toolset=$TOOLSET cxxstd=$CXXSTD variant=debug,release ${UBSAN:+cxxflags=-fsanitize=undefined cxxflags=-fno-sanitize-recover=undefined linkflags=-fsanitize=undefined define=UBSAN=1 debug-symbols=on} ${LINKFLAGS:+linkflags=$LINKFLAGS}
-
-notifications:
-  email:
-    on_success: always
@@ -1,8 +1,9 @@
-# Copyright 2018, 2019 Peter Dimov
+# Generated by `boostdep --cmake core`
+# Copyright 2020, 2021 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
+# https://www.boost.org/LICENSE_1_0.txt

-cmake_minimum_required(VERSION 3.5...3.16)
+cmake_minimum_required(VERSION 3.5...3.20)

 project(boost_core VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)

@@ -15,16 +16,19 @@ target_link_libraries(boost_core
  INTERFACE
    Boost::assert
    Boost::config
+    Boost::throw_exception
 )

-if(BOOST_SUPERPROJECT_VERSION)
+if(NOT CMAKE_VERSION VERSION_LESS 3.19 AND CMAKE_GENERATOR MATCHES "Visual Studio")

-  include(BoostInstall)
-  boost_install(TARGETS boost_core HEADER_DIRECTORY include/)
+  file(GLOB_RECURSE boost_core_IDEFILES CONFIGURE_DEPENDS include/*.hpp)
+  source_group(TREE ${PROJECT_SOURCE_DIR}/include FILES ${boost_core_IDEFILES} PREFIX "Header Files")
+  list(APPEND boost_core_IDEFILES extra/boost_core.natvis)
+  target_sources(boost_core PRIVATE ${boost_core_IDEFILES})

 endif()

-if(BUILD_TESTING)
+if(BUILD_TESTING AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/test/CMakeLists.txt")

  add_subdirectory(test)

@@ -6,14 +6,14 @@ The criteria for inclusion is that the utility component be:

 * simple,
 * used by other Boost libraries, and
-* not dependent on any other Boost modules except Core itself, Config, Assert, Static Assert, or Predef.
+* not dependent on any other Boost modules except Core itself, Config, Assert, or ThrowException.

-### CI Status
+### Build Status

-Branch   | Travis | Appveyor
---------|--------|---------
-Develop  | [![Build Status](https://travis-ci.org/boostorg/core.svg?branch=develop)](https://travis-ci.org/boostorg/core) | [![Build Status](https://ci.appveyor.com/api/projects/status/github/boostorg/core?branch=develop&svg=true)](https://ci.appveyor.com/project/pdimov/core)
-Master   | [![Build Status](https://travis-ci.org/boostorg/core.svg?branch=master)](https://travis-ci.org/boostorg/core) | [![Build Status](https://ci.appveyor.com/api/projects/status/github/boostorg/core?branch=master&svg=true)](https://ci.appveyor.com/project/pdimov/core)
+Branch   | GitHub Actions | AppVeyor | Test Matrix | Dependencies |
+---------|----------------|--------- | ----------- | ------------ |
+Develop  | [![GitHub Actions](https://github.com/boostorg/core/actions/workflows/ci.yml/badge.svg?branch=develop)](https://github.com/boostorg/core/actions?query=branch%3Adevelop) | [![AppVeyor](https://ci.appveyor.com/api/projects/status/75arrvfh5ibryd0p/branch/develop?svg=true)](https://ci.appveyor.com/project/cppalliance/core) | [![Tests](https://img.shields.io/badge/matrix-develop-brightgreen.svg)](https://regression.boost.io/develop/developer/core.html) | [![Dependencies](https://img.shields.io/badge/deps-develop-brightgreen.svg)](https://pdimov.github.io/boostdep-report/develop/core.html)
+Master   | [![GitHub Actions](https://github.com/boostorg/core/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/boostorg/core/actions?query=branch%3Amaster) | [![AppVeyor](https://ci.appveyor.com/api/projects/status/75arrvfh5ibryd0p/branch/master?svg=true)](https://ci.appveyor.com/project/cppalliance/core) | [![Tests](https://img.shields.io/badge/matrix-master-brightgreen.svg)](https://regression.boost.io/master/developer/core.html) | [![Dependencies](https://img.shields.io/badge/deps-master-brightgreen.svg)](https://pdimov.github.io/boostdep-report/master/core.html)

 ### Directories

@@ -24,8 +24,8 @@ Master   | [![Build Status](https://travis-ci.org/boostorg/core.svg?branch=maste
 ### More information

 * [Documentation](https://boost.org/libs/core)
-* [Report bugs](https://svn.boost.org/trac/boost/newticket?component=core;version=Boost%20Release%20Branch). Be sure to mention Boost version, platform and compiler you're using. A small compilable code sample to reproduce the problem is always good as well.
-* Submit your patches as pull requests against **develop** branch. Note that by submitting patches you agree to license your modifications under the [Boost Software License, Version 1.0](https://www.boost.org/LICENSE_1_0.txt).
+* Report bugs by opening issues in this repository. Be sure to mention Boost version, platform and compiler you're using. A small compilable code sample to reproduce the problem is always good as well.
+* Submit your patches as pull requests against the **develop** branch. Note that by submitting patches you agree to license your modifications under the [Boost Software License, Version 1.0](https://www.boost.org/LICENSE_1_0.txt).

 ### License

@@ -1,4 +1,4 @@
-# Copyright 2016-2019 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)

@@ -16,6 +16,7 @@ environment:
  matrix:
    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
      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
@@ -26,17 +27,15 @@ environment:
      ADDRMD: 32,64
      CXXSTD: 14,17

-    # clang-win 32 bit fails to link with "unable to load mspdbcore.dll (error code: 126)"
-
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
      TOOLSET: clang-win
      ADDRMD: 64
      CXXSTD: 14,17

    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
-      TOOLSET: msvc-14.2
-      ADDRMD: 32,64
-      CXXSTD: 14,17
+      TOOLSET: clang-win
+      ADDRMD: 64
+      CXXSTD: 20,latest

    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
      ADDPATH: C:\cygwin\bin;
@@ -63,25 +62,25 @@ environment:
      TOOLSET: gcc
      CXXSTD: 03,11,14,1z

+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      CMAKE: 1
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      CMAKE_SUBDIR: 1
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      CMAKE_INSTALL: 1
+
 install:
+  - set GIT_FETCH_JOBS=8
  - set BOOST_BRANCH=develop
  - if "%APPVEYOR_REPO_BRANCH%" == "master" set BOOST_BRANCH=master
  - cd ..
  - git clone -b %BOOST_BRANCH% https://github.com/boostorg/boost.git boost-root
  - cd boost-root
-  - git submodule init libs/headers
-  - git submodule init libs/assert
-  - git submodule init libs/config
-  - git submodule init libs/predef
-  - git submodule init libs/static_assert
-  - git submodule init libs/throw_exception
-  - git submodule init libs/type_traits
-  - git submodule init tools/build
-  - git submodule init tools/boost_install
-  - git submodule update --jobs 4
+  - git submodule update --init tools/boostdep
  - xcopy /s /e /q %APPVEYOR_BUILD_FOLDER% libs\core\
+  - python tools/boostdep/depinst/depinst.py --git_args "--jobs %GIT_FETCH_JOBS%" core
  - cmd /c bootstrap
-  - b2 headers
+  - b2 -d0 headers

 build: off

@@ -89,4 +88,27 @@ test_script:
  - PATH=%ADDPATH%%PATH%
  - if not "%CXXSTD%" == "" set CXXSTD=cxxstd=%CXXSTD%
  - if not "%ADDRMD%" == "" set ADDRMD=address-model=%ADDRMD%
-  - b2 -j %NUMBER_OF_PROCESSORS% libs/core/test toolset=%TOOLSET% %CXXSTD% %ADDRMD% variant=debug,release
+  - if "%CMAKE%%CMAKE_SUBDIR%%CMAKE_INSTALL%" == ""  b2 -j %NUMBER_OF_PROCESSORS% libs/core/test toolset=%TOOLSET% %CXXSTD% %ADDRMD% variant=debug,release embed-manifest-via=linker
+
+  - if not "%CMAKE%" == ""  mkdir __build__ && cd __build__
+  - if not "%CMAKE%" == ""  cmake -DBUILD_TESTING=ON -DBOOST_INCLUDE_LIBRARIES=core ..
+  - if not "%CMAKE%" == ""  cmake --build . --target tests -j 3 --config Debug & ctest --output-on-failure --no-tests=error -j 3 -C Debug
+  - if not "%CMAKE%" == ""  cmake --build . --target tests -j 3 --config Release & ctest --output-on-failure --no-tests=error -j 3 -C Release
+  - if not "%CMAKE%" == ""  cmake --build . --target tests -j 3 --config MinSizeRel & ctest --output-on-failure --no-tests=error -j 3 -C MinSizeRel
+  - if not "%CMAKE%" == ""  cmake --build . --target tests -j 3 --config RelWithDebInfo & ctest --output-on-failure --no-tests=error -j 3 -C RelWithDebInfo
+
+  - if not "%CMAKE_SUBDIR%" == ""  cd libs/core/test/cmake_subdir_test && mkdir __build__ && cd __build__
+  - if not "%CMAKE_SUBDIR%" == ""  cmake ..
+  - if not "%CMAKE_SUBDIR%" == ""  cmake --build . --config Debug && cmake --build . --target check --config Debug
+  - if not "%CMAKE_SUBDIR%" == ""  cmake --build . --config Release && cmake --build . --target check --config Release
+  - if not "%CMAKE_SUBDIR%" == ""  cmake --build . --config MinSizeRel && cmake --build . --target check --config MinSizeRel
+  - if not "%CMAKE_SUBDIR%" == ""  cmake --build . --config RelWithDebInfo && cmake --build . --target check --config RelWithDebInfo
+
+  - if not "%CMAKE_INSTALL%" == ""  mkdir __build__ && cd __build__
+  - if not "%CMAKE_INSTALL%" == ""  cmake -DBOOST_INCLUDE_LIBRARIES=core -DCMAKE_INSTALL_PREFIX=C:/cmake-prefix ..
+  - if not "%CMAKE_INSTALL%" == ""  cmake --build . --target install --config Debug
+  - if not "%CMAKE_INSTALL%" == ""  cmake --build . --target install --config Release
+  - if not "%CMAKE_INSTALL%" == ""  cd ../libs/core/test/cmake_install_test && mkdir __build__ && cd __build__
+  - if not "%CMAKE_INSTALL%" == ""  cmake -DCMAKE_INSTALL_PREFIX=C:/cmake-prefix ..
+  - if not "%CMAKE_INSTALL%" == ""  cmake --build . --config Debug && cmake --build . --target check --config Debug
+  - if not "%CMAKE_INSTALL%" == ""  cmake --build . --config Release && cmake --build . --target check --config Release
@@ -0,0 +1,8 @@
+# Copyright 2020, 2025 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+
+project : default-build release <link>static <cxxstd>17
+    : requirements <library>/boost/core//boost_core ;
+
+exe sv_find_first_of : sv_find_first_of.cpp ;
+exe sv_find_first_not_of : sv_find_first_not_of.cpp ;
@@ -0,0 +1,277 @@
+// Copyright 2021, 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/utility/string_view.hpp>
+#include <boost/core/detail/string_view.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/core/type_name.hpp>
+#include <boost/cstdint.hpp>
+#include <string_view>
+#include <chrono>
+#include <iostream>
+
+using namespace std::chrono_literals;
+
+template<class Sv> void test()
+{
+    constexpr char const* q1 = "{";
+    constexpr char const* q2 = "<(";
+    constexpr char const* q3 = " :=";
+    constexpr char const* q4 = " \t\r\n";
+    constexpr char const* q6 = " \t\r\n\f\v";
+    constexpr char const* q10 = "0123456789";
+    constexpr char const* q52 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+
+    constexpr std::size_t npos = static_cast<std::size_t>( -1 );
+
+    constexpr std::size_t N = 1'000'000'000;
+
+    std::cout << boost::core::type_name<Sv>() << ":\n\n";
+
+    auto t0 = std::chrono::steady_clock::now();
+
+    {
+        constexpr char const* q = q1;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q2;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q3;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q4;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q6;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q10;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q52;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    auto tn = std::chrono::steady_clock::now();
+
+    std::cout << "\nTotal for " << boost::core::type_name<Sv>() << ": " << ( tn - t0 ) / 1ms << " ms\n\n";
+}
+
+int main()
+{
+    test<std::string_view>();
+    test<boost::string_view>();
+    test<boost::core::string_view>();
+
+    return boost::report_errors();
+}
@@ -0,0 +1,259 @@
+// Copyright 2021, 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/utility/string_view.hpp>
+#include <boost/core/detail/string_view.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/core/type_name.hpp>
+#include <boost/cstdint.hpp>
+#include <string_view>
+#include <chrono>
+#include <iostream>
+
+using namespace std::chrono_literals;
+
+template<class Sv> void test()
+{
+    std::string s1( 1'000'000, '\x00' );
+    std::string s2( 100, '\x00' );
+
+    constexpr char const* q1 = "{";
+    constexpr char const* q2 = "<(";
+    constexpr char const* q3 = " :=";
+    constexpr char const* q4 = " \t\r\n";
+    constexpr char const* q6 = " \t\r\n\f\v";
+    constexpr char const* q10 = "0123456789";
+    constexpr char const* q52 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+
+    constexpr std::size_t npos = static_cast<std::size_t>( -1 );
+
+    constexpr std::size_t N = 1'000'000'000;
+
+    std::cout << boost::core::type_name<Sv>() << ":\n\n";
+
+    auto t0 = std::chrono::steady_clock::now();
+
+    {
+        constexpr char const* q = q1;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q2;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q3;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q4;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q6;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q10;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q52;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    auto tn = std::chrono::steady_clock::now();
+
+    std::cout << "\nTotal for " << boost::core::type_name<Sv>() << ": " << ( tn - t0 ) / 1ms << " ms\n\n";
+}
+
+int main()
+{
+    test<std::string_view>();
+    test<boost::string_view>();
+    test<boost::core::string_view>();
+
+    return boost::report_errors();
+}
@@ -0,0 +1,22 @@
+# 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/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
+    ;
@@ -5,12 +5,15 @@
 # Version 1.0. (See accompanying file LICENSE_1_0.txt
 # or copy at http://boost.org/LICENSE_1_0.txt)

+import project ;
 import doxygen ;
 import quickbook ;

+path-constant INCLUDES : ../include ;
+
 doxygen ref_reference
  :
-    [ glob ../../../boost/core/ref.hpp ]
+    $(INCLUDES)/boost/core/ref.hpp
  :
    <doxygen:param>ENABLE_PREPROCESSING=YES
    <doxygen:param>EXPAND_ONLY_PREDEF=YES
@@ -0,0 +1,33 @@
+[/
+  Copyright 2023 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:alignof alignof]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/alignof.hpp>]
+
+The header `<boost/core/alignof.hpp>` defines the macro `BOOST_CORE_ALIGNOF`,
+a portable equivalent of the `alignof` operator from C++11.
+
+[section Example]
+
+``
+#include <boost/core/alignof.hpp>
+#include <cstddef>
+
+constexpr std::size_t alignment_of_double = BOOST_CORE_ALIGNOF(double);
+``
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -1,149 +0,0 @@
-[/
-Copyright 2019 Glen Joseph Fernandes
-(glenjofe@gmail.com)
-
-Distributed under the Boost Software License, Version 1.0.
-(http://www.boost.org/LICENSE_1_0.txt)
-]
-
-[section:alloc_construct alloc_construct, alloc_destroy]
-
-[simplesect Authors]
-
-* Glen Fernandes
-
-[endsimplesect]
-
-[section Overview]
-
-The header <boost/core/alloc_construct.hpp> provides function templates
-`alloc_construct`, `alloc_construct_n`, `alloc_destroy`, and `alloc_destroy_n`
-for allocator aware and exception safe construction and destruction of objects
-and arrays.
-
-[endsect]
-
-[section Example]
-
-The following example allocates storage for an array of `n` elements of `T`
-using an allocator `a` and constructs `T` elements in that storage. If any
-exception was thrown during construction of an element, the constructed
-elements are destroyed in reverse order.
-
-```
-template<class A>
-auto create(A& a, std::size_t n)
-{
-    auto p = a.allocate(n);
-    try {
-        boost::alloc_construct_n(a, boost::to_address(p), n);
-    } catch (...) {
-        a.deallocate(p, n);
-        throw;
-    }
-    return p;
-}
-```
-
-[endsect]
-
-[section Reference]
-
-```
-namespace boost {
-
-template<class A, class T>
-void alloc_destroy(A& a, T* p);
-
-template<class A, class T>
-void alloc_destroy_n(A& a, T* p, std::size_t n);
-
-template<class A, class T, class Args>
-void alloc_construct(A& a, T* p, Args&&... args);
-
-template<class A, class T>
-void alloc_construct_n(A& a, T* p, std::size_t n);
-
-template<class A, class T>
-void alloc_construct_n(A& a, T* p, std::size_t n, const T* l, std::size_t m);
-
-template<class A, class T, class I>
-void alloc_construct_n(A& a, T* p, std::size_t n, I begin);
-
-} /* boost */
-```
-
-[section Functions]
-
-[variablelist
-[[`template<class A, class T> void alloc_destroy(A& a, T* p);`]
-[[variablelist
-[[Requires][`A` is an /Allocator/]]
-[[Effects][`std::allocator_traits<A>::destroy(a, p)`.]]]]]
-[[`template<class A, class T> void alloc_destroy_n(A& a, T* p,
-std::size_t n);`]
-[[variablelist
-[[Requires][`A` is an /Allocator/]]
-[[Effects]
-[Destroys each `i`-th element in reverse order by calling
-`std::allocator_traits<A>::destroy(a, &p[i])`.]]]]]
-[[`template<class A, class T, class Args> void alloc_construct(A& a, T* p,
-Args&&... args);`]
-[[variablelist
-[[Requires][`A` is an /Allocator/]]
-[[Effects]
-[`std::allocator_traits<A>::construct(a, p, std::forward<Args>(args)...)`.]]]]]
-[[`template<class A, class T> void alloc_construct_n(A& a, T* p,
-std::size_t n);`]
-[[variablelist
-[[Requires][`A` is an /Allocator/]]
-[[Effects]
-[Constructs each `i`-th element in order by calling
-`std::allocator_traits<A>::construct(a, &p[i])`.]]
-[[Remarks]
-[If an exception is thrown destroys each already constructed `j`-th element in
-reverse order by calling `std::allocator_traits<A>::destroy(a, &p[j])`.]]]]]
-[[`template<class A, class T> void alloc_construct_n(A& a, T* p, std::size_t n,
-const T* l, std::size_t m);`]
-[[variablelist
-[[Requires][`A` is an /Allocator/]]
-[[Effects]
-[Constructs each `i`-th element in order by calling
-`std::allocator_traits<A>::construct(a, &p[i], l[i % m])`.]]
-[[Remarks]
-[If an exception is thrown destroys each already constructed `j`-th element in
-reverse order by calling `std::allocator_traits<A>::destroy(a, &p[j])`.]]]]]
-[[`template<class A, class T, class I> void alloc_construct_n(A& a, T* p,
-std::size_t n, I begin);`]
-[[variablelist
-[[Requires]
-[[itemized_list
-[`A` is an /Allocator/][`I` is an /InputIterator/]]]]
-[[Effects]
-[Constructs each `i`-th element in order by calling
-`std::allocator_traits<A>::construct(a, &p[i], *begin++])`.]]
-[[Remarks]
-[If an exception is thrown destroys each already constructed `j`-th element in
-reverse order by calling `std::allocator_traits<A>::destroy(a, &p[j])`.]]]]]]
-
-[endsect]
-
-[endsect]
-
-[section Compatibility]
-
-When `BOOST_NO_CXX11_ALLOCATOR` is defined, and the C++11 allocator model is
-not supported, these functions invoke constructors and destructors directly
-without going through the supplied allocator.
-
-[endsect]
-
-[section Acknowledgments]
-
-Glen Fernandes originally implemented this functionality in Boost.Smart_Ptr and
-later moved these functions to Boost.Core for use in other Boost libraries,
-such as Boost.Multi_Array and Boost.Histogram.
-
-[endsect]
-
-[endsect]
@@ -1,12 +1,12 @@
 [/
-Copyright 2020 Glen Joseph Fernandes
+Copyright 2020-2022 Glen Joseph Fernandes
 (glenjofe@gmail.com)

 Distributed under the Boost Software License, Version 1.0.
 (http://www.boost.org/LICENSE_1_0.txt)
 ]

-[section Allocator Access]
+[section allocator_access]

 [simplesect Authors]

@@ -21,6 +21,9 @@ templates to simplify allocator use. It provides the same functionality as the
 C++ standard library `std::allocator_traits` but with individual templates for
 each allocator feature.

+It also adds additional functionality for allocator aware exception safe
+construction and destruction of arrays.
+
 These facilities also simplify existing libraries by avoiding having to check
 for `BOOST_NO_CXX11_ALLOCATOR` and conditionally use `std::allocator_traits`.

@@ -51,6 +54,26 @@ public:
 In C++11 or above, aliases such as `boost::allocator_pointer_t<A>` can be used
 instead of `typename boost::allocator_pointer<A>::type`.

+The following example allocates storage for an array of `n` elements of `T`
+using an allocator `a` and constructs `T` elements in that storage. If any
+exception was thrown during construction of an element, the constructed
+elements are destroyed in reverse order.
+
+```
+template<class A>
+auto create(A& a, std::size_t n)
+{
+    auto p = a.allocate(n);
+    try {
+        boost::allocator_construct_n(a, boost::to_address(p), n);
+    } catch (...) {
+        a.deallocate(p, n);
+        throw;
+    }
+    return p;
+}
+```
+
 [endsect]

 [section Reference]
@@ -150,9 +173,22 @@ void allocator_deallocate(A& a, allocator_pointer_t<A> p,
 template<class A, class T, class... Args>
 void allocator_construct(A& a, T* p, Args&&... args);

+template<class A, class T>
+void allocator_construct_n(A& a, T* p, std::size_t n);
+
+template<class A, class T>
+void allocator_construct_n(A& a, T* p, std::size_t n, const T* l,
+    std::size_t m);
+
+template<class A, class T, class I>
+void allocator_construct_n(A& a, T* p, std::size_t n, I begin);
+
 template<class A, class T>
 void allocator_destroy(A& a, T* p);

+template<class A, class T>
+void allocator_destroy_n(A& a, T* p, std::size_t n);
+
 template<class A>
 allocator_size_type_t<A> allocator_max_size(const A& a);

@@ -168,7 +204,8 @@ A allocator_select_on_container_copy_construction(const A& a);
 [[`template<class A> struct allocator_value_type;`]
 [The member `type` is `A::value_type`.]]
 [[`template<class A> struct allocator_pointer;`]
-[The member `type` is `A::pointer` if valid, otherwise `A::value_type*`.]]
+[The member `type` is `A::pointer` if valid, otherwise
+`allocator_value_type_t<A>*`.]]
 [[`template<class A> struct allocator_const_pointer;`]
 [The member `type` is `A::const_pointer` if valid, otherwise
 `pointer_traits<allocator_pointer_t<A> >::rebind<const
@@ -219,12 +256,34 @@ allocator_size_type_t<A> n);`]
 void allocator_construct(A& a, T*p, Args&&... args);`]
 [Calls `a.construct(p, std::forward<Args>(args)...)` if valid, otherwise calls
 `::new(static_cast<void*>(p)) T(std::forward<Args>(args)...)`.]]
+[[`template<class A, class T>
+void alloc_construct_n(A& a, T* p, std::size_t n);`]
+[Constructs each `i`-th element in order by calling
+`boost::allocator_construct(a, &p[i])`.
+If an exception is thrown destroys each already constructed `j`-th element in
+reverse order by calling `boost::allocator_destroy(a, &p[j])`.]]
+[[`template<class A, class T>
+void alloc_construct_n(A& a, T* p, std::size_t n, const T* l, std::size_t m);`]
+[Constructs each `i`-th element in order by calling
+`boost::allocator_construct(a, &p[i], l[i % m])`.
+If an exception is thrown destroys each already constructed `j`-th element in
+reverse order by calling `boost::allocator_destroy(a, &p[j])`.]]
+[[`template<class A, class T, class I>
+void alloc_construct_n(A& a, T* p, std::size_t n, I begin);`]
+[Constructs each `i`-th element in order by calling
+`boost::allocator_construct(a, &p[i], *begin++)`.
+If an exception is thrown destroys each already constructed `j`-th element in
+reverse order by calling `boost::allocator_destroy(a, &p[j])`.]]
 [[`template<class A, class T> void allocator_destroy(A& a, T* p);`]
 [Calls `a.destroy(p)` if valid, otherwise calls `p->~T()`.]]
+[[`template<class A, class T>
+void allocator_destroy_n(A& a, T* p, std::size_t n);`]
+[Destroys each `i`-th element in reverse order by calling
+`boost::allocator_destroy(a, &p[i])`.]]
 [[`template<class A> allocator_size_type_t<A> allocator_max_size(const A& a);`]
 [Returns `a.max_size()` if valid, otherwise returns
 `std::numeric_limits<allocator_size_type_t<A> >::max() /
-sizeof(A::value_type)`.]]
+sizeof(allocator_value_type_t<A>)`.]]
 [[`template<class A> A allocator_select_on_container_copy_construction(const
 A& a);`]
 [Returns `a.select_on_container_copy_construction()` if valid, otherwise
@@ -234,7 +293,7 @@ returns `a`.]]]

 [endsect]

-[section Acknowledgments]
+[section Acknowledgements]

 Glen Fernandes implemented the allocator access utilities.

@@ -0,0 +1,116 @@
+[/
+Copyright 2021 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+]
+
+[section:allocator_traits allocator_traits]
+
+[simplesect Authors]
+
+* Glen Fernandes
+
+[endsimplesect]
+
+[section Overview]
+
+This header <boost/core/allocator_traits.hpp> provides an implementation of the
+C++ standard library class template `allocator_traits` based on the facilities
+in [link core.allocator_access Allocator Access]. Users should still prefer the
+individual traits, but this utility exists to simplify migration.
+
+[endsect]
+
+[section Reference]
+
+```
+namespace boost {
+
+template<class A>
+struct allocator_traits {
+    using allocator_type = A;
+
+    using value_type = allocator_value_type_t<A>;
+
+    using pointer = allocator_pointer_t<A>;
+
+    using const_pointer = allocator_const_pointer_t<A>;
+
+    using void_pointer = allocator_void_pointer_t<A>;
+
+    using const_pointer = allocator_const_void_pointer_t<A>;
+
+    using difference_type = allocator_difference_type_t<A>;
+
+    using size_type = allocator_size_type_t<A>;
+
+    using propagate_on_container_copy_assignment =
+        allocator_propagate_on_container_copy_assignment_t<A>;
+
+    using propagate_on_container_move_assignment =
+        allocator_propagate_on_container_move_assignment_t<A>;
+
+    using propagate_on_container_swap =
+        allocator_propagate_on_container_swap_t<A>;
+
+    using is_always_equal = allocator_is_always_equal_t<A>;
+
+    template<class T>
+    using rebind_traits = allocator_traits<allocator_rebind_t<A, T> >;
+
+    static pointer allocate(A& a, size_type n);
+
+    static pointer allocate(A& a, size_type n, const_void_pointer h);
+
+    static void deallocate(A& a, pointer p, size_type n);
+
+    template<class T, class... Args>
+    static void construct(A& a, T* p, Args&&... args);
+
+    static void destroy(A& a, T* p);
+
+    static size_type max_size(const A& a) noexcept;
+
+    static A select_on_container_copy_construction(const A& a);
+};
+
+} /* boost */
+```
+
+[section Static member functions]
+
+[variablelist
+[[`static pointer allocate(A& a, size_type n);`]
+[Equivalent to: `return boost::allocator_allocate(a, n);`]]
+[[`static pointer allocate(A& a, size_type n, const_void_pointer h);`]
+[Equivalent to: `return boost::allocator_allocate(a, n, h);`]]
+[[`static void deallocate(A& a, pointer p, size_type n);`]
+[Equivalent to: `boost::allocator_deallocate(a, n, h);`]]
+[[`template<class T, class... Args>
+static void construct(A& a, T* p, Args&&... args);`]
+[Equivalent to:
+`boost::allocator_construct(a, p, std::forward<Args>(args)...);`]]
+[[`static void destroy(A& a, T* p);`]
+[Equivalent to: `boost::allocator_destroy(a, p);`]]
+[[`static size_type max_size(const A& a) noexcept;`]
+[Equivalent to: `return boost::allocator_max_size(a);`]]
+[[`static A select_on_container_copy_construction(const A& a);`]
+[Equivalent to:
+`return boost::allocator_select_on_container_copy_construction(a);`]]]
+
+[endsect]
+
+[endsect]
+
+[section Notes]
+
+# The member `rebind_alloc` is not provided for parity with C++03 where it is
+unimplementable. Instead of `allocator_traits<A>::rebind_alloc<U>` you can
+express the same with `allocator_traits<A>::rebind_traits<U>::allocator_type`
+or more simply with `allocator_rebind_t<A, U>`.
+
+[endsect]
+
+[endsect]
@@ -0,0 +1,219 @@
+[/
+  Copyright 2020 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
+]
+
+[section:bit bit]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/bit.hpp>]
+
+The header `<boost/core/bit.hpp>` implements, in a portable way,
+the C++20 `<bit>` header.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+// bit_cast
+
+template<class To, class From>
+To bit_cast(From const& from) noexcept;
+
+// byteswap
+
+template<class T>
+constexpr T byteswap(T x) noexcept;
+
+// Integral powers of 2
+
+template<class T>
+constexpr bool has_single_bit(T x) noexcept;
+
+template<class T>
+constexpr T bit_ceil(T x) noexcept;
+
+template<class T>
+constexpr T bit_floor(T x) noexcept;
+
+template<class T>
+constexpr int bit_width(T x) noexcept;
+
+// Rotating
+
+template<class T>
+constexpr T rotl(T x, int s) noexcept;
+
+template<class T>
+constexpr T rotr(T x, int s) noexcept;
+
+// Counting
+
+template<class T>
+constexpr int countl_zero(T x) noexcept;
+
+template<class T>
+constexpr int countl_one(T x) noexcept;
+
+template<class T>
+constexpr int countr_zero(T x) noexcept;
+
+template<class T>
+constexpr int countr_one(T x) noexcept;
+
+template<class T>
+constexpr int popcount(T x) noexcept;
+
+// Endian
+
+enum class endian
+{
+    little = see below,
+    big = see below,
+    native = see below
+};
+
+using endian_type = endian; // portable alias for C++03 code
+
+} // namespace core
+} // namespace boost
+``
+
+Note: even though the functions are shown as `constexpr` in the synopsis, since they are implemented
+via compiler-specific intrinsics, portable code cannot generally rely on their being usable in a
+constant expression context.
+
+[endsect]
+
+[section bit_cast]
+
+`template<class To, class From> To bit_cast(From const& from) noexcept;`
+
+* *Requires:* `To` and `From` must be trivially copyable and `sizeof(To)` must be the same as `sizeof(From)`.
+* *Returns:* A value of type `To` with the storage bytes copied from `from`.
+
+[endsect]
+
+[section byteswap]
+
+`template<class T> constexpr T byteswap(T x) noexcept;`
+
+* *Requires:* `T` must be an integer type (i.e. one of `char`, `signed char`,
+  `unsigned char`, `short`, `unsigned short`, `int`, `unsigned int`, `long`,
+  `unsigned long`, `long long`, `unsigned long long`) without padding bits.
+* *Returns:* `x` with the storage bytes reversed.
+
+[endsect]
+
+[section Integral powers of 2]
+
+`template<class T> constexpr bool has_single_bit(T x) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type (i.e. one of `unsigned char`, `unsigned short`, `unsigned int`, `unsigned long`, `unsigned long long`).
+* *Returns:* `true` if `x` is an integral power of two, `false` otherwise. (`has_single_bit(0u)` is false.)
+
+`template<class T> constexpr T bit_ceil(T x) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* The smallest integral power of 2 greater than or equal to `x`. If this value is not representable in `T`, behavior is undefined.
+
+`template<class T> constexpr T bit_floor(T x) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* If `x == 0`, 0; otherwise the maximal value `y` such that `has_single_bit(y)` is `true` and `y <= x`.
+
+`template<class T> constexpr int bit_width(T x) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* If `x == 0`, 0; otherwise one plus the base-2 logarithm of `x`, with any fractional part discarded.
+
+[endsect]
+
+[section Rotating]
+
+In the following descriptions, `N` denotes `numeric_limits<T>::digits` and `r` denotes `s % N`.
+
+`template<class T> constexpr T rotl(T x, int s) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* If `s` is negative, `rotr(x, -s)`; if `r` is 0, `x`; if `r` is positive, `(x << r) | (x >> (N - r))`.
+
+`template<class T> constexpr T rotr(T x, int s) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* If `s` is negative, `rotl(x, -s)`; if `r` is 0, `x`; if `r` is positive, `(x >> r) | (x << (N - r))`.
+
+[endsect]
+
+[section Counting]
+
+`template<class T> constexpr int countl_zero(T x) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* The number of consecutive 0 bits in the value of `x`, starting from the most significant ("left") bit.
+
+`template<class T> constexpr int countl_one(T x) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* The number of consecutive 1 bits in the value of `x`, starting from the most significant bit.
+
+`template<class T> constexpr int countr_zero(T x) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* The number of consecutive 0 bits in the value of `x`, starting from the least significant ("right") bit.
+
+`template<class T> constexpr int countr_one(T x) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* The number of consecutive 1 bits in the value of `x`, starting from the least significant bit.
+
+`template<class T> constexpr int popcount(T x) noexcept;`
+
+* *Requires:* `T` must be an unsigned integer type.
+* *Returns:* The number of 1 bits in the value of `x`.
+
+[endsect]
+
+[section Endian]
+
+Under C++11, `endian` is defined as `enum class endian` as shown in the synopsis. Under C++03, its definition is
+
+``
+namespace endian
+{
+enum type
+{
+    little = see below,
+    big = see below,
+    native = see below
+};
+}
+
+typedef endian::type endian_type;
+``
+
+The values of `endian::big` and `endian::little` are distinct. `endian::native` is equal to `endian::big` on
+big endian platforms, equal to `endian::little` on little endian platforms, and a distinct value on platforms
+that are neither.
+
+Note that you should not rely on `little` and `big` having any specific values, because the C++20 standard
+leaves these unspecified.
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -0,0 +1,240 @@
+[/
+  Copyright 2021 Peter Dimov
+  Copyright 2022-2025 Andrey Semashev
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt)
+]
+
+[section Revision History]
+
+[section Changes in 1.91.0]
+
+* The header [link core.is_placeholder `boost/is_placeholder.hpp`] has been moved from Bind to Core. ([github_issue 90])
+
+[endsect]
+
+[section Changes in 1.90.0]
+
+* The implementation of `BOOST_TEST_THROWS` and `BOOST_TEST_NO_THROW` macros defined in
+  [link core.lightweight_test `boost/core/lightweight_test.hpp`] has been changed to avoid
+  compiler warnings on some compilers, when the macros are used in `if`/`else` blocks. As
+  a side effect of this change, the semicolon after the macro is now necessary. ([github_pr 205])
+* [link core.data `boost::data`] and [link core.size `boost::size`] are now aliases for `std::data`
+  and `std::size`, respectively, when the latter are provided by compiler. This resolves potential
+  ambiguities when both `boost::` and `std::` alternatives are found by the compiler, e.g. as a result
+  of ADL. ([github_issue 206])
+
+[endsect]
+
+[section Changes in 1.89.0]
+
+* Fixed `bit_ceil` to return 1 for input 0 as per specification. ([github_pr 199])
+* Added support for `std::format` to `boost::core::string_view`. ([github_issue 190])
+
+[endsect]
+
+[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 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;
+  swap(p1, p2); // no longer looks for boost::swap as part of ADL
+  ```
+  Users may need to either explicitly qualify the namespace of the called function or add a
+  `using`-declaration.
+
+[endsect]
+
+[section Changes in 1.84.0]
+
+* `boost::swap` utility function has been renamed to `boost::core::invoke_swap` to
+  avoid forming a potential infinite recursion when the arguments are not swappable.
+  The new function is defined in `boost/core/invoke_swap.hpp` and is functionally equivalent
+  to `boost::swap`. The old `boost::swap` name is preserved for backward compatibility
+  but deprecated and will be removed in a future release. Its `noexcept` specification
+  has been removed to avoid compile errors caused by compile-time recursion.
+  `BOOST_ALLOW_DEPRECATED_SYMBOLS` or `BOOST_ALLOW_DEPRECATED` can be defined to suppress
+  deprecation warnings for the transition period. ([@https://github.com/boostorg/core/issues/148 #148])
+* Headers `boost/swap.hpp`, `boost/utility/swap.hpp` and `boost/core/swap.hpp` are
+  deprecated and will be removed. Please, switch to `boost/core/invoke_swap.hpp`.
+  `BOOST_ALLOW_DEPRECATED_HEADERS` or `BOOST_ALLOW_DEPRECATED` can be defined to suppress
+  deprecation warnings.
+
+[endsect]
+
+[section Changes in 1.83.0]
+
+* Added support for incomplete types to [link core.type_name `boost::core::type_name`].
+* Bit manipulation functions in [link core.bit `boost/core/bit.hpp`] are now
+  `constexpr` on recent MSVC versions (VS2019 update 5 and later.)
+* Added `boost::core::byteswap` (an implementation of `std::byteswap` from
+  C++23) to [link core.bit `boost/core/bit.hpp`].
+* Moved the yield primitives `sp_thread_pause`, `sp_thread_yield`, `sp_thread_sleep`
+  from SmartPtr implementation details to `boost/core/yield_primitives.hpp`.
+
+[endsect]
+
+[section Changes in 1.82.0]
+
+* Added [link core.snprintf `boost/core/snprintf.hpp`] header with portable definitions of `snprintf`, `vsnprintf` and
+  their `wchar_t` counterparts.
+* Deprecated `boost/core/is_same.hpp` and `boost::core::is_same`. The header will be removed in a future release.
+  Users are advised to use [@http://www.boost.org/doc/libs/release/libs/type_traits/doc/html/index.html Boost.TypeTraits]
+  or C++ standard library type traits instead.
+* Marked `boost::ref` member functions and associated methods with `noexcept`.
+* Marked `boost::swap` function with `noexcept`, depending on whether the type supports a non-throwing swap operation.
+* Added [link core.launder `boost::core::launder`], a portable implementation of `std::launder`.
+* Added [link core.alignof `BOOST_CORE_ALIGNOF`], a portable implementation of `alignof`.
+* Added [link core.max_align `boost::core::max_align_t`], a portable equivalent of `std::max_align_t`, and
+  `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]
+
+[section Changes in 1.81.0]
+
+* [link core.empty_value `empty_value`] members are now marked as `constexpr`.
+* Added [link core.fclose_deleter `fclose_deleter`], a deleter that calls `std::fclose` on a pointer to `std::FILE`.
+* Bit manipulation utilities in [link core.bit `boost/core/bit.hpp`] now explicitly require unsigned integers on input.
+  ([@https://github.com/boostorg/core/issues/129 #129])
+* `bit_width` now returns `int` instead of a value of the input argument type. This follows the
+  resolution of [@https://cplusplus.github.io/LWG/issue3656 LWG3656].
+
+[endsect]
+
+[section Changes in 1.80.0]
+
+* In [link core.allocator_access `boost/core/allocator_access.hpp`], added detection of `construct` and `destroy`
+  members of an allocator.
+* `boost/core/alloc_construct.hpp` header is now deprecated and will be removed in a future release. Its functionality
+  was moved to [link core.allocator_access `boost/core/allocator_access.hpp`]. In particular, new methods
+  `allocator_construct_n` and `allocator_destroy_n` were added for allocating and destroying arrays.
+* Worked around MSVC bug that failed to compile [link core.span `span`] in C++17 mode when Boost.Range headers were included.
+  ([@https://github.com/boostorg/core/issues/105 #105], [@https://github.com/boostorg/core/pull/115 PR#115])
+* Added support for 128-bit integer types in [link core.type_name `type_name`].
+* In [link core.pointer_traits `pointer_traits`], pointer rebinding now supports C++03 compilers.
+
+[endsect]
+
+[section Changes in 1.79.0]
+
+* Added `boost::allocator_traits`, an implementation of `std::allocator_traits`.
+* Made `boost::pointer_traits` SFINAE friendly.
+* `boost/iterator.hpp` is deprecated and will be removed in a future release. The header defines the
+  `boost::iterator` template, which is equivalent to `std::iterator` in the `<iterator>` header. However,
+  since `std::iterator` is itself deprecated in C++17, users are advised to remove the use of `boost::iterator`
+  or `std::iterator` from their code.
+* Added `boost::core::verbose_terminate_handler`, a utility function intended
+  to be passed to `std::set_terminate` that prints information about the
+  uncaught exception to `stderr`.
+
+[endsect]
+
+[section Changes in 1.78.0]
+
+* Added a generic implementation to `boost/core/cmath.hpp`, enabled when `BOOST_CORE_USE_GENERIC_CMATH`
+  is defined or when the platform does not provide the necessary facilities in `<cmath>`.
+* Added `boost::core::type_name`, a utility function that returns the name of a type as a string.
+* Added `boost::span`, a C++11 implementation of C++20's `std::span`.
+
+[endsect]
+
+[section Changes in 1.77.0]
+
+* `boost/core/uncaught_exceptions.hpp` has been modified for compatibility with Mac OS 10.4 and older.
+
+[endsect]
+
+[section Changes in 1.76.0]
+
+* Added implicit conversion between compatible reference wrappers.
+* Added `boost/core/cmath.hpp`, a portable implementation of the floating point classification functions from `<cmath>`.
+* Added `boost/core/bit.hpp`, a portable implementation of the C++20 standard header `<bit>`.
+* Fixed `BOOST_TEST_EQ`, `BOOST_TEST_NE` for character types under C++20.
+* Revised allocator access utilities (now support VS2013, and no workarounds use `allocator_traits`.)
+
+[endsect]
+
+[section Changes in 1.74.0]
+
+* Implemented the allocator access utilities which provide a replacement for `allocator_traits`
+  with individual traits and functions for each facility. They support the C++11 allocator model
+  when possible and provide a fallback for C++98 compatibility.
+* Added `BOOST_TEST_WITH` to Lightweight Test.
+
+[endsect]
+
+[section Changes in 1.71.0]
+
+* Added functions `alloc_construct`, `alloc_construct_n`, `alloc_destroy`, and `alloc_destroy_n`
+  in `<boost/core/alloc_construct.hpp>` for allocator aware and exception safe construction and
+  destruction of objects and arrays.
+* Added constexpr functions `first_scalar` in `<boost/core/first_scalar.hpp>` for obtaining a pointer
+  to the first scalar element of an array. Given a pointer of type `T*` they return a pointer of type
+  `remove_all_extents_t<T>*`.
+* Added class template `noinit_adaptor` in `<boost/core/noinit_adaptor.hpp>` which is an allocator adaptor
+  that converts any allocator into one whose `construct(ptr)` performs default initialization via placement
+  `new`, and whose `destroy(ptr)` invokes the `value_type` destructor directly.
+* Added class template `default_allocator` in `<boost/core/default_allocator.hpp>`, which can serve as a minimal
+  default allocator that has interface similar to C++20 `std::allocator`, supports configurations with disabled
+  exceptions and does not have `std` as an associated namespace. The allocator uses `operator new` and
+  `operator delete` for allocation.
+* In `<boost/core/uncaught_exceptions.hpp>` header, added workarounds for better compatibility with QNX SDP 7.0
+  when libc++/libc++abi libraries are used.
+* The `<boost/detail/sp_typeinfo.hpp>` header is now marked as deprecated and will be removed in a future release.
+  `<boost/core/typeinfo.hpp>` should be used instead.
+
+[endsect]
+
+[section Changes in 1.69.0]
+
+* Implemented `boost::empty_value`, for library authors to conveniently leverage the Empty Base Optimization to
+  store objects of potentially empty types.
+* Implemented `boost::quick_exit` to provide the C++11 standard library facility `std::quick_exit` functionality.
+* Reduced the number of statics in Lightweight Test, and employ lighter abort behavior for MSVC compilers upon
+  failure to call `boost::report_errors`.
+
+[endsect]
+
+[section Changes in 1.67.0]
+
+* Updated `to_address` and `pointer_traits` to reflect the design adopted for C++20 in
+  [@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0653r2.html P0653R2].
+
+[endsect]
+
+[section Changes in 1.65.0]
+
+* Implemented `pointer_traits` for C++03 and higher, that implements
+  [@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0653r0.html P0653r0].
+* Added `BOOST_TEST_GT` and `BOOST_TEST_GE` to Lightweight Test.
+
+[endsect]
+
+[endsect]
@@ -0,0 +1,122 @@
+[/
+  Copyright 2018 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
+]
+
+[section:cmath cmath]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/cmath.hpp>]
+
+The header `<boost/core/cmath.hpp>` defines, in a portable way, the floating
+point classification and sign manipulation functions from C++11.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+// fpclassify return values
+
+int const fp_zero = /*unspecified*/;
+int const fp_subnormal = /*unspecified*/;
+int const fp_normal = /*unspecified*/;
+int const fp_infinite = /*unspecified*/;
+int const fp_nan = /*unspecified*/;
+
+// Classification functions
+
+template<class T> bool isfinite( T x );
+template<class T> bool isnan( T x );
+template<class T> bool isinf( T x );
+template<class T> bool isnormal( T x );
+template<class T> int fpclassify( T x );
+
+// Sign manipulation functions
+
+template<class T> bool signbit( T x );
+template<class T> T copysign( T x, T y );
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[section Classification Functions]
+
+[section template<class T> bool isfinite( T x );]
+
+* *Requires:* `T` must be `float`, `double`, or `long double`.
+* *Returns:* `true` when `x` is finite (not infinity or NaN), `false` otherwise.
+
+[endsect]
+
+[section template<class T> bool isnan( T x );]
+
+* *Requires:* `T` must be `float`, `double`, or `long double`.
+* *Returns:* `true` when `x` is NaN, `false` otherwise.
+
+[endsect]
+
+[section template<class T> bool isinf( T x );]
+
+* *Requires:* `T` must be `float`, `double`, or `long double`.
+* *Returns:* `true` when `x` is infinity, `false` otherwise.
+
+[endsect]
+
+[section template<class T> bool isnormal( T x );]
+
+* *Requires:* `T` must be `float`, `double`, or `long double`.
+* *Returns:* `true` when `x` is a normal number (not zero, subnormal, infinity, or NaN), `false` otherwise.
+
+[endsect]
+
+[section template<class T> int fpclassify( T x );]
+
+* *Requires:* `T` must be `float`, `double`, or `long double`.
+* *Returns:*
+  * `fp_zero` when `x` is zero;
+  * `fp_subnormal` when `x` is subnormal;
+  * `fp_infinite` when `x` is infinity;
+  * `fp_nan` when `x` is NaN;
+  * `fp_normal` otherwise.
+
+[endsect]
+
+[endsect]
+
+[section Sign Manipulation Functions]
+
+[section template<class T> bool signbit( T x );]
+
+* *Requires:* `T` must be `float`, `double`, or `long double`.
+* *Returns:* `true` when `x` is negative, `false` otherwise.
+
+[endsect]
+
+[section template<class T> bool copysign( T x, T y );]
+
+* *Requires:* `T` must be `float`, `double`, or `long double`.
+* *Returns:* `x` with the sign copied from `y`.
+
+[endsect]
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -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>''']]

@@ -34,14 +37,20 @@ criteria for inclusion is that the utility component be:
 * simple,
 * used by other Boost libraries, and
 * not dependent on any other Boost modules except Core
-  itself, Config, Assert, Static Assert, or Predef.
+  itself, Config, Assert, or ThrowException.

 [endsect]

+[include changes.qbk]
+
 [include addressof.qbk]
+[include alignof.qbk]
 [include allocator_access.qbk]
-[include alloc_construct.qbk]
+[include allocator_traits.qbk]
+[include bit.qbk]
 [include checked_delete.qbk]
+[include cmath.qbk]
+[include data.qbk]
 [include default_allocator.qbk]
 [include demangle.qbk]
 [include empty_value.qbk]
@@ -49,19 +58,35 @@ criteria for inclusion is that the utility component be:
 [include exchange.qbk]
 [include explicit_operator_bool.qbk]
 [include first_scalar.qbk]
+[include functor.qbk]
+[include identity.qbk]
 [include ignore_unused.qbk]
+[include is_placeholder.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]
 [include noinit_adaptor.qbk]
 [include noncopyable.qbk]
 [include null_deleter.qbk]
+[include fclose_deleter.qbk]
 [include nvp.qbk]
+[include pointer_in_range.qbk]
 [include pointer_traits.qbk]
 [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]
+[include type_name.qbk]
+[include snprintf.qbk]
 [include uncaught_exceptions.qbk]
 [include use_default.qbk]
+[include verbose_terminate_handler.qbk]
+[include yield_primitives.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]
@@ -125,7 +125,7 @@ return `nullptr` if demangling failed.

 [endsect]

-[section Acknowledgments]
+[section Acknowledgements]

 The implementation of `core::demangle` was taken from
 `boost/exception/detail/type_info.hpp`, which in turn was adapted
@@ -90,11 +90,11 @@ public:
    empty_value() = default;

    template<class... Args>
-    empty_value(empty_init_t, Args&&... args);
+    constepxr empty_value(empty_init_t, Args&&... args);

-    const T& get() const noexcept;
+    constepxr const T& get() const noexcept;

-    T& get() noexcept;
+    constepxr T& get() noexcept;
 };

 inline constexpr empty_init_t empty_init{ };
@@ -121,8 +121,9 @@ inline constexpr empty_init_t empty_init{ };
 [section Constructors]

 [variablelist
-[[`empty_value() = default;`][Default initialize the value]]
-[[`template<class... Args> empty_value(empty_init_t, Args&&... args);`]
+[[`constepxr empty_value() = default;`][Default initialize the value]]
+[[`template<class... Args>
+constepxr empty_value(empty_init_t, Args&&... args);`]
 [Initialize the value with `std::forward<Args>(args)...`]]]

 [endsect]
@@ -130,8 +131,8 @@ inline constexpr empty_init_t empty_init{ };
 [section Member functions]

 [variablelist
-[[`const T& get() const noexcept;`][Returns the value]]
-[[`T& get() noexcept;`][Returns the value]]]
+[[`constepxr const T& get() const noexcept;`][Returns the value]]
+[[`constepxr T& get() noexcept;`][Returns the value]]]

 [endsect]

@@ -304,8 +304,8 @@ depends on the template arguments of the class. Note that
 again, the second argument to `enable_if` is not needed; the
 default (`void`) is the correct value.

-The `enable_if_has_type` template is usable this scenario but instead of
-using a type traits to enable or disable a specialization, it use a
+The `enable_if_has_type` template is usable in this scenario but instead of
+using a type trait to enable or disable a specialization, it uses a
 SFINAE context to check for the existence of a dependent type inside
 its parameter. For example, the following structure extracts a dependent
 `value_type` from T if and only if `T::value_type` exists.
@@ -0,0 +1,34 @@
+[/
+ / Copyright (c) 2022 Andrey Semashev
+ /
+ / 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)
+ /]
+
+[section:fclose_deleter fclose_deleter]
+
+[simplesect Authors]
+
+* Andrey Semashev
+
+[endsimplesect]
+
+[section Header <boost/core/fclose_deleter.hpp>]
+
+The header `<boost/core/fclose_deleter.hpp>` defines the `boost::fclose_deleter` function object,
+which can be used as a deleter with smart pointers such as `unique_ptr` or `shared_ptr` pointing to `std::FILE`.
+structures returned by `std::fopen` calls. The deleter calls `std::fclose` on the passed pointer, causing
+the file stream to be flushed and closed.
+
+[section Example]
+``
+std::unique_ptr< std::FILE, boost::fclose_deleter > make_file(const char* filename, const char* open_mode)
+{
+    return { std::fopen(filename, open_mode) };
+}
+``
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -0,0 +1,101 @@
+[/
+ / Copyright (c) 2024 Andrey Semashev
+ /
+ / 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)
+ /]
+
+[section:functor functor]
+
+[simplesect Authors]
+
+* Andrey Semashev
+
+[endsimplesect]
+
+[section Header <boost/core/functor.hpp>]
+
+[note This component requires a compiler supporting C++17 or newer.]
+
+The header `<boost/core/functor.hpp>` defines the `boost::core::functor` class template
+that wraps a raw function specified in its template parameter into a function object class.
+The function object forwards any arguments passed to it to the wrapped function and returns
+the result of the call.
+
+The `functor` wrapper can be useful in cases when a function object class type is required,
+for example, for use with smart pointers such as `std::unique_ptr`, where the actual logic
+of the function object is already implemented as a raw function, possibly provided by a
+third party library. Since `functor` is default-constructible and does not store a pointer
+to the wrapped function internally, using `functor` is less error-prone and more efficient
+than using the pointer to function instead. For example, with `std::unique_ptr` you don't
+need to pass a pointer to the deleter function in the `std::unique_ptr` constructor, and
+the `std::unique_ptr` object does not store and invoke a pointer to the deleter function.
+With `functor`, the deleter function becomes part of the `std::unique_ptr` type, which
+prevents mixing pointers with incompatible deleters.
+
+```
+void my_deleter(void* p);
+
+using malloc_ptr = std::unique_ptr< char, boost::core::functor< std::free > >;
+using my_ptr = std::unique_ptr< char, boost::core::functor< my_deleter > >;
+
+my_ptr create_string(std::size_t size);
+void consume_string(my_ptr&& str);
+
+malloc_ptr ptr1(static_cast< char* >(std::malloc(size)));
+// ptr1 = allocate_string(size); // error, cannot convert my_ptr to malloc_ptr
+my_ptr ptr2 = create_string(size); // ok
+
+// consume_string(std::move(ptr1)); // error, cannot convert malloc_ptr&& to my_ptr
+consume_string(std::move(ptr2)); // ok
+```
+
+Using `functor` may also be beneficial for reducing generated code sizes. For example, in
+order to avoid storing and invoking a pointer to the deleter function in `std::shared_ptr`,
+one may be inclined to use lambda functions to wrap the deleter function call like this:
+
+```
+std::shared_ptr< int > ptr(static_cast< int* >(std::malloc(sizeof(int))), [](int* p) { std::free(p); });
+```
+
+The problem is that every lambda function declaration introduces a unique type, even if
+the lambda function definition matches exactly one of the previously declared lambda
+functions. Thus, if `std::shared_ptr` objects like the one above are created in multiple
+places in the program, the definition of the shared pointer counter and associated code
+and data (e.g. virtual function table) will be duplicated for each instance.
+
+Replacing the lambda function with `functor` solves this problem without sacrificing
+readability or efficiency:
+
+```
+std::shared_ptr< int > ptr(static_cast< int* >(std::malloc(sizeof(int))), boost::core::functor< std::free >());
+```
+
+[section Synopsis]
+
+```
+namespace boost::core {
+
+template< auto Function >
+struct functor
+{
+    template< typename... Args >
+    decltype(auto) operator() (Args&&... args) const noexcept(...);
+};
+
+} // namespace boost::core
+```
+
+[endsect]
+
+[section `template< typename... Args > decltype(auto) operator() (Args&&... args) const noexcept(...);`]
+
+* *Effects:* `return Function(std::forward< Args >(args)...)`.
+* *Throws:* Nothing, unless invoking `Function` throws.
+* *Note:* This function only participates in overload resolution if `Function(std::forward< Args >(args)...)` is a valid call expression.
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -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]
@@ -51,7 +51,7 @@ int fun( int foo, int bar )

 [endsect]

-[section Acknowledgments]
+[section Acknowledgements]

 `boost::ignore_unused()` was contributed by Adam Wulkiewicz.

@@ -0,0 +1,69 @@
+[/
+  Copyright 2014, 2025 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
+]
+
+[section:is_placeholder is_placeholder]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/is_placeholder.hpp>]
+
+The header `<boost/is_placeholder.hpp>` defines the class template
+`boost::is_placeholder<T>`. It defines a nested integral constant
+`value` which is `0` when `T` is not a `boost::bind` placeholder
+type, and a positive value corresponding to the placeholder index
+otherwise.
+
+That is, `is_placeholder<_1>::value` is `1`,
+`is_placeholder<_2>::value` is `2`, and so on.
+
+`is_placeholder` can be specialized for user types. If it is,
+`boost::bind` will recognize these types as placeholders.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+    template<class T> struct is_placeholder;
+}
+``
+
+[endsect]
+
+[section Example]
+
+``
+#include <boost/is_placeholder.hpp>
+#include <boost/bind.hpp>
+
+struct arg1_type {};
+constexpr arg1_type arg1{};
+
+template<> struct boost::is_placeholder<arg1_type>
+{
+    static constexpr int value = 1;
+};
+
+int f( int x ) { return x + 1; }
+
+int main()
+{
+    return boost::bind( f, arg1 )( -1 );
+}
+``
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -17,6 +17,11 @@

 [section Header <boost/core/is_same.hpp>]

+[warning This component is deprecated and will be removed in a future release.
+Users are recommended to use `boost::is_same` from
+[@http://www.boost.org/doc/libs/release/libs/type_traits/doc/html/index.html Boost.TypeTraits]
+or `std::is_same` from C++ standard library `<type_traits>` instead.]
+
 The header `<boost/core/is_same.hpp>` defines the class template
 `boost::core::is_same<T1,T2>`. It defines a nested integral constant
 `value` which is `true` when `T1` and `T2` are the same type, and
@@ -0,0 +1,39 @@
+[/
+  Copyright 2023 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:launder launder]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/launder.hpp>]
+
+The header `<boost/core/launder.hpp>` defines the function
+`void boost::core::launder()`, a portable implementation of
+`std::launder`.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+template<class T> T* launder( T* p );
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -51,8 +51,16 @@ When using `lightweight_test.hpp`, *do not forget* to

 namespace boost
 {
-    int report_errors();
-}
+
+int report_errors();
+
+namespace core
+{
+
+void lwt_init();
+
+} // namespace core
+} // namespace boost
 ``

 [endsect]
@@ -246,6 +254,25 @@ Return the error count from `main`.

 [endsect]

+[section lwt_init]
+
+``
+void boost::core::lwt_init()
+``
+
+Performs one-time initialization. Disables the interactive message
+boxes displayed by the Microsoft Windows debug runtime library on
+`abort`, failing `assert`, and other abnormal program terminations
+(to facilitate unattended testing), and ensures that in case
+`boost::report_errors` is not called (a common mistake), the program
+ends with a nonzero exit code.
+
+`lwt_init` is automatically called by the test macros. There is
+no need to call it explicitly, except in cases where a test fails due
+to e.g. an assertion failure before the first test macro is invoked.
+
+[endsect]
+
 [section Example]

 ``
@@ -326,14 +353,14 @@ parentheses.)

 ``
 #include <boost/core/lightweight_test_trait.hpp>
-#include <boost/core/is_same.hpp>
+#include <boost/type_traits/is_same.hpp>

 template<class T, class U> struct X
 {
    typedef T type;
 };

-using boost::core::is_same;
+using boost::is_same;

 int main()
 {
@@ -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]
@@ -0,0 +1,42 @@
+[/
+  Copyright 2023 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:max_align max_align]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/max_align.hpp>]
+
+The header `<boost/core/max_align.hpp>` defines the type
+`boost::core::max_align_t`, a portable equivalent of
+`std::max_align_t`, and the constant `boost::core::max_align`,
+the alignment of `max_align_t`.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+union max_align_t;
+
+constexpr std::size_t max_align = alignof(max_align_t);
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -0,0 +1,139 @@
+[/
+  Copyright 2023 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:memory_resource memory_resource]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/memory_resource.hpp>]
+
+The header `<boost/core/memory_resource.hpp>` defines the class
+`boost::core::memory_resource`, a portable equivalent of
+`std::pmr::memory_resource` from C++17.
+
+This is not a complete implementation of the standard `<memory_resource>`
+header; for such, one should use Boost.Container. The abstract base class
+is only provided by Core so that Boost libraries that provide and take
+advantage of PMR facilities such as concrete implementations of memory
+resources, or implementations of `polymorphic_allocator`, can interoperate.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+class memory_resource
+{
+public:
+
+    virtual ~memory_resource() = default;
+
+    [[nodiscard]] void* allocate( std::size_t bytes, std::size_t alignment = max_align );
+    void deallocate( void* p, std::size_t bytes, std::size_t alignment = max_align );
+
+    bool is_equal( memory_resource const & other ) const noexcept;
+
+private:
+
+    virtual void* do_allocate( std::size_t bytes, std::size_t alignment ) = 0;
+    virtual void do_deallocate( void* p, std::size_t bytes, std::size_t alignment ) = 0;
+
+    virtual bool do_is_equal( memory_resource const& other ) const noexcept = 0;
+};
+
+inline bool operator==( memory_resource const& a, memory_resource const& b ) noexcept;
+inline bool operator!=( memory_resource const& a, memory_resource const& b ) noexcept;
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[section `allocate`]
+
+`[[nodiscard]] void* allocate( std::size_t bytes, std::size_t alignment = max_align );`
+
+* *Returns:* `do_allocate( bytes, alignment )`.
+* *Remarks:* Implicitly creates objects in the returned region of storage.
+
+[endsect]
+
+[section `deallocate`]
+
+`void deallocate( void* p, std::size_t bytes, std::size_t alignment = max_align );`
+
+* *Effects:* `do_deallocate( bytes, alignment )`.
+
+[endsect]
+
+[section `is_equal`]
+
+`bool is_equal( memory_resource const& other ) const noexcept;`
+
+* *Returns:* `do_is_equal( other )`.
+
+[endsect]
+
+[section `do_allocate`]
+
+`void* do_allocate( std::size_t bytes, std::size_t alignment ) = 0;`
+
+* *Remarks:* A derived class should implement this member function to return
+  a pointer to allocated storage of size at least `bytes` and alignment at
+  least `alignment`.
+* *Throws:* An appropriate exception (by convention `std::bad_alloc` or
+  derived) when storage with the specified size and alignment could not be
+  obtained.
+
+[endsect]
+
+[section `do_deallocate`]
+
+`void do_deallocate( void* p, std::size_t bytes, std::size_t alignment ) = 0;`
+
+* *Remarks:* A derived class should implement this member function to deallocate
+  a region of storage previously allocated by `do_allocate`.
+* *Throws:* Nothing.
+
+[endsect]
+
+[section `do_is_equal`]
+
+`bool do_is_equal( memory_resource const& other ) const noexcept = 0;`
+
+* *Remarks:* A derived class shall implement this function to return `true` if
+  memory allocated from `*this` can be deallocated from `other` and vice-versa,
+  otherwise `false`.
+
+[endsect]
+
+[section `operator==`]
+
+`bool operator==( memory_resource const& a, memory_resource const& b ) noexcept;`
+
+* *Returns:* `&a == &b || a.is_equal( b )`.
+
+[endsect]
+
+[section `operator!=`]
+
+`bool operator!=( memory_resource const& a, memory_resource const& b ) noexcept;`
+
+* *Returns:* `!( a == b )`.
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -18,7 +18,7 @@
 The header `<boost/core/null_deleter.hpp>` defines the `boost::null_deleter` function object,
 which can be used as a deleter with smart pointers such as `unique_ptr` or `shared_ptr`. The
 deleter doesn't do anything with the pointer provided upon deallocation, which makes it useful
-when the pointed object is deallocated elsewhere.
+when the pointed object doesn't need to be deallocated or is deallocated elsewhere.

 [section Example]
 ``
@@ -0,0 +1,81 @@
+[/
+Copyright 2024 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+]
+
+[section:pointer_in_range pointer_in_range]
+
+[simplesect Authors]
+
+* Glen Fernandes
+
+[endsimplesect]
+
+[section Overview]
+
+The header <boost/core/pointer_in_range.hpp> provides the function template
+`boost::pointer_in_range` to check if a pointer is in a given range. This
+can be used in constant expressions in C++14 or higher when the compiler has a
+builtin to support `std::is_constant_evaluated`.
+
+[endsect]
+
+[section Examples]
+
+The following is an example of an allocator's deallocation function that does
+nothing if the pointer falls within a small automatically allocated buffer.
+
+```
+template<class T, class N>
+void
+Allocator<T, N>::deallocate(pointer ptr, size_type)
+{
+    if (!boost::pointer_in_range(ptr, buffer_, buffer_ + N)) {
+        ::operator delete(ptr);
+    }
+}
+```
+
+[endsect]
+
+[section Reference]
+
+```
+namespace boost {
+
+template<class T>
+constexpr bool pointer_in_range(const T* ptr, const T* begin, const T* end);
+
+} /* boost */
+```
+
+[section Functions]
+
+[variablelist
+[[`template<class T> constexpr bool pointer_in_range(const T* ptr,
+const T* begin, const T* end);`]
+[[variablelist
+[[Requires][`[begin,end)` is a valid range.]]
+[[Returns][`true` if `ptr` is in range `[begin,end)`, otherwise `false`.]]]]]]
+
+[endsect]
+
+[endsect]
+
+[section Notes]
+
+If `boost::pointer_in_range` is not usable in constant expressions the macro
+`BOOST_CORE_NO_CONSTEXPR_POINTER_IN_RANGE` is defined.
+
+[endsect]
+
+[section History]
+
+Glen Fernandes implemented `pointer_in_range`.
+
+[endsect]
+
+[endsect]
@@ -1,5 +1,5 @@
 [/
-Copyright 2017-2018 Glen Joseph Fernandes
+Copyright 2017-2021 Glen Joseph Fernandes
 (glenjofe@gmail.com)

 Distributed under the Boost Software License, Version 1.0.
@@ -47,68 +47,91 @@ void function(Allocator& a)

 ```
 namespace boost {
-  template<class T> struct pointer_traits {
+
+template<class T>
+struct pointer_traits {
    typedef T pointer;
    typedef ``['see below]`` element_type;
    typedef ``['see below]`` difference_type;

-    template<class U> struct rebind_to { typedef ``['see below]`` type; };
-    template<class U> using rebind = typename rebind_to<U>::type;
+    template<class U>
+    struct rebind_to {
+        typedef ``['see below]`` type;
+    };

-    static pointer pointer_to(``['see below]`` v);
-  };
+    template<class U>
+    using rebind = typename rebind_to<U>::type;

-  template<class T> struct pointer_traits<T*> {
+    static pointer pointer_to(element_type& v);
+};
+
+template<class T>
+struct pointer_traits<T*> {
    typedef T* pointer;
    typedef T element_type;
    typedef std::ptrdiff_t difference_type;

-    template<class U> struct rebind_to { typedef U* type; };
-    template<class U> using rebind = typename rebind_to<U>::type;
+    template<class U>
+    struct rebind_to {
+        typedef U* type;
+    };
+
+    template<class U>
+    using rebind = typename rebind_to<U>::type;

    static pointer pointer_to(``['see below]`` v) noexcept;
-  };
+};

-  template<class T>
-  constexpr T* to_address(T* v) noexcept;
+template<class T>
+constexpr T* to_address(T* v) noexcept;

-  template<class T>
-  auto to_address(const T& v) noexcept;
-}
+template<class T>
+auto to_address(const T& v) noexcept;
+
+} // boost
 ```

+[section Overview]
+
+If the member type `element_type` is not defined, then all other members are
+also not defined (`pointer_traits` is SFINAE-friendly).
+
+[endsect]
+
 [section Member types]

 [variablelist
 [[`typedef` ['see below] `element_type;`]
 [`T::element_type` if such a type exists; otherwise `U` if `T` is a class
  template instantiation of the form `Pointer<U, Args>`, where `Args` is zero
-  or more type arguments; otherwise the specialization is ill-formed.]]
+  or more type arguments; otherwise the member is not defined.]]
 [[`typedef` ['see below] `difference_type;`]
 [`T::difference_type` if such a type exists; otherwise `std::ptrdiff_t`.]]
 [[`template<class U> struct rebind_to { typedef` ['see below] `type; };`]
 [`type` is `T::rebind<U>` if such a type exists; otherwise, `Pointer<V, Args>`
  if `T` is a class template instantiation of the form `Pointer<T, Args>`,
-  where `Args` is zero or more type arguments; otherwise, the instantiation of
-  `rebind_to` is ill-formed.]]]
+  where `Args` is zero or more type arguments; otherwise, the member is not
+  defined.]]]
+
+[note When C++11 template aliases are not supported, the `type` for `rebind` is
+`T::rebind<U>::other` if such a type exists.]

 [endsect]

 [section Member functions]

 [variablelist
-[[`static pointer pointer_traits::pointer_to(`['see below] `v);`]
+[[`static pointer pointer_traits::pointer_to(element_type& v);`]
 [[variablelist
 [[Remark]
-[If `element_type` is a void type, the type of `v` is unspecified; otherwise,
-  it is `element_type&`.]]
+[If `element_type` is a void type, or if `T::pointer_to(v)` is not well-formed,
+  this member is not defined.]]
 [[Returns]
 [A pointer to `v` obtained by calling `T::pointer_to(v)`.]]]]]
-[[`static pointer pointer_traits<T*>::pointer_to(`['see below] `v) noexcept;`]
+[[`static pointer pointer_traits<T*>::pointer_to(element_type& v) noexcept;`]
 [[variablelist
 [[Remark]
-[If `element_type` is a void type, the type of `v` is unspecified; otherwise,
-  it is `element_type&`.]]
+[If `element_type` is a void type, this member is not defined.]]
 [[Returns][`addressof(v)`.]]]]]]

 [endsect]
@@ -142,7 +165,7 @@ namespace boost {

 [endsect]

-[section Acknowledgments]
+[section Acknowledgements]

 Glen Fernandes implemented `pointer_traits` and `to_address` with reviews and
 guidance from Peter Dimov.
@@ -68,7 +68,7 @@ The type-expression `boost::unwrap_reference<T>::type` is

 [xinclude ref_reference.xml]

-[section Acknowledgments]
+[section Acknowledgements]

 `ref` and `cref` were originally part of the Tuple library by
 Jaakko J\u00E4rvi. They were "promoted to `boost::` status" by
@@ -46,7 +46,7 @@ The user can portably declare such enumeration as follows:
    }
    BOOST_SCOPED_ENUM_DECLARE_END(future_errc)

-These macros allows to use `future_errc` in almost all the cases as an scoped enum.
+These macros allow using `future_errc` in almost all the cases as a scoped enum.

    future_errc ev = future_errc::no_state;

@@ -179,7 +179,7 @@ such cases.

 [endsect]

-[section Acknowledgments]
+[section Acknowledgements]

 This scoped enum emulation was developed by Beman Dawes, Vicente J. Botet Escriba and Anthony Williams.

@@ -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]
@@ -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]
@@ -0,0 +1,47 @@
+[/
+ / Copyright (c) 2022 Andrey Semashev
+ /
+ / 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)
+ /]
+
+[section:snprintf snprintf]
+
+[simplesect Authors]
+
+* Andrey Semashev
+
+[endsimplesect]
+
+[section Header <boost/core/snprintf.hpp>]
+
+The header `<boost/core/snprintf.hpp>` provides portable definition of [@https://en.cppreference.com/w/c/io/fprintf `snprintf`],
+`vsnprintf` and their corresponding `wchar_t` counterparts. On a platform that supports these functions in the standard library,
+these definitions are equivalent to the standard functions. On other platforms (mainly, older MSVC versions) these functions
+are emulated through non-standard functions that have similar behavior.
+
+Depending on the standard library, certain implementation differences are exposed to the user:
+
+* Any non-standard behavior with respect to string format description are not hidden by the emulation.
+* Returned value of `boost::core::snprintf` in case if the output buffer is too small may not be equal to the number of characters
+  that would have been written if the buffer was large enough. It is, however, equal or larger than the buffer size,
+  which still allows the caller to detect the buffer overflow condition. The formatted output is still properly null-terminated
+  in this case.
+
+[note Unlike `snprintf`, `swprintf` does not return the number of characters to be written if the output buffer is too small
+but returns -1 instead. Furthermore, `swprintf` may or may not produce characters in the output buffer in this case.]
+
+[section Example]
+``
+char buf[10];
+int n = boost::core::snprintf(buf, sizeof(buf), "%d", i);
+if (n < 0)
+    throw std::runtime_error("Formatting error");
+if (n >= sizeof(buf))
+    throw std::runtime_error("Formatting buffer overflow");
+``
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -0,0 +1,396 @@
+[/
+Copyright 2019 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+]
+
+[section:span span]
+
+[simplesect Authors]
+
+* Glen Fernandes
+
+[endsimplesect]
+
+[section Overview]
+
+This header <boost/core/span.hpp> provides class template `span`, which is a
+view over a sequence of objects. It implements the C++20 standard library
+`std::span` facility. This implementation supports C++11 and higher.
+
+In addition to referencing the sequence of objects, the span knows the count of
+objects. There are two kinds of spans:
+
+* Dynamic size (`span<T>` or `span<T, dynamic_extent>`)
+* Static size (`span<T, N>`)
+
+Dynamic size spans have a count that can be a value known at run time. Static
+size spans have a count that must be known at compile time.
+
+[endsect]
+
+[section Examples]
+
+The following snippet shows a function to compute a SHA1 hash whose parameters
+and return type use spans.
+
+```
+auto sha1(boost::span<const unsigned char> input,
+    boost::span<unsigned char, SHA_DIGEST_LENGTH> output)
+{
+    SHA_CTX context;
+    SHA1_Init(&context);
+    SHA1_Update(&context, input.data(), input.size());
+    SHA1_Final(output.data(), &context);
+    return output;
+}
+```
+
+[endsect]
+
+[section Reference]
+
+```
+namespace boost {
+
+constexpr std::size_t dynamic_extent = -1;
+
+template<class T, std::size_t E = dynamic_extent>
+class span {
+public:
+    typedef T element_type;
+    typedef std::remove_cv_t<T> value_type;
+    typedef std::size_t size_type;
+    typedef std::ptrdiff_t difference_type;
+    typedef T* pointer;
+    typedef const T* const_pointer;
+    typedef T& reference;
+    typedef const T& const_reference;
+    typedef T* iterator;
+    typedef const T* const_iterator;
+    typedef std::reverse_iterator<T*> reverse_iterator;
+    typedef std::reverse_iterator<const T*> const_reverse_iterator;
+
+    static constexpr std::size_t extent = E;
+
+    constexpr span() noexcept;
+
+    explicit(E != dynamic_extent)
+    template<class I>
+    constexpr span(I* f, size_type c);
+
+    explicit(E != dynamic_extent)
+    template<class I, class L>
+    constexpr span(I* f, L* l);
+
+    template<std::size_t N>
+    constexpr span(type_identity_t<T> (&a)[N]);
+
+    template<class U, std::size_t N>
+    constexpr span(std::array<U, N>& a) noexcept;
+
+    template<class U, std::size_t N>
+    constexpr span(const std::array<U, N>& a) noexcept;
+
+    explicit(E != dynamic_extent)
+    template<class R>
+    constexpr span(R&& r);
+
+    explicit(E != dynamic_extent && N == dynamic_extent)
+    template<class U, std::size_t N>
+    constexpr span(const span<U, N>& s) noexcept;
+
+    template<std::size_t C>
+    constexpr span<T, C> first() const;
+
+    template<std::size_t C>
+    constexpr span<T, C> last() const;
+
+    template<std::size_t O, std::size_t C = dynamic_extent>
+    constexpr span<T, see below> subspan() const;
+
+    constexpr span<T, dynamic_extent> first(size_type c) const;
+    constexpr span<T, dynamic_extent> last(size_type c) const;
+
+    constexpr span<T, dynamic_extent> subspan(size_type o,
+        size_type c = dynamic_extent) const;
+
+    constexpr size_type size() const noexcept;
+    constexpr size_type size_bytes() const noexcept;
+    constexpr bool empty() const noexcept;
+
+    constexpr reference operator[](size_type i) const;
+    constexpr reference front() const;
+    constexpr reference back() const;
+    constexpr pointer data() const noexcept;
+
+    constexpr iterator begin() const noexcept;
+    constexpr iterator end() const noexcept;
+    constexpr reverse_iterator rbegin() const noexcept;
+    constexpr reverse_iterator rend() const noexcept;
+    constexpr const_iterator cbegin() const noexcept;
+    constexpr const_iterator cend() const noexcept;
+    constexpr const_reverse_iterator crbegin() const noexcept;
+    constexpr const_reverse_iterator crend() const noexcept;
+};
+
+template<class I, class L>
+span(I*, L) -> span<I>;
+
+template<class T, std::size_t N>
+span(T(&)[N]) -> span<T, N>;
+
+template<class T, std::size_t N>
+span(std::array<T, N>&) -> span<T, N>;
+
+template<class T, std::size_t N>
+span(const std::array<T, N>&) -> span<const T, N>;
+
+template<class R>
+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>
+as_bytes(span<T, E> s) noexcept;
+
+template<class T, std::size_t E>
+span<std::byte, E == dynamic_extent ? dynamic_extent : sizeof(T) * E>
+as_writable_bytes(span<T, E> s) noexcept;
+
+} /* boost */
+```
+
+[section Constructors]
+
+[variablelist
+[[`constexpr span() noexcept;`]
+[[variablelist
+[[Constraints][`E == dynamic_extent || E == 0` is `true`.]]
+[[Postconditions][`size() == 0 && data() == nullptr`.]]]]]
+[[`explicit(E != dynamic_extent)
+template<class I>
+constexpr span(I* f, size_type c);`]
+[[variablelist
+[[Constraints]
+[`is_convertible_v<I(*)[], T(*)[]>` is `true`.]]
+[[Preconditions]
+[[itemized_list
+[`[f, f + c)` is a valid range.]
+[If `E` is not equal to `dynamic_extent`, then `c` is equal to `E`.]]]]
+[[Effects][Constructs a `span` with data `f` and size `c`.]]
+[[Throws][Nothing.]]]]]
+[[`explicit(E != dynamic_extent)
+template<class I, class L>
+constexpr span(I* f, L* l);`]
+[[variablelist
+[[Constraints]
+[`is_convertible_v<I(*)[], T(*)[]>` is `true`.]]
+[[Preconditions]
+[[itemized_list
+[If `E` is not equal to `dynamic_extent`, then `l - f` is equal to `E`.]
+[`[f, l)` is a valid range.]]]]
+[[Effects][Constructs a `span` with data `f` and size `l - f`.]]
+[[Throws][Nothing.]]]]]
+[[`template<std::size_t N>
+constexpr span(type_identity_t<T> (&a)[N]);`]
+[[variablelist
+[[Constraints][`E == dynamic_extent || E == N` is `true`.]]
+[[Effects][Constructs a `span` that is a view over the supplied array.]]
+[[Postconditions][`size() == N && data() == &a[0]` is `true`.]]]]]
+[[`template<class U, std::size_t N>
+constexpr span(std::array<U, N>& a) noexcept;`]
+[[variablelist
+[[Constraints]
+[[itemized_list
+[`E == dynamic_extent || E == N` is `true`, and]
+[`U(*)[]` is convertible to `T(*)[]`.]]]]
+[[Effects][Constructs a `span` that is a view over the supplied array.]]
+[[Postconditions][`size() == N && data() == a.data()` is `true`.]]]]]
+[[`template<class U, std::size_t N>
+constexpr span(const std::array<U, N>& a) noexcept;`]
+[[variablelist
+[[Constraints]
+[[itemized_list
+[`E == dynamic_extent || E == N` is `true`, and]
+[`U(*)[]` is convertible to `T(*)[]`.]]]]
+[[Effects][Constructs a `span` that is a view over the supplied array.]]
+[[Postconditions][`size() == N && data() == a.data()` is `true`.]]]]]
+[[`explicit(E != dynamic_extent)
+template<class R>
+constexpr span(R&& r);`]
+[[variablelist
+[[Constraints]
+[[itemized_list
+[`is_lvalue_reference_v<R> || is_const_v<T>` is `true`]
+[`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`,]
+[`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 `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;`]
+[[variablelist
+[[Constraints]
+[[itemized_list
+[`E == dynamic_extent || N == dynamic_extent || E == N` is `true`, and]
+[`is_convertible_v<U(*)[], T(*)[]>` is `true`.]]]]
+[[Preconditions]
+[If `E` is not equal to `dynamic_extent`, then `s.size()` is equal to `E`.]]
+[[Effects]
+[Constructs a `span` that is a view over the range
+`[s.data(), s.data() + s.size())`.]]
+[[Postconditions][`size() == s.size() && data() == s.data()`.]]]]]]
+
+[endsect]
+
+[section Subviews]
+
+[variablelist
+[[`template<std::size_t C> constexpr span<T, C> first() const;`]
+[[variablelist
+[[Mandates][`C <= E` is `true`.]]
+[[Preconditions][`C <= size()` is `true`.]]
+[[Effects]
+[Equivalent to `return R{data(), C};` where `R` is the return type.]]]]]
+[[`template<std::size_t C> constexpr span<T, C> last() const;`]
+[[variablelist
+[[Mandates][`C <= E` is `true`.]]
+[[Preconditions][`C <= size()` is `true`.]]
+[[Effects]
+[Equivalent to `return R{data() + (size() - C), C};` where `R` is the return
+type.]]]]]
+[[`template<std::size_t O, std::size_t C = dynamic_extent>
+constexpr span<T, see below> subspan() const;`]
+[[variablelist
+[[Mandates][`O <= E && (C == dynamic_extent || C <= E - O)` is `true`.]]
+[[Preconditions]
+[`O <= size() && (C == dynamic_extent || C <= size() - O)` is `true`.]]
+[[Effects]
+[Equivalent to
+`return span<T, see below>(data() + O,
+C != dynamic_extent ? C : size() - O);`.]]
+[[Remarks]
+[The second template argument of the returned span type is:
+`C != dynamic_extent ? C : (E != dynamic_extent ? E - O :
+dynamic_extent)`]]]]]
+[[`constexpr span<T, dynamic_extent> first(size_type c) const;`]
+[[variablelist
+[[Preconditions][`c <= size()` is `true`.]]
+[[Effects][Equivalent to: `return {data(), c};`]]]]]
+[[`constexpr span<T, dynamic_extent> last(size_type c) const;`]
+[[variablelist
+[[Preconditions][`c <= size()` is `true`.]]
+[[Effects][Equivalent to: `return {data() + (size() - c), c};`]]]]]
+[[`constexpr span<T, dynamic_extent> subspan(size_type o,
+size_type c = dynamic_extent) const;`]
+[[variablelist
+[[Preconditions]
+[`o <= size() && (c == dynamic_extent || o + c <= size())` is `true`.]]
+[[Effects]
+[Equivalent to:
+`return {data() + o, c == dynamic_extent ? size() - o : c};`]]]]]]
+
+[endsect]
+
+[section Observers]
+
+[variablelist
+[[`constexpr size_type size() const noexcept;`]
+[[variablelist
+[[Returns][The number of elements in the span.]]]]]
+[[`constexpr size_type size_bytes() const noexcept;`]
+[[variablelist
+[[Effects][Equivalent to: `return size() * sizeof(T);`]]]]]
+[[`constexpr bool empty() const noexcept;`]
+[[variablelist
+[[Effects][Equivalent to: `return size() == 0;`]]]]]]
+
+[endsect]
+
+[section Element access]
+
+[variablelist
+[[`constexpr reference operator[](size_type i) const;`]
+[[variablelist
+[[Preconditions][`i < size()` is `true`.]]
+[[Effects][Equivalent to: `return *(data() + i);`]]]]]
+[[`constexpr reference front() const;`]
+[[variablelist
+[[Preconditions][`empty()` is `false`.]]
+[[Effects][Equivalent to: `return *data();`]]]]]
+[[`constexpr reference back() const;`]
+[[variablelist
+[[Preconditions][`empty()` is `false`.]]
+[[Effects][Equivalent to: `return *(data() + (size() - 1);`]]]]]
+[[`constexpr pointer data() const noexcept;`]
+[[variablelist
+[[Returns][A pointer to the first element in the span.]]]]]]
+
+[endsect]
+
+[section Iterator support]
+
+[variablelist
+[[`constexpr iterator begin() const noexcept;`]
+[[variablelist
+[[Returns][A constant iterator referring to the first element in the span. If `empty()`,
+then it returns the same value as `cend()`.]]]]]
+[[`constexpr iterator end() const noexcept;`]
+[[variablelist
+[[Returns][A constant iterator which is the past-the-end value.]]]]]
+[[`constexpr reverse_iterator rbegin() const noexcept;`]
+[[variablelist
+[[Effects][Equivalent to: `return reverse_iterator(end());`]]]]]
+[[`constexpr reverse_iterator rend() const noexcept;`]
+[[variablelist
+[[Effects][Equivalent to: `return reverse_iterator(begin());`]]]]]
+[[`constexpr const_iterator cbegin() const noexcept;`]
+[[variablelist
+[[Returns]
+[A constant iterator referring to the first element in the span. If `empty()`,
+then it returns the same value as `cend()`.]]]]]
+[[`constexpr const_iterator cend() const noexcept;`]
+[[variablelist
+[[Returns][A constant iterator which is the past-the-end value.]]]]]
+[[`constexpr const_reverse_iterator crbegin() const noexcept;`]
+[[variablelist
+[[Effects][Equivalent to: `return const_reverse_iterator(cend());`]]]]]
+[[`constexpr const_reverse_iterator crend() const noexcept;`]
+[[variablelist
+[[Effects]
+[Equivalent to: `return const_reverse_iterator(cbegin());`]]]]]]
+
+[endsect]
+
+[section Views of object representation]
+
+[variablelist
+[[`template<class T, std::size_t E>
+span<const std::byte, E == dynamic_extent ? dynamic_extent : sizeof(T) * E>
+as_bytes(span<T, E> s) noexcept;`]
+[[variablelist
+[[Effects]
+[Equivalent to:
+`return {reinterpret_cast<const byte*>(s.data()), s.size_bytes()};`.]]]]]
+[[`template<class T, std::size_t E>
+span<std::byte, E == dynamic_extent ? dynamic_extent : sizeof(T) * E>
+as_writable_bytes(span<T, E> s) noexcept;`]
+[[variablelist
+[[Constraints][`is_const_v<T>` is `false`.]]
+[[Effects]
+[Equivalent to: `return R{reinterpret_cast<byte*>(s.data()), s.size_bytes()};`
+where `R` is the return type.]]]]]]
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -0,0 +1,768 @@
+[/
+  Copyright 2021 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:string_view string_view]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/string_view.hpp>]
+
+The header `<boost/core/string_view.hpp>` defines `boost::core::string_view`,
+a portable and interoperable implementation of `std::string_view`.
+
+Unlike `boost::string_view`, `boost::core::string_view` has implicit
+conversions from and to `std::string_view`, which allows Boost libraries that
+support C++11/C++14 to use it in interfaces without forcing users to forgo the
+use of `std::string_view` in their code.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+template<class Ch> class basic_string_view
+{
+public:
+
+    // types
+
+    typedef std::char_traits<Ch> traits_type;
+    typedef Ch value_type;
+    typedef Ch* pointer;
+    typedef Ch const* const_pointer;
+    typedef Ch& reference;
+    typedef Ch const& const_reference;
+    typedef Ch const* const_iterator;
+    typedef const_iterator iterator;
+    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+    typedef const_reverse_iterator reverse_iterator;
+    typedef std::size_t size_type;
+    typedef std::ptrdiff_t difference_type;
+
+    // npos
+
+    static constexpr size_type npos = static_cast<size_type>( -1 );
+
+public:
+
+    // construction and assignment
+
+    constexpr basic_string_view() noexcept;
+    constexpr basic_string_view( basic_string_view const& ) noexcept = default;
+    constexpr basic_string_view& operator=( basic_string_view const& ) noexcept & = default;
+    constexpr basic_string_view( Ch const* str ) noexcept;
+    constexpr basic_string_view( Ch const* str, size_type len ) noexcept;
+    constexpr basic_string_view( Ch const* begin, Ch const* end ) noexcept;
+    template<class A> basic_string_view( std::basic_string<Ch, std::char_traits<Ch>, A> const& str ) noexcept;
+    basic_string_view( std::basic_string_view<Ch, std::char_traits<Ch>> const& str ) noexcept;
+
+    // conversions
+
+    template<class A> operator std::basic_string<Ch, std::char_traits<Ch>, A>() const;
+    template<class Ch2> operator std::basic_string_view<Ch2>() const noexcept;
+
+    // iterator support
+
+    constexpr const_iterator begin() const noexcept;
+    constexpr const_iterator end() const noexcept;
+    constexpr const_iterator cbegin() const noexcept;
+    constexpr const_iterator cend() const noexcept;
+    constexpr const_reverse_iterator rbegin() const noexcept;
+    constexpr const_reverse_iterator rend() const noexcept;
+    constexpr const_reverse_iterator crbegin() const noexcept;
+    constexpr const_reverse_iterator crend() const noexcept;
+
+    // capacity
+
+    constexpr size_type size() const noexcept;
+    constexpr size_type length() const noexcept;
+    constexpr size_type max_size() const noexcept;
+    constexpr bool empty() const noexcept;
+
+    // element access
+
+    constexpr const_reference operator[]( size_type pos ) const noexcept;
+    constexpr const_reference at( size_type pos ) const;
+    constexpr const_reference front() const noexcept;
+    constexpr const_reference back() const noexcept;
+    constexpr const_pointer data() const noexcept;
+
+    // modifiers
+
+    constexpr void remove_prefix( size_type n ) noexcept;
+    constexpr void remove_suffix( size_type n ) noexcept;
+    constexpr void swap( basic_string_view& s ) noexcept;
+
+    // string operations
+
+    constexpr size_type copy( Ch* s, size_type n, size_type pos = 0 ) const;
+    constexpr basic_string_view substr( size_type pos = 0, size_type n = npos ) const;
+
+    // compare
+
+    constexpr int compare( basic_string_view str ) const noexcept;
+    constexpr int compare( size_type pos1, size_type n1, basic_string_view str ) const;
+    constexpr int compare( size_type pos1, size_type n1, basic_string_view str, size_type pos2, size_type n2 ) const;
+    constexpr int compare( Ch const* s ) const;
+    constexpr int compare( size_type pos1, size_type n1, Ch const* s ) const;
+    constexpr int compare( size_type pos1, size_type n1, Ch const* s, size_type n2 ) const;
+
+    // starts_with
+
+    constexpr bool starts_with( basic_string_view x ) const noexcept;
+    constexpr bool starts_with( Ch x ) const noexcept;
+    constexpr bool starts_with( Ch const* x ) const noexcept;
+
+    // ends_with
+
+    constexpr bool ends_with( basic_string_view x ) const noexcept;
+    constexpr bool ends_with( Ch x ) const noexcept;
+    constexpr bool ends_with( Ch const* x ) const noexcept;
+
+    // find
+
+    constexpr size_type find( basic_string_view str, size_type pos = 0 ) const noexcept;
+    constexpr size_type find( Ch c, size_type pos = 0 ) const noexcept;
+    constexpr size_type find( Ch const* s, size_type pos, size_type n ) const noexcept;
+    constexpr size_type find( Ch const* s, size_type pos = 0 ) const noexcept;
+
+    // rfind
+
+    constexpr size_type rfind( basic_string_view str, size_type pos = npos ) const noexcept;
+    constexpr size_type rfind( Ch c, size_type pos = npos ) const noexcept;
+    constexpr size_type rfind( Ch const* s, size_type pos, size_type n ) const noexcept;
+    constexpr size_type rfind( Ch const* s, size_type pos = npos ) const noexcept;
+
+    // find_first_of
+
+    constexpr size_type find_first_of( basic_string_view str, size_type pos = 0 ) const noexcept;
+    constexpr size_type find_first_of( Ch c, size_type pos = 0 ) const noexcept;
+    constexpr size_type find_first_of( Ch const* s, size_type pos, size_type n ) const noexcept;
+    constexpr size_type find_first_of( Ch const* s, size_type pos = 0 ) const noexcept;
+
+    // find_last_of
+
+    constexpr size_type find_last_of( basic_string_view str, size_type pos = npos ) const noexcept;
+    constexpr size_type find_last_of( Ch c, size_type pos = npos ) const noexcept;
+    constexpr size_type find_last_of( Ch const* s, size_type pos, size_type n ) const noexcept;
+    constexpr size_type find_last_of( Ch const* s, size_type pos = npos ) const noexcept;
+
+    // find_first_not_of
+
+    constexpr size_type find_first_not_of( basic_string_view str, size_type pos = 0 ) const noexcept;
+    constexpr size_type find_first_not_of( Ch c, size_type pos = 0 ) const noexcept;
+    constexpr size_type find_first_not_of( Ch const* s, size_type pos, size_type n ) const noexcept;
+    constexpr size_type find_first_not_of( Ch const* s, size_type pos = 0 ) const noexcept;
+
+    // find_last_not_of
+
+    constexpr size_type find_last_not_of( basic_string_view str, size_type pos = npos ) const noexcept;
+    constexpr size_type find_last_not_of( Ch c, size_type pos = npos ) const noexcept;
+    constexpr size_type find_last_not_of( Ch const* s, size_type pos, size_type n ) const noexcept;
+    constexpr size_type find_last_not_of( Ch const* s, size_type pos = npos ) const noexcept;
+
+    // contains
+
+    constexpr bool contains( basic_string_view sv ) const noexcept;
+    constexpr bool contains( Ch c ) const noexcept;
+    constexpr bool contains( Ch const* s ) const noexcept;
+
+    // relational operators
+
+    constexpr friend bool operator==( basic_string_view sv1, basic_string_view sv2 ) noexcept;
+    constexpr friend bool operator!=( basic_string_view sv1, basic_string_view sv2 ) noexcept;
+    constexpr friend bool operator<( basic_string_view sv1, basic_string_view sv2 ) noexcept;
+    constexpr friend bool operator<=( basic_string_view sv1, basic_string_view sv2 ) noexcept;
+    constexpr friend bool operator>( basic_string_view sv1, basic_string_view sv2 ) noexcept;
+    constexpr friend bool operator>=( basic_string_view sv1, basic_string_view sv2 ) noexcept;
+};
+
+// stream inserter
+
+template<class Ch> std::basic_ostream<Ch>& operator<<( std::basic_ostream<Ch>& os, basic_string_view<Ch> str );
+
+// typedef names
+
+typedef basic_string_view<char> string_view;
+typedef basic_string_view<wchar_t> wstring_view;
+typedef basic_string_view<char16_t> u16string_view;
+typedef basic_string_view<char32_t> u32string_view;
+typedef basic_string_view<char8_t> u8string_view;
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[section Construction]
+
+[section `constexpr basic_string_view() noexcept;`]
+
+* *Ensures:* `data() == 0`; `size() == 0`.
+
+[endsect]
+
+[section `constexpr basic_string_view( Ch const* str ) noexcept;`]
+
+* *Ensures:* `data() == str`; `size() == traits_type::length( str )`.
+
+[endsect]
+
+[section `constexpr basic_string_view( Ch const* str, size_type len ) noexcept;`]
+
+* *Ensures:* `data() == str`; `size() == len`.
+
+[endsect]
+
+[section `constexpr basic_string_view( Ch const* begin, Ch const* end ) noexcept;`]
+
+* *Requires:* `end >= begin`.
+* *Ensures:* `data() == begin`; `size() == end - begin`.
+
+[endsect]
+
+[section `template<class A> basic_string_view( std::basic_string<Ch, std::char_traits<Ch>, A> const& str ) noexcept;`]
+
+* *Ensures:* `data() == str.data()`; `size() == str.size()`.
+
+[endsect]
+
+[section `basic_string_view( std::basic_string_view<Ch, std::char_traits<Ch>> const& str ) noexcept;`]
+
+* *Ensures:* `data() == str.data()`; `size() == str.size()`.
+
+[endsect]
+
+[endsect]
+
+[section Conversions]
+
+[section `template<class A> operator std::basic_string<Ch, std::char_traits<Ch>, A>() const;`]
+
+* *Returns:* `std::basic_string<Ch, std::char_traits<Ch>, A>( data(), size() )`.
+
+[endsect]
+
+[section `template<class Ch2> operator std::basic_string_view<Ch2>() const noexcept;`]
+
+* *Constraints:* `Ch2` is the same type as `Ch`.
+* *Returns:* `std::basic_string_view<Ch2>( data(), size() )`.
+
+[endsect]
+
+[endsect]
+
+[section Iterator Support]
+
+[section `constexpr const_iterator begin() const noexcept;`]
+
+* *Returns:* `data()`.
+
+[endsect]
+
+[section `constexpr const_iterator end() const noexcept;`]
+
+* *Returns:* `data() + size()`.
+
+[endsect]
+
+[section `constexpr const_iterator cbegin() const noexcept;`]
+
+* *Returns:* `begin()`.
+
+[endsect]
+
+[section `constexpr const_iterator cend() const noexcept;`]
+
+* *Returns:* `end()`.
+
+[endsect]
+
+[section `constexpr const_reverse_iterator rbegin() const noexcept;`]
+
+* *Returns:* `const_reverse_iterator( end() )`.
+
+[endsect]
+
+[section `constexpr const_reverse_iterator rend() const noexcept;`]
+
+* *Returns:* `const_reverse_iterator( begin() )`.
+
+[endsect]
+
+[section `constexpr const_reverse_iterator crbegin() const noexcept;`]
+
+* *Returns:* `rbegin()`.
+
+[endsect]
+
+[section `constexpr const_reverse_iterator crend() const noexcept;`]
+
+* *Returns:* `rend()`.
+
+[endsect]
+
+[endsect]
+
+[section Capacity]
+
+[section `constexpr size_type size() const noexcept;`]
+
+* *Returns:* the length of the referenced character sequence.
+
+[endsect]
+
+[section `constexpr size_type length() const noexcept;`]
+
+* *Returns:* `size()`.
+
+[endsect]
+
+[section `constexpr size_type max_size() const noexcept;`]
+
+* *Returns:* `std::numeric_limits<size_type>::max() / sizeof(Ch)`.
+
+[endsect]
+
+[section `constexpr bool empty() const noexcept;`]
+
+* *Returns:* `size() == 0`.
+
+[endsect]
+
+[endsect]
+
+[section Element Access]
+
+[section `constexpr const_reference operator[]( size_type pos ) const noexcept;`]
+
+* *Requires:* `pos < size()`.
+* *Returns:* `data()[ pos ]`.
+
+[endsect]
+
+[section `constexpr const_reference at( size_type pos ) const;`]
+
+* *Returns:* `data()[ pos ]`.
+* *Throws:* `std::out_of_range` when `pos >= size()`.
+
+[endsect]
+
+[section `constexpr const_reference front() const noexcept;`]
+
+* *Requires:* `!empty()`.
+* *Returns:* `data()[ 0 ]`.
+
+[endsect]
+
+[section `constexpr const_reference back() const noexcept;`]
+
+* *Requires:* `!empty()`.
+* *Returns:* `data()[ size() - 1 ]`.
+
+[endsect]
+
+[section `constexpr const_pointer data() const noexcept;`]
+
+* *Returns:* a pointer to the beginning of the referenced character sequence.
+
+[endsect]
+
+[endsect]
+
+[section Modifiers]
+
+[section `constexpr void remove_prefix( size_type n ) noexcept;`]
+
+* *Requires:* `n <= size()`.
+* *Effects:* advances `data()` by `n` and decreases `size()` by `n`.
+
+[endsect]
+
+[section `constexpr void remove_suffix( size_type n ) noexcept;`]
+
+* *Requires:* `n <= size()`.
+* *Effects:* decreases `size()` by `n`.
+
+[endsect]
+
+[section `constexpr void swap( basic_string_view& s ) noexcept;`]
+
+* *Effects:* exchanges the contents of `*this` and `s`.
+
+[endsect]
+
+[endsect]
+
+[section String Operations]
+
+[section copy]
+
+[section `constexpr size_type copy( Ch* s, size_type n, size_type pos = 0 ) const;`]
+
+* *Effects:* copies to `s` the contents of `substr( pos, n )`.
+* *Throws:* `std::out_of_range` when `pos >= size()`.
+
+[endsect]
+
+[endsect]
+
+[section substr]
+
+[section `constexpr basic_string_view substr( size_type pos = 0, size_type n = npos ) const;`]
+
+* *Returns:* `basic_string_view( data() + pos, std::min( size() - pos, n ) )`.
+* *Throws:* `std::out_of_range` when `pos >= size()`.
+
+[endsect]
+
+[endsect]
+
+[section compare]
+
+[section `constexpr int compare( basic_string_view str ) const noexcept;`]
+
+* *Returns:*
+  * if `traits_type::compare( data(), str.data(), std::min( size(), str.size() ) )` is not zero, returns it. Otherwise,
+  * if `size() < str.size()`, returns a negative number. Otherwise,
+  * if `size() > str.size()`, returns a positive number. Otherwise,
+  * returns 0.
+
+[endsect]
+
+[section `constexpr int compare( size_type pos1, size_type n1, basic_string_view str ) const;`]
+
+* *Returns:* `substr( pos1, n1 ).compare( str )`.
+
+[endsect]
+
+[section `constexpr int compare( size_type pos1, size_type n1, basic_string_view str, size_type pos2, size_type n2 ) const;`]
+
+* *Returns:* `substr( pos1, n1 ).compare( str.substr( pos2, n2 ) )`.
+
+[endsect]
+
+[section `constexpr int compare( Ch const* s ) const noexcept;`]
+
+* *Returns:* `compare( basic_string_view( s ) )`.
+
+[endsect]
+
+[section `constexpr int compare( size_type pos1, size_type n1, Ch const* s ) const;`]
+
+* *Returns:* `substr( pos1, n1 ).compare( basic_string_view( s ) )`.
+
+[endsect]
+
+[section `constexpr int compare( size_type pos1, size_type n1, Ch const* s, size_type n2 ) const;`]
+
+* *Returns:* `substr( pos1, n1 ).compare( basic_string_view( s, n2 ) )`.
+
+[endsect]
+
+[endsect]
+
+[section starts_with]
+
+[section `constexpr bool starts_with( basic_string_view x ) const noexcept;`]
+
+* *Returns:* `substr( 0, x.size() ) == x`.
+
+[endsect]
+
+[section `constexpr bool starts_with( Ch x ) const noexcept;`]
+
+* *Returns:* `starts_with( basic_string_view( &x, 1 ) )`.
+
+[endsect]
+
+[section `constexpr bool starts_with( Ch const* x ) const noexcept;`]
+
+* *Returns:* `starts_with( basic_string_view( x ) )`.
+
+[endsect]
+
+[endsect]
+
+[section ends_with]
+
+[section `constexpr bool ends_with( basic_string_view x ) const noexcept;`]
+
+* *Returns:* `size() >= x.size() && substr( size() - x.size(), x.size() ) == x`.
+
+[endsect]
+
+[section `constexpr bool ends_with( Ch x ) const noexcept;`]
+
+* *Returns:* `ends_with( basic_string_view( &x, 1 ) )`.
+
+[endsect]
+
+[section `constexpr bool ends_with( Ch const* x ) const noexcept;`]
+
+* *Returns:* `ends_with( basic_string_view( x ) )`.
+
+[endsect]
+
+[endsect]
+
+[endsect]
+
+[section Searching]
+
+[section find]
+
+[section `constexpr size_type find( basic_string_view str, size_type pos = 0 ) const noexcept;`]
+
+* *Returns:* The lowest position `i` such that `i >= pos` and `substr( i, str.size() ) == str`, or `npos` if such a position doesn't exist.
+
+[endsect]
+
+[section `constexpr size_type find( Ch c, size_type pos = 0 ) const noexcept;`]
+
+* *Returns:* `find( basic_string_view( &c, 1 ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find( Ch const* s, size_type pos, size_type n ) const noexcept;`]
+
+* *Returns:* `find( basic_string_view( s, n ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find( Ch const* s, size_type pos = 0 ) const noexcept;`]
+
+* *Returns:* `find( basic_string_view( s ), pos )`.
+
+[endsect]
+
+[endsect]
+
+[section rfind]
+
+[section `constexpr size_type rfind( basic_string_view str, size_type pos = npos ) const noexcept;`]
+
+* *Returns:* The highest position `i` such that `i <= pos` and `substr( i, str.size() ) == str`, or `npos` if such a position doesn't exist.
+
+[endsect]
+
+[section `constexpr size_type rfind( Ch c, size_type pos = npos ) const noexcept;`]
+
+* *Returns:* `rfind( basic_string_view( &c, 1 ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type rfind( Ch const* s, size_type pos, size_type n ) const noexcept;`]
+
+* *Returns:* `rfind( basic_string_view( s, n ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type rfind( Ch const* s, size_type pos = npos ) const noexcept;`]
+
+* *Returns:* `rfind( basic_string_view( s ), pos )`.
+
+[endsect]
+
+[endsect]
+
+[section find_first_of]
+
+[section `constexpr size_type find_first_of( basic_string_view str, size_type pos = 0 ) const noexcept;`]
+
+* *Returns:* The lowest position `i` such that `i >= pos` and the character at position `i` is equal to one of the characters in `str`, or `npos` if such a position doesn't exist.
+
+[endsect]
+
+[section `constexpr size_type find_first_of( Ch c, size_type pos = 0 ) const noexcept;`]
+
+* *Returns:* `find_first_of( basic_string_view( &c, 1 ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find_first_of( Ch const* s, size_type pos, size_type n ) const noexcept;`]
+
+* *Returns:* `find_first_of( basic_string_view( s, n ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find_first_of( Ch const* s, size_type pos = 0 ) const noexcept;`]
+
+* *Returns:* `find_first_of( basic_string_view( s ), pos )`.
+
+[endsect]
+
+[endsect]
+
+[section find_last_of]
+
+[section `constexpr size_type find_last_of( basic_string_view str, size_type pos = npos ) const noexcept;`]
+
+* *Returns:* The highest position `i` such that `i <= pos` and the character at position `i` is equal to one of the characters in `str`, or `npos` if such a position doesn't exist.
+
+[endsect]
+
+[section `constexpr size_type find_last_of( Ch c, size_type pos = npos ) const noexcept;`]
+
+* *Returns:* `find_last_of( basic_string_view( &c, 1 ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find_last_of( Ch const* s, size_type pos, size_type n ) const noexcept;`]
+
+* *Returns:* `find_last_of( basic_string_view( s, n ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find_last_of( Ch const* s, size_type pos = npos ) const noexcept;`]
+
+* *Returns:* `find_last_of( basic_string_view( s ), pos )`.
+
+[endsect]
+
+[endsect]
+
+[section find_first_not_of]
+
+[section `constexpr size_type find_first_not_of( basic_string_view str, size_type pos = 0 ) const noexcept;`]
+
+* *Returns:* The lowest position `i` such that `i >= pos` and the character at position `i` is not equal to one of the characters in `str`, or `npos` if such a position doesn't exist.
+
+[endsect]
+
+[section `constexpr size_type find_first_not_of( Ch c, size_type pos = 0 ) const noexcept;`]
+
+* *Returns:* `find_first_not_of( basic_string_view( &c, 1 ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find_first_not_of( Ch const* s, size_type pos, size_type n ) const noexcept;`]
+
+* *Returns:* `find_first_not_of( basic_string_view( s, n ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find_first_not_of( Ch const* s, size_type pos = 0 ) const noexcept;`]
+
+* *Returns:* `find_first_not_of( basic_string_view( s ), pos )`.
+
+[endsect]
+
+[endsect]
+
+[section find_last_not_of]
+
+[section `constexpr size_type find_last_not_of( basic_string_view str, size_type pos = npos ) const noexcept;`]
+
+* *Returns:* The highest position `i` such that `i <= pos` and the character at position `i` is not equal to one of the characters in `str`, or `npos` if such a position doesn't exist.
+
+[endsect]
+
+[section `constexpr size_type find_last_not_of( Ch c, size_type pos = npos ) const noexcept;`]
+
+* *Returns:* `find_last_not_of( basic_string_view( &c, 1 ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find_last_not_of( Ch const* s, size_type pos, size_type n ) const noexcept;`]
+
+* *Returns:* `find_last_not_of( basic_string_view( s, n ), pos )`.
+
+[endsect]
+
+[section `constexpr size_type find_last_not_of( Ch const* s, size_type pos = npos ) const noexcept;`]
+
+* *Returns:* `find_last_not_of( basic_string_view( s ), pos )`.
+
+[endsect]
+
+[endsect]
+
+[section contains]
+
+[section `constexpr bool contains( basic_string_view sv ) const noexcept;`]
+
+* *Returns:* `find( sv ) != npos`.
+
+[endsect]
+
+[section `constexpr bool contains( Ch c ) const noexcept;`]
+
+* *Returns:* `find( c ) != npos`.
+
+[endsect]
+
+[section `constexpr bool contains( Ch const* s ) const noexcept;`]
+
+* *Returns:* `find( s ) != npos`.
+
+[endsect]
+
+[endsect]
+
+[endsect]
+
+[section Relational Operators]
+
+[section `constexpr friend bool operator==( basic_string_view sv1, basic_string_view sv2 ) noexcept;`]
+
+* *Returns:* `sv1.compare( sv2 ) == 0`.
+
+[endsect]
+
+[section `constexpr friend bool operator!=( basic_string_view sv1, basic_string_view sv2 ) noexcept;`]
+
+* *Returns:* `sv1.compare( sv2 ) != 0`.
+
+[endsect]
+
+[section `constexpr friend bool operator<( basic_string_view sv1, basic_string_view sv2 ) noexcept;`]
+
+* *Returns:* `sv1.compare( sv2 ) < 0`.
+
+[endsect]
+
+[section `constexpr friend bool operator<=( basic_string_view sv1, basic_string_view sv2 ) noexcept;`]
+
+* *Returns:* `sv1.compare( sv2 ) <= 0`.
+
+[endsect]
+
+[section `constexpr friend bool operator>( basic_string_view sv1, basic_string_view sv2 ) noexcept;`]
+
+* *Returns:* `sv1.compare( sv2 ) > 0`.
+
+[endsect]
+
+[section `constexpr friend bool operator>=( basic_string_view sv1, basic_string_view sv2 ) noexcept;`]
+
+* *Returns:* `sv1.compare( sv2 ) >= 0`.
+
+[endsect]
+
+[endsect]
+
+[section Stream Inserter]
+
+[section `template<class Ch> std::basic_ostream<Ch>& operator<<( std::basic_ostream<Ch>& os, basic_string_view<Ch> str );`]
+
+* *Effects:* equivalent to `os << x`, where `x` is a pointer to a null-terminated character sequence with the same contents as `str`.
+
+[endsect]
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -20,17 +20,17 @@

 [endsimplesect]

-[section Header <boost/core/swap.hpp>]
+[section Header <boost/core/invoke_swap.hpp>]

-`template<class T> void swap(T& left, T& right);`
+[^template<class T> void invoke_swap(T& left, T& right) noexcept(['see below]);]

 [endsect]

 [section Introduction]

-The template function `boost::swap` allows the values of two
-variables to be swapped, using argument dependent lookup to
-select a specialized swap function if available. If no
+The template function `boost::core::invoke_swap` allows the
+values of two variables to be swapped, using argument dependent
+lookup to select a specialized swap function if available. If no
 specialized swap function is available, `std::swap` is used.

 [endsect]
@@ -40,13 +40,14 @@ specialized swap function is available, `std::swap` is used.
 The generic `std::swap` function requires that the elements
 to be swapped are assignable and copy constructible. It is
 usually implemented using one copy construction and two
-assignments - this is often both unnecessarily restrictive and
-unnecessarily slow. In addition, where the generic swap
-implementation provides only the basic guarantee, specialized
-swap functions are often able to provide the no-throw exception
-guarantee (and it is considered best practice to do so where
-possible [footnote Scott Meyers, Effective C++ Third Edition,
-Item 25: "Consider support for a non-throwing swap"].
+assignments (C++11 replaces copy operations with move) - this
+is often both unnecessarily restrictive and unnecessarily slow.
+In addition, where the generic swap implementation provides
+only the basic guarantee, specialized swap functions are often
+able to provide the no-throw exception guarantee (and it is
+considered best practice to do so where possible[footnote Scott
+Meyers, Effective C++ Third Edition, Item 25: "Consider support
+for a non-throwing swap"].

 The alternative to using argument dependent lookup in this
 situation is to provide a template specialization of
@@ -55,23 +56,27 @@ Although this is legal C++, no Boost libraries use this method,
 whereas many Boost libraries provide specialized swap functions
 in their own namespaces.

-`boost::swap` also supports swapping built-in arrays. Note that
-`std::swap` originally did not do so, but a request to add an
-overload of `std::swap` for built-in arrays has been accepted
+`boost::core::invoke_swap` also supports swapping built-in arrays.
+Note that `std::swap` originally did not do so, but a request to
+add an overload of `std::swap` for built-in arrays has been accepted
 by the C++ Standards Committee[footnote
-  [@http://open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#809 
+  [@http://open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#809
  LWG Defect Report 809: std::swap should be overloaded for array
  types]].

 [endsect]
-    
+
 [section Exception Safety]

-`boost::swap` provides the same exception guarantee as the
-underlying swap function used, with one exception; for an array
+`boost::core::invoke_swap` provides the same exception guarantee as
+the underlying swap function used, with one exception; for an array
 of type `T[n]`, where `n > 1` and the underlying swap function
-for `T` provides the strong exception guarantee, `boost::swap`
-provides only the basic exception guarantee.
+for `T` provides the strong exception guarantee,
+`boost::core::invoke_swap` provides only the basic exception guarantee.
+
+In C++11 and later, `boost::core::invoke_swap` propagates the same
+`noexcept` specification as the one specified in the underlying swap
+function.

 [endsect]

@@ -79,42 +84,44 @@ provides only the basic exception guarantee.

 Either:

-* T must be assignable
-* T must be copy constructible
+* `T` must be copy assignable (/since C++11:/ move assignable)
+* `T` must be copy constructible (/since C++11:/ move constructible)

 Or:

-* A function with the signature `swap(T&,T&)` is available via
+* A function with the signature `swap(T&, T&)` is available via
  argument dependent lookup

 Or:

-* A template specialization of `std::swap` exists for T
+* A template specialization of `std::swap` exists for `T`

 Or:

-* T is a built-in array of swappable elements
+* `T` is a built-in array of swappable elements

 [endsect]
-    
+
 [section Portability]

 Several older compilers do not support argument dependent
-lookup. On these compilers `boost::swap` will call
+lookup. On these compilers `boost::core::invoke_swap` will call
 `std::swap`, ignoring any specialized swap functions that
 could be found as a result of argument dependent lookup.

-[endsect]    
+[endsect]

 [section Credits]

-* *Niels Dekker* - for implementing and documenting support for 
+* *Niels Dekker* - for implementing and documenting support for
  built-in arrays
 * *Joseph Gauterin* - for the initial idea, implementation,
  tests, and documentation
 * *Steven Watanabe* - for the idea to make `boost::swap` less
  specialized than `std::swap`, thereby allowing the function
-  to have the name 'swap' without introducing ambiguity
+  to have the name 'swap' without introducing ambiguity. However,
+  later the function was renamed to `boost::core::invoke_swap`
+  to avoid potential infinite recursion.

 [endsect]

@@ -0,0 +1,77 @@
+[/
+  Copyright 2021 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:type_name type_name]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/type_name.hpp>]
+
+The header `<boost/core/type_name.hpp>` defines the function
+template `boost::core::type_name<T>()` that returns a string
+representation of the name of `T`, suitable for logging or
+diagnostic display purposes.
+
+The result is similar to `boost::core::demangle( typeid(T).name() )`,
+but it's made more regular by eliminating some of the platform-specific
+differences and extra template parameters of the standard library
+container types.
+
+For example, `type_name< std::map<std::string, int> >()` returns
+`"std::map<std::string, int>"` and not
+
+```
+  std::map<std::__cxx11::basic_string<char, std::char_traits<char>,
+    std::allocator<char> >, int, std::less<std::__cxx11::basic_string<char,
+    std::char_traits<char>, std::allocator<char> > >, std::allocator<
+    std::pair<std::__cxx11::basic_string<char, std::char_traits<char>,
+    std::allocator<char> > const, int> > >
+```
+
+or
+
+```
+  class std::map<class std::basic_string<char,struct std::char_traits<char>,
+    class std::allocator<char> >,int,struct std::less<class std::basic_string<
+    char,struct std::char_traits<char>,class std::allocator<char> > >,class
+    std::allocator<struct std::pair<class std::basic_string<char,struct
+    std::char_traits<char>,class std::allocator<char> > const ,int> > >
+```
+
+The return values aren't guaranteed to be stable across Boost releases.
+
+Compilation with `-fno-rtti` is supported, but the returned type names aren't
+guaranteed to be particularly useful or unique.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+template<class T> std::string type_name();
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[section template<class T> std::string type_name();]
+
+* *Returns:* A string representation of the name of `T`.
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -11,7 +11,7 @@ Distributed under the Boost Software License, Version 1.0.
 [section Overview]

 The header <boost/core/use_default.hpp> provides the type `boost::use_default`
-which is used by other Boost libraries as a sentinel type in a templates to
+which is used by other Boost libraries as a sentinel type in templates to
 indicate defaults.

 [endsect]
@@ -0,0 +1,70 @@
+[/
+  Copyright 2022 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:verbose_terminate_handler verbose_terminate_handler]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/verbose_terminate_handler.hpp>]
+
+The header `<boost/core/verbose_terminate_handler.hpp>` defines
+the function `void boost::core::verbose_terminate_handler()`. Its
+purpose is to be set as a terminate handler as in
+```
+    std::set_terminate( boost::core::verbose_terminate_handler );
+```
+
+When invoked, the function prints information about the current
+uncaught exception to `stderr` and then calls `std::abort`.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+[[noreturn]] void verbose_terminate_handler();
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[section Example]
+
+```
+#include <boost/core/verbose_terminate_handler.hpp>
+#include <boost/throw_exception.hpp>
+#include <exception>
+
+int main()
+{
+    std::set_terminate( boost::core::verbose_terminate_handler );
+    boost::throw_with_location( std::exception() );
+}
+```
+
+Sample output:
+```
+std::terminate called after throwing an exception:
+
+      type: class boost::detail::with_throw_location<class std::exception>
+    what(): Unknown exception
+  location: example.cpp:8:12 in function 'main'
+```
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -0,0 +1,79 @@
+[/
+  Copyright 2023 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:yield_primitives Yield Primitives]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/yield_primitives.hpp>]
+
+The header `<boost/core/yield_primitives.hpp>` implements a
+collection of primitives that allow the current thread to
+yield the CPU in various ways.
+
+Very low level, specialized functionality, generally only useful for
+implementing spinlocks. Normal synchronization primitives should
+almost always be preferable in application code.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+void sp_thread_pause() noexcept;
+void sp_thread_yield() noexcept;
+void sp_thread_sleep() noexcept;
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[section sp_thread_pause]
+
+`void sp_thread_pause() noexcept;`
+
+Emits a PAUSE instruction (on x86) or a YIELD instruction (on ARM).
+
+A portable equivalent of the GCC builtin function `__builtin_ia32_pause`.
+
+[endsect]
+
+[section sp_thread_yield]
+
+`void sp_thread_yield() noexcept;`
+
+Informs the scheduler that the current thread wishes to relinquish
+the rest of its timeslice.
+
+A portable equivalent of POSIX `sched_yield`.
+
+[endsect]
+
+[section sp_thread_sleep]
+
+`void sp_thread_sleep() noexcept;`
+
+Sleeps for a short period, as if by calling POSIX `nanosleep` with
+a small, implementation-dependent, interval (usually one microsecond).
+
+A more forcing yield primitive than `sp_thread_yield`, because it's
+generally not ignored even if all other waiting threads are of lower
+priority.
+
+[endsect]
+
+[endsect]
+
+[endsect]
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+
+  <Type Name="boost::core::basic_string_view&lt;*&gt;">
+    <DisplayString>{p_,[n_]s}</DisplayString>
+  </Type>
+
+</AutoVisualizer>
@@ -0,0 +1,57 @@
+#ifndef BOOST_CORE_ALIGNOF_HPP_INCLUDED
+#define BOOST_CORE_ALIGNOF_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
+
+#include <boost/config.hpp>
+#include <cstddef>
+
+#if !defined(BOOST_NO_CXX11_ALIGNOF)
+
+#define BOOST_CORE_ALIGNOF alignof
+
+#elif defined(__GNUC__)
+
+#define BOOST_CORE_ALIGNOF __alignof__
+
+#elif defined(_MSC_VER)
+
+#define BOOST_CORE_ALIGNOF __alignof
+
+#else
+
+namespace boost
+{
+namespace core
+{
+namespace detail
+{
+
+template<class T> struct alignof_helper
+{
+    char x;
+    T t;
+};
+
+} // namespace detail
+} // namespace core
+} // namespace boost
+
+#if defined(__GNUC__)
+// ignoring -Wvariadic-macros with #pragma doesn't work under GCC
+# pragma GCC system_header
+#endif
+
+#define BOOST_CORE_ALIGNOF(...) offsetof( ::boost::core::detail::alignof_helper<__VA_ARGS__>, t );
+
+#endif
+
+#endif  // #ifndef BOOST_CORE_ALIGNOF_HPP_INCLUDED
@@ -8,6 +8,9 @@ Distributed under the Boost Software License, Version 1.0.
 #ifndef BOOST_CORE_ALLOC_CONSTRUCT_HPP
 #define BOOST_CORE_ALLOC_CONSTRUCT_HPP

+/*
+This functionality is now in <boost/core/allocator_access.hpp>.
+*/
 #include <boost/core/noinit_adaptor.hpp>

 namespace boost {
@@ -23,56 +26,9 @@ template<class A, class T>
 inline void
 alloc_destroy_n(A& a, T* p, std::size_t n)
 {
-    while (n > 0) {
-        boost::allocator_destroy(a, p + --n);
-    }
+    boost::allocator_destroy_n(a, p, n);
 }

-template<class A, class T>
-inline void
-alloc_destroy(noinit_adaptor<A>&, T* p)
-{
-    p->~T();
-}
-
-template<class A, class T>
-inline void
-alloc_destroy_n(noinit_adaptor<A>&, T* p, std::size_t n)
-{
-    while (n > 0) {
-        p[--n].~T();
-    }
-}
-
-namespace detail {
-
-template<class A, class T>
-class alloc_destroyer {
-public:
-    alloc_destroyer(A& a, T* p) BOOST_NOEXCEPT
-        : a_(a),
-          p_(p),
-          n_(0) { }
-
-    ~alloc_destroyer() {
-        boost::alloc_destroy_n(a_, p_, n_);
-    }
-
-    std::size_t& size() BOOST_NOEXCEPT {
-        return n_;
-    }
-
-private:
-    alloc_destroyer(const alloc_destroyer&);
-    alloc_destroyer& operator=(const alloc_destroyer&);
-
-    A& a_;
-    T* p_;
-    std::size_t n_;
-};
-
-} /* detail */
-
 template<class A, class T>
 inline void
 alloc_construct(A& a, T* p)
@@ -117,51 +73,21 @@ template<class A, class T>
 inline void
 alloc_construct_n(A& a, T* p, std::size_t n)
 {
-    detail::alloc_destroyer<A, T> hold(a, p);
-    for (std::size_t& i = hold.size(); i < n; ++i) {
-        boost::allocator_construct(a, p + i);
-    }
-    hold.size() = 0;
+    boost::allocator_construct_n(a, p, n);
 }

 template<class A, class T>
 inline void
 alloc_construct_n(A& a, T* p, std::size_t n, const T* l, std::size_t m)
 {
-    detail::alloc_destroyer<A, T> hold(a, p);
-    for (std::size_t& i = hold.size(); i < n; ++i) {
-        boost::allocator_construct(a, p + i, l[i % m]);
-    }
-    hold.size() = 0;
+    boost::allocator_construct_n(a, p, n, l, m);
 }

 template<class A, class T, class I>
 inline void
 alloc_construct_n(A& a, T* p, std::size_t n, I b)
 {
-    detail::alloc_destroyer<A, T> hold(a, p);
-    for (std::size_t& i = hold.size(); i < n; void(++i), void(++b)) {
-        boost::allocator_construct(a, p + i, *b);
-    }
-    hold.size() = 0;
-}
-
-template<class A, class T>
-inline void
-alloc_construct(noinit_adaptor<A>&, T* p)
-{
-    ::new(static_cast<void*>(p)) T;
-}
-
-template<class A, class T>
-inline void
-alloc_construct_n(noinit_adaptor<A>& a, T* p, std::size_t n)
-{
-    detail::alloc_destroyer<noinit_adaptor<A>, T> hold(a, p);
-    for (std::size_t& i = hold.size(); i < n; ++i) {
-        ::new(static_cast<void*>(p + i)) T;
-    }
-    hold.size() = 0;
+    boost::allocator_construct_n(a, p, n, b);
 }

 } /* boost */
@@ -0,0 +1,112 @@
+/*
+Copyright 2021 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_ALLOCATOR_TRAITS_HPP
+#define BOOST_CORE_ALLOCATOR_TRAITS_HPP
+
+#include <boost/core/allocator_access.hpp>
+
+namespace boost {
+
+template<class A>
+struct allocator_traits {
+    typedef A allocator_type;
+
+    typedef typename allocator_value_type<A>::type value_type;
+
+    typedef typename allocator_pointer<A>::type pointer;
+
+    typedef typename allocator_const_pointer<A>::type const_pointer;
+
+    typedef typename allocator_void_pointer<A>::type void_pointer;
+
+    typedef typename allocator_const_void_pointer<A>::type const_void_pointer;
+
+    typedef typename allocator_difference_type<A>::type difference_type;
+
+    typedef typename allocator_size_type<A>::type size_type;
+
+    typedef typename allocator_propagate_on_container_copy_assignment<A>::type
+        propagate_on_container_copy_assignment;
+
+    typedef typename allocator_propagate_on_container_move_assignment<A>::type
+        propagate_on_container_move_assignment;
+
+    typedef typename allocator_propagate_on_container_swap<A>::type
+        propagate_on_container_swap;
+
+    typedef typename allocator_is_always_equal<A>::type is_always_equal;
+
+#if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
+    template<class T>
+    using rebind_traits = allocator_traits<typename
+        allocator_rebind<A, T>::type>;
+#else
+    template<class T>
+    struct rebind_traits
+        : allocator_traits<typename allocator_rebind<A, T>::type> { };
+#endif
+
+    static pointer allocate(A& a, size_type n) {
+        return boost::allocator_allocate(a, n);
+    }
+
+    static pointer allocate(A& a, size_type n, const_void_pointer h) {
+        return boost::allocator_allocate(a, n, h);
+    }
+
+    static void deallocate(A& a, pointer p, size_type n) {
+        return boost::allocator_deallocate(a, p, n);
+    }
+
+    template<class T>
+    static void construct(A& a, T* p) {
+        boost::allocator_construct(a, p);
+    }
+
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
+    template<class T, class V, class... Args>
+    static void construct(A& a, T* p, V&& v, Args&&... args) {
+        boost::allocator_construct(a, p, std::forward<V>(v),
+            std::forward<Args>(args)...);
+    }
+#else
+    template<class T, class V>
+    static void construct(A& a, T* p, V&& v) {
+        boost::allocator_construct(a, p, std::forward<V>(v));
+    }
+#endif
+#else
+    template<class T, class V>
+    static void construct(A& a, T* p, const V& v) {
+        boost::allocator_construct(a, p, v);
+    }
+
+    template<class T, class V>
+    static void construct(A& a, T* p, V& v) {
+        boost::allocator_construct(a, p, v);
+    }
+#endif
+
+    template<class T>
+    static void destroy(A& a, T* p) {
+        boost::allocator_destroy(a, p);
+    }
+
+    static size_type max_size(const A& a) BOOST_NOEXCEPT {
+        return boost::allocator_max_size(a);
+    }
+
+    static A select_on_container_copy_construction(const A& a) {
+        return boost::allocator_select_on_container_copy_construction(a);
+    }
+};
+
+} /* boost */
+
+#endif
@@ -0,0 +1,954 @@
+#ifndef BOOST_CORE_BIT_HPP_INCLUDED
+#define BOOST_CORE_BIT_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+// boost/core/bit.hpp
+//
+// A portable version of the C++20 standard header <bit>
+//
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/static_assert.hpp>
+#include <boost/config.hpp>
+#include <boost/cstdint.hpp>
+#include <limits>
+#include <cstring>
+#include <cstdlib>
+
+#if defined(_MSC_VER)
+
+# include <intrin.h>
+# pragma intrinsic(_BitScanForward)
+# pragma intrinsic(_BitScanReverse)
+
+# if defined(_M_X64) || defined(_M_ARM64)
+#  pragma intrinsic(_BitScanForward64)
+#  pragma intrinsic(_BitScanReverse64)
+# endif
+
+# pragma warning(push)
+# pragma warning(disable: 4127) // conditional expression is constant
+# pragma warning(disable: 4244) // conversion from int to T
+
+#endif // defined(_MSC_VER)
+
+#if defined(BOOST_MSVC) && BOOST_MSVC >= 1925
+# define BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL
+#endif
+
+#if defined(__has_builtin)
+# if __has_builtin(__builtin_bit_cast)
+#  define BOOST_CORE_HAS_BUILTIN_BIT_CAST
+# endif
+# if __has_builtin(__builtin_bswap16)
+#  define BOOST_CORE_HAS_BUILTIN_BSWAP16
+# endif
+#endif
+
+#if !defined(BOOST_CORE_HAS_BUILTIN_BIT_CAST) && (defined(BOOST_MSVC) && BOOST_MSVC >= 1926)
+#  define BOOST_CORE_HAS_BUILTIN_BIT_CAST
+#endif
+
+#if !defined(BOOST_CORE_HAS_BUILTIN_BSWAP16) && (defined(BOOST_GCC) && BOOST_GCC >= 40800)
+#  define BOOST_CORE_HAS_BUILTIN_BSWAP16
+#endif
+
+namespace boost
+{
+namespace core
+{
+
+// bit_cast
+
+#if defined(BOOST_CORE_HAS_BUILTIN_BIT_CAST)
+
+template<class To, class From>
+BOOST_CONSTEXPR To bit_cast( From const & from ) BOOST_NOEXCEPT
+{
+    return __builtin_bit_cast( To, from );
+}
+
+#else
+
+template<class To, class From>
+To bit_cast( From const & from ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( sizeof(To) == sizeof(From) );
+
+    To to;
+    std::memcpy( &to, &from, sizeof(To) );
+    return to;
+}
+
+#endif
+
+// countl
+
+#if defined(__GNUC__) || defined(__clang__)
+
+namespace detail
+{
+
+BOOST_CONSTEXPR inline int countl_impl( unsigned char x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_clz( x ) - ( std::numeric_limits<unsigned int>::digits - std::numeric_limits<unsigned char>::digits ): std::numeric_limits<unsigned char>::digits;
+}
+
+BOOST_CONSTEXPR inline int countl_impl( unsigned short x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_clz( x ) - ( std::numeric_limits<unsigned int>::digits - std::numeric_limits<unsigned short>::digits ): std::numeric_limits<unsigned short>::digits;
+}
+
+BOOST_CONSTEXPR inline int countl_impl( unsigned int x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_clz( x ): std::numeric_limits<unsigned int>::digits;
+}
+
+BOOST_CONSTEXPR inline int countl_impl( unsigned long x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_clzl( x ): std::numeric_limits<unsigned long>::digits;
+}
+
+BOOST_CONSTEXPR inline int countl_impl( boost::ulong_long_type x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_clzll( x ): std::numeric_limits<boost::ulong_long_type>::digits;
+}
+
+} // namespace detail
+
+template<class T>
+BOOST_CONSTEXPR int countl_zero( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    return boost::core::detail::countl_impl( x );
+}
+
+#else // defined(__GNUC__) || defined(__clang__)
+
+namespace detail
+{
+
+#if defined(_MSC_VER) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
+
+BOOST_CXX14_CONSTEXPR inline int countl_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    if( __builtin_is_constant_evaluated() )
+    {
+        constexpr unsigned char mod37[ 37 ] = { 32, 31, 6, 30, 9, 5, 0, 29, 16, 8, 2, 4, 21, 0, 19, 28, 25, 15, 0, 7, 10, 1, 17, 3, 22, 20, 26, 0, 11, 18, 23, 27, 12, 24, 13, 14, 0 };
+
+        x |= x >> 1;
+        x |= x >> 2;
+        x |= x >> 4;
+        x |= x >> 8;
+        x |= x >> 16;
+
+        return mod37[ x % 37 ];
+    }
+    else
+    {
+        unsigned long r;
+
+        if( _BitScanReverse( &r, x ) )
+        {
+            return 31 - static_cast<int>( r );
+        }
+        else
+        {
+            return 32;
+        }
+    }
+}
+
+BOOST_CXX14_CONSTEXPR inline int countl_impl( boost::uint8_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) ) - 24;
+}
+
+BOOST_CXX14_CONSTEXPR inline int countl_impl( boost::uint16_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) ) - 16;
+}
+
+#elif defined(_MSC_VER)
+
+inline int countl_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    unsigned long r;
+
+    if( _BitScanReverse( &r, x ) )
+    {
+        return 31 - static_cast<int>( r );
+    }
+    else
+    {
+        return 32;
+    }
+}
+
+inline int countl_impl( boost::uint8_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) ) - 24;
+}
+
+inline int countl_impl( boost::uint16_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) ) - 16;
+}
+
+#else
+
+inline int countl_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    static unsigned char const mod37[ 37 ] = { 32, 31, 6, 30, 9, 5, 0, 29, 16, 8, 2, 4, 21, 0, 19, 28, 25, 15, 0, 7, 10, 1, 17, 3, 22, 20, 26, 0, 11, 18, 23, 27, 12, 24, 13, 14, 0 };
+
+    x |= x >> 1;
+    x |= x >> 2;
+    x |= x >> 4;
+    x |= x >> 8;
+    x |= x >> 16;
+
+    return mod37[ x % 37 ];
+}
+
+inline int countl_impl( boost::uint8_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) ) - 24;
+}
+
+inline int countl_impl( boost::uint16_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) ) - 16;
+}
+
+#endif
+
+#if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64)) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
+
+BOOST_CXX14_CONSTEXPR inline int countl_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    if( __builtin_is_constant_evaluated() )
+    {
+        return static_cast<boost::uint32_t>( x >> 32 ) != 0?
+            boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x >> 32 ) ):
+            boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) ) + 32;
+    }
+    else
+    {
+        unsigned long r;
+
+        if( _BitScanReverse64( &r, x ) )
+        {
+            return 63 - static_cast<int>( r );
+        }
+        else
+        {
+            return 64;
+        }
+    }
+}
+
+#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64))
+
+inline int countl_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    unsigned long r;
+
+    if( _BitScanReverse64( &r, x ) )
+    {
+        return 63 - static_cast<int>( r );
+    }
+    else
+    {
+        return 64;
+    }
+}
+
+#elif defined(_MSC_VER) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
+
+BOOST_CXX14_CONSTEXPR inline int countl_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    return static_cast<boost::uint32_t>( x >> 32 ) != 0?
+        boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x >> 32 ) ):
+        boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) ) + 32;
+}
+
+#else
+
+inline int countl_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    return static_cast<boost::uint32_t>( x >> 32 ) != 0?
+        boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x >> 32 ) ):
+        boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) ) + 32;
+}
+
+#endif
+
+} // namespace detail
+
+template<class T>
+BOOST_CXX14_CONSTEXPR int countl_zero( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) == sizeof(boost::uint8_t) || sizeof(T) == sizeof(boost::uint16_t) || sizeof(T) == sizeof(boost::uint32_t) || sizeof(T) == sizeof(boost::uint64_t) );
+
+    BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint8_t) )
+    {
+        return boost::core::detail::countl_impl( static_cast<boost::uint8_t>( x ) );
+    }
+    else BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint16_t) )
+    {
+        return boost::core::detail::countl_impl( static_cast<boost::uint16_t>( x ) );
+    }
+    else BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint32_t) )
+    {
+        return boost::core::detail::countl_impl( static_cast<boost::uint32_t>( x ) );
+    }
+    else
+    {
+        return boost::core::detail::countl_impl( static_cast<boost::uint64_t>( x ) );
+    }
+}
+
+#endif // defined(__GNUC__) || defined(__clang__)
+
+template<class T>
+BOOST_CONSTEXPR int countl_one( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    return boost::core::countl_zero( static_cast<T>( ~x ) );
+}
+
+// countr
+
+#if defined(__GNUC__) || defined(__clang__)
+
+namespace detail
+{
+
+BOOST_CONSTEXPR inline int countr_impl( unsigned char x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_ctz( x ): std::numeric_limits<unsigned char>::digits;
+}
+
+BOOST_CONSTEXPR inline int countr_impl( unsigned short x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_ctz( x ): std::numeric_limits<unsigned short>::digits;
+}
+
+BOOST_CONSTEXPR inline int countr_impl( unsigned int x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_ctz( x ): std::numeric_limits<unsigned int>::digits;
+}
+
+BOOST_CONSTEXPR inline int countr_impl( unsigned long x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_ctzl( x ): std::numeric_limits<unsigned long>::digits;
+}
+
+BOOST_CONSTEXPR inline int countr_impl( boost::ulong_long_type x ) BOOST_NOEXCEPT
+{
+    return x? __builtin_ctzll( x ): std::numeric_limits<boost::ulong_long_type>::digits;
+}
+
+} // namespace detail
+
+template<class T>
+BOOST_CONSTEXPR int countr_zero( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    return boost::core::detail::countr_impl( x );
+}
+
+#else // defined(__GNUC__) || defined(__clang__)
+
+namespace detail
+{
+
+#if defined(_MSC_VER) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
+
+BOOST_CXX14_CONSTEXPR inline int countr_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    if( __builtin_is_constant_evaluated() )
+    {
+        constexpr unsigned char mod37[ 37 ] = { 32, 0, 1, 26, 2, 23, 27, 0, 3, 16, 24, 30, 28, 11, 0, 13, 4, 7, 17, 0, 25, 22, 31, 15, 29, 10, 12, 6, 0, 21, 14, 9, 5, 20, 8, 19, 18 };
+        return mod37[ ( -(boost::int32_t)x & x ) % 37 ];
+    }
+    else
+    {
+        unsigned long r;
+
+        if( _BitScanForward( &r, x ) )
+        {
+            return static_cast<int>( r );
+        }
+        else
+        {
+            return 32;
+        }
+    }
+}
+
+BOOST_CXX14_CONSTEXPR inline int countr_impl( boost::uint8_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) | 0x100 );
+}
+
+BOOST_CXX14_CONSTEXPR inline int countr_impl( boost::uint16_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) | 0x10000 );
+}
+
+#elif defined(_MSC_VER)
+
+inline int countr_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    unsigned long r;
+
+    if( _BitScanForward( &r, x ) )
+    {
+        return static_cast<int>( r );
+    }
+    else
+    {
+        return 32;
+    }
+}
+
+inline int countr_impl( boost::uint8_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) | 0x100 );
+}
+
+inline int countr_impl( boost::uint16_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) | 0x10000 );
+}
+
+#else
+
+inline int countr_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    static unsigned char const mod37[ 37 ] = { 32, 0, 1, 26, 2, 23, 27, 0, 3, 16, 24, 30, 28, 11, 0, 13, 4, 7, 17, 0, 25, 22, 31, 15, 29, 10, 12, 6, 0, 21, 14, 9, 5, 20, 8, 19, 18 };
+    return mod37[ ( -(boost::int32_t)x & x ) % 37 ];
+}
+
+inline int countr_impl( boost::uint8_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) | 0x100 );
+}
+
+inline int countr_impl( boost::uint16_t x ) BOOST_NOEXCEPT
+{
+    return boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) | 0x10000 );
+}
+
+#endif
+
+#if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64)) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
+
+BOOST_CXX14_CONSTEXPR inline int countr_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    if( __builtin_is_constant_evaluated() )
+    {
+        return static_cast<boost::uint32_t>( x ) != 0?
+            boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) ):
+            boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x >> 32 ) ) + 32;
+    }
+    else
+    {
+        unsigned long r;
+
+        if( _BitScanForward64( &r, x ) )
+        {
+            return static_cast<int>( r );
+        }
+        else
+        {
+            return 64;
+        }
+    }
+}
+
+#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64))
+
+inline int countr_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    unsigned long r;
+
+    if( _BitScanForward64( &r, x ) )
+    {
+        return static_cast<int>( r );
+    }
+    else
+    {
+        return 64;
+    }
+}
+
+#elif defined(_MSC_VER) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
+
+BOOST_CXX14_CONSTEXPR inline int countr_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    return static_cast<boost::uint32_t>( x ) != 0?
+        boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) ):
+        boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x >> 32 ) ) + 32;
+}
+
+#else
+
+inline int countr_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    return static_cast<boost::uint32_t>( x ) != 0?
+        boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) ):
+        boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x >> 32 ) ) + 32;
+}
+
+#endif
+
+} // namespace detail
+
+template<class T>
+BOOST_CXX14_CONSTEXPR int countr_zero( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) == sizeof(boost::uint8_t) || sizeof(T) == sizeof(boost::uint16_t) || sizeof(T) == sizeof(boost::uint32_t) || sizeof(T) == sizeof(boost::uint64_t) );
+
+    BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint8_t) )
+    {
+        return boost::core::detail::countr_impl( static_cast<boost::uint8_t>( x ) );
+    }
+    else BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint16_t) )
+    {
+        return boost::core::detail::countr_impl( static_cast<boost::uint16_t>( x ) );
+    }
+    else BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint32_t) )
+    {
+        return boost::core::detail::countr_impl( static_cast<boost::uint32_t>( x ) );
+    }
+    else
+    {
+        return boost::core::detail::countr_impl( static_cast<boost::uint64_t>( x ) );
+    }
+}
+
+#endif // defined(__GNUC__) || defined(__clang__)
+
+template<class T>
+BOOST_CONSTEXPR int countr_one( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    return boost::core::countr_zero( static_cast<T>( ~x ) );
+}
+
+// popcount
+
+#if defined(__GNUC__) || defined(__clang__)
+
+#if defined(__clang__) && __clang_major__ * 100 + __clang_minor__ < 304
+# define BOOST_CORE_POPCOUNT_CONSTEXPR
+#else
+# define BOOST_CORE_POPCOUNT_CONSTEXPR BOOST_CONSTEXPR
+#endif
+
+namespace detail
+{
+
+BOOST_CORE_POPCOUNT_CONSTEXPR inline int popcount_impl( unsigned char x ) BOOST_NOEXCEPT
+{
+    return __builtin_popcount( x );
+}
+
+BOOST_CORE_POPCOUNT_CONSTEXPR inline int popcount_impl( unsigned short x ) BOOST_NOEXCEPT
+{
+    return __builtin_popcount( x );
+}
+
+BOOST_CORE_POPCOUNT_CONSTEXPR inline int popcount_impl( unsigned int x ) BOOST_NOEXCEPT
+{
+    return __builtin_popcount( x );
+}
+
+BOOST_CORE_POPCOUNT_CONSTEXPR inline int popcount_impl( unsigned long x ) BOOST_NOEXCEPT
+{
+    return __builtin_popcountl( x );
+}
+
+BOOST_CORE_POPCOUNT_CONSTEXPR inline int popcount_impl( boost::ulong_long_type x ) BOOST_NOEXCEPT
+{
+    return __builtin_popcountll( x );
+}
+
+} // namespace detail
+
+#undef BOOST_CORE_POPCOUNT_CONSTEXPR
+
+template<class T>
+BOOST_CONSTEXPR int popcount( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    return boost::core::detail::popcount_impl( x );
+}
+
+#else // defined(__GNUC__) || defined(__clang__)
+
+namespace detail
+{
+
+BOOST_CXX14_CONSTEXPR inline int popcount_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    x = x - ( ( x >> 1 ) & 0x55555555 );
+    x = ( x & 0x33333333 ) + ( ( x >> 2 ) & 0x33333333 );
+    x = ( x + ( x >> 4 ) ) & 0x0F0F0F0F;
+
+    return static_cast<unsigned>( ( x * 0x01010101 ) >> 24 );
+}
+
+BOOST_CXX14_CONSTEXPR inline int popcount_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    x = x - ( ( x >> 1 ) & 0x5555555555555555 );
+    x = ( x & 0x3333333333333333 ) + ( ( x >> 2 ) & 0x3333333333333333 );
+    x = ( x + ( x >> 4 ) ) & 0x0F0F0F0F0F0F0F0F;
+
+    return static_cast<unsigned>( ( x * 0x0101010101010101 ) >> 56 );
+}
+
+} // namespace detail
+
+template<class T>
+BOOST_CXX14_CONSTEXPR int popcount( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) <= sizeof(boost::uint64_t) );
+
+    BOOST_IF_CONSTEXPR ( sizeof(T) <= sizeof(boost::uint32_t) )
+    {
+        return boost::core::detail::popcount_impl( static_cast<boost::uint32_t>( x ) );
+    }
+    else
+    {
+        return boost::core::detail::popcount_impl( static_cast<boost::uint64_t>( x ) );
+    }
+}
+
+#endif // defined(__GNUC__) || defined(__clang__)
+
+// rotating
+
+template<class T>
+BOOST_CXX14_CONSTEXPR T rotl( T x, int s ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    unsigned const mask = std::numeric_limits<T>::digits - 1;
+    return static_cast<T>( x << (static_cast<unsigned>( s ) & mask) | x >> (static_cast<unsigned>( -s ) & mask) );
+}
+
+template<class T>
+BOOST_CXX14_CONSTEXPR T rotr( T x, int s ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    unsigned const mask = std::numeric_limits<T>::digits - 1;
+    return static_cast<T>( x >> (static_cast<unsigned>( s ) & mask) | x << (static_cast<unsigned>( -s ) & mask) );
+}
+
+// integral powers of 2
+
+template<class T>
+BOOST_CONSTEXPR bool has_single_bit( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    return x != 0 && ( x & ( x - 1 ) ) == 0;
+}
+
+// bit_width returns `int` now, https://cplusplus.github.io/LWG/issue3656
+// has been applied to C++20 as a DR
+
+template<class T>
+BOOST_CONSTEXPR int bit_width( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    return std::numeric_limits<T>::digits - boost::core::countl_zero( x );
+}
+
+template<class T>
+BOOST_CONSTEXPR T bit_floor( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    return x == 0? T(0): static_cast<T>( T(1) << ( boost::core::bit_width( x ) - 1 ) );
+}
+
+namespace detail
+{
+
+BOOST_CXX14_CONSTEXPR inline boost::uint32_t bit_ceil_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    if( x == 0 )
+    {
+        return 1;
+    }
+
+    --x;
+
+    x |= x >> 1;
+    x |= x >> 2;
+    x |= x >> 4;
+    x |= x >> 8;
+    x |= x >> 16;
+
+    ++x;
+
+    return x;
+}
+
+BOOST_CXX14_CONSTEXPR inline boost::uint64_t bit_ceil_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    if( x == 0 )
+    {
+        return 1;
+    }
+
+    --x;
+
+    x |= x >> 1;
+    x |= x >> 2;
+    x |= x >> 4;
+    x |= x >> 8;
+    x |= x >> 16;
+    x |= x >> 32;
+
+    ++x;
+
+    return x;
+}
+
+} // namespace detail
+
+template<class T>
+BOOST_CXX14_CONSTEXPR T bit_ceil( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) <= sizeof(boost::uint64_t) );
+
+    BOOST_IF_CONSTEXPR ( sizeof(T) <= sizeof(boost::uint32_t) )
+    {
+        return static_cast<T>( boost::core::detail::bit_ceil_impl( static_cast<boost::uint32_t>( x ) ) );
+    }
+    else
+    {
+        return static_cast<T>( boost::core::detail::bit_ceil_impl( static_cast<boost::uint64_t>( x ) ) );
+    }
+}
+
+// endian
+
+#if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+
+# define BOOST_CORE_BIT_NATIVE_INITIALIZER =little
+
+#elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+
+# define BOOST_CORE_BIT_NATIVE_INITIALIZER =big
+
+#elif defined(__BYTE_ORDER__) && defined(__ORDER_PDP_ENDIAN__) && __BYTE_ORDER__ == __ORDER_PDP_ENDIAN__
+
+# define BOOST_CORE_BIT_NATIVE_INITIALIZER
+
+#elif defined(__LITTLE_ENDIAN__)
+
+# define BOOST_CORE_BIT_NATIVE_INITIALIZER =little
+
+#elif defined(__BIG_ENDIAN__)
+
+# define BOOST_CORE_BIT_NATIVE_INITIALIZER =big
+
+#elif defined(_MSC_VER) || defined(__i386__) || defined(__x86_64__)
+
+# define BOOST_CORE_BIT_NATIVE_INITIALIZER =little
+
+#else
+
+# define BOOST_CORE_BIT_NATIVE_INITIALIZER
+
+#endif
+
+#if !defined(BOOST_NO_CXX11_SCOPED_ENUMS)
+
+enum class endian
+{
+    big,
+    little,
+    native BOOST_CORE_BIT_NATIVE_INITIALIZER
+};
+
+typedef endian endian_type;
+
+#else
+
+namespace endian
+{
+
+enum type
+{
+    big,
+    little,
+    native BOOST_CORE_BIT_NATIVE_INITIALIZER
+};
+
+} // namespace endian
+
+typedef endian::type endian_type;
+
+#endif
+
+#undef BOOST_CORE_BIT_NATIVE_INITIALIZER
+
+// byteswap
+
+namespace detail
+{
+
+BOOST_CONSTEXPR inline boost::uint8_t byteswap_impl( boost::uint8_t x ) BOOST_NOEXCEPT
+{
+    return x;
+}
+
+#if defined(BOOST_CORE_HAS_BUILTIN_BSWAP16)
+
+BOOST_CONSTEXPR inline boost::uint16_t byteswap_impl( boost::uint16_t x ) BOOST_NOEXCEPT
+{
+    return __builtin_bswap16( x );
+}
+
+#else
+
+BOOST_CONSTEXPR inline boost::uint16_t byteswap_impl( boost::uint16_t x ) BOOST_NOEXCEPT
+{
+    return static_cast<boost::uint16_t>( x << 8 | x >> 8 );
+}
+
+#endif
+
+#if defined(__GNUC__) || defined(__clang__)
+
+BOOST_CXX14_CONSTEXPR inline boost::uint32_t byteswap_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    return __builtin_bswap32( x );
+}
+
+BOOST_CXX14_CONSTEXPR inline boost::uint64_t byteswap_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    return __builtin_bswap64( x );
+}
+
+#elif defined(_MSC_VER) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
+
+BOOST_CXX14_CONSTEXPR inline boost::uint32_t byteswap_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    if( __builtin_is_constant_evaluated() )
+    {
+        boost::uint32_t step16 = x << 16 | x >> 16;
+        return ((step16 << 8) & 0xff00ff00) | ((step16 >> 8) & 0x00ff00ff);
+    }
+    else
+    {
+        return _byteswap_ulong( x );
+    }
+}
+
+BOOST_CXX14_CONSTEXPR inline boost::uint64_t byteswap_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    if( __builtin_is_constant_evaluated() )
+    {
+        boost::uint64_t step32 = x << 32 | x >> 32;
+        boost::uint64_t step16 = (step32 & 0x0000FFFF0000FFFFULL) << 16 | (step32 & 0xFFFF0000FFFF0000ULL) >> 16;
+        return (step16 & 0x00FF00FF00FF00FFULL) << 8 | (step16 & 0xFF00FF00FF00FF00ULL) >> 8;
+    }
+    else
+    {
+        return _byteswap_uint64( x );
+    }
+}
+
+#elif defined(_MSC_VER)
+
+inline boost::uint32_t byteswap_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    return _byteswap_ulong( x );
+}
+
+inline boost::uint64_t byteswap_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    return _byteswap_uint64( x );
+}
+
+#else
+
+BOOST_CXX14_CONSTEXPR inline boost::uint32_t byteswap_impl( boost::uint32_t x ) BOOST_NOEXCEPT
+{
+    boost::uint32_t step16 = x << 16 | x >> 16;
+    return ((step16 << 8) & 0xff00ff00) | ((step16 >> 8) & 0x00ff00ff);
+}
+
+BOOST_CXX14_CONSTEXPR inline boost::uint64_t byteswap_impl( boost::uint64_t x ) BOOST_NOEXCEPT
+{
+    boost::uint64_t step32 = x << 32 | x >> 32;
+    boost::uint64_t step16 = (step32 & 0x0000FFFF0000FFFFULL) << 16 | (step32 & 0xFFFF0000FFFF0000ULL) >> 16;
+    return (step16 & 0x00FF00FF00FF00FFULL) << 8 | (step16 & 0xFF00FF00FF00FF00ULL) >> 8;
+}
+
+#endif
+
+} // namespace detail
+
+template<class T> BOOST_CXX14_CONSTEXPR T byteswap( T x ) BOOST_NOEXCEPT
+{
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer );
+
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) == sizeof(boost::uint8_t) || sizeof(T) == sizeof(boost::uint16_t) || sizeof(T) == sizeof(boost::uint32_t) || sizeof(T) == sizeof(boost::uint64_t) );
+
+    BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint8_t) )
+    {
+        return static_cast<T>( boost::core::detail::byteswap_impl( static_cast<boost::uint8_t>( x ) ) );
+    }
+    else BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint16_t) )
+    {
+        return static_cast<T>( boost::core::detail::byteswap_impl( static_cast<boost::uint16_t>( x ) ) );
+    }
+    else BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint32_t) )
+    {
+        return static_cast<T>( boost::core::detail::byteswap_impl( static_cast<boost::uint32_t>( x ) ) );
+    }
+    else
+    {
+        return static_cast<T>( boost::core::detail::byteswap_impl( static_cast<boost::uint64_t>( x ) ) );
+    }
+}
+
+} // namespace core
+} // namespace boost
+
+#if defined(_MSC_VER)
+# pragma warning(pop)
+#endif
+
+#endif  // #ifndef BOOST_CORE_BIT_HPP_INCLUDED
@@ -30,19 +30,40 @@ namespace boost

 template<class T> inline void checked_delete(T * x) BOOST_NOEXCEPT
 {
-    // intentionally complex - simplification causes regressions
-    typedef char type_must_be_complete[ sizeof(T)? 1: -1 ];
+#if defined(__cpp_static_assert) && __cpp_static_assert >= 200410L
+
+    static_assert( sizeof(T) != 0, "Type must be complete" );
+
+#else
+
+    typedef char type_must_be_complete[ sizeof(T) ];
    (void) sizeof(type_must_be_complete);
+
+#endif
+
    delete x;
 }

 template<class T> inline void checked_array_delete(T * x) BOOST_NOEXCEPT
 {
-    typedef char type_must_be_complete[ sizeof(T)? 1: -1 ];
+#if defined(__cpp_static_assert) && __cpp_static_assert >= 200410L
+
+    static_assert( sizeof(T) != 0, "Type must be complete" );
+
+#else
+
+    typedef char type_must_be_complete[ sizeof(T) ];
    (void) sizeof(type_must_be_complete);
+
+#endif
+
    delete [] x;
 }

+// Block unintended ADL
+namespace checked_deleters
+{
+
 template<class T> struct checked_deleter
 {
    typedef void result_type;
@@ -66,6 +87,11 @@ template<class T> struct checked_array_deleter
    }
 };

+} // namespace checked_deleters
+
+using checked_deleters::checked_deleter;
+using checked_deleters::checked_array_deleter;
+
 } // namespace boost

 #endif  // #ifndef BOOST_CORE_CHECKED_DELETE_HPP
@@ -0,0 +1,298 @@
+#ifndef BOOST_CORE_CMATH_HPP_INCLUDED
+#define BOOST_CORE_CMATH_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+// boost/core/cmath.hpp
+//
+// Floating point classification and sign manipulation functions
+// Extracted from https://github.com/boostorg/lexical_cast/pull/37
+//
+// Copyright 2020, 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <cmath>
+
+#if defined(BOOST_CORE_USE_GENERIC_CMATH) || (!defined(_MSC_VER) && !defined(FP_SUBNORMAL))
+
+#include <boost/core/detail/static_assert.hpp>
+#include <boost/cstdint.hpp>
+#include <limits>
+#include <cstring>
+
+namespace boost
+{
+namespace core
+{
+
+// fpclassify return values
+
+int const fp_zero = 0;
+int const fp_subnormal = 1;
+int const fp_normal = 2;
+int const fp_infinite = 3;
+int const fp_nan = 4;
+
+// Classification functions
+
+template<class T> bool isfinite( T x )
+{
+    return x <= (std::numeric_limits<T>::max)() && x >= -(std::numeric_limits<T>::max)();
+}
+
+template<class T> bool isinf( T x )
+{
+    return x > (std::numeric_limits<T>::max)() || x < -(std::numeric_limits<T>::max)();
+}
+
+template<class T> bool isnan( T x )
+{
+    return !isfinite( x ) && !isinf( x );
+}
+
+template<class T> bool isnormal( T x )
+{
+    return isfinite( x ) && ( x >= (std::numeric_limits<T>::min)() || x <= -(std::numeric_limits<T>::min)() );
+}
+
+template<class T> int fpclassify( T x )
+{
+    if( x == 0 ) return fp_zero;
+
+    if( x < 0 ) x = -x;
+
+    if( x > (std::numeric_limits<T>::max)() ) return fp_infinite;
+
+    if( x >= (std::numeric_limits<T>::min)() ) return fp_normal;
+
+    if( x < (std::numeric_limits<T>::min)() ) return fp_subnormal;
+
+    return fp_nan;
+}
+
+// Sign manipulation functions
+
+inline bool signbit( float x )
+{
+    boost::int32_t y;
+
+    BOOST_CORE_STATIC_ASSERT( sizeof( x ) == sizeof( y ) );
+
+    std::memcpy( &y, &x, sizeof( y ) );
+
+    return y < 0;
+}
+
+inline bool signbit( double x )
+{
+    boost::int64_t y;
+
+    BOOST_CORE_STATIC_ASSERT( sizeof( x ) == sizeof( y ) );
+
+    std::memcpy( &y, &x, sizeof( y ) );
+
+    return y < 0;
+}
+
+inline bool signbit( long double x )
+{
+    return signbit( static_cast<double>( x ) );
+}
+
+template<class T> T copysign( T x, T y )
+{
+    return signbit( x ) == signbit( y )? x: -x;
+}
+
+} // namespace core
+} // namespace boost
+
+#else // defined(BOOST_CORE_USE_GENERIC_CMATH)
+
+#if defined(_MSC_VER) && _MSC_VER < 1800
+# include <float.h>
+#endif
+
+namespace boost
+{
+namespace core
+{
+#if defined(_MSC_VER) && _MSC_VER < 1800
+
+template<class T> T copysign( T x, T y )
+{
+    return static_cast<T>( _copysign( static_cast<double>( x ), static_cast<double>( y ) ) );
+}
+
+template<class T> bool isnan( T x )
+{
+    return _isnan( static_cast<double>( x ) ) != 0;
+}
+
+template<class T> bool isfinite( T x )
+{
+    return _finite( static_cast<double>( x ) ) != 0;
+}
+
+template<class T> bool isinf( T x )
+{
+    return ( _fpclass( static_cast<double>( x ) ) & ( _FPCLASS_PINF | _FPCLASS_NINF ) ) != 0;
+}
+
+inline bool isnormal( float x )
+{
+    // no _fpclassf in 32 bit mode
+    unsigned y = reinterpret_cast< unsigned const& >( x );
+    unsigned exp = ( y >> 23 ) & 0xFF;
+    return exp != 0 && exp != 0xFF;
+}
+
+inline bool isnormal( double x )
+{
+    return ( _fpclass( x ) & ( _FPCLASS_PN | _FPCLASS_NN ) ) != 0;
+}
+
+inline bool isnormal( long double x )
+{
+    return boost::core::isnormal( static_cast<double>( x ) );
+}
+
+template<class T> bool signbit( T x )
+{
+    return _copysign( 1.0, static_cast<double>( x ) ) < 0.0;
+}
+
+int const fp_zero = 0;
+int const fp_subnormal = 1;
+int const fp_normal = 2;
+int const fp_infinite = 3;
+int const fp_nan = 4;
+
+inline int fpclassify( float x )
+{
+    switch( _fpclass( x ) )
+    {
+    case _FPCLASS_SNAN:
+    case _FPCLASS_QNAN:
+
+        return fp_nan;
+
+    case _FPCLASS_NINF:
+    case _FPCLASS_PINF:
+
+        return fp_infinite;
+
+    case _FPCLASS_NZ:
+    case _FPCLASS_PZ:
+
+        return fp_zero;
+
+    default:
+
+        return boost::core::isnormal( x )? fp_normal: fp_subnormal;
+    }
+}
+
+inline int fpclassify( double x )
+{
+    switch( _fpclass( x ) )
+    {
+    case _FPCLASS_SNAN:
+    case _FPCLASS_QNAN:
+
+        return fp_nan;
+
+    case _FPCLASS_NINF:
+    case _FPCLASS_PINF:
+
+        return fp_infinite;
+
+    case _FPCLASS_NZ:
+    case _FPCLASS_PZ:
+
+        return fp_zero;
+
+    case _FPCLASS_ND:
+    case _FPCLASS_PD:
+
+        return fp_subnormal;
+
+    default:
+
+        return fp_normal;
+    }
+}
+
+inline int fpclassify( long double x )
+{
+    return boost::core::fpclassify( static_cast<double>( x ) );
+}
+
+#else
+
+using std::isfinite;
+using std::isnan;
+using std::isinf;
+using std::isnormal;
+using std::fpclassify;
+
+int const fp_zero = FP_ZERO;
+int const fp_subnormal = FP_SUBNORMAL;
+int const fp_normal = FP_NORMAL;
+int const fp_infinite = FP_INFINITE;
+int const fp_nan = FP_NAN;
+
+using std::signbit;
+
+// std::copysign doesn't exist in libstdc++ under -std=c++03
+
+#if !defined(__GNUC__)
+
+template<class T> T copysign( T x, T y )
+{
+    return std::copysign( x, y );
+}
+
+#else
+
+namespace detail
+{
+
+// ::copysignl is unreliable, use the built-ins
+
+inline float copysign_impl( float x, float y )
+{
+    return __builtin_copysignf( x, y );
+}
+
+inline double copysign_impl( double x, double y )
+{
+    return __builtin_copysign( x, y );
+}
+
+inline long double copysign_impl( long double x, long double y )
+{
+    return __builtin_copysignl( x, y );
+}
+
+} // namespace detail
+
+template<class T> T copysign( T x, T y )
+{
+    return boost::core::detail::copysign_impl( x, y );
+}
+
+#endif // !defined(__GNUC__)
+#endif // #if defined(_MSC_VER) && _MSC_VER < 1800
+
+} // namespace core
+} // namespace boost
+
+#endif // defined(BOOST_CORE_USE_GENERIC_CMATH)
+
+#endif  // #ifndef BOOST_CORE_CMATH_HPP_INCLUDED
@@ -0,0 +1,60 @@
+/*
+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 <iterator>
+
+// Note: MSVC doesn't define __cpp_lib_nonmember_container_access but supports the feature even in C++14 mode
+#if (defined(__cpp_lib_nonmember_container_access) && (__cpp_lib_nonmember_container_access >= 201411l)) || \
+    (defined(_MSC_VER) && (_MSC_VER >= 1900))
+
+namespace boost {
+using std::data;
+} /* boost */
+
+#else // (defined(__cpp_lib_nonmember_container_access) ...
+
+#include <cstddef>
+#include <initializer_list>
+
+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 // (defined(__cpp_lib_nonmember_container_access) ...
+
+#endif
@@ -10,6 +10,7 @@ Distributed under the Boost Software License, Version 1.0.

 #include <boost/config.hpp>
 #include <new>
+#include <cstddef>

 namespace boost {

@@ -19,21 +20,25 @@ BOOST_NORETURN void throw_exception(const std::exception&);

 namespace default_ {

-struct true_type {
+template<bool V>
+struct bool_constant {
    typedef bool value_type;
-    typedef true_type type;
+    typedef bool_constant type;

-    BOOST_STATIC_CONSTANT(bool, value = true);
+    static const bool value = V;

-    BOOST_CONSTEXPR operator bool() const BOOST_NOEXCEPT {
-        return true;
+    operator bool() const BOOST_NOEXCEPT {
+        return V;
    }

-    BOOST_CONSTEXPR bool operator()() const BOOST_NOEXCEPT {
-        return true;
+    bool operator()() const BOOST_NOEXCEPT {
+        return V;
    }
 };

+template<bool V>
+const bool bool_constant<V>::value;
+
 template<class T>
 struct add_reference {
    typedef T& type;
@@ -58,8 +63,8 @@ struct default_allocator {
    typedef typename add_reference<const T>::type const_reference;
    typedef std::size_t size_type;
    typedef std::ptrdiff_t difference_type;
-    typedef true_type propagate_on_container_move_assignment;
-    typedef true_type is_always_equal;
+    typedef bool_constant<true> propagate_on_container_move_assignment;
+    typedef bool_constant<true> is_always_equal;

    template<class U>
    struct rebind {
@@ -108,6 +113,12 @@ struct default_allocator {
    }
 #endif

+#if defined(BOOST_NO_CXX11_ALLOCATOR)
+    T* allocate(std::size_t n, const void*) {
+        return allocate(n);
+    }
+#endif
+
 #if (defined(BOOST_LIBSTDCXX_VERSION) && BOOST_LIBSTDCXX_VERSION < 60000) || \
    defined(BOOST_NO_CXX11_ALLOCATOR)
    template<class U, class V>
@@ -30,7 +30,7 @@

 #if defined( BOOST_CORE_HAS_CXXABI_H )
 # include <cxxabi.h>
-// For some archtectures (mips, mips64, x86, x86_64) cxxabi.h in Android NDK is implemented by gabi++ library
+// For some architectures (mips, mips64, x86, x86_64) cxxabi.h in Android NDK is implemented by gabi++ library
 // (https://android.googlesource.com/platform/ndk/+/master/sources/cxx-stl/gabi++/), which does not implement
 // abi::__cxa_demangle(). We detect this implementation by checking the include guard here.
 # if defined( __GABIXX_CXXABI_H__ )
@@ -0,0 +1,18 @@
+/*
+Copyright 2025 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#undef BOOST_CORE_DETAIL_ASSERT
+
+#if !defined(__clang__) && \
+    !defined(__INTEL_COMPILER) && \
+    defined(__GNUC__) && \
+    (__GNUC__ < 5)
+#define BOOST_CORE_DETAIL_ASSERT(expr) void(0)
+#else
+#include <boost/assert.hpp>
+#define BOOST_CORE_DETAIL_ASSERT(expr) BOOST_ASSERT(expr)
+#endif
@@ -0,0 +1,39 @@
+#ifndef BOOST_CORE_DETAIL_IS_SAME_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_IS_SAME_HPP_INCLUDED
+
+// is_same<T1,T2>::value is true when T1 == T2
+//
+// Copyright 2014 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
+
+#include <boost/config.hpp>
+
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+# pragma once
+#endif
+
+namespace boost
+{
+namespace core
+{
+namespace detail
+{
+
+template< class T1, class T2 > struct is_same
+{
+    BOOST_STATIC_CONSTANT( bool, value = false );
+};
+
+template< class T > struct is_same< T, T >
+{
+    BOOST_STATIC_CONSTANT( bool, value = true );
+};
+
+} // namespace detail
+} // namespace core
+} // namespace boost
+
+#endif // #ifndef BOOST_CORE_DETAIL_IS_SAME_HPP_INCLUDED
@@ -0,0 +1,66 @@
+#ifndef BOOST_CORE_DETAIL_LWT_UNATTENDED_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_LWT_UNATTENDED_HPP_INCLUDED
+
+// Copyright 2014, 2022 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <cstdlib>
+#if defined(_MSC_VER) && defined(_CPPLIB_VER) && defined(_DEBUG)
+# include <crtdbg.h>
+#endif
+
+namespace boost
+{
+namespace core
+{
+namespace detail
+{
+
+// Setup unattended mode by disabling interactive popups on
+// assertion failures
+
+inline void lwt_unattended()
+{
+#if defined(_MSC_VER) && (_MSC_VER > 1310)
+
+    // disable message boxes on assert(), abort()
+    ::_set_abort_behavior( 0, _WRITE_ABORT_MSG | _CALL_REPORTFAULT );
+
+# pragma warning(push)
+# pragma warning(disable: 4996)
+
+# if defined(__clang__)
+#  pragma clang diagnostic push
+#  pragma clang diagnostic ignored "-Wdeprecated-declarations"
+# endif
+
+#if !defined(WINAPI_FAMILY) || WINAPI_FAMILY == 100 /*WINAPI_FAMILY_DESKTOP_APP*/
+
+    // disable message box on crash
+    ::_seterrormode( /*SEM_NOGPFAULTERRORBOX*/ 0x0002 );
+
+#endif
+
+# if defined(__clang__)
+#  pragma clang diagnostic pop
+# endif
+
+# pragma warning(pop)
+
+#endif
+
+#if defined(_MSC_VER) && defined(_CPPLIB_VER) && defined(_DEBUG)
+
+    // disable message boxes on iterator debugging violations
+    _CrtSetReportMode( _CRT_ASSERT, _CRTDBG_MODE_FILE );
+    _CrtSetReportFile( _CRT_ASSERT, _CRTDBG_FILE_STDERR );
+
+#endif
+}
+
+} // namespace detail
+} // namespace core
+} // namespace boost
+
+#endif // #ifndef BOOST_CORE_DETAIL_LWT_UNATTENDED_HPP_INCLUDED
@@ -0,0 +1,58 @@
+#ifndef BOOST_CORE_DETAIL_MINSTD_RAND_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_MINSTD_RAND_HPP_INCLUDED
+
+// Copyright 2017 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
+//
+// An implementation of minstd_rand that does not require
+// the Random library
+
+#include <boost/cstdint.hpp>
+
+namespace boost
+{
+namespace detail
+{
+
+class minstd_rand
+{
+private:
+
+    boost::uint_least32_t x_;
+
+    enum { a = 48271, m = 2147483647 };
+
+public:
+
+    minstd_rand(): x_( 1 )
+    {
+    }
+
+    explicit minstd_rand( boost::uint_least32_t x ): x_( x % m )
+    {
+        if( x_ == 0 )
+        {
+            x_ = 1;
+        }
+    }
+
+    boost::uint_least32_t operator()()
+    {
+        boost::uint_least64_t y = x_;
+
+        y = ( a * y ) % m;
+
+        x_ = static_cast<boost::uint_least32_t>( y );
+
+        return x_;
+    }
+};
+
+} // namespace detail
+} // namespace boost
+
+#endif // #ifndef BOOST_CORE_DETAIL_MINSTD_RAND_HPP_INCLUDED
@@ -0,0 +1,71 @@
+#ifndef BOOST_CORE_DETAIL_SP_THREAD_PAUSE_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_SP_THREAD_PAUSE_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+// boost/core/detail/sp_thread_pause.hpp
+//
+// inline void bost::core::sp_thread_pause();
+//
+//   Emits a "pause" instruction.
+//
+// Copyright 2008, 2020, 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/config.hpp>
+
+#if defined(__has_builtin)
+# if __has_builtin(__builtin_ia32_pause) && !defined(__INTEL_COMPILER)
+#  define BOOST_CORE_HAS_BUILTIN_IA32_PAUSE
+# endif
+#endif
+
+#if defined(BOOST_CORE_HAS_BUILTIN_IA32_PAUSE)
+
+# define BOOST_CORE_SP_PAUSE() __builtin_ia32_pause()
+
+#elif defined(_MSC_VER) && ( defined(_M_IX86) || defined(_M_X64) )
+
+# include <intrin.h>
+# define BOOST_CORE_SP_PAUSE() _mm_pause()
+
+#elif defined(_MSC_VER) && ( defined(_M_ARM) || defined(_M_ARM64) )
+
+# include <intrin.h>
+# define BOOST_CORE_SP_PAUSE() __yield()
+
+#elif defined(__GNUC__) && ( defined(__i386__) || defined(__x86_64__) )
+
+# define BOOST_CORE_SP_PAUSE() __asm__ __volatile__( "rep; nop" : : : "memory" )
+
+#elif defined(__GNUC__) && ( (defined(__ARM_ARCH) && __ARM_ARCH >= 8) || defined(__ARM_ARCH_8A__) || defined(__aarch64__) )
+
+# define BOOST_CORE_SP_PAUSE() __asm__ __volatile__( "yield" : : : "memory" )
+
+#else
+
+# define BOOST_CORE_SP_PAUSE() ((void)0)
+
+#endif
+
+namespace boost
+{
+namespace core
+{
+
+BOOST_FORCEINLINE void sp_thread_pause() BOOST_NOEXCEPT
+{
+    BOOST_CORE_SP_PAUSE();
+}
+
+} // namespace core
+} // namespace boost
+
+#undef BOOST_CORE_SP_PAUSE
+
+#endif // #ifndef BOOST_CORE_DETAIL_SP_THREAD_PAUSE_HPP_INCLUDED
@@ -0,0 +1,122 @@
+#ifndef BOOST_CORE_DETAIL_SP_THREAD_SLEEP_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_SP_THREAD_SLEEP_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+// boost/core/detail/sp_thread_sleep.hpp
+//
+// inline void bost::core::sp_thread_sleep();
+//
+//   Cease execution for a while to yield to other threads,
+//   as if by calling nanosleep() with an appropriate interval.
+//
+// Copyright 2008, 2020, 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/config.hpp>
+#include <boost/config/pragma_message.hpp>
+
+#if defined( _WIN32 ) || defined( __WIN32__ ) || defined( __CYGWIN__ )
+
+#if defined(BOOST_SP_REPORT_IMPLEMENTATION)
+  BOOST_PRAGMA_MESSAGE("Using Sleep(1) in sp_thread_sleep")
+#endif
+
+#include <boost/core/detail/sp_win32_sleep.hpp>
+
+namespace boost
+{
+namespace core
+{
+namespace detail
+{
+
+inline void sp_thread_sleep() BOOST_NOEXCEPT
+{
+    Sleep( 1 );
+}
+
+} // namespace detail
+
+using boost::core::detail::sp_thread_sleep;
+
+} // namespace core
+} // namespace boost
+
+#elif defined(BOOST_HAS_NANOSLEEP)
+
+#if defined(BOOST_SP_REPORT_IMPLEMENTATION)
+  BOOST_PRAGMA_MESSAGE("Using nanosleep() in sp_thread_sleep")
+#endif
+
+#include <time.h>
+
+#if defined(BOOST_HAS_PTHREADS) && !defined(__ANDROID__)
+# include <pthread.h>
+#endif
+
+namespace boost
+{
+namespace core
+{
+
+inline void sp_thread_sleep() BOOST_NOEXCEPT
+{
+#if defined(BOOST_HAS_PTHREADS) && !defined(__ANDROID__) && !defined(__OHOS__)
+
+    int oldst;
+    pthread_setcancelstate( PTHREAD_CANCEL_DISABLE, &oldst );
+
+#endif
+
+    // g++ -Wextra warns on {} or {0}
+    struct timespec rqtp = { 0, 0 };
+
+    // POSIX says that timespec has tv_sec and tv_nsec
+    // But it doesn't guarantee order or placement
+
+    rqtp.tv_sec = 0;
+    rqtp.tv_nsec = 1000;
+
+    nanosleep( &rqtp, 0 );
+
+#if defined(BOOST_HAS_PTHREADS) && !defined(__ANDROID__) && !defined(__OHOS__)
+
+    pthread_setcancelstate( oldst, &oldst );
+
+#endif
+
+}
+
+} // namespace core
+} // namespace boost
+
+#else
+
+#if defined(BOOST_SP_REPORT_IMPLEMENTATION)
+  BOOST_PRAGMA_MESSAGE("Using sp_thread_yield() in sp_thread_sleep")
+#endif
+
+#include <boost/core/detail/sp_thread_yield.hpp>
+
+namespace boost
+{
+namespace core
+{
+
+inline void sp_thread_sleep() BOOST_NOEXCEPT
+{
+    sp_thread_yield();
+}
+
+} // namespace core
+} // namespace boost
+
+#endif
+
+#endif // #ifndef BOOST_CORE_DETAIL_SP_THREAD_SLEEP_HPP_INCLUDED
@@ -0,0 +1,100 @@
+#ifndef BOOST_CORE_DETAIL_SP_THREAD_YIELD_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_SP_THREAD_YIELD_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+// boost/core/detail/sp_thread_yield.hpp
+//
+// inline void bost::core::sp_thread_yield();
+//
+//   Gives up the remainder of the time slice,
+//   as if by calling sched_yield().
+//
+// Copyright 2008, 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/config.hpp>
+#include <boost/config/pragma_message.hpp>
+
+#if defined( _WIN32 ) || defined( __WIN32__ ) || defined( __CYGWIN__ )
+
+#if defined(BOOST_SP_REPORT_IMPLEMENTATION)
+  BOOST_PRAGMA_MESSAGE("Using SwitchToThread() in sp_thread_yield")
+#endif
+
+#include <boost/core/detail/sp_win32_sleep.hpp>
+
+namespace boost
+{
+namespace core
+{
+namespace detail
+{
+
+inline void sp_thread_yield() BOOST_NOEXCEPT
+{
+    SwitchToThread();
+}
+
+} // namespace detail
+
+using boost::core::detail::sp_thread_yield;
+
+} // namespace core
+} // namespace boost
+
+#elif defined(BOOST_HAS_SCHED_YIELD)
+
+#if defined(BOOST_SP_REPORT_IMPLEMENTATION)
+  BOOST_PRAGMA_MESSAGE("Using sched_yield() in sp_thread_yield")
+#endif
+
+#ifndef _AIX
+# include <sched.h>
+#else
+  // AIX's sched.h defines ::var which sometimes conflicts with Lambda's var
+  extern "C" int sched_yield(void);
+#endif
+
+namespace boost
+{
+namespace core
+{
+
+inline void sp_thread_yield() BOOST_NOEXCEPT
+{
+    sched_yield();
+}
+
+} // namespace core
+} // namespace boost
+
+#else
+
+#if defined(BOOST_SP_REPORT_IMPLEMENTATION)
+  BOOST_PRAGMA_MESSAGE("Using sp_thread_pause() in sp_thread_yield")
+#endif
+
+#include <boost/core/detail/sp_thread_pause.hpp>
+
+namespace boost
+{
+namespace core
+{
+
+inline void sp_thread_yield() BOOST_NOEXCEPT
+{
+    sp_thread_pause();
+}
+
+} // namespace core
+} // namespace boost
+
+#endif
+
+#endif // #ifndef BOOST_CORE_DETAIL_SP_THREAD_YIELD_HPP_INCLUDED
@@ -0,0 +1,54 @@
+#ifndef BOOST_CORE_DETAIL_SP_WIN32_SLEEP_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_SP_WIN32_SLEEP_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+// boost/core/detail/sp_win32_sleep.hpp
+//
+// Declares the Win32 Sleep() function.
+//
+// Copyright 2008, 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined( BOOST_USE_WINDOWS_H )
+# include <windows.h>
+#endif
+
+namespace boost
+{
+namespace core
+{
+namespace detail
+{
+
+#if !defined( BOOST_USE_WINDOWS_H )
+
+#if defined(__clang__) && defined(__x86_64__)
+// clang x64 warns that __stdcall is ignored
+# define BOOST_CORE_SP_STDCALL
+#else
+# define BOOST_CORE_SP_STDCALL __stdcall
+#endif
+
+#if defined(__LP64__) // Cygwin 64
+  extern "C" __declspec(dllimport) void BOOST_CORE_SP_STDCALL Sleep( unsigned int ms );
+#else
+  extern "C" __declspec(dllimport) void BOOST_CORE_SP_STDCALL Sleep( unsigned long ms );
+#endif
+
+extern "C" __declspec(dllimport) int BOOST_CORE_SP_STDCALL SwitchToThread();
+
+#undef BOOST_CORE_SP_STDCALL
+
+#endif // !defined( BOOST_USE_WINDOWS_H )
+
+} // namespace detail
+} // namespace core
+} // namespace boost
+
+#endif // #ifndef BOOST_CORE_DETAIL_SP_WIN32_SLEEP_HPP_INCLUDED
@@ -0,0 +1,54 @@
+#ifndef BOOST_CORE_DETAIL_SPLITMIX64_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_SPLITMIX64_HPP_INCLUDED
+
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+//
+// An implementation of splitmix64 for testing purposes,
+// derived from Sebastiano Vigna's public domain implementation
+// http://xorshift.di.unimi.it/splitmix64.c
+
+#include <boost/cstdint.hpp>
+
+namespace boost
+{
+namespace detail
+{
+
+class splitmix64
+{
+private:
+
+    boost::uint64_t x_;
+
+public:
+
+    splitmix64(): x_( 0 )
+    {
+    }
+
+    explicit splitmix64( boost::uint64_t seed ): x_( seed )
+    {
+    }
+
+    boost::uint64_t operator()()
+    {
+        x_ += ( boost::uint64_t(0x9e3779b9u) << 32 ) + 0x7f4a7c15u;
+
+        boost::uint64_t z = x_;
+
+        z ^= z >> 30;
+        z *= ( boost::uint64_t(0xbf58476du) << 32 ) + 0x1ce4e5b9u;
+        z ^= z >> 27;
+        z *= ( boost::uint64_t(0x94d049bbu) << 32 ) + 0x133111ebu;
+        z ^= z >> 31;
+
+        return z;
+    }
+};
+
+} // namespace detail
+} // namespace boost
+
+#endif // #ifndef BOOST_CORE_DETAIL_SPLITMIX64_HPP_INCLUDED
@@ -0,0 +1,42 @@
+#ifndef BOOST_CORE_DETAIL_STATIC_ASSERT_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_STATIC_ASSERT_HPP_INCLUDED
+
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__cpp_static_assert) && __cpp_static_assert >= 200410L
+
+#define BOOST_CORE_STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
+
+#else
+
+#include <boost/config.hpp>
+#include <cstddef>
+
+namespace boost
+{
+namespace core
+{
+
+template<bool> struct STATIC_ASSERTION_FAILURE;
+
+template<> struct STATIC_ASSERTION_FAILURE<true>
+{
+};
+
+template<std::size_t> struct static_assert_test
+{
+};
+
+} // namespace core
+} // namespace boost
+
+#define BOOST_CORE_STATIC_ASSERT(expr) \
+    typedef ::boost::core::static_assert_test< \
+        sizeof( ::boost::core::STATIC_ASSERTION_FAILURE<(expr)? true: false> ) \
+    > BOOST_JOIN(boost_static_assert_typedef_,__LINE__) BOOST_ATTRIBUTE_UNUSED
+
+#endif
+
+#endif  // #ifndef BOOST_CORE_DETAIL_STATIC_ASSERT_HPP_INCLUDED
@@ -25,6 +25,11 @@ Distributed under the Boost Software License, Version 1.0.
 #endif
 #endif

+#if defined(_MSC_VER)
+#pragma warning(push)
+#pragma warning(disable:4510)
+#endif
+
 namespace boost {

 template<class T>
@@ -51,37 +56,37 @@ public:
 #if !defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS)
    empty_value() = default;
 #else
-    empty_value() { }
+    BOOST_CONSTEXPR empty_value() { }
 #endif

-    empty_value(boost::empty_init_t)
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t)
        : value_() { }

 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
 #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
    template<class U, class... Args>
-    empty_value(boost::empty_init_t, U&& value, Args&&... args)
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t, U&& value, Args&&... args)
        : value_(std::forward<U>(value), std::forward<Args>(args)...) { }
 #else
    template<class U>
-    empty_value(boost::empty_init_t, U&& value)
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t, U&& value)
        : value_(std::forward<U>(value)) { }
 #endif
 #else
    template<class U>
-    empty_value(boost::empty_init_t, const U& value)
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t, const U& value)
        : value_(value) { }

    template<class U>
-    empty_value(boost::empty_init_t, U& value)
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t, U& value)
        : value_(value) { }
 #endif

-    const T& get() const BOOST_NOEXCEPT {
+    BOOST_CONSTEXPR const T& get() const BOOST_NOEXCEPT {
        return value_;
    }

-    T& get() BOOST_NOEXCEPT {
+    BOOST_CXX14_CONSTEXPR T& get() BOOST_NOEXCEPT {
        return value_;
    }

@@ -90,46 +95,94 @@ 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;

 #if !defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS)
    empty_value() = default;
 #else
-    empty_value() { }
+    BOOST_CONSTEXPR empty_value() { }
 #endif

-    empty_value(boost::empty_init_t)
-        : T() { }
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t)
+        : empty_base_() { }

 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
 #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
    template<class U, class... Args>
-    empty_value(boost::empty_init_t, U&& value, Args&&... args)
-        : T(std::forward<U>(value), std::forward<Args>(args)...) { }
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t, U&& value, Args&&... args)
+        : empty_base_(std::forward<U>(value), std::forward<Args>(args)...) { }
 #else
    template<class U>
-    empty_value(boost::empty_init_t, U&& value)
-        : T(std::forward<U>(value)) { }
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t, U&& value)
+        : empty_base_(std::forward<U>(value)) { }
 #endif
 #else
    template<class U>
-    empty_value(boost::empty_init_t, const U& value)
-        : T(value) { }
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t, const U& value)
+        : empty_base_(value) { }

    template<class U>
-    empty_value(boost::empty_init_t, U& value)
-        : T(value) { }
+    BOOST_CONSTEXPR empty_value(boost::empty_init_t, U& value)
+        : empty_base_(value) { }
 #endif

-    const T& get() const BOOST_NOEXCEPT {
+    BOOST_CONSTEXPR const T& get() const BOOST_NOEXCEPT {
        return *this;
    }

-    T& get() BOOST_NOEXCEPT {
+    BOOST_CXX14_CONSTEXPR T& get() BOOST_NOEXCEPT {
        return *this;
    }
 };
@@ -143,4 +196,8 @@ BOOST_INLINE_CONSTEXPR empty_init_t empty_init = empty_init_t();

 } /* boost */

+#if defined(_MSC_VER)
+#pragma warning(pop)
+#endif
+
 #endif
@@ -0,0 +1,53 @@
+/*
+ *             Copyright Andrey Semashev 2022.
+ * 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)
+ */
+/*!
+ * \file   fclose_deleter.hpp
+ * \author Andrey Semashev
+ * \date   21.09.2022
+ *
+ * This header contains an \c fclose_deleter implementation. This is a deleter
+ * function object that invokes <tt>std::fclose</tt> on the passed pointer to
+ * a <tt>std::FILE</tt> structure.
+ */
+
+#ifndef BOOST_CORE_FCLOSE_DELETER_HPP
+#define BOOST_CORE_FCLOSE_DELETER_HPP
+
+#include <cstdio>
+#include <boost/config.hpp>
+
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#pragma once
+#endif
+
+namespace boost {
+
+// Block unintended ADL
+namespace fclose_deleter_ns {
+
+//! A function object that closes a file
+struct fclose_deleter
+{
+    //! Function object result type
+    typedef void result_type;
+    /*!
+     * Closes the file handle
+     */
+    void operator() (std::FILE* p) const BOOST_NOEXCEPT
+    {
+        if (BOOST_LIKELY(!!p))
+            std::fclose(p);
+    }
+};
+
+} // namespace fclose_deleter_ns
+
+using fclose_deleter_ns::fclose_deleter;
+
+} // namespace boost
+
+#endif // BOOST_CORE_FCLOSE_DELETER_HPP
@@ -0,0 +1,41 @@
+/*
+ *             Copyright Andrey Semashev 2024.
+ * 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)
+ */
+/*!
+ * \file   functor.hpp
+ * \author Andrey Semashev
+ * \date   2024-01-23
+ *
+ * This header contains a \c functor implementation. This is a function object
+ * that invokes a function that is specified as its template parameter.
+ */
+
+#ifndef BOOST_CORE_FUNCTOR_HPP
+#define BOOST_CORE_FUNCTOR_HPP
+
+namespace boost::core {
+
+// Block unintended ADL
+namespace functor_ns {
+
+//! A function object that invokes a function specified as its template parameter
+template< auto Function >
+struct functor
+{
+    template< typename... Args >
+    auto operator() (Args&&... args) const noexcept(noexcept(Function(static_cast< Args&& >(args)...))) -> decltype(Function(static_cast< Args&& >(args)...))
+    {
+        return Function(static_cast< Args&& >(args)...);
+    }
+};
+
+} // namespace functor_ns
+
+using functor_ns::functor;
+
+} // namespace boost::core
+
+#endif // BOOST_CORE_FUNCTOR_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
@@ -11,34 +11,64 @@

 namespace boost {

-#ifndef BOOST_NO_CXX11_VARIADIC_TEMPLATES
+#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
+
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+
+template <typename... Ts>
+BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(Ts&& ...)
+{}
+
+#else

 template <typename... Ts>
 BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(Ts const& ...)
 {}

+#endif
+
 template <typename... Ts>
 BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused()
 {}

-#else
+#else // !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
+
+template <typename T1>
+BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1&)
+{}

 template <typename T1>
 BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1 const&)
 {}

+template <typename T1, typename T2>
+BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1&, T2&)
+{}
+
 template <typename T1, typename T2>
 BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1 const&, T2 const&)
 {}

+template <typename T1, typename T2, typename T3>
+BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1&, T2&, T3&)
+{}
+
 template <typename T1, typename T2, typename T3>
 BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1 const&, T2 const&, T3 const&)
 {}

+template <typename T1, typename T2, typename T3, typename T4>
+BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1&, T2&, T3&, T4&)
+{}
+
 template <typename T1, typename T2, typename T3, typename T4>
 BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1 const&, T2 const&, T3 const&, T4 const&)
 {}

+template <typename T1, typename T2, typename T3, typename T4, typename T5>
+BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1&, T2&, T3&, T4&, T5&)
+{}
+
 template <typename T1, typename T2, typename T3, typename T4, typename T5>
 BOOST_FORCEINLINE BOOST_CXX14_CONSTEXPR void ignore_unused(T1 const&, T2 const&, T3 const&, T4 const&, T5 const&)
 {}
@@ -0,0 +1,93 @@
+// Copyright (C) 2007, 2008 Steven Watanabe, Joseph Gauterin, Niels Dekker
+// Copyright (C) 2023 Andrey Semashev
+//
+// 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)
+// For more information, see http://www.boost.org
+
+#ifndef BOOST_CORE_INVOKE_SWAP_HPP
+#define BOOST_CORE_INVOKE_SWAP_HPP
+
+// Note: the implementation of this utility contains various workarounds:
+// - invoke_swap_impl is put outside the boost namespace, to avoid infinite
+// recursion (causing stack overflow) when swapping objects of a primitive
+// type.
+// - std::swap is imported with a using-directive, rather than
+// a using-declaration, because some compilers (including MSVC 7.1,
+// Borland 5.9.3, and Intel 8.1) don't do argument-dependent lookup
+// when it has a using-declaration instead.
+// - The main entry function is called invoke_swap rather than swap
+// to avoid forming an infinite recursion when the arguments are not
+// swappable.
+
+#include <boost/core/enable_if.hpp>
+#include <boost/config.hpp>
+#if __cplusplus >= 201103L || defined(BOOST_DINKUMWARE_STDLIB)
+#include <utility> // for std::swap (C++11)
+#else
+#include <algorithm> // for std::swap (C++98)
+#endif
+#include <cstddef> // for std::size_t
+
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#pragma once
+#endif
+
+#if defined(BOOST_GCC) && (BOOST_GCC < 40700)
+// gcc 4.6 ICEs on noexcept specifications below
+#define BOOST_CORE_SWAP_NOEXCEPT_IF(x)
+#else
+#define BOOST_CORE_SWAP_NOEXCEPT_IF(x) BOOST_NOEXCEPT_IF(x)
+#endif
+
+namespace boost_swap_impl {
+
+// we can't use type_traits here
+
+template<class T> struct is_const { enum _vt { value = 0 }; };
+template<class T> struct is_const<T const> { enum _vt { value = 1 }; };
+
+// Use std::swap if argument dependent lookup fails.
+// We need to have this at namespace scope to be able to use unqualified swap() call
+// in noexcept specification.
+using namespace std;
+
+template<class T>
+BOOST_GPU_ENABLED
+inline void invoke_swap_impl(T& left, T& right) BOOST_CORE_SWAP_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(swap(left, right)))
+{
+    swap(left, right);
+}
+
+template<class T, std::size_t N>
+BOOST_GPU_ENABLED
+inline void invoke_swap_impl(T (& left)[N], T (& right)[N])
+    BOOST_CORE_SWAP_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(::boost_swap_impl::invoke_swap_impl(left[0], right[0])))
+{
+    for (std::size_t i = 0; i < N; ++i)
+    {
+        ::boost_swap_impl::invoke_swap_impl(left[i], right[i]);
+    }
+}
+
+} // namespace boost_swap_impl
+
+namespace boost {
+namespace core {
+
+template<class T>
+BOOST_GPU_ENABLED
+inline typename enable_if_c< !::boost_swap_impl::is_const<T>::value >::type
+invoke_swap(T& left, T& right)
+    BOOST_CORE_SWAP_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(::boost_swap_impl::invoke_swap_impl(left, right)))
+{
+    ::boost_swap_impl::invoke_swap_impl(left, right);
+}
+
+} // namespace core
+} // namespace boost
+
+#undef BOOST_CORE_SWAP_NOEXCEPT_IF
+
+#endif // BOOST_CORE_INVOKE_SWAP_HPP
@@ -1,12 +1,6 @@
 #ifndef BOOST_CORE_IS_SAME_HPP_INCLUDED
 #define BOOST_CORE_IS_SAME_HPP_INCLUDED

-// MS compatible compilers support #pragma once
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1020)
-# pragma once
-#endif
-
 // is_same<T1,T2>::value is true when T1 == T2
 //
 // Copyright 2014 Peter Dimov
@@ -16,6 +10,15 @@
 // http://www.boost.org/LICENSE_1_0.txt

 #include <boost/config.hpp>
+#include <boost/core/detail/is_same.hpp>
+
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+# pragma once
+#endif
+
+#include <boost/config/header_deprecated.hpp>
+
+BOOST_HEADER_DEPRECATED("<boost/type_traits/is_same.hpp>")

 namespace boost
 {
@@ -23,15 +26,7 @@ namespace boost
 namespace core
 {

-template< class T1, class T2 > struct is_same
-{
-    BOOST_STATIC_CONSTANT( bool, value = false );
-};
-
-template< class T > struct is_same< T, T >
-{
-    BOOST_STATIC_CONSTANT( bool, value = true );
-};
+using boost::core::detail::is_same;

 } // namespace core

@@ -0,0 +1,69 @@
+#ifndef BOOST_CORE_LAUNDER_HPP_INCLUDED
+#define BOOST_CORE_LAUNDER_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
+
+#include <boost/config.hpp>
+
+#if defined(__has_builtin)
+# if __has_builtin(__builtin_launder)
+#  define BOOST_CORE_HAS_BUILTIN_LAUNDER
+# endif
+#endif
+
+#if defined(BOOST_MSVC) && BOOST_MSVC < 1920
+
+// msvc-14.1 suffers from internal compiler errors when using std::launder
+// https://github.com/boostorg/core/issues/160
+// https://github.com/boostorg/optional/issues/122
+
+#elif (BOOST_CXX_VERSION >= 201703L) && !defined(BOOST_CORE_HAS_BUILTIN_LAUNDER)
+
+#include <new>
+
+#if defined(__cpp_lib_launder)
+# define BOOST_CORE_HAS_STD_LAUNDER
+#endif
+
+#endif
+
+namespace boost
+{
+namespace core
+{
+
+#if defined(BOOST_CORE_HAS_BUILTIN_LAUNDER)
+
+template<class T> T* launder( T* p )
+{
+    return __builtin_launder( p );
+}
+
+#elif defined(BOOST_CORE_HAS_STD_LAUNDER)
+
+template<class T> T* launder( T* p )
+{
+    return std::launder( p );
+}
+
+#else
+
+template<class T> T* launder( T* p )
+{
+    return p;
+}
+
+#endif
+
+} // namespace core
+} // namespace boost
+
+#endif  // #ifndef BOOST_CORE_LAUNDER_HPP_INCLUDED
@@ -22,18 +22,17 @@
 //  http://www.boost.org/LICENSE_1_0.txt
 //

+#include <boost/core/detail/lwt_unattended.hpp>
 #include <boost/current_function.hpp>
 #include <boost/config.hpp>
 #include <exception>
 #include <iostream>
 #include <iterator>
+#include <string>
 #include <cstdlib>
 #include <cstring>
 #include <cstddef>
-
-#if defined(_MSC_VER) && defined(_CPPLIB_VER) && defined(_DEBUG)
-# include <crtdbg.h>
-#endif
+#include <cctype>

 //  IDE's like Visual Studio perform better if output goes to std::cout or
 //  some other stream, so allow user to configure output stream:
@@ -43,42 +42,39 @@

 namespace boost
 {
-
 namespace detail
 {

-class test_result {
+class test_result
+{
 public:
-    test_result()
-        : report_(false)
-        , errors_(0) {
-#if defined(_MSC_VER) && (_MSC_VER > 1310)
-        // disable message boxes on assert(), abort()
-        ::_set_abort_behavior(0, _WRITE_ABORT_MSG | _CALL_REPORTFAULT);
-#endif
-#if defined(_MSC_VER) && defined(_CPPLIB_VER) && defined(_DEBUG)
-        // disable message boxes on iterator debugging violations
-        _CrtSetReportMode( _CRT_ASSERT, _CRTDBG_MODE_FILE );
-        _CrtSetReportFile( _CRT_ASSERT, _CRTDBG_FILE_STDERR );
-#endif
+
+    test_result(): report_( false ), errors_( 0 )
+    {
+        core::detail::lwt_unattended();
    }

-    ~test_result() {
-        if (!report_) {
+    ~test_result()
+    {
+        if( !report_ )
+        {
            BOOST_LIGHTWEIGHT_TEST_OSTREAM << "main() should return report_errors()" << std::endl;
            std::abort();
        }
    }

-    int& errors() {
+    int& errors()
+    {
        return errors_;
    }

-    void done() {
+    void done()
+    {
        report_ = true;
    }

 private:
+
    bool report_;
    int errors_;
 };
@@ -157,20 +153,68 @@ inline void no_throw_failed_impl(const char* expr, const char* what, const char*
 #elif defined(__GNUC__) && !(defined(__INTEL_COMPILER) || defined(__ICL) || defined(__ICC) || defined(__ECC)) && (__GNUC__ * 100 + __GNUC_MINOR__) >= 406
 # pragma GCC diagnostic push
 # pragma GCC diagnostic ignored "-Wsign-compare"
+# pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif

-// specialize test output for char pointers to avoid printing as cstring
-template <class T> inline const T& test_output_impl(const T& v) { return v; }
-inline const void* test_output_impl(const char* v) { return v; }
-inline const void* test_output_impl(const unsigned char* v) { return v; }
-inline const void* test_output_impl(const signed char* v) { return v; }
-inline const void* test_output_impl(char* v) { return v; }
-inline const void* test_output_impl(unsigned char* v) { return v; }
-inline const void* test_output_impl(signed char* v) { return v; }
-template<class T> inline const void* test_output_impl(T volatile* v) { return const_cast<T*>(v); }
+// specialize test output for pointers to avoid printing as cstring
+
+template<class T> inline T const& test_output_impl( T const& v ) { return v; }
+
+template<class T> inline void const* test_output_impl( T* const& v ) { return v; }
+template<class T> inline void const* test_output_impl( T volatile* const& v ) { return const_cast<T*>(v); }

 #if !defined( BOOST_NO_CXX11_NULLPTR )
-inline const void* test_output_impl(std::nullptr_t) { return nullptr; }
+inline const void* test_output_impl( std::nullptr_t ) { return nullptr; }
+#endif
+
+// print chars as numeric
+
+inline int test_output_impl( signed char const& v ) { return v; }
+inline unsigned test_output_impl( unsigned char const& v ) { return v; }
+
+// Whether wchar_t is signed is implementation-defined
+
+template<bool Signed> struct lwt_long_type {};
+template<> struct lwt_long_type<true> { typedef long type; };
+template<> struct lwt_long_type<false> { typedef unsigned long type; };
+
+inline lwt_long_type<(static_cast<wchar_t>(-1) < static_cast<wchar_t>(0))>::type test_output_impl( wchar_t const& v ) { return v; }
+
+#if !defined( BOOST_NO_CXX11_CHAR16_T )
+inline unsigned long test_output_impl( char16_t const& v ) { return v; }
+#endif
+
+#if !defined( BOOST_NO_CXX11_CHAR32_T )
+inline unsigned long test_output_impl( char32_t const& v ) { return v; }
+#endif
+
+inline std::string test_output_impl( char const& v )
+{
+    if( std::isprint( static_cast<unsigned char>( v ) ) )
+    {
+        return std::string( 1, v );
+    }
+    else
+    {
+        static const char char_table[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
+        char buffer[ 4 ];
+        buffer[ 0 ] = '\\';
+        buffer[ 1 ] = 'x';
+        buffer[ 2 ] = char_table[ (static_cast<unsigned char>( v ) >> 4u) & 0x0f ];
+        buffer[ 3 ] = char_table[ static_cast<unsigned char>( v ) & 0x0f ];
+
+        return std::string( buffer, 4u );
+    }
+}
+
+#if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
+
+inline std::string test_output_impl( char8_t const& v )
+{
+    // assume that char is ASCII, compatible with char8_t
+    return test_output_impl( static_cast<char>( v ) );
+}
+
 #endif

 // predicates
@@ -482,6 +526,15 @@ inline int report_errors()
    return errors < 256? errors: 255;
 }

+namespace core
+{
+
+inline void lwt_init()
+{
+    boost::detail::test_results();
+}
+
+} // namespace core
 } // namespace boost

 #define BOOST_TEST(expr) ( ::boost::detail::test_impl(#expr, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION, (expr)? true: false) )
@@ -505,39 +558,47 @@ inline int report_errors()
 #define BOOST_TEST_ALL_EQ(begin1, end1, begin2, end2) ( ::boost::detail::test_all_eq_impl(BOOST_LIGHTWEIGHT_TEST_OSTREAM, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION, begin1, end1, begin2, end2) )
 #define BOOST_TEST_ALL_WITH(begin1, end1, begin2, end2, predicate) ( ::boost::detail::test_all_with_impl(BOOST_LIGHTWEIGHT_TEST_OSTREAM, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION, begin1, end1, begin2, end2, predicate) )

-#ifndef BOOST_NO_EXCEPTIONS
-   #define BOOST_TEST_THROWS( EXPR, EXCEP )                           \
-      try {                                                           \
-         EXPR;                                                        \
-         ::boost::detail::throw_failed_impl                           \
-         (#EXPR, #EXCEP, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION); \
-      }                                                               \
-      catch(EXCEP const&) {                                           \
-         ::boost::detail::test_results();                             \
-      }                                                               \
-      catch(...) {                                                    \
-         ::boost::detail::throw_failed_impl                           \
-         (#EXPR, #EXCEP, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION); \
-      }                                                               \
-   //
+#if defined(BOOST_MSVC) && BOOST_MSVC < 1900
+# define BOOST_LWT_DETAIL_WHILE_FALSE __pragma(warning(push)) __pragma(warning(disable:4127)) while(false) __pragma(warning(pop))
 #else
-   #define BOOST_TEST_THROWS( EXPR, EXCEP )
+# define BOOST_LWT_DETAIL_WHILE_FALSE while(false)
 #endif

 #ifndef BOOST_NO_EXCEPTIONS
-#  define BOOST_TEST_NO_THROW(EXPR)                                    \
-    try {                                                              \
-        EXPR;                                                          \
-    } catch (const std::exception& e) {                                \
-        ::boost::detail::no_throw_failed_impl                          \
-        (#EXPR, e.what(), __FILE__, __LINE__, BOOST_CURRENT_FUNCTION); \
-    } catch (...) {                                                    \
-        ::boost::detail::no_throw_failed_impl                          \
-        (#EXPR, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION);           \
-    }
-    //
+   #define BOOST_TEST_THROWS( EXPR, EXCEP )                              \
+      do {                                                               \
+         try {                                                           \
+            EXPR;                                                        \
+            ::boost::detail::throw_failed_impl                           \
+            (#EXPR, #EXCEP, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION); \
+         }                                                               \
+         catch(EXCEP const&) {                                           \
+            ::boost::detail::test_results();                             \
+         }                                                               \
+         catch(...) {                                                    \
+            ::boost::detail::throw_failed_impl                           \
+            (#EXPR, #EXCEP, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION); \
+         }                                                               \
+      } BOOST_LWT_DETAIL_WHILE_FALSE
 #else
-#  define BOOST_TEST_NO_THROW(EXPR) { EXPR; }
+   #define BOOST_TEST_THROWS( EXPR, EXCEP ) do {} BOOST_LWT_DETAIL_WHILE_FALSE
+#endif
+
+#ifndef BOOST_NO_EXCEPTIONS
+#  define BOOST_TEST_NO_THROW(EXPR)                                        \
+    do {                                                                   \
+        try {                                                              \
+            EXPR;                                                          \
+        } catch (const std::exception& e) {                                \
+            ::boost::detail::no_throw_failed_impl                          \
+            (#EXPR, e.what(), __FILE__, __LINE__, BOOST_CURRENT_FUNCTION); \
+        } catch (...) {                                                    \
+            ::boost::detail::no_throw_failed_impl                          \
+            (#EXPR, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION);           \
+        }                                                                  \
+    } BOOST_LWT_DETAIL_WHILE_FALSE
+#else
+#  define BOOST_TEST_NO_THROW(EXPR) do { EXPR; } BOOST_LWT_DETAIL_WHILE_FALSE
 #endif

 #endif // #ifndef BOOST_CORE_LIGHTWEIGHT_TEST_HPP
@@ -11,7 +11,7 @@
 //
 // BOOST_TEST_TRAIT_TRUE, BOOST_TEST_TRAIT_FALSE, BOOST_TEST_TRAIT_SAME
 //
-// Copyright 2014 Peter Dimov
+// Copyright 2014, 2021 Peter Dimov
 //
 // Copyright 2019 Glen Joseph Fernandes
 // (glenjofe@gmail.com)
@@ -21,60 +21,15 @@
 // http://www.boost.org/LICENSE_1_0.txt

 #include <boost/core/lightweight_test.hpp>
-#include <boost/core/typeinfo.hpp>
-#include <boost/core/is_same.hpp>
+#include <boost/core/type_name.hpp>
+#include <boost/core/detail/is_same.hpp>
 #include <boost/config.hpp>

 namespace boost
 {
-
 namespace detail
 {

-template<class, int = 0> struct test_print { };
-
-template<class T> inline std::ostream& operator<<(std::ostream& o, test_print<T, 2>)
-{
-    return o << boost::core::demangled_name(BOOST_CORE_TYPEID(T));
-}
-
-template<class T> inline std::ostream& operator<<(std::ostream& o, test_print<T, 1>)
-{
-    return o << test_print<T, 2>();
-}
-
-template<class T> inline std::ostream& operator<<(std::ostream& o, test_print<const T, 1>)
-{
-    return o << test_print<T, 2>() << " const";
-}
-
-template<class T> inline std::ostream& operator<<(std::ostream& o, test_print<volatile T, 1>)
-{
-    return o << test_print<T, 2>() << " volatile";
-}
-
-template<class T> inline std::ostream& operator<<(std::ostream& o, test_print<const volatile T, 1>)
-{
-    return o << test_print<T, 2>() << " const volatile";
-}
-
-template<class T> inline std::ostream& operator<<(std::ostream& o, test_print<T>)
-{
-    return o << test_print<T, 1>();
-}
-
-template<class T> inline std::ostream& operator<<(std::ostream& o, test_print<T&>)
-{
-    return o << test_print<T, 1>() << " &";
-}
-
-#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
-template<class T> inline std::ostream& operator<<(std::ostream& o, test_print<T&&>)
-{
-    return o << test_print<T, 1>() << " &&";
-}
-#endif
-
 template< class T > inline void test_trait_impl( char const * trait, void (*)( T ),
  bool expected, char const * file, int line, char const * function )
 {
@@ -86,7 +41,7 @@ template< class T > inline void test_trait_impl( char const * trait, void (*)( T
    {
        BOOST_LIGHTWEIGHT_TEST_OSTREAM
            << file << "(" << line << "): predicate '" << trait << "' ["
-            << boost::core::demangled_name( BOOST_CORE_TYPEID(T) ) << "]"
+            << boost::core::type_name<T>() << "]"
            << " test failed in function '" << function
            << "' (should have been " << ( expected? "true": "false" ) << ")"
            << std::endl;
@@ -101,7 +56,7 @@ template<class T> inline bool test_trait_same_impl_( T )
 }

 template<class T1, class T2> inline void test_trait_same_impl( char const * types,
-  boost::core::is_same<T1, T2> same, char const * file, int line, char const * function )
+  boost::core::detail::is_same<T1, T2> same, char const * file, int line, char const * function )
 {
    if( test_trait_same_impl_( same ) )
    {
@@ -112,8 +67,8 @@ template<class T1, class T2> inline void test_trait_same_impl( char const * type
        BOOST_LIGHTWEIGHT_TEST_OSTREAM
            << file << "(" << line << "): test 'is_same<" << types << ">'"
            << " failed in function '" << function
-            << "' ('" << test_print<T1>()
-            << "' != '" << test_print<T2>() << "')"
+            << "' ('" << boost::core::type_name<T1>()
+            << "' != '" << boost::core::type_name<T2>() << "')"
            << std::endl;

        ++test_results().errors();
@@ -121,7 +76,6 @@ template<class T1, class T2> inline void test_trait_same_impl( char const * type
 }

 } // namespace detail
-
 } // namespace boost

 #define BOOST_TEST_TRAIT_TRUE(type) ( ::boost::detail::test_trait_impl(#type, (void(*)type)0, true, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION) )
@@ -132,6 +86,6 @@ template<class T1, class T2> inline void test_trait_same_impl( char const * type
 # pragma GCC system_header
 #endif

-#define BOOST_TEST_TRAIT_SAME(...) ( ::boost::detail::test_trait_same_impl(#__VA_ARGS__, ::boost::core::is_same<__VA_ARGS__>(), __FILE__, __LINE__, BOOST_CURRENT_FUNCTION) )
+#define BOOST_TEST_TRAIT_SAME(...) ( ::boost::detail::test_trait_same_impl(#__VA_ARGS__, ::boost::core::detail::is_same< __VA_ARGS__ >(), __FILE__, __LINE__, BOOST_CURRENT_FUNCTION) )

 #endif // #ifndef BOOST_CORE_LIGHTWEIGHT_TEST_TRAIT_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
@@ -0,0 +1,82 @@
+#ifndef BOOST_CORE_MAX_ALIGN_HPP_INCLUDED
+#define BOOST_CORE_MAX_ALIGN_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
+
+#include <boost/core/alignof.hpp>
+#include <boost/config.hpp>
+#include <cstddef>
+
+// BOOST_CORE_HAS_FLOAT128
+
+#if defined(BOOST_HAS_FLOAT128)
+
+# define BOOST_CORE_HAS_FLOAT128
+
+#elif defined(__SIZEOF_FLOAT128__)
+
+# define BOOST_CORE_HAS_FLOAT128
+
+#elif defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 404) && defined(__i386__)
+
+# define BOOST_CORE_HAS_FLOAT128
+
+#endif
+
+// max_align_t, max_align
+
+namespace boost
+{
+namespace core
+{
+
+union max_align_t
+{
+    char c;
+    short s;
+    int i;
+    long l;
+
+#if !defined(BOOST_NO_LONG_LONG)
+
+    boost::long_long_type ll;
+
+#endif
+
+#if defined(BOOST_HAS_INT128)
+
+    boost::int128_type i128;
+
+#endif
+
+    float f;
+    double d;
+    long double ld;
+
+#if defined(BOOST_CORE_HAS_FLOAT128)
+
+    __float128 f128;
+
+#endif
+
+    void* p;
+    void (*pf) ();
+
+    int max_align_t::* pm;
+    void (max_align_t::*pmf)();
+};
+
+BOOST_CONSTEXPR_OR_CONST std::size_t max_align = BOOST_CORE_ALIGNOF( max_align_t );
+
+} // namespace core
+} // namespace boost
+
+#endif  // #ifndef BOOST_CORE_MAX_ALIGN_HPP_INCLUDED
@@ -0,0 +1,108 @@
+#ifndef BOOST_CORE_MEMORY_RESOURCE_HPP_INCLUDED
+#define BOOST_CORE_MEMORY_RESOURCE_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
+
+#include <boost/core/max_align.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+#include <cstddef>
+
+// Define our own placement new to avoid the inclusion of <new>
+// (~9K extra lines) at Ion Gaztanhaga's request.
+//
+// We can use our own because [intro.object] p13 says:
+//
+// Any implicit or explicit invocation of a function named `operator new`
+// or `operator new[]` implicitly creates objects in the returned region of
+// storage and returns a pointer to a suitable created object.
+
+namespace boost
+{
+namespace core
+{
+namespace detail
+{
+
+struct placement_new_tag {};
+
+} // namespace detail
+} // namespace core
+} // namespace boost
+
+inline void* operator new( std::size_t, void* p, boost::core::detail::placement_new_tag )
+{
+    return p;
+}
+
+inline void operator delete( void*, void*, boost::core::detail::placement_new_tag )
+{
+}
+
+namespace boost
+{
+namespace core
+{
+
+class memory_resource
+{
+public:
+
+#if defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS) || BOOST_WORKAROUND(BOOST_GCC, < 40700)
+
+    virtual ~memory_resource() {}
+
+#else
+
+    virtual ~memory_resource() = default;
+
+#endif
+
+    BOOST_ATTRIBUTE_NODISCARD void* allocate( std::size_t bytes, std::size_t alignment = max_align )
+    {
+        // https://github.com/boostorg/container/issues/199
+        // https://cplusplus.github.io/LWG/issue3471
+
+        return ::operator new( bytes, do_allocate( bytes, alignment ), core::detail::placement_new_tag() );
+    }
+
+    void deallocate( void* p, std::size_t bytes, std::size_t alignment = max_align )
+    {
+        do_deallocate( p, bytes, alignment );
+    }
+
+    bool is_equal( memory_resource const & other ) const BOOST_NOEXCEPT
+    {
+        return do_is_equal( other );
+    }
+
+private:
+
+    virtual void* do_allocate( std::size_t bytes, std::size_t alignment ) = 0;
+    virtual void do_deallocate( void* p, std::size_t bytes, std::size_t alignment ) = 0;
+
+    virtual bool do_is_equal( memory_resource const & other ) const BOOST_NOEXCEPT = 0;
+};
+
+inline bool operator==( memory_resource const& a, memory_resource const& b ) BOOST_NOEXCEPT
+{
+    return &a == &b || a.is_equal( b );
+}
+
+inline bool operator!=( memory_resource const& a, memory_resource const& b ) BOOST_NOEXCEPT
+{
+    return !( a == b );
+}
+
+} // namespace core
+} // namespace boost
+
+#endif  // #ifndef BOOST_CORE_MEMORY_RESOURCE_HPP_INCLUDED
@@ -15,6 +15,8 @@ namespace boost {
 template<class A>
 struct noinit_adaptor
    : A {
+    typedef void _default_construct_destroy;
+
    template<class U>
    struct rebind {
        typedef noinit_adaptor<typename allocator_rebind<A, U>::type> other;
@@ -56,6 +58,7 @@ struct noinit_adaptor
    template<class U>
    void destroy(U* p) {
        p->~U();
+        (void)p;
    }
 };

@@ -27,7 +27,7 @@ namespace noncopyable_  // protection from unintended ADL
 // whether a type derives from noncopyable without needing the definition
 // of noncopyable itself.
 //
-// The definition of base_token is macro-guarded so that Type Trais can
+// The definition of base_token is macro-guarded so that Type Traits can
 // define it locally without including this header, to avoid a dependency
 // on Core.

@@ -27,6 +27,9 @@

 namespace boost {

+// Block unintended ADL
+namespace null_deleter_ns {
+
 //! A function object that does nothing and can be used as an empty deleter for \c shared_ptr
 struct null_deleter
 {
@@ -39,6 +42,10 @@ struct null_deleter
    void operator() (T*) const BOOST_NOEXCEPT {}
 };

+} // namespace null_deleter_ns
+
+using null_deleter_ns::null_deleter;
+
 } // namespace boost

 #endif // BOOST_CORE_NULL_DELETER_HPP
@@ -0,0 +1,49 @@
+/*
+Copyright 2024 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_POINTER_IN_RANGE_HPP
+#define BOOST_CORE_POINTER_IN_RANGE_HPP
+
+#include <boost/config.hpp>
+#include <functional>
+
+#if !defined(BOOST_NO_CXX14_CONSTEXPR)
+#if defined(BOOST_MSVC) && BOOST_MSVC >= 1925
+#define BOOST_CORE_DETAIL_HAS_IS_CONSTEVAL
+#elif defined(__has_builtin)
+#if __has_builtin(__builtin_is_constant_evaluated)
+#define BOOST_CORE_DETAIL_HAS_IS_CONSTEVAL
+#endif
+#endif
+#endif
+
+#if !defined(BOOST_CORE_DETAIL_HAS_IS_CONSTEVAL)
+#define BOOST_CORE_NO_CONSTEXPR_POINTER_IN_RANGE
+#endif
+
+namespace boost {
+
+template<class T>
+inline BOOST_CONSTEXPR bool
+pointer_in_range(const T* p, const T* b, const T* e)
+{
+#if defined(BOOST_CORE_DETAIL_HAS_IS_CONSTEVAL)
+    if ( __builtin_is_constant_evaluated()) {
+        for (; b != e; ++b) {
+            if (b == p) {
+                return true;
+            }
+        }
+        return false;
+    }
+#endif
+    return std::less_equal<const T*>()(b, p) && std::less<const T*>()(p, e);
+}
+
+} /* boost */
+
+#endif
@@ -1,5 +1,5 @@
 /*
-Copyright 2017-2018 Glen Joseph Fernandes
+Copyright 2017-2021 Glen Joseph Fernandes
 (glenjofe@gmail.com)

 Distributed under the Boost Software License, Version 1.0.
@@ -9,43 +9,23 @@ Distributed under the Boost Software License, Version 1.0.
 #define BOOST_CORE_POINTER_TRAITS_HPP

 #include <boost/config.hpp>
-#if !defined(BOOST_NO_CXX11_POINTER_TRAITS)
-#include <memory>
-#else
 #include <boost/core/addressof.hpp>
 #include <cstddef>
-#endif

 namespace boost {
-
-#if !defined(BOOST_NO_CXX11_POINTER_TRAITS)
-template<class T>
-struct pointer_traits
-    : std::pointer_traits<T> {
-    template<class U>
-    struct rebind_to {
-        typedef typename std::pointer_traits<T>::template rebind<U> type;
-    };
-};
-
-template<class T>
-struct pointer_traits<T*>
-    : std::pointer_traits<T*> {
-    template<class U>
-    struct rebind_to {
-        typedef U* type;
-    };
-};
-#else
 namespace detail {

+struct ptr_none { };
+
 template<class>
-struct ptr_void {
+struct ptr_valid {
    typedef void type;
 };

-template<class T>
-struct ptr_first;
+template<class>
+struct ptr_first {
+    typedef ptr_none type;
+};

 #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 template<template<class, class...> class T, class U, class... Args>
@@ -75,7 +55,7 @@ struct ptr_element {
 };

 template<class T>
-struct ptr_element<T, typename ptr_void<typename T::element_type>::type> {
+struct ptr_element<T, typename ptr_valid<typename T::element_type>::type> {
    typedef typename T::element_type type;
 };

@@ -86,12 +66,12 @@ struct ptr_difference {

 template<class T>
 struct ptr_difference<T,
-    typename ptr_void<typename T::difference_type>::type> {
+    typename ptr_valid<typename T::difference_type>::type> {
    typedef typename T::difference_type type;
 };

-template<class T, class V>
-struct ptr_transform;
+template<class, class>
+struct ptr_transform { };

 #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 template<template<class, class...> class T, class U, class... Args, class V>
@@ -117,68 +97,139 @@ struct ptr_transform<T<U1, U2, U3>, V> {
 #endif

 template<class T, class U, class = void>
-struct ptr_rebind {
-    typedef typename ptr_transform<T, U>::type type;
-};
+struct ptr_rebind
+    : ptr_transform<T, U> { };

 #if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
 template<class T, class U>
 struct ptr_rebind<T, U,
-    typename ptr_void<typename T::template rebind<U> >::type> {
+    typename ptr_valid<typename T::template rebind<U> >::type> {
    typedef typename T::template rebind<U> type;
 };
+#else
+template<class T, class U>
+struct ptr_rebind<T, U,
+    typename ptr_valid<typename T::template rebind<U>::other>::type> {
+    typedef typename T::template rebind<U>::other type;
+};
+#endif
+
+#if !defined(BOOST_NO_CXX11_DECLTYPE_N3276)
+template<class T, class E>
+class ptr_to_expr {
+    template<class>
+    struct result {
+        char x, y;
+    };
+
+    static E& source();
+
+    template<class O>
+    static auto check(int) -> result<decltype(O::pointer_to(source()))>;
+
+    template<class>
+    static char check(long);
+
+public:
+    BOOST_STATIC_CONSTEXPR bool value = sizeof(check<T>(0)) > 1;
+};
+
+template<class T, class E>
+struct ptr_to_expr<T*, E> {
+    BOOST_STATIC_CONSTEXPR bool value = true;
+};
+
+template<class T, class E>
+struct ptr_has_to {
+    BOOST_STATIC_CONSTEXPR bool value = ptr_to_expr<T, E>::value;
+};
+#else
+template<class, class>
+struct ptr_has_to {
+    BOOST_STATIC_CONSTEXPR bool value = true;
+};
 #endif

 template<class T>
-struct ptr_value {
-    typedef T type;
+struct ptr_has_to<T, void> {
+    BOOST_STATIC_CONSTEXPR bool value = false;
 };

-template<>
-struct ptr_value<void> {
-    typedef struct { } type;
+template<class T>
+struct ptr_has_to<T, const void> {
+    BOOST_STATIC_CONSTEXPR bool value = false;
 };

+template<class T>
+struct ptr_has_to<T, volatile void> {
+    BOOST_STATIC_CONSTEXPR bool value = false;
+};
+
+template<class T>
+struct ptr_has_to<T, const volatile void> {
+    BOOST_STATIC_CONSTEXPR bool value = false;
+};
+
+template<class T, class E, bool = ptr_has_to<T, E>::value>
+struct ptr_to { };
+
+template<class T, class E>
+struct ptr_to<T, E, true> {
+    static T pointer_to(E& v) {
+        return T::pointer_to(v);
+    }
+};
+
+template<class T>
+struct ptr_to<T*, T, true> {
+    static T* pointer_to(T& v) BOOST_NOEXCEPT {
+        return boost::addressof(v);
+    }
+};
+
+template<class T, class E>
+struct ptr_traits
+    : ptr_to<T, E> {
+    typedef T pointer;
+    typedef E element_type;
+    typedef typename ptr_difference<T>::type difference_type;
+
+    template<class U>
+    struct rebind_to
+        : ptr_rebind<T, U> { };
+
+#if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
+    template<class U>
+    using rebind = typename rebind_to<U>::type;
+#endif
+};
+
+template<class T>
+struct ptr_traits<T, ptr_none> { };
+
 } /* detail */

 template<class T>
-struct pointer_traits {
-    typedef T pointer;
-    typedef typename detail::ptr_element<T>::type element_type;
-    typedef typename detail::ptr_difference<T>::type difference_type;
-    template<class U>
-    struct rebind_to {
-        typedef typename detail::ptr_rebind<T, U>::type type;
-    };
-#if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
-    template<class U>
-    using rebind = typename detail::ptr_rebind<T, U>::type;
-#endif
-    static pointer
-    pointer_to(typename detail::ptr_value<element_type>::type& v) {
-        return pointer::pointer_to(v);
-    }
-};
+struct pointer_traits
+    : detail::ptr_traits<T, typename detail::ptr_element<T>::type> { };

 template<class T>
-struct pointer_traits<T*> {
+struct pointer_traits<T*>
+    : detail::ptr_to<T*, T> {
    typedef T* pointer;
    typedef T element_type;
    typedef std::ptrdiff_t difference_type;
+
    template<class U>
    struct rebind_to {
        typedef U* type;
    };
+
 #if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
    template<class U>
-    using rebind = U*;
+    using rebind = typename rebind_to<U>::type;
 #endif
-    static T*
-    pointer_to(typename detail::ptr_value<T>::type& v) BOOST_NOEXCEPT {
-        return boost::addressof(v);
-    }
 };
-#endif

 template<class T>
 BOOST_CONSTEXPR inline T*
@@ -33,7 +33,7 @@ extern "C" _Noreturn void quick_exit(int);
 namespace boost
 {

-BOOST_NORETURN void quick_exit( int code ) BOOST_NOEXCEPT
+BOOST_NORETURN inline void quick_exit( int code ) BOOST_NOEXCEPT
 {
 #if defined(_MSC_VER) && _MSC_VER < 1900

@@ -1,15 +1,14 @@
 #ifndef BOOST_CORE_REF_HPP
 #define BOOST_CORE_REF_HPP

-// MS compatible compilers support #pragma once
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1020)
-# pragma once
-#endif
-
 #include <boost/config.hpp>
 #include <boost/config/workaround.hpp>
 #include <boost/core/addressof.hpp>
+#include <boost/core/enable_if.hpp>
+
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+# pragma once
+#endif

 //
 //  ref.hpp - ref/cref, useful helper functions
@@ -46,6 +45,28 @@ namespace boost

 #endif

+namespace detail
+{
+
+template< class Y, class T > struct ref_convertible
+{
+    typedef char (&yes) [1];
+    typedef char (&no)  [2];
+
+    static yes f( T* );
+    static no  f( ... );
+
+    enum _vt { value = sizeof( (f)( static_cast<Y*>(0) ) ) == sizeof(yes) };
+};
+
+#if defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS)
+struct ref_empty
+{
+};
+#endif
+
+} // namespace detail
+
 // reference_wrapper

 /**
@@ -71,11 +92,11 @@ public:

     @remark Does not throw.
    */
-    BOOST_FORCEINLINE explicit reference_wrapper(T& t): t_(boost::addressof(t)) {}
+    BOOST_FORCEINLINE explicit reference_wrapper(T& t) BOOST_NOEXCEPT : t_(boost::addressof(t)) {}

 #if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1600 )

-    BOOST_FORCEINLINE explicit reference_wrapper( T & t, ref_workaround_tag ): t_( boost::addressof( t ) ) {}
+    BOOST_FORCEINLINE explicit reference_wrapper( T & t, ref_workaround_tag ) BOOST_NOEXCEPT : t_( boost::addressof( t ) ) {}

 #endif

@@ -87,24 +108,46 @@ public:
 public:
 #endif

+    template<class Y> friend class reference_wrapper;
+
    /**
-     @return The stored reference.
+     Constructs a `reference_wrapper` object that stores the
+     reference stored in the compatible `reference_wrapper` `r`.
+
+     @remark Only enabled when `Y*` is convertible to `T*`.
     @remark Does not throw.
    */
-    BOOST_FORCEINLINE operator T& () const { return *t_; }
+#if !defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS)
+    template<class Y, class = typename enable_if_c<boost::detail::ref_convertible<Y, T>::value>::type>
+    reference_wrapper( reference_wrapper<Y> r ) BOOST_NOEXCEPT : t_( r.t_ )
+    {
+    }
+#else
+    template<class Y> reference_wrapper( reference_wrapper<Y> r,
+        typename enable_if_c<boost::detail::ref_convertible<Y, T>::value,
+            boost::detail::ref_empty>::type = boost::detail::ref_empty() ) BOOST_NOEXCEPT : t_( r.t_ )
+    {
+    }
+#endif

    /**
     @return The stored reference.
     @remark Does not throw.
    */
-    BOOST_FORCEINLINE T& get() const { return *t_; }
+    BOOST_FORCEINLINE operator T& () const BOOST_NOEXCEPT { return *t_; }
+
+    /**
+     @return The stored reference.
+     @remark Does not throw.
+    */
+    BOOST_FORCEINLINE T& get() const BOOST_NOEXCEPT { return *t_; }

    /**
     @return A pointer to the object referenced by the stored
       reference.
     @remark Does not throw.
    */
-    BOOST_FORCEINLINE T* get_pointer() const { return t_; }
+    BOOST_FORCEINLINE T* get_pointer() const BOOST_NOEXCEPT { return t_; }

 private:

@@ -129,7 +172,7 @@ private:
 @return `reference_wrapper<T>(t)`
 @remark Does not throw.
 */
-template<class T> BOOST_FORCEINLINE reference_wrapper<T> BOOST_REF_CONST ref( T & t )
+template<class T> BOOST_FORCEINLINE reference_wrapper<T> BOOST_REF_CONST ref( T & t ) BOOST_NOEXCEPT
 {
 #if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1600 )

@@ -148,7 +191,7 @@ template<class T> BOOST_FORCEINLINE reference_wrapper<T> BOOST_REF_CONST ref( T
 @return `reference_wrapper<T const>(t)`
 @remark Does not throw.
 */
-template<class T> BOOST_FORCEINLINE reference_wrapper<T const> BOOST_REF_CONST cref( T const & t )
+template<class T> BOOST_FORCEINLINE reference_wrapper<T const> BOOST_REF_CONST cref( T const & t ) BOOST_NOEXCEPT
 {
    return reference_wrapper<T const>(t);
 }
@@ -279,7 +322,7 @@ template<typename T> struct unwrap_reference< reference_wrapper<T> const volatil
 @return `unwrap_reference<T>::type&(t)`
 @remark Does not throw.
 */
-template<class T> BOOST_FORCEINLINE typename unwrap_reference<T>::type& unwrap_ref( T & t )
+template<class T> BOOST_FORCEINLINE typename unwrap_reference<T>::type& unwrap_ref( T & t ) BOOST_NOEXCEPT
 {
    return t;
 }
@@ -289,7 +332,7 @@ template<class T> BOOST_FORCEINLINE typename unwrap_reference<T>::type& unwrap_r
 /**
 @cond
 */
-template<class T> BOOST_FORCEINLINE T* get_pointer( reference_wrapper<T> const & r )
+template<class T> BOOST_FORCEINLINE T* get_pointer( reference_wrapper<T> const & r ) BOOST_NOEXCEPT
 {
    return r.get_pointer();
 }
@@ -37,7 +37,7 @@ namespace boost
  /**
   * Casts a scoped enum to its underlying type.
   *
-   * This function is useful when working with scoped enum classes, which doens't implicitly convert to the underlying type.
+   * This function is useful when working with scoped enum classes, which doesn't implicitly convert to the underlying type.
   * @param v A scoped enum.
   * @returns The underlying type.
   * @throws No-throws.
@@ -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
@@ -0,0 +1,45 @@
+/*
+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 <iterator>
+
+// Note: MSVC doesn't define __cpp_lib_nonmember_container_access but supports the feature even in C++14 mode
+#if (defined(__cpp_lib_nonmember_container_access) && (__cpp_lib_nonmember_container_access >= 201411l)) || \
+    (defined(_MSC_VER) && (_MSC_VER >= 1900))
+
+namespace boost {
+using std::size;
+} /* boost */
+
+#else // (defined(__cpp_lib_nonmember_container_access) ...
+
+#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 // (defined(__cpp_lib_nonmember_container_access) ...
+
+#endif
@@ -0,0 +1,173 @@
+/*
+ *             Copyright Andrey Semashev 2022.
+ * 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)
+ */
+/*!
+ * \file   snprintf.hpp
+ * \author Andrey Semashev
+ * \date   06.12.2022
+ *
+ * \brief  The header provides more portable definition of snprintf and vsnprintf,
+ *         as well as \c wchar_t counterparts.
+ */
+
+#ifndef BOOST_CORE_SNPRINTF_HPP_INCLUDED_
+#define BOOST_CORE_SNPRINTF_HPP_INCLUDED_
+
+#include <stdio.h>
+#include <wchar.h>
+#include <boost/config.hpp>
+
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#pragma once
+#endif
+
+#if defined(__MINGW32__)
+
+#include <cstddef>
+#include <cstdarg>
+#if !defined(__MINGW64_VERSION_MAJOR)
+#include <climits>
+#endif
+
+// MinGW32 and MinGW-w64 provide their own snprintf implementations that are compliant with the C standard.
+#define BOOST_CORE_DETAIL_MINGW_SNPRINTF
+
+#elif (defined(BOOST_MSSTL_VERSION) && BOOST_MSSTL_VERSION < 140)
+
+#include <cstddef>
+#include <cstdarg>
+#include <climits>
+
+// MSVC snprintfs are not conforming but they are good enough for typical use cases.
+#define BOOST_CORE_DETAIL_MSVC_LEGACY_SNPRINTF
+
+#endif
+
+namespace boost {
+
+namespace core {
+
+#if defined(BOOST_CORE_DETAIL_MINGW_SNPRINTF) || defined(BOOST_CORE_DETAIL_MSVC_LEGACY_SNPRINTF)
+
+#if defined(BOOST_CORE_DETAIL_MINGW_SNPRINTF)
+
+inline int vsnprintf(char* buf, std::size_t size, const char* format, std::va_list args)
+{
+    return __mingw_vsnprintf(buf, size, format, args);
+}
+
+inline int vswprintf(wchar_t* buf, std::size_t size, const wchar_t* format, std::va_list args)
+{
+#if defined(__MINGW64_VERSION_MAJOR)
+    int res = __mingw_vsnwprintf(buf, size, format, args);
+    // __mingw_vsnwprintf returns the number of characters to be printed, but (v)swprintf is expected to return -1 on truncation
+    if (static_cast< unsigned int >(res) >= size)
+        res = -1;
+    return res;
+#else
+    // Legacy MinGW32 does not provide __mingw_vsnwprintf, so use _vsnwprintf from MSVC CRT
+    if (BOOST_UNLIKELY(size == 0u || size > static_cast< std::size_t >(INT_MAX)))
+        return -1;
+
+    int res = _vsnwprintf(buf, size, format, args);
+    // (v)swprintf is expected to return -1 on truncation, so we only need to ensure the output is null-terminated
+    if (static_cast< unsigned int >(res) >= size)
+    {
+        buf[size - 1u] = L'\0';
+        res = -1;
+    }
+
+    return res;
+#endif
+}
+
+#elif defined(BOOST_CORE_DETAIL_MSVC_LEGACY_SNPRINTF)
+
+#if defined(_MSC_VER)
+#pragma warning(push)
+// '_vsnprintf': This function or variable may be unsafe. Consider using _vsnprintf_s instead.
+#pragma warning(disable: 4996)
+#endif
+
+inline int vsnprintf(char* buf, std::size_t size, const char* format, std::va_list args)
+{
+    if (BOOST_UNLIKELY(size == 0u))
+        return 0;
+    if (BOOST_UNLIKELY(size > static_cast< std::size_t >(INT_MAX)))
+        return -1;
+
+    buf[size - 1u] = '\0';
+    int res = _vsnprintf(buf, size, format, args);
+    if (static_cast< unsigned int >(res) >= size)
+    {
+        // _vsnprintf returns -1 if the output was truncated and in case of other errors.
+        // Detect truncation by checking whether the output buffer was written over entirely.
+        if (buf[size - 1u] != '\0')
+        {
+            buf[size - 1u] = '\0';
+            res = static_cast< int >(size);
+        }
+    }
+
+    return res;
+}
+
+inline int vswprintf(wchar_t* buf, std::size_t size, const wchar_t* format, std::va_list args)
+{
+    if (BOOST_UNLIKELY(size == 0u || size > static_cast< std::size_t >(INT_MAX)))
+        return -1;
+
+    int res = _vsnwprintf(buf, size, format, args);
+    // (v)swprintf is expected to return -1 on truncation, so we only need to ensure the output is null-terminated
+    if (static_cast< unsigned int >(res) >= size)
+    {
+        buf[size - 1u] = L'\0';
+        res = -1;
+    }
+
+    return res;
+}
+
+#if defined(_MSC_VER)
+#pragma warning(pop)
+#endif
+
+#endif
+
+inline int snprintf(char* buf, std::size_t size, const char* format, ...)
+{
+    std::va_list args;
+    va_start(args, format);
+    int res = vsnprintf(buf, size, format, args);
+    va_end(args);
+    return res;
+}
+
+inline int swprintf(wchar_t* buf, std::size_t size, const wchar_t* format, ...)
+{
+    std::va_list args;
+    va_start(args, format);
+    int res = vswprintf(buf, size, format, args);
+    va_end(args);
+    return res;
+}
+
+#else // defined(BOOST_CORE_DETAIL_MINGW_SNPRINTF) || defined(BOOST_CORE_DETAIL_MSVC_LEGACY_SNPRINTF)
+
+// Standard-conforming compilers already have the correct snprintfs
+using ::snprintf;
+using ::vsnprintf;
+
+using ::swprintf;
+using ::vswprintf;
+
+#endif // defined(BOOST_CORE_DETAIL_MINGW_SNPRINTF) || defined(BOOST_CORE_DETAIL_MSVC_LEGACY_SNPRINTF)
+
+} // namespace core
+
+} // namespace boost
+
+#endif // BOOST_CORE_SNPRINTF_HPP_INCLUDED_
@@ -0,0 +1,412 @@
+/*
+Copyright 2019-2023 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_SPAN_HPP
+#define BOOST_CORE_SPAN_HPP
+
+#include <boost/core/detail/assert.hpp>
+#include <boost/core/data.hpp>
+#include <array>
+#include <iterator>
+#include <type_traits>
+
+namespace boost {
+
+constexpr std::size_t dynamic_extent = static_cast<std::size_t>(-1);
+
+template<class T, std::size_t E = dynamic_extent>
+class span;
+
+namespace detail {
+
+template<class U, class T, class = void>
+struct span_convertible {
+    static constexpr bool value = false;
+};
+
+template<class U, class T>
+struct span_convertible<U, T, typename
+    std::enable_if<std::is_convertible<U(*)[], T(*)[]>::value>::type> {
+    static constexpr bool value = true;
+};
+
+template<std::size_t E, std::size_t N>
+struct span_capacity {
+    static constexpr bool value = E == boost::dynamic_extent || E == N;
+};
+
+template<class T, std::size_t E, class U, std::size_t N>
+struct span_compatible {
+    static constexpr bool value = span_capacity<E, N>::value &&
+        span_convertible<U, T>::value;
+};
+
+template<class T>
+using span_uncvref = typename std::remove_cv<typename
+    std::remove_reference<T>::type>::type;
+
+template<class>
+struct span_is_span {
+    static constexpr bool value = false;
+};
+
+template<class T, std::size_t E>
+struct span_is_span<boost::span<T, E> > {
+    static constexpr bool value = true;
+};
+
+template<class T>
+struct span_is_array {
+    static constexpr bool value = false;
+};
+
+template<class T, std::size_t N>
+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<span_ptr<T> >::value>::type> {
+    typedef typename std::remove_pointer<span_ptr<T> >::type type;
+};
+
+template<class, class, class = void>
+struct span_has_data {
+    static constexpr bool value = false;
+};
+
+template<class R, class T>
+struct span_has_data<R, T, typename std::enable_if<span_convertible<typename
+    span_data<R>::type, T>::value>::type> {
+    static constexpr bool value = true;
+};
+
+template<class, class = void>
+struct span_has_size {
+    static constexpr bool value = false;
+};
+
+template<class R>
+struct span_has_size<R, typename
+    std::enable_if<std::is_convertible<decltype(std::declval<R&>().size()),
+        std::size_t>::value>::type> {
+    static constexpr bool value = true;
+};
+
+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<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;
+};
+
+template<std::size_t E, std::size_t N>
+struct span_implicit {
+    static constexpr bool value = E == boost::dynamic_extent ||
+        N != boost::dynamic_extent;
+};
+
+template<class T, std::size_t E, class U, std::size_t N>
+struct span_copyable {
+    static constexpr bool value = (N == boost::dynamic_extent ||
+        span_capacity<E, N>::value) && span_convertible<U, T>::value;
+};
+
+template<std::size_t E, std::size_t O>
+struct span_sub {
+    static constexpr std::size_t value = E == boost::dynamic_extent ?
+        boost::dynamic_extent : E - O;
+};
+
+template<class T, std::size_t E>
+struct span_store {
+    constexpr span_store(T* p_, std::size_t) noexcept
+        : p(p_) { }
+    static constexpr std::size_t n = E;
+    T* p;
+};
+
+template<class T>
+struct span_store<T, boost::dynamic_extent> {
+    constexpr span_store(T* p_, std::size_t n_) noexcept
+        : p(p_)
+        , n(n_) { }
+    T* p;
+    std::size_t n;
+};
+
+template<class T, std::size_t E>
+struct span_bytes {
+    static constexpr std::size_t value = sizeof(T) * E;
+};
+
+template<class T>
+struct span_bytes<T, boost::dynamic_extent> {
+    static constexpr std::size_t value = boost::dynamic_extent;
+};
+
+} /* detail */
+
+template<class T, std::size_t E>
+class span {
+public:
+    typedef T element_type;
+    typedef typename std::remove_cv<T>::type value_type;
+    typedef std::size_t size_type;
+    typedef std::ptrdiff_t difference_type;
+    typedef T* pointer;
+    typedef const T* const_pointer;
+    typedef T& reference;
+    typedef const T& const_reference;
+    typedef T* iterator;
+    typedef const T* const_iterator;
+    typedef std::reverse_iterator<T*> reverse_iterator;
+    typedef std::reverse_iterator<const T*> const_reverse_iterator;
+
+    static constexpr std::size_t extent = E;
+
+    template<std::size_t N = E,
+        typename std::enable_if<N == dynamic_extent || N == 0, int>::type = 0>
+    constexpr span() noexcept
+        : s_(0, 0) { }
+
+    template<class I,
+        typename std::enable_if<E == dynamic_extent &&
+            detail::span_convertible<I, T>::value, int>::type = 0>
+    constexpr span(I* f, size_type c)
+        : s_(f, c) { }
+
+    template<class I,
+        typename std::enable_if<E != dynamic_extent &&
+            detail::span_convertible<I, T>::value, int>::type = 0>
+    explicit constexpr span(I* f, size_type c)
+        : s_(f, c) { }
+
+    template<class I, class L,
+        typename std::enable_if<E == dynamic_extent &&
+            detail::span_convertible<I, T>::value, int>::type = 0>
+    constexpr span(I* f, L* l)
+        : s_(f, l - f) { }
+
+    template<class I, class L,
+        typename std::enable_if<E != dynamic_extent &&
+            detail::span_convertible<I, T>::value, int>::type = 0>
+    explicit constexpr span(I* f, L* l)
+        : s_(f, l - f) { }
+
+    template<std::size_t N,
+        typename std::enable_if<detail::span_capacity<E, N>::value,
+            int>::type = 0>
+    constexpr span(typename std::enable_if<true, T>::type (&a)[N]) noexcept
+        : s_(a, N) { }
+
+    template<class U, std::size_t N,
+        typename std::enable_if<detail::span_compatible<T, E, U, N>::value,
+            int>::type = 0>
+    constexpr span(std::array<U, N>& a) noexcept
+        : s_(a.data(), N) { }
+
+    template<class U, std::size_t N,
+        typename std::enable_if<detail::span_compatible<T, E, const U,
+            N>::value, int>::type = 0>
+    constexpr span(const std::array<U, N>& a) noexcept
+        : s_(a.data(), N) { }
+
+    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(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(boost::data(r)) &&
+        noexcept(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 &&
+            detail::span_copyable<T, E, U, N>::value, int>::type = 0>
+    constexpr span(const span<U, N>& s) noexcept
+        : s_(s.data(), s.size()) { }
+
+    template<class U, std::size_t N,
+        typename std::enable_if<!detail::span_implicit<E, N>::value &&
+            detail::span_copyable<T, E, U, N>::value, int>::type = 0>
+    explicit constexpr span(const span<U, N>& s) noexcept
+        : s_(s.data(), s.size()) { }
+
+    template<std::size_t C>
+    constexpr span<T, C> first() const {
+        static_assert(C <= E, "Count <= Extent");
+        return span<T, C>(s_.p, C);
+    }
+
+    template<std::size_t C>
+    constexpr span<T, C> last() const {
+        static_assert(C <= E, "Count <= Extent");
+        return span<T, C>(s_.p + (s_.n - C), C);
+    }
+
+    template<std::size_t O, std::size_t C = dynamic_extent>
+    constexpr typename std::enable_if<C == dynamic_extent,
+        span<T, detail::span_sub<E, O>::value> >::type subspan() const {
+        static_assert(O <= E, "Offset <= Extent");
+        return span<T, detail::span_sub<E, O>::value>(s_.p + O, s_.n - O);
+    }
+
+    template<std::size_t O, std::size_t C = dynamic_extent>
+    constexpr typename std::enable_if<C != dynamic_extent,
+        span<T, C> >::type subspan() const {
+        static_assert(O <= E && C <= E - O,
+            "Offset <= Extent && Count <= Extent - Offset");
+        return span<T, C>(s_.p + O, C);
+    }
+
+    constexpr span<T, dynamic_extent> first(size_type c) const {
+        return BOOST_CORE_DETAIL_ASSERT(c <= size()),
+            span<T, dynamic_extent>(s_.p, c);
+    }
+
+    constexpr span<T, dynamic_extent> last(size_type c) const {
+        return BOOST_CORE_DETAIL_ASSERT(c <= size()),
+            span<T, dynamic_extent>(s_.p + (s_.n - c), c);
+    }
+
+    constexpr span<T, dynamic_extent> subspan(size_type o,
+        size_type c = dynamic_extent) const {
+        return BOOST_CORE_DETAIL_ASSERT(o <= size() &&
+                (c == dynamic_extent || c + o <= size())),
+            span<T, dynamic_extent>(s_.p + o,
+                c == dynamic_extent ? s_.n - o : c);
+    }
+
+    constexpr size_type size() const noexcept {
+        return s_.n;
+    }
+
+    constexpr size_type size_bytes() const noexcept {
+        return s_.n * sizeof(T);
+    }
+
+    constexpr bool empty() const noexcept {
+        return s_.n == 0;
+    }
+
+    constexpr reference operator[](size_type i) const {
+        return BOOST_CORE_DETAIL_ASSERT(i < size()), s_.p[i];
+    }
+
+    constexpr reference front() const {
+        return BOOST_CORE_DETAIL_ASSERT(!empty()), *s_.p;
+    }
+
+    constexpr reference back() const {
+        return BOOST_CORE_DETAIL_ASSERT(!empty()), s_.p[s_.n - 1];
+    }
+
+    constexpr pointer data() const noexcept {
+        return s_.p;
+    }
+
+    constexpr iterator begin() const noexcept {
+        return s_.p;
+    }
+
+    constexpr iterator end() const noexcept {
+        return s_.p + s_.n;
+    }
+
+    constexpr reverse_iterator rbegin() const noexcept {
+        return reverse_iterator(s_.p + s_.n);
+    }
+
+    constexpr reverse_iterator rend() const noexcept {
+        return reverse_iterator(s_.p);
+    }
+
+    constexpr const_iterator cbegin() const noexcept {
+        return s_.p;
+    }
+
+    constexpr const_iterator cend() const noexcept {
+        return s_.p + s_.n;
+    }
+
+    constexpr const_reverse_iterator crbegin() const noexcept {
+        return const_reverse_iterator(s_.p + s_.n);
+    }
+
+    constexpr const_reverse_iterator crend() const noexcept {
+        return const_reverse_iterator(s_.p);
+    }
+
+private:
+    detail::span_store<T, E> s_;
+};
+
+#if defined(BOOST_NO_CXX17_INLINE_VARIABLES)
+template<class T, std::size_t E>
+constexpr std::size_t span<T, E>::extent;
+#endif
+
+#ifdef __cpp_deduction_guides
+template<class I, class L>
+span(I*, L) -> span<I>;
+
+template<class T, std::size_t N>
+span(T(&)[N]) -> span<T, N>;
+
+template<class T, std::size_t N>
+span(std::array<T, N>&) -> span<T, N>;
+
+template<class T, std::size_t N>
+span(const std::array<T, N>&) -> span<const T, N>;
+
+template<class R>
+span(R&&) -> span<typename detail::span_data<R>::type>;
+
+template<class T, std::size_t E>
+span(span<T, E>) -> span<T, E>;
+#endif
+
+#ifdef __cpp_lib_byte
+template<class T, std::size_t E>
+inline span<const std::byte, detail::span_bytes<T, E>::value>
+as_bytes(span<T, E> s) noexcept
+{
+    return span<const std::byte, detail::span_bytes<T,
+        E>::value>(reinterpret_cast<const std::byte*>(s.data()),
+            s.size_bytes());
+}
+
+template<class T, std::size_t E>
+inline typename std::enable_if<!std::is_const<T>::value,
+    span<std::byte, detail::span_bytes<T, E>::value> >::type
+as_writable_bytes(span<T, E> s) noexcept
+{
+    return span<std::byte, detail::span_bytes<T,
+        E>::value>(reinterpret_cast<std::byte*>(s.data()), s.size_bytes());
+}
+#endif
+
+} /* boost */
+
+#endif
@@ -10,61 +10,31 @@
 #define BOOST_CORE_SWAP_HPP

 // Note: the implementation of this utility contains various workarounds:
-// - swap_impl is put outside the boost namespace, to avoid infinite
-// recursion (causing stack overflow) when swapping objects of a primitive
-// type.
-// - swap_impl has a using-directive, rather than a using-declaration,
-// because some compilers (including MSVC 7.1, Borland 5.9.3, and
-// Intel 8.1) don't do argument-dependent lookup when it has a
-// using-declaration instead.
 // - boost::swap has two template arguments, instead of one, to
 // avoid ambiguity when swapping objects of a Boost type that does
 // not have its own boost::swap overload.

 #include <boost/core/enable_if.hpp>
 #include <boost/config.hpp>
-#if __cplusplus >= 201103L || defined(BOOST_DINKUMWARE_STDLIB)
-#include <utility> // for std::swap (C++11)
-#else
-#include <algorithm> // for std::swap (C++98)
+#include <boost/config/header_deprecated.hpp>
+#include <boost/core/invoke_swap.hpp>
+
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#pragma once
 #endif
-#include <cstddef> // for std::size_t

-namespace boost_swap_impl
-{
-  // we can't use type_traits here
-
-  template<class T> struct is_const { enum _vt { value = 0 }; };
-  template<class T> struct is_const<T const> { enum _vt { value = 1 }; };
-
-  template<class T>
-  BOOST_GPU_ENABLED
-  void swap_impl(T& left, T& right)
-  {
-    using namespace std;//use std::swap if argument dependent lookup fails
-    swap(left,right);
-  }
-
-  template<class T, std::size_t N>
-  BOOST_GPU_ENABLED
-  void swap_impl(T (& left)[N], T (& right)[N])
-  {
-    for (std::size_t i = 0; i < N; ++i)
-    {
-      ::boost_swap_impl::swap_impl(left[i], right[i]);
-    }
-  }
-}
+BOOST_HEADER_DEPRECATED("boost/core/invoke_swap.hpp")

 namespace boost
 {
  template<class T1, class T2>
  BOOST_GPU_ENABLED
-  typename enable_if_c< !boost_swap_impl::is_const<T1>::value && !boost_swap_impl::is_const<T2>::value >::type
+  BOOST_DEPRECATED("This function is deprecated, use boost::core::invoke_swap instead.")
+  inline typename enable_if_c< !boost_swap_impl::is_const<T1>::value && !boost_swap_impl::is_const<T2>::value >::type
  swap(T1& left, T2& right)
  {
-    ::boost_swap_impl::swap_impl(left, right);
+    boost::core::invoke_swap(left, right);
  }
 }

-#endif
+#endif // BOOST_CORE_SWAP_HPP
--- a/Show More
+++ b/Show More