diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bd3f639..3a188bf 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,3 +1,9 @@
+# Copyright 2020-2021 Peter Dimov
+# Copyright 2021 Andrey Semashev
+#
+# 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)
+
 name: CI
 
 on:
@@ -14,32 +20,48 @@ concurrency:
 
 env:
   GIT_FETCH_JOBS: 8
-  UBSAN_OPTIONS: print_stacktrace=1
 
 jobs:
   posix:
+    defaults:
+      run:
+        shell: bash
+
     strategy:
       fail-fast: false
       matrix:
         include:
+          - toolset: gcc-4.4
+            cxxstd: "98,0x"
+            os: ubuntu-20.04
+            container: ubuntu:16.04
+            install: g++-4.4
+          - toolset: gcc-4.6
+            cxxstd: "03,0x"
+            os: ubuntu-20.04
+            container: ubuntu:16.04
+            install: g++-4.6
           - toolset: gcc-4.7
             cxxstd: "03,11"
-            os: ubuntu-16.04
+            os: ubuntu-20.04
+            container: ubuntu:16.04
             install: g++-4.7
           - toolset: gcc-4.8
             cxxstd: "03,11"
-            os: ubuntu-16.04
+            os: ubuntu-18.04
             install: g++-4.8
           - toolset: gcc-4.9
             cxxstd: "03,11"
-            os: ubuntu-16.04
+            os: ubuntu-20.04
+            container: ubuntu:16.04
             install: g++-4.9
           - toolset: gcc-5
             cxxstd: "03,11,14,1z"
-            os: ubuntu-16.04
+            os: ubuntu-20.04
+            container: ubuntu:16.04
           - toolset: gcc-6
             cxxstd: "03,11,14,1z"
-            os: ubuntu-16.04
+            os: ubuntu-18.04
             install: g++-6
           - toolset: gcc-7
             cxxstd: "03,11,14,17"
@@ -58,40 +80,51 @@ jobs:
             cxxstd: "03,11,14,17,20"
             os: ubuntu-20.04
             install: g++-11
+          - name: UBSAN
+            toolset: gcc-11
+            cxxstd: "03,11,14,17,20"
+            ubsan: 1
+            os: ubuntu-20.04
+            install: g++-11
+
           - toolset: clang
             compiler: clang++-3.5
             cxxstd: "03,11"
-            os: ubuntu-16.04
+            os: ubuntu-20.04
+            container: ubuntu:16.04
             install: clang-3.5
           - toolset: clang
             compiler: clang++-3.6
             cxxstd: "03,11,14"
-            os: ubuntu-16.04
+            os: ubuntu-20.04
+            container: ubuntu:16.04
             install: clang-3.6
           - toolset: clang
             compiler: clang++-3.7
             cxxstd: "03,11,14"
-            os: ubuntu-16.04
+            os: ubuntu-20.04
+            container: ubuntu:16.04
             install: clang-3.7
           - toolset: clang
             compiler: clang++-3.8
             cxxstd: "03,11,14"
-            os: ubuntu-16.04
+            os: ubuntu-20.04
+            container: ubuntu:16.04
             install: clang-3.8
           - toolset: clang
             compiler: clang++-3.9
             cxxstd: "03,11,14"
-            os: ubuntu-16.04
+            os: ubuntu-18.04
             install: clang-3.9
           - toolset: clang
             compiler: clang++-4.0
             cxxstd: "03,11,14"
-            os: ubuntu-16.04
+            os: ubuntu-18.04
             install: clang-4.0
           - toolset: clang
             compiler: clang++-5.0
             cxxstd: "03,11,14,1z"
-            os: ubuntu-16.04
+            os: ubuntu-18.04
             install: clang-5.0
           - toolset: clang
             compiler: clang++-6.0
@@ -126,71 +159,166 @@ jobs:
             compiler: clang++-12
             cxxstd: "03,11,14,17,20"
             os: ubuntu-20.04
+          - toolset: clang
+            compiler: clang++-12
+            cxxstd: "03,11,14,17,20"
+            os: ubuntu-20.04
+            install: libc++-12-dev libc++abi-12-dev
+            cxxflags: -stdlib=libc++
+            linkflags: -stdlib=libc++
+          - name: UBSAN
+            toolset: clang
+            compiler: clang++-12
+            cxxstd: "03,11,14,17,20"
+            ubsan: 1
+            os: ubuntu-20.04
+            install: libc++-12-dev libc++abi-12-dev
+            cxxflags: -stdlib=libc++
+            linkflags: -stdlib=libc++
+
           - toolset: clang
             cxxstd: "03,11,14,17,2a"
             os: macos-10.15
 
+          - name: CMake tests
+            cmake_tests: 1
+            os: ubuntu-20.04
+
     runs-on: ${{matrix.os}}
+    container: ${{matrix.container}}
 
     steps:
+      - name: Setup container
+        if: matrix.container
+        run: |
+            echo "GHA_CONTAINER=${{matrix.container}}" >> $GITHUB_ENV
+            apt-get -o Acquire::Retries=3 update && DEBIAN_FRONTEND=noninteractive apt-get -o Acquire::Retries=3 install -y sudo software-properties-common tzdata wget curl apt-transport-https make apt-file unzip libssl-dev build-essential autotools-dev autoconf automake g++ libc++-helpers python ruby cpio gcc-multilib g++-multilib pkgconf python3 ccache libpython-dev git cmake
+
       - uses: actions/checkout@v2
 
       - name: Install packages
         if: matrix.install
         run: |
-          sudo apt-get update
-          sudo apt-get install ${{matrix.install}}
+            for i in {1..3}; do sudo -E apt-add-repository -y "ppa:ubuntu-toolchain-r/test" && break || sleep 2; done
+            sudo apt-get update
+            sudo apt-get install -y ${{matrix.install}}
 
       - name: Setup GCC Toolchain
         if: matrix.gcc_toolchain
         run: |
-          GCC_TOOLCHAIN_ROOT="$HOME/gcc-toolchain"
-          echo "GCC_TOOLCHAIN_ROOT=\"$GCC_TOOLCHAIN_ROOT\"" >> $GITHUB_ENV
-          MULTIARCH_TRIPLET="$(dpkg-architecture -qDEB_HOST_MULTIARCH)"
-          mkdir -p "$GCC_TOOLCHAIN_ROOT"
-          ln -s /usr/include "$GCC_TOOLCHAIN_ROOT/include"
-          ln -s /usr/bin "$GCC_TOOLCHAIN_ROOT/bin"
-          mkdir -p "$GCC_TOOLCHAIN_ROOT/lib/gcc/$MULTIARCH_TRIPLET"
-          ln -s "/usr/lib/gcc/$MULTIARCH_TRIPLET/${{matrix.gcc_toolchain}}" "$GCC_TOOLCHAIN_ROOT/lib/gcc/$MULTIARCH_TRIPLET/${{matrix.gcc_toolchain}}"
+            GCC_TOOLCHAIN_ROOT="$HOME/gcc-toolchain"
+            echo "GCC_TOOLCHAIN_ROOT=\"$GCC_TOOLCHAIN_ROOT\"" >> $GITHUB_ENV
+            MULTIARCH_TRIPLET="$(dpkg-architecture -qDEB_HOST_MULTIARCH)"
+            mkdir -p "$GCC_TOOLCHAIN_ROOT"
+            ln -s /usr/include "$GCC_TOOLCHAIN_ROOT/include"
+            ln -s /usr/bin "$GCC_TOOLCHAIN_ROOT/bin"
+            mkdir -p "$GCC_TOOLCHAIN_ROOT/lib/gcc/$MULTIARCH_TRIPLET"
+            ln -s "/usr/lib/gcc/$MULTIARCH_TRIPLET/${{matrix.gcc_toolchain}}" "$GCC_TOOLCHAIN_ROOT/lib/gcc/$MULTIARCH_TRIPLET/${{matrix.gcc_toolchain}}"
 
       - name: Setup Boost
         run: |
-          echo GITHUB_REPOSITORY: $GITHUB_REPOSITORY
-          LIBRARY=${GITHUB_REPOSITORY#*/}
-          echo LIBRARY: $LIBRARY
-          echo "LIBRARY=$LIBRARY" >> $GITHUB_ENV
-          echo GITHUB_BASE_REF: $GITHUB_BASE_REF
-          echo GITHUB_REF: $GITHUB_REF
-          REF=${GITHUB_BASE_REF:-$GITHUB_REF}
-          REF=${REF#refs/heads/}
-          echo REF: $REF
-          BOOST_BRANCH=develop && [ "$REF" == "master" ] && BOOST_BRANCH=master || true
-          echo BOOST_BRANCH: $BOOST_BRANCH
-          cd ..
-          git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
-          cd boost-root
-          mkdir -p libs/$LIBRARY
-          cp -r $GITHUB_WORKSPACE/* libs/$LIBRARY
-          git submodule update --init tools/boostdep
-          python tools/boostdep/depinst/depinst.py --git_args "--jobs $GIT_FETCH_JOBS" $LIBRARY
-          ./bootstrap.sh
-          ./b2 -d0 headers
+            echo GITHUB_REPOSITORY: $GITHUB_REPOSITORY
+            LIBRARY=${GITHUB_REPOSITORY#*/}
+            echo LIBRARY: $LIBRARY
+            echo "LIBRARY=$LIBRARY" >> $GITHUB_ENV
+            echo GITHUB_BASE_REF: $GITHUB_BASE_REF
+            echo GITHUB_REF: $GITHUB_REF
+            REF=${GITHUB_BASE_REF:-$GITHUB_REF}
+            REF=${REF#refs/heads/}
+            echo REF: $REF
+            BOOST_BRANCH=develop && [ "$REF" == "master" ] && BOOST_BRANCH=master || true
+            echo BOOST_BRANCH: $BOOST_BRANCH
+            BUILD_JOBS=$((nproc || sysctl -n hw.ncpu) 2> /dev/null)
+            echo "BUILD_JOBS=$BUILD_JOBS" >> $GITHUB_ENV
+            echo "CMAKE_BUILD_PARALLEL_LEVEL=$BUILD_JOBS" >> $GITHUB_ENV
+            DEPINST_ARGS=()
+            GIT_VERSION="$(git --version | sed -e 's/git version //')"
+            if $(dpkg --compare-versions "$GIT_VERSION" ge 2.8.0)
+            then
+                DEPINST_ARGS+=("--git_args" "--jobs $GIT_FETCH_JOBS")
+            fi
+            cd ..
+            git clone -b "$BOOST_BRANCH" --depth 1 "https://github.com/boostorg/boost.git" "boost-root"
+            cd boost-root
+            mkdir -p libs/$LIBRARY
+            cp -r $GITHUB_WORKSPACE/* libs/$LIBRARY
+            git submodule update --init tools/boostdep
+            if [ -n "${{matrix.extra_tests}}" ]
+            then
+                DEPINST_ARGS+=("--include" "example")
+            fi
+            DEPINST_ARGS+=("$LIBRARY")
+            python tools/boostdep/depinst/depinst.py "${DEPINST_ARGS[@]}"
+            ./bootstrap.sh
+            ./b2 headers
 
       - name: Create user-config.jam
-        if: matrix.compiler
+        if: matrix.cmake_tests == '' && matrix.compiler != ''
         run: |
-          echo -n "using ${{matrix.toolset}} : : ${{matrix.compiler}}" > ~/user-config.jam
-          if [ -n "$GCC_TOOLCHAIN_ROOT" ]
-          then
-            echo -n " : <compileflags>\"--gcc-toolchain=$GCC_TOOLCHAIN_ROOT\" <linkflags>\"--gcc-toolchain=$GCC_TOOLCHAIN_ROOT\"" >> ~/user-config.jam
-          fi
-          echo " ;" >> ~/user-config.jam
+            echo -n "using ${{matrix.toolset}} : : ${{matrix.compiler}}" > ~/user-config.jam
+            if [ -n "$GCC_TOOLCHAIN_ROOT" ]
+            then
+                echo -n " : <compileflags>\"--gcc-toolchain=$GCC_TOOLCHAIN_ROOT\" <linkflags>\"--gcc-toolchain=$GCC_TOOLCHAIN_ROOT\"" >> ~/user-config.jam
+            fi
+            echo " ;" >> ~/user-config.jam
 
       - name: Run tests
+        if: matrix.cmake_tests == ''
         run: |
-          BUILD_JOBS=$((nproc || sysctl -n hw.ncpu) 2> /dev/null)
-          cd ../boost-root
-          ./b2 -j $BUILD_JOBS libs/$LIBRARY/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} variant=debug,release
+            cd ../boost-root
+            B2_ARGS=("-j" "$BUILD_JOBS" "toolset=${{matrix.toolset}}" "cxxstd=${{matrix.cxxstd}}" "variant=debug,release")
+            if [ -n "${{matrix.threading}}" ]
+            then
+                B2_ARGS+=("threading=${{matrix.threading}}")
+            fi
+            if [ -n "${{matrix.ubsan}}" ]
+            then
+                export UBSAN_OPTIONS="print_stacktrace=1"
+                B2_ARGS+=("cxxflags=-fsanitize=undefined -fno-sanitize-recover=undefined" "linkflags=-fsanitize=undefined -fuse-ld=gold" "define=UBSAN=1" "debug-symbols=on" "visibility=global")
+            fi
+            if [ -n "${{matrix.cxxflags}}" ]
+            then
+                B2_ARGS+=("cxxflags=${{matrix.cxxflags}}")
+            fi
+            if [ -n "${{matrix.linkflags}}" ]
+            then
+                B2_ARGS+=("linkflags=${{matrix.linkflags}}")
+            fi
+            B2_ARGS+=("libs/$LIBRARY/test")
+            ./b2 "${B2_ARGS[@]}"
+
+      - name: Run CMake tests
+        if: matrix.cmake_tests != ''
+        run: |
+            cd ../boost-root
+            export CMAKE_TEST=1
+            mkdir __build_cmake_test__ && cd __build_cmake_test__
+            cmake -DBUILD_TESTING=ON -DBOOST_INCLUDE_LIBRARIES=$LIBRARY ..
+            cmake --build . --target tests
+            ctest --output-on-failure
+
+      - name: Run CMake subdir tests
+        if: matrix.cmake_tests != ''
+        run: |
+            cd ../boost-root
+            export CMAKE_SUBDIR_TEST=1
+            cd libs/$LIBRARY/test/cmake_subdir_test && mkdir __build_cmake_subdir_test__ && cd __build_cmake_subdir_test__
+            cmake ..
+            cmake --build .
+            cmake --build . --target check
+
+      - name: Run CMake install tests
+        if: matrix.cmake_tests != ''
+        run: |
+            cd ../boost-root
+            export CMAKE_INSTALL_TEST=1
+            mkdir __build_cmake_install_test__ && cd __build_cmake_install_test__
+            cmake -DBOOST_INCLUDE_LIBRARIES=$LIBRARY -DCMAKE_INSTALL_PREFIX=~/.local ..
+            cmake --build . --target install
+            cd libs/$LIBRARY/test/cmake_install_test && mkdir __build_cmake_install_test__ && cd __build_cmake_install_test__
+            cmake -DCMAKE_INSTALL_PREFIX=~/.local ..
+            cmake --build .
+            cmake --build . --target check
 
   windows:
     strategy:
@@ -218,27 +346,27 @@ jobs:
       - name: Setup Boost
         shell: cmd
         run: |
-          echo GITHUB_REPOSITORY: %GITHUB_REPOSITORY%
-          for /f %%i in ("%GITHUB_REPOSITORY%") do set LIBRARY=%%~nxi
-          echo LIBRARY: %LIBRARY%
-          echo LIBRARY=%LIBRARY%>>%GITHUB_ENV%
-          echo GITHUB_BASE_REF: %GITHUB_BASE_REF%
-          echo GITHUB_REF: %GITHUB_REF%
-          if "%GITHUB_BASE_REF%" == "" set GITHUB_BASE_REF=%GITHUB_REF%
-          set BOOST_BRANCH=develop
-          for /f %%i in ("%GITHUB_BASE_REF%") do if "%%~nxi" == "master" set BOOST_BRANCH=master
-          echo BOOST_BRANCH: %BOOST_BRANCH%
-          cd ..
-          git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
-          cd boost-root
-          xcopy /s /e /q %GITHUB_WORKSPACE% libs\%LIBRARY%\
-          git submodule update --init tools/boostdep
-          python tools/boostdep/depinst/depinst.py --git_args "--jobs %GIT_FETCH_JOBS%" %LIBRARY%
-          cmd /c bootstrap
-          b2 -d0 headers
+            echo GITHUB_REPOSITORY: %GITHUB_REPOSITORY%
+            for /f %%i in ("%GITHUB_REPOSITORY%") do set LIBRARY=%%~nxi
+            echo LIBRARY: %LIBRARY%
+            echo LIBRARY=%LIBRARY%>>%GITHUB_ENV%
+            echo GITHUB_BASE_REF: %GITHUB_BASE_REF%
+            echo GITHUB_REF: %GITHUB_REF%
+            if "%GITHUB_BASE_REF%" == "" set GITHUB_BASE_REF=%GITHUB_REF%
+            set BOOST_BRANCH=develop
+            for /f %%i in ("%GITHUB_BASE_REF%") do if "%%~nxi" == "master" set BOOST_BRANCH=master
+            echo BOOST_BRANCH: %BOOST_BRANCH%
+            cd ..
+            git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
+            cd boost-root
+            xcopy /s /e /q %GITHUB_WORKSPACE% libs\%LIBRARY%\
+            git submodule update --init tools/boostdep
+            python tools/boostdep/depinst/depinst.py --git_args "--jobs %GIT_FETCH_JOBS%" %LIBRARY%
+            cmd /c bootstrap
+            b2 -d0 headers
 
       - name: Run tests
         shell: cmd
         run: |
-          cd ../boost-root
-          b2 -j %NUMBER_OF_PROCESSORS% libs/%LIBRARY%/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} variant=debug,release
+            cd ../boost-root
+            b2 -j %NUMBER_OF_PROCESSORS% libs/%LIBRARY%/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} variant=debug,release