g++ 4.7 doesn't have std::is_trivially_destructible

Use variant=release for variant_visit_r under g++/windows
Add .github/workflows
2025-12-23 15:18:10 +01:00 · 2021-01-13 04:51:27 +02:00 · 2021-01-13 04:44:56 +02:00 · 2021-01-13 04:19:15 +02:00 · 2021-01-13 02:32:05 +02:00 · 2020-12-16 18:45:01 +02:00
27 changed files with 1737 additions and 227 deletions
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,201 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - develop
+      - feature/**
+
+env:
+  UBSAN_OPTIONS: print_stacktrace=1
+
+jobs:
+  posix:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - toolset: gcc-4.7
+            cxxstd: "03,11"
+            os: ubuntu-16.04
+            install: g++-4.7
+          - toolset: gcc-4.8
+            cxxstd: "03,11"
+            os: ubuntu-16.04
+            install: g++-4.8
+          - toolset: gcc-4.9
+            cxxstd: "03,11"
+            os: ubuntu-16.04
+            install: g++-4.9
+          - toolset: gcc-5
+            cxxstd: "03,11,14,1z"
+            os: ubuntu-16.04
+          - toolset: gcc-6
+            cxxstd: "03,11,14,1z"
+            os: ubuntu-16.04
+            install: g++-6
+          - toolset: gcc-7
+            cxxstd: "03,11,14,17"
+            os: ubuntu-18.04
+          - toolset: gcc-8
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-18.04
+          - toolset: gcc-9
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-18.04
+          - toolset: gcc-10
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-18.04
+          - toolset: clang
+            compiler: clang++-3.5
+            cxxstd: "03,11,14"
+            os: ubuntu-16.04
+            install: clang-3.5
+          - toolset: clang
+            compiler: clang++-3.6
+            cxxstd: "03,11,14"
+            os: ubuntu-16.04
+            install: clang-3.6
+          - toolset: clang
+            compiler: clang++-3.7
+            cxxstd: "03,11,14"
+            os: ubuntu-16.04
+            install: clang-3.7
+          - toolset: clang
+            compiler: clang++-3.8
+            cxxstd: "03,11,14"
+            os: ubuntu-16.04
+            install: clang-3.8
+          - toolset: clang
+            compiler: clang++-3.9
+            cxxstd: "03,11,14"
+            os: ubuntu-16.04
+            install: clang-3.9
+          - toolset: clang
+            compiler: clang++-4.0
+            cxxstd: "03,11,14"
+            os: ubuntu-16.04
+            install: clang-4.0
+          - toolset: clang
+            compiler: clang++-5.0
+            cxxstd: "03,11,14,1z"
+            os: ubuntu-16.04
+            install: clang-5.0
+          - toolset: clang
+            compiler: clang++-6.0
+            cxxstd: "03,11,14,17"
+            os: ubuntu-18.04
+          - toolset: clang
+            compiler: clang++-7
+            cxxstd: "03,11,14,17"
+            os: ubuntu-18.04
+            install: clang-7
+          - toolset: clang
+            compiler: clang++-8
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-20.04
+          - toolset: clang
+            compiler: clang++-9
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-20.04
+          - toolset: clang
+            compiler: clang++-10
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-20.04
+          - toolset: clang
+            cxxstd: "03,11,14,17,2a"
+            os: macos-10.15
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install packages
+        if: matrix.install
+        run: sudo apt install ${{matrix.install}}
+
+      - 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
+          cp -r $GITHUB_WORKSPACE/* libs/$LIBRARY
+          git submodule update --init tools/boostdep
+          python tools/boostdep/depinst/depinst.py --git_args "--jobs 3" $LIBRARY
+          ./bootstrap.sh
+          ./b2 -d0 headers
+
+      - name: Create user-config.jam
+        if: matrix.compiler
+        run: |
+          echo "using ${{matrix.toolset}} : : ${{matrix.compiler}} ;" > ~/user-config.jam
+
+      - name: Run tests
+        run: |
+          cd ../boost-root
+          ./b2 -j3 libs/$LIBRARY/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} variant=debug,release
+
+  windows:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - toolset: msvc-14.1
+            cxxstd: "14,17,latest"
+            addrmd: 32,64
+            os: windows-2016
+          - toolset: msvc-14.2
+            cxxstd: "14,17,latest"
+            addrmd: 32,64
+            os: windows-2019
+          - toolset: gcc
+            cxxstd: "03,11,14,17,2a"
+            addrmd: 64
+            os: windows-2019
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Setup Boost
+        shell: cmd
+        run: |
+          echo GITHUB_REPOSITORY: %GITHUB_REPOSITORY%
+          for /f %%i in ("%GITHUB_REPOSITORY%") do set LIBRARY=%%~nxi
+          echo LIBRARY: %LIBRARY%
+          echo LIBRARY=%LIBRARY%>>%GITHUB_ENV%
+          echo GITHUB_BASE_REF: %GITHUB_BASE_REF%
+          echo GITHUB_REF: %GITHUB_REF%
+          if "%GITHUB_BASE_REF%" == "" set GITHUB_BASE_REF=%GITHUB_REF%
+          set BOOST_BRANCH=develop
+          for /f %%i in ("%GITHUB_BASE_REF%") do if "%%~nxi" == "master" set BOOST_BRANCH=master
+          echo BOOST_BRANCH: %BOOST_BRANCH%
+          cd ..
+          git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          xcopy /s /e /q %GITHUB_WORKSPACE% libs\%LIBRARY%\
+          git submodule update --init tools/boostdep
+          python tools/boostdep/depinst/depinst.py --git_args "--jobs 3" %LIBRARY%
+          cmd /c bootstrap
+          b2 -d0 headers
+
+      - name: Run tests
+        shell: cmd
+        run: |
+          cd ../boost-root
+          b2 -j3 libs/%LIBRARY%/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} variant=debug,release
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,9 +4,7 @@

 language: cpp

-sudo: false
-
-dist: trusty
+dist: xenial

 branches:
  only:
@@ -25,8 +23,14 @@ matrix:

  include:
    - os: linux
-      compiler: g++
-      env: TOOLSET=gcc COMPILER=g++ CXXSTD=11
+      compiler: g++-4.8
+      env: TOOLSET=gcc COMPILER=g++-4.8 CXXSTD=11
+      addons:
+        apt:
+          packages:
+            - g++-4.8
+          sources:
+            - ubuntu-toolchain-r-test

    - os: linux
      compiler: g++-4.9
@@ -88,6 +92,17 @@ matrix:
          sources:
            - ubuntu-toolchain-r-test

+    - os: linux
+      dist: bionic
+      compiler: g++-10
+      env: TOOLSET=gcc COMPILER=g++-10 CXXSTD=11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - g++-10
+          sources:
+            - ubuntu-toolchain-r-test
+
    - os: linux
      compiler: g++-8
      env: UBSAN=1 TOOLSET=gcc COMPILER=g++-8 CXXSTD=11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1 LINKFLAGS=-fuse-ld=gold
@@ -98,6 +113,11 @@ matrix:
          sources:
            - ubuntu-toolchain-r-test

+    - os: linux
+      dist: trusty
+      compiler: clang++
+      env: DIST=trusty TOOLSET=clang COMPILER=clang++ CXXSTD=11,14,1z
+
    - os: linux
      compiler: clang++-3.5
      env: TOOLSET=clang COMPILER=clang++-3.5 CXXSTD=11,14,1z
@@ -108,7 +128,6 @@ matrix:
            - libstdc++-4.9-dev
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.5

    - os: linux
      compiler: clang++-3.6
@@ -119,7 +138,6 @@ matrix:
            - clang-3.6
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.6

    - os: linux
      compiler: clang++-3.7
@@ -130,7 +148,6 @@ matrix:
            - clang-3.7
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.7

    - os: linux
      compiler: clang++-3.8
@@ -141,7 +158,6 @@ matrix:
            - clang-3.8
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.8

    - os: linux
      compiler: clang++-3.9
@@ -152,7 +168,6 @@ matrix:
            - clang-3.9
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.9

    - os: linux
      compiler: clang++-4.0
@@ -163,7 +178,6 @@ matrix:
            - clang-4.0
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-4.0

    - os: linux
      compiler: clang++-5.0
@@ -174,7 +188,6 @@ matrix:
            - clang-5.0
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-5.0

    - os: linux
      compiler: clang++-6.0
@@ -185,7 +198,6 @@ matrix:
            - clang-6.0
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-6.0

    - os: linux
      compiler: clang++-7
@@ -196,7 +208,7 @@ matrix:
            - clang-7
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-7
+            - llvm-toolchain-xenial-7

    - os: linux
      compiler: clang++-8
@@ -207,20 +219,47 @@ matrix:
            - clang-8
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-8
+            - llvm-toolchain-xenial-8

    - os: linux
-      compiler: clang++-6.0
-      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-6.0 CXXSTD=11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1
+      dist: xenial
+      compiler: clang++-9
+      env: TOOLSET=clang COMPILER=clang++-9 CXXSTD=11,14,17,2a
      addons:
        apt:
          packages:
-            - clang-6.0
+            - clang-9
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-6.0
+            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'

    - os: linux
+      dist: xenial
+      compiler: clang++-10
+      env: TOOLSET=clang COMPILER=clang++-10 CXXSTD=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++-8
+      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-8 CXXSTD=11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1
+      addons:
+        apt:
+          packages:
+            - clang-8
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-xenial-8
+
+    - os: linux
+      dist: trusty
      compiler: clang++-libc++
      env: TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=11,14,1z
      addons:
@@ -229,6 +268,7 @@ matrix:
            - libc++-dev

    - os: linux
+      dist: trusty
      compiler: clang++-libc++
      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=11,14,1z UBSAN_OPTIONS=print_stacktrace=1
      addons:
@@ -240,22 +280,48 @@ matrix:
      compiler: clang++
      env: TOOLSET=clang COMPILER=clang++ CXXSTD=11,14,1z

+    - os: osx
+      compiler: clang++
+      env: UBSAN=1 TOOLSET=clang COMPILER=clang++ CXXSTD=11,14,1z UBSAN_OPTIONS=print_stacktrace=1
+
    - os: linux
-      compiler: g++
-      env: CMAKE_SUBDIR_TEST=1
+      env: CMAKE_TEST=1
      script:
-      - cd libs/variant2/test/cmake_subdir_test && mkdir __build__ && cd __build__
+        - mkdir __build__ && cd __build__
+        - cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=variant2 ..
+        - ctest --output-on-failure -R boost_variant2
+
+    - os: linux
+      env: CMAKE_SUBDIR_TEST=1
+      install:
+        - BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+        - git clone -b $BOOST_BRANCH https://github.com/boostorg/assert.git ../assert
+        - git clone -b $BOOST_BRANCH https://github.com/boostorg/config.git ../config
+        - git clone -b $BOOST_BRANCH https://github.com/boostorg/core.git ../core
+        - git clone -b $BOOST_BRANCH https://github.com/boostorg/mp11.git ../mp11
+      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:
+        - pip install --user cmake
+        - mkdir __build__ && cd __build__
+        - cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=variant2 -DCMAKE_INSTALL_PREFIX=~/.local ..
+        - cmake --build . --target install
+        - cd ../libs/variant2/test/cmake_install_test && mkdir __build__ && cd __build__
+        - cmake -DCMAKE_INSTALL_PREFIX=~/.local ..
+        - cmake --build .
+        - cmake --build . --target check
+
 install:
  - BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
  - cd ..
  - git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
  - cd boost-root
-  - git submodule update --init tools/build
-  - git submodule update --init libs/config
  - git submodule update --init tools/boostdep
  - mkdir -p libs/variant2
  - cp -r $TRAVIS_BUILD_DIR/* libs/variant2
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,12 +2,9 @@
 # Distributed under the Boost Software License, Version 1.0.
 # http://www.boost.org/LICENSE_1_0.txt

-# Partial (add_subdirectory only) and experimental CMake support
-# Subject to change; please do not rely on the contents of this file yet
+cmake_minimum_required(VERSION 3.5...3.16)

-cmake_minimum_required(VERSION 3.5)
-
-project(BoostVariant2 LANGUAGES CXX)
+project(boost_variant2 VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)

 add_library(boost_variant2 INTERFACE)
 add_library(Boost::variant2 ALIAS boost_variant2)
@@ -15,7 +12,13 @@ add_library(Boost::variant2 ALIAS boost_variant2)
 target_include_directories(boost_variant2 INTERFACE include)

 target_link_libraries(boost_variant2
-    INTERFACE
-        Boost::config
-        Boost::mp11
+  INTERFACE
+    Boost::config
+    Boost::mp11
 )
+
+if(BUILD_TESTING)
+
+  add_subdirectory(test)
+
+endif()
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,4 +1,4 @@
-# Copyright 2016-2018 Peter Dimov
+# Copyright 2016-2020 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)

@@ -21,6 +21,14 @@ environment:
      TOOLSET: msvc-14.1
      ADDRMD: 32,64
      CXXSTD: 14,17
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      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

 install:
  - set BOOST_BRANCH=develop
@@ -28,8 +36,6 @@ install:
  - cd ..
  - git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
  - cd boost-root
-  - git submodule update --init tools/build
-  - git submodule update --init libs/config
  - git submodule update --init tools/boostdep
  - xcopy /s /e /q %APPVEYOR_BUILD_FOLDER% libs\variant2\
  - python tools/boostdep/depinst/depinst.py variant2
@@ -41,4 +47,4 @@ build: off
 test_script:
  - if not "%CXXSTD%" == "" set CXXSTD=cxxstd=%CXXSTD%
  - if not "%ADDRMD%" == "" set ADDRMD=address-model=%ADDRMD%
-  - b2 libs/variant2/test toolset=%TOOLSET% %CXXSTD% %ADDRMD% variant=debug,release
+  - b2 -j3 libs/variant2/test toolset=%TOOLSET% %CXXSTD% %ADDRMD% variant=debug,release
--- a/doc/variant2/changelog.adoc
+++ b/doc/variant2/changelog.adoc
@@ -1,5 +1,5 @@
 ////
-Copyright 2019 Peter Dimov
+Copyright 2019, 2020 Peter Dimov

 Distributed under the Boost Software License, Version 1.0.

@@ -11,6 +11,19 @@ http://www.boost.org/LICENSE_1_0.txt
 # Revision History
 :idprefix: changelog_

+## Changes in 1.74.0
+
+* Added support for derived types in `visit`
+* Improved compilation performance for many (hundreds of) alternatives.
+* Added support for `visit<R>`
+
+## Changes in 1.73.0
+
+* Added support for `std::hash`, `boost::hash`.
+* `variant<T...>` is now trivial when all types in `T...` are trivial.
+  This improves performance by enabling it to be passed to, and returned
+  from, functions in registers.
+
 ## Changes in 1.71.0

 After the Boost formal review, the implementation has been
--- a/doc/variant2/design.adoc
+++ b/doc/variant2/design.adoc
@@ -169,8 +169,6 @@ The main differences between this implementation and `std::variant` are:
  `variant<int, float>` is provided as the member function `subset<U...>`.
  (This operation can throw if the current state of the variant cannot be
  represented.)
-* `variant<T...>` is not (yet) trivial when all contained types are trivial,
-   as mandated by {cpp}17.
 * The {cpp}20 additions and changes to `std::variant` have not yet been
  implemented.

--- a/doc/variant2/reference.adoc
+++ b/doc/variant2/reference.adoc
@@ -134,7 +134,7 @@ template<class... T>

 // visit

-template<class F, class... V>
+template<class R = /*unspecified*/, class F, class... V>
  constexpr /*see below*/ visit(F&& f, V&&... v);

 // monostate
@@ -838,7 +838,7 @@ Returns: ::
 ### visit

 ```
-template<class F, class... V>
+template<class R = /*unspecified*/, class F, class... V>
  constexpr /*see below*/ visit(F&& f, V&&... v);
 ```
 [none]
@@ -846,6 +846,10 @@ template<class F, class... V>
 +
 Returns: :: `std::forward<F>(f)(get<I>(std::forward<V>(v))...)`, where
  `I...` is `v.index()...`.
+Remarks: :: If `R` is given explicitly, as in `visit<int>`, the return
+  type is `R`. Otherwise, it's deduced from `F`. All possible applications
+  of `F` to the variant alternatives must have the same return type for
+  this deduction to succeed.

 ### swap

--- a/include/boost/variant2/variant.hpp
+++ b/include/boost/variant2/variant.hpp
@@ -18,12 +18,14 @@
 #endif
 #include <boost/config.hpp>
 #include <boost/detail/workaround.hpp>
+#include <boost/cstdint.hpp>
 #include <cstddef>
 #include <type_traits>
 #include <exception>
 #include <cassert>
 #include <initializer_list>
 #include <utility>
+#include <functional> // std::hash

 //

@@ -502,11 +504,23 @@ using std::is_trivially_move_assignable;

 #endif

+#if defined( BOOST_LIBSTDCXX_VERSION ) && BOOST_LIBSTDCXX_VERSION < 40800
+
+template<class T> struct is_trivially_destructible: std::has_trivial_destructor<T>
+{
+};
+
+#else
+
+using std::is_trivially_destructible;
+
+#endif
+
 // variant_storage

 template<class D, class... T> union variant_storage_impl;

-template<class... T> using variant_storage = variant_storage_impl<mp11::mp_all<std::is_trivially_destructible<T>...>, T...>;
+template<class... T> using variant_storage = variant_storage_impl<mp11::mp_all<detail::is_trivially_destructible<T>...>, T...>;

 template<class D> union variant_storage_impl<D>
 {
@@ -547,6 +561,88 @@ template<class T1, class... T> union variant_storage_impl<mp11::mp_false, T1, T.
    template<std::size_t I> constexpr mp11::mp_at_c<mp11::mp_list<T...>, I-1> const& get( mp11::mp_size_t<I> ) const noexcept { return rest_.get( mp11::mp_size_t<I-1>() ); }
 };

+template<class T0, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class... T> union variant_storage_impl<mp11::mp_false, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T...>
+{
+    T0 t0_;
+    T1 t1_;
+    T2 t2_;
+    T3 t3_;
+    T4 t4_;
+    T5 t5_;
+    T6 t6_;
+    T7 t7_;
+    T8 t8_;
+    T9 t9_;
+
+    variant_storage<T...> rest_;
+
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<0>, A&&... a ): t0_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<1>, A&&... a ): t1_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<2>, A&&... a ): t2_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<3>, A&&... a ): t3_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<4>, A&&... a ): t4_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<5>, A&&... a ): t5_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<6>, A&&... a ): t6_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<7>, A&&... a ): t7_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<8>, A&&... a ): t8_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<9>, A&&... a ): t9_( std::forward<A>(a)... ) {}
+
+    template<std::size_t I, class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<I>, A&&... a ): rest_( mp11::mp_size_t<I-10>(), std::forward<A>(a)... ) {}
+
+    ~variant_storage_impl()
+    {
+    }
+
+    template<class... A> void emplace( mp11::mp_size_t<0>, A&&... a ) { ::new( &t0_ ) T0( std::forward<A>(a)... ); }
+    template<class... A> void emplace( mp11::mp_size_t<1>, A&&... a ) { ::new( &t1_ ) T1( std::forward<A>(a)... ); }
+    template<class... A> void emplace( mp11::mp_size_t<2>, A&&... a ) { ::new( &t2_ ) T2( std::forward<A>(a)... ); }
+    template<class... A> void emplace( mp11::mp_size_t<3>, A&&... a ) { ::new( &t3_ ) T3( std::forward<A>(a)... ); }
+    template<class... A> void emplace( mp11::mp_size_t<4>, A&&... a ) { ::new( &t4_ ) T4( std::forward<A>(a)... ); }
+    template<class... A> void emplace( mp11::mp_size_t<5>, A&&... a ) { ::new( &t5_ ) T5( std::forward<A>(a)... ); }
+    template<class... A> void emplace( mp11::mp_size_t<6>, A&&... a ) { ::new( &t6_ ) T6( std::forward<A>(a)... ); }
+    template<class... A> void emplace( mp11::mp_size_t<7>, A&&... a ) { ::new( &t7_ ) T7( std::forward<A>(a)... ); }
+    template<class... A> void emplace( mp11::mp_size_t<8>, A&&... a ) { ::new( &t8_ ) T8( std::forward<A>(a)... ); }
+    template<class... A> void emplace( mp11::mp_size_t<9>, A&&... a ) { ::new( &t9_ ) T9( std::forward<A>(a)... ); }
+
+    template<std::size_t I, class... A> void emplace( mp11::mp_size_t<I>, A&&... a )
+    {
+        rest_.emplace( mp11::mp_size_t<I-10>(), std::forward<A>(a)... );
+    }
+
+    BOOST_CXX14_CONSTEXPR T0& get( mp11::mp_size_t<0> ) noexcept { return t0_; }
+    constexpr T0 const& get( mp11::mp_size_t<0> ) const noexcept { return t0_; }
+
+    BOOST_CXX14_CONSTEXPR T1& get( mp11::mp_size_t<1> ) noexcept { return t1_; }
+    constexpr T1 const& get( mp11::mp_size_t<1> ) const noexcept { return t1_; }
+
+    BOOST_CXX14_CONSTEXPR T2& get( mp11::mp_size_t<2> ) noexcept { return t2_; }
+    constexpr T2 const& get( mp11::mp_size_t<2> ) const noexcept { return t2_; }
+
+    BOOST_CXX14_CONSTEXPR T3& get( mp11::mp_size_t<3> ) noexcept { return t3_; }
+    constexpr T3 const& get( mp11::mp_size_t<3> ) const noexcept { return t3_; }
+
+    BOOST_CXX14_CONSTEXPR T4& get( mp11::mp_size_t<4> ) noexcept { return t4_; }
+    constexpr T4 const& get( mp11::mp_size_t<4> ) const noexcept { return t4_; }
+
+    BOOST_CXX14_CONSTEXPR T5& get( mp11::mp_size_t<5> ) noexcept { return t5_; }
+    constexpr T5 const& get( mp11::mp_size_t<5> ) const noexcept { return t5_; }
+
+    BOOST_CXX14_CONSTEXPR T6& get( mp11::mp_size_t<6> ) noexcept { return t6_; }
+    constexpr T6 const& get( mp11::mp_size_t<6> ) const noexcept { return t6_; }
+
+    BOOST_CXX14_CONSTEXPR T7& get( mp11::mp_size_t<7> ) noexcept { return t7_; }
+    constexpr T7 const& get( mp11::mp_size_t<7> ) const noexcept { return t7_; }
+
+    BOOST_CXX14_CONSTEXPR T8& get( mp11::mp_size_t<8> ) noexcept { return t8_; }
+    constexpr T8 const& get( mp11::mp_size_t<8> ) const noexcept { return t8_; }
+
+    BOOST_CXX14_CONSTEXPR T9& get( mp11::mp_size_t<9> ) noexcept { return t9_; }
+    constexpr T9 const& get( mp11::mp_size_t<9> ) const noexcept { return t9_; }
+
+    template<std::size_t I> BOOST_CXX14_CONSTEXPR mp11::mp_at_c<mp11::mp_list<T...>, I-10>& get( mp11::mp_size_t<I> ) noexcept { return rest_.get( mp11::mp_size_t<I-10>() ); }
+    template<std::size_t I> constexpr mp11::mp_at_c<mp11::mp_list<T...>, I-10> const& get( mp11::mp_size_t<I> ) const noexcept { return rest_.get( mp11::mp_size_t<I-10>() ); }
+};
+
 // all trivially destructible
 template<class T1, class... T> union variant_storage_impl<mp11::mp_true, T1, T...>
 {
@@ -588,6 +684,105 @@ template<class T1, class... T> union variant_storage_impl<mp11::mp_true, T1, T..
    template<std::size_t I> constexpr mp11::mp_at_c<mp11::mp_list<T...>, I-1> const& get( mp11::mp_size_t<I> ) const noexcept { return rest_.get( mp11::mp_size_t<I-1>() ); }
 };

+template<class T0, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class... T> union variant_storage_impl<mp11::mp_true, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T...>
+{
+    T0 t0_;
+    T1 t1_;
+    T2 t2_;
+    T3 t3_;
+    T4 t4_;
+    T5 t5_;
+    T6 t6_;
+    T7 t7_;
+    T8 t8_;
+    T9 t9_;
+
+    variant_storage<T...> rest_;
+
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<0>, A&&... a ): t0_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<1>, A&&... a ): t1_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<2>, A&&... a ): t2_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<3>, A&&... a ): t3_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<4>, A&&... a ): t4_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<5>, A&&... a ): t5_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<6>, A&&... a ): t6_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<7>, A&&... a ): t7_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<8>, A&&... a ): t8_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<9>, A&&... a ): t9_( std::forward<A>(a)... ) {}
+
+    template<std::size_t I, class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<I>, A&&... a ): rest_( mp11::mp_size_t<I-10>(), std::forward<A>(a)... ) {}
+
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<0>, A&&... a ) { ::new( &t0_ ) T0( std::forward<A>(a)... ); }
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<1>, A&&... a ) { ::new( &t1_ ) T1( std::forward<A>(a)... ); }
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<2>, A&&... a ) { ::new( &t2_ ) T2( std::forward<A>(a)... ); }
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<3>, A&&... a ) { ::new( &t3_ ) T3( std::forward<A>(a)... ); }
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<4>, A&&... a ) { ::new( &t4_ ) T4( std::forward<A>(a)... ); }
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<5>, A&&... a ) { ::new( &t5_ ) T5( std::forward<A>(a)... ); }
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<6>, A&&... a ) { ::new( &t6_ ) T6( std::forward<A>(a)... ); }
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<7>, A&&... a ) { ::new( &t7_ ) T7( std::forward<A>(a)... ); }
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<8>, A&&... a ) { ::new( &t8_ ) T8( std::forward<A>(a)... ); }
+    template<class... A> void emplace_impl( mp11::mp_false, mp11::mp_size_t<9>, A&&... a ) { ::new( &t9_ ) T9( std::forward<A>(a)... ); }
+
+    template<std::size_t I, class... A> BOOST_CXX14_CONSTEXPR void emplace_impl( mp11::mp_false, mp11::mp_size_t<I>, A&&... a )
+    {
+        rest_.emplace( mp11::mp_size_t<I-10>(), std::forward<A>(a)... );
+    }
+
+    template<std::size_t I, class... A> BOOST_CXX14_CONSTEXPR void emplace_impl( mp11::mp_true, mp11::mp_size_t<I>, A&&... a )
+    {
+        *this = variant_storage_impl( mp11::mp_size_t<I>(), std::forward<A>(a)... );
+    }
+
+    template<std::size_t I, class... A> BOOST_CXX14_CONSTEXPR void emplace( mp11::mp_size_t<I>, A&&... a )
+    {
+        this->emplace_impl( mp11::mp_all<
+            detail::is_trivially_move_assignable<T0>,
+            detail::is_trivially_move_assignable<T1>,
+            detail::is_trivially_move_assignable<T2>,
+            detail::is_trivially_move_assignable<T3>,
+            detail::is_trivially_move_assignable<T4>,
+            detail::is_trivially_move_assignable<T5>,
+            detail::is_trivially_move_assignable<T6>,
+            detail::is_trivially_move_assignable<T7>,
+            detail::is_trivially_move_assignable<T8>,
+            detail::is_trivially_move_assignable<T9>,
+            detail::is_trivially_move_assignable<T>...>(), mp11::mp_size_t<I>(), std::forward<A>(a)... );
+    }
+
+    BOOST_CXX14_CONSTEXPR T0& get( mp11::mp_size_t<0> ) noexcept { return t0_; }
+    constexpr T0 const& get( mp11::mp_size_t<0> ) const noexcept { return t0_; }
+
+    BOOST_CXX14_CONSTEXPR T1& get( mp11::mp_size_t<1> ) noexcept { return t1_; }
+    constexpr T1 const& get( mp11::mp_size_t<1> ) const noexcept { return t1_; }
+
+    BOOST_CXX14_CONSTEXPR T2& get( mp11::mp_size_t<2> ) noexcept { return t2_; }
+    constexpr T2 const& get( mp11::mp_size_t<2> ) const noexcept { return t2_; }
+
+    BOOST_CXX14_CONSTEXPR T3& get( mp11::mp_size_t<3> ) noexcept { return t3_; }
+    constexpr T3 const& get( mp11::mp_size_t<3> ) const noexcept { return t3_; }
+
+    BOOST_CXX14_CONSTEXPR T4& get( mp11::mp_size_t<4> ) noexcept { return t4_; }
+    constexpr T4 const& get( mp11::mp_size_t<4> ) const noexcept { return t4_; }
+
+    BOOST_CXX14_CONSTEXPR T5& get( mp11::mp_size_t<5> ) noexcept { return t5_; }
+    constexpr T5 const& get( mp11::mp_size_t<5> ) const noexcept { return t5_; }
+
+    BOOST_CXX14_CONSTEXPR T6& get( mp11::mp_size_t<6> ) noexcept { return t6_; }
+    constexpr T6 const& get( mp11::mp_size_t<6> ) const noexcept { return t6_; }
+
+    BOOST_CXX14_CONSTEXPR T7& get( mp11::mp_size_t<7> ) noexcept { return t7_; }
+    constexpr T7 const& get( mp11::mp_size_t<7> ) const noexcept { return t7_; }
+
+    BOOST_CXX14_CONSTEXPR T8& get( mp11::mp_size_t<8> ) noexcept { return t8_; }
+    constexpr T8 const& get( mp11::mp_size_t<8> ) const noexcept { return t8_; }
+
+    BOOST_CXX14_CONSTEXPR T9& get( mp11::mp_size_t<9> ) noexcept { return t9_; }
+    constexpr T9 const& get( mp11::mp_size_t<9> ) const noexcept { return t9_; }
+
+    template<std::size_t I> BOOST_CXX14_CONSTEXPR mp11::mp_at_c<mp11::mp_list<T...>, I-10>& get( mp11::mp_size_t<I> ) noexcept { return rest_.get( mp11::mp_size_t<I-10>() ); }
+    template<std::size_t I> constexpr mp11::mp_at_c<mp11::mp_list<T...>, I-10> const& get( mp11::mp_size_t<I> ) const noexcept { return rest_.get( mp11::mp_size_t<I-10>() ); }
+};
+
 // resolve_overload_*

 template<class... T> struct overload;
@@ -624,7 +819,7 @@ template<class U, class... T> using resolve_overload_index = mp11::mp_find<mp11:
 // variant_base

 template<bool is_trivially_destructible, bool is_single_buffered, class... T> struct variant_base_impl;
-template<class... T> using variant_base = variant_base_impl<mp11::mp_all<std::is_trivially_destructible<T>...>::value, mp11::mp_all<std::is_nothrow_move_constructible<T>...>::value, T...>;
+template<class... T> using variant_base = variant_base_impl<mp11::mp_all<detail::is_trivially_destructible<T>...>::value, mp11::mp_all<std::is_nothrow_move_constructible<T>...>::value, T...>;

 struct none {};

@@ -1050,20 +1245,317 @@ template<class T> struct is_nothrow_swappable: mp11::mp_valid<det2::is_nothrow_s

 #endif

+// variant_cc_base
+
+template<bool CopyConstructible, bool TriviallyCopyConstructible, class... T> struct variant_cc_base_impl;
+
+template<class... T> using variant_cc_base = variant_cc_base_impl<
+    mp11::mp_all<std::is_copy_constructible<T>...>::value,
+    mp11::mp_all<detail::is_trivially_copy_constructible<T>...>::value,
+    T...>;
+
+template<class... T> struct variant_cc_base_impl<true, true, T...>: public variant_base<T...>
+{
+    using variant_base = detail::variant_base<T...>;
+    using variant_base::variant_base;
+
+    variant_cc_base_impl() = default;
+    variant_cc_base_impl( variant_cc_base_impl const& ) = default;
+    variant_cc_base_impl( variant_cc_base_impl && ) = default;
+    variant_cc_base_impl& operator=( variant_cc_base_impl const& ) = default;
+    variant_cc_base_impl& operator=( variant_cc_base_impl && ) = default;
+};
+
+template<bool B, class... T> struct variant_cc_base_impl<false, B, T...>: public variant_base<T...>
+{
+    using variant_base = detail::variant_base<T...>;
+    using variant_base::variant_base;
+
+    variant_cc_base_impl() = default;
+    variant_cc_base_impl( variant_cc_base_impl const& ) = delete;
+    variant_cc_base_impl( variant_cc_base_impl && ) = default;
+    variant_cc_base_impl& operator=( variant_cc_base_impl const& ) = default;
+    variant_cc_base_impl& operator=( variant_cc_base_impl && ) = default;
+};
+
+template<class... T> struct variant_cc_base_impl<true, false, T...>: public variant_base<T...>
+{
+    using variant_base = detail::variant_base<T...>;
+    using variant_base::variant_base;
+
+public:
+
+    // constructors
+
+    variant_cc_base_impl() = default;
+
+    // copy constructor
+
+private:
+
+    struct L1
+    {
+        variant_base * this_;
+        variant_base const & r;
+
+        template<class I> void operator()( I i ) const
+        {
+            this_->_replace( i, r._get_impl( i ) );
+        }
+    };
+
+public:
+
+    variant_cc_base_impl( variant_cc_base_impl const& r )
+        noexcept( mp11::mp_all<std::is_nothrow_copy_constructible<T>...>::value )
+        : variant_base()
+    {
+        mp11::mp_with_index<sizeof...(T)>( r.index(), L1{ this, r } );
+    }
+
+    // move constructor
+
+    variant_cc_base_impl( variant_cc_base_impl && ) = default;
+
+    // assignment
+
+    variant_cc_base_impl& operator=( variant_cc_base_impl const & ) = default;
+    variant_cc_base_impl& operator=( variant_cc_base_impl && ) = default;
+};
+
+// variant_ca_base
+
+template<bool CopyAssignable, bool TriviallyCopyAssignable, class... T> struct variant_ca_base_impl;
+
+template<class... T> using variant_ca_base = variant_ca_base_impl<
+    mp11::mp_all<std::is_copy_constructible<T>..., std::is_copy_assignable<T>...>::value,
+    mp11::mp_all<detail::is_trivially_destructible<T>..., detail::is_trivially_copy_constructible<T>..., detail::is_trivially_copy_assignable<T>...>::value,
+    T...>;
+
+template<class... T> struct variant_ca_base_impl<true, true, T...>: public variant_cc_base<T...>
+{
+    using variant_base = detail::variant_cc_base<T...>;
+    using variant_base::variant_base;
+
+    variant_ca_base_impl() = default;
+    variant_ca_base_impl( variant_ca_base_impl const& ) = default;
+    variant_ca_base_impl( variant_ca_base_impl && ) = default;
+    variant_ca_base_impl& operator=( variant_ca_base_impl const& ) = default;
+    variant_ca_base_impl& operator=( variant_ca_base_impl && ) = default;
+};
+
+template<bool B, class... T> struct variant_ca_base_impl<false, B, T...>: public variant_cc_base<T...>
+{
+    using variant_base = detail::variant_cc_base<T...>;
+    using variant_base::variant_base;
+
+    variant_ca_base_impl() = default;
+    variant_ca_base_impl( variant_ca_base_impl const& ) = default;
+    variant_ca_base_impl( variant_ca_base_impl && ) = default;
+    variant_ca_base_impl& operator=( variant_ca_base_impl const& ) = delete;
+    variant_ca_base_impl& operator=( variant_ca_base_impl && ) = default;
+};
+
+template<class... T> struct variant_ca_base_impl<true, false, T...>: public variant_cc_base<T...>
+{
+    using variant_base = detail::variant_cc_base<T...>;
+    using variant_base::variant_base;
+
+public:
+
+    // constructors
+
+    variant_ca_base_impl() = default;
+    variant_ca_base_impl( variant_ca_base_impl const& ) = default;
+    variant_ca_base_impl( variant_ca_base_impl && ) = default;
+
+    // copy assignment
+
+private:
+
+    struct L3
+    {
+        variant_base * this_;
+        variant_base const & r;
+
+        template<class I> void operator()( I i ) const
+        {
+            this_->template emplace<I::value>( r._get_impl( i ) );
+        }
+    };
+
+public:
+
+    BOOST_CXX14_CONSTEXPR variant_ca_base_impl& operator=( variant_ca_base_impl const & r )
+        noexcept( mp11::mp_all<std::is_nothrow_copy_constructible<T>...>::value )
+    {
+        mp11::mp_with_index<sizeof...(T)>( r.index(), L3{ this, r } );
+        return *this;
+    }
+
+    // move assignment
+
+    variant_ca_base_impl& operator=( variant_ca_base_impl && ) = default;
+};
+
+// variant_mc_base
+
+template<bool MoveConstructible, bool TriviallyMoveConstructible, class... T> struct variant_mc_base_impl;
+
+template<class... T> using variant_mc_base = variant_mc_base_impl<
+    mp11::mp_all<std::is_move_constructible<T>...>::value,
+    mp11::mp_all<detail::is_trivially_move_constructible<T>...>::value,
+    T...>;
+
+template<class... T> struct variant_mc_base_impl<true, true, T...>: public variant_ca_base<T...>
+{
+    using variant_base = detail::variant_ca_base<T...>;
+    using variant_base::variant_base;
+
+    variant_mc_base_impl() = default;
+    variant_mc_base_impl( variant_mc_base_impl const& ) = default;
+    variant_mc_base_impl( variant_mc_base_impl && ) = default;
+    variant_mc_base_impl& operator=( variant_mc_base_impl const& ) = default;
+    variant_mc_base_impl& operator=( variant_mc_base_impl && ) = default;
+};
+
+template<bool B, class... T> struct variant_mc_base_impl<false, B, T...>: public variant_ca_base<T...>
+{
+    using variant_base = detail::variant_ca_base<T...>;
+    using variant_base::variant_base;
+
+    variant_mc_base_impl() = default;
+    variant_mc_base_impl( variant_mc_base_impl const& ) = default;
+    variant_mc_base_impl( variant_mc_base_impl && ) = delete;
+    variant_mc_base_impl& operator=( variant_mc_base_impl const& ) = default;
+    variant_mc_base_impl& operator=( variant_mc_base_impl && ) = default;
+};
+
+template<class... T> struct variant_mc_base_impl<true, false, T...>: public variant_ca_base<T...>
+{
+    using variant_base = detail::variant_ca_base<T...>;
+    using variant_base::variant_base;
+
+public:
+
+    // constructors
+
+    variant_mc_base_impl() = default;
+    variant_mc_base_impl( variant_mc_base_impl const& ) = default;
+
+    // move constructor
+
+private:
+
+    struct L2
+    {
+        variant_base * this_;
+        variant_base & r;
+
+        template<class I> void operator()( I i ) const
+        {
+            this_->_replace( i, std::move( r._get_impl( i ) ) );
+        }
+    };
+
+public:
+
+    variant_mc_base_impl( variant_mc_base_impl && r )
+        noexcept( mp11::mp_all<std::is_nothrow_move_constructible<T>...>::value )
+    {
+        mp11::mp_with_index<sizeof...(T)>( r.index(), L2{ this, r } );
+    }
+
+    // assignment
+
+    variant_mc_base_impl& operator=( variant_mc_base_impl const & ) = default;
+    variant_mc_base_impl& operator=( variant_mc_base_impl && ) = default;
+};
+
+// variant_ma_base
+
+template<bool MoveAssignable, bool TriviallyMoveAssignable, class... T> struct variant_ma_base_impl;
+
+template<class... T> using variant_ma_base = variant_ma_base_impl<
+    mp11::mp_all<std::is_move_constructible<T>..., std::is_move_assignable<T>...>::value,
+    mp11::mp_all<detail::is_trivially_destructible<T>..., detail::is_trivially_move_constructible<T>..., detail::is_trivially_move_assignable<T>...>::value,
+    T...>;
+
+template<class... T> struct variant_ma_base_impl<true, true, T...>: public variant_mc_base<T...>
+{
+    using variant_base = detail::variant_mc_base<T...>;
+    using variant_base::variant_base;
+
+    variant_ma_base_impl() = default;
+    variant_ma_base_impl( variant_ma_base_impl const& ) = default;
+    variant_ma_base_impl( variant_ma_base_impl && ) = default;
+    variant_ma_base_impl& operator=( variant_ma_base_impl const& ) = default;
+    variant_ma_base_impl& operator=( variant_ma_base_impl && ) = default;
+};
+
+template<bool B, class... T> struct variant_ma_base_impl<false, B, T...>: public variant_mc_base<T...>
+{
+    using variant_base = detail::variant_mc_base<T...>;
+    using variant_base::variant_base;
+
+    variant_ma_base_impl() = default;
+    variant_ma_base_impl( variant_ma_base_impl const& ) = default;
+    variant_ma_base_impl( variant_ma_base_impl && ) = default;
+    variant_ma_base_impl& operator=( variant_ma_base_impl const& ) = default;
+    variant_ma_base_impl& operator=( variant_ma_base_impl && ) = delete;
+};
+
+template<class... T> struct variant_ma_base_impl<true, false, T...>: public variant_mc_base<T...>
+{
+    using variant_base = detail::variant_mc_base<T...>;
+    using variant_base::variant_base;
+
+public:
+
+    // constructors
+
+    variant_ma_base_impl() = default;
+    variant_ma_base_impl( variant_ma_base_impl const& ) = default;
+    variant_ma_base_impl( variant_ma_base_impl && ) = default;
+
+    // copy assignment
+
+    variant_ma_base_impl& operator=( variant_ma_base_impl const & ) = default;
+
+    // move assignment
+
+private:
+
+    struct L4
+    {
+        variant_base * this_;
+        variant_base & r;
+
+        template<class I> void operator()( I i ) const
+        {
+            this_->template emplace<I::value>( std::move( r._get_impl( i ) ) );
+        }
+    };
+
+public:
+
+    variant_ma_base_impl& operator=( variant_ma_base_impl && r )
+        noexcept( mp11::mp_all<std::is_nothrow_move_constructible<T>...>::value )
+    {
+        mp11::mp_with_index<sizeof...(T)>( r.index(), L4{ this, r } );
+        return *this;
+    }
+};
+
 } // namespace detail

 // variant

-template<class... T> class variant: private detail::variant_base<T...>
+template<class... T> class variant: private detail::variant_ma_base<T...>
 {
 private:

-    using variant_base = detail::variant_base<T...>;
-
-private:
-
-    variant( variant const volatile& r ) = delete;
-    variant& operator=( variant const volatile& r ) = delete;
+    using variant_base = detail::variant_ma_base<T...>;

 public:

@@ -1076,71 +1568,8 @@ public:
    {
    }

-    template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_all<detail::is_trivially_copy_constructible<T>...>, E1>
-    >
-    constexpr variant( variant const& r ) noexcept
-        : variant_base( static_cast<variant_base const&>(r) )
-    {
-    }
-
-private:
-
-    struct L1
-    {
-        variant_base * this_;
-        variant const & r;
-
-        template<class I> void operator()( I i ) const
-        {
-            this_->_replace( i, r._get_impl( i ) );
-        }
-    };
-
-public:
-
-    template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_not<mp11::mp_all<detail::is_trivially_copy_constructible<T>...>>, E1>,
-        class E3 = mp11::mp_if<mp11::mp_all<std::is_copy_constructible<T>...>, E1>
-    >
-    variant( variant const& r )
-        noexcept( mp11::mp_all<std::is_nothrow_copy_constructible<T>...>::value )
-    {
-        mp11::mp_with_index<sizeof...(T)>( r.index(), L1{ this, r } );
-    }
-
-    template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_all<detail::is_trivially_move_constructible<T>...>, E1>
-    >
-    constexpr variant( variant && r ) noexcept
-        : variant_base( static_cast<variant_base&&>(r) )
-    {
-    }
-
-private:
-
-    struct L2
-    {
-        variant_base * this_;
-        variant & r;
-
-        template<class I> void operator()( I i ) const
-        {
-            this_->_replace( i, std::move( r._get_impl( i ) ) );
-        }
-    };
-
-public:
-
-    template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_not<mp11::mp_all<detail::is_trivially_move_constructible<T>...>>, E1>,
-        class E3 = mp11::mp_if<mp11::mp_all<std::is_move_constructible<T>...>, E1>
-    >
-    variant( variant && r )
-        noexcept( mp11::mp_all<std::is_nothrow_move_constructible<T>...>::value )
-    {
-        mp11::mp_with_index<sizeof...(T)>( r.index(), L2{ this, r } );
-    }
+    // variant( variant const& ) = default;
+    // variant( variant && ) = default;

    template<class U,
        class Ud = typename std::decay<U>::type,
@@ -1175,75 +1604,9 @@ public:
    }

    // assignment
-    template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_copy_constructible<T>..., detail::is_trivially_copy_assignable<T>...>, E1>
-    >
-    BOOST_CXX14_CONSTEXPR variant& operator=( variant const & r ) noexcept
-    {
-        static_cast<variant_base&>( *this ) = static_cast<variant_base const&>( r );
-        return *this;
-    }

-private:
-
-    struct L3
-    {
-        variant * this_;
-        variant const & r;
-
-        template<class I> void operator()( I i ) const
-        {
-            this_->variant_base::template emplace<I::value>( r._get_impl( i ) );
-        }
-    };
-
-public:
-
-    template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_not<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_copy_constructible<T>..., detail::is_trivially_copy_assignable<T>...>>, E1>,
-        class E3 = mp11::mp_if<mp11::mp_all<std::is_copy_constructible<T>..., std::is_copy_assignable<T>...>, E1>
-    >
-    BOOST_CXX14_CONSTEXPR variant& operator=( variant const & r )
-        noexcept( mp11::mp_all<std::is_nothrow_copy_constructible<T>...>::value )
-    {
-        mp11::mp_with_index<sizeof...(T)>( r.index(), L3{ this, r } );
-        return *this;
-    }
-
-    template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_move_constructible<T>..., detail::is_trivially_move_assignable<T>...>, E1>
-    >
-    BOOST_CXX14_CONSTEXPR variant& operator=( variant && r ) noexcept
-    {
-        static_cast<variant_base&>( *this ) = static_cast<variant_base&&>( r );
-        return *this;
-    }
-
-private:
-
-    struct L4
-    {
-        variant * this_;
-        variant & r;
-
-        template<class I> void operator()( I i ) const
-        {
-            this_->variant_base::template emplace<I::value>( std::move( r._get_impl( i ) ) );
-        }
-    };
-
-public:
-
-    template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_not<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_move_constructible<T>..., detail::is_trivially_move_assignable<T>...>>, E1>,
-        class E3 = mp11::mp_if<mp11::mp_all<std::is_move_constructible<T>..., std::is_move_assignable<T>...>, E1>
-    >
-    variant& operator=( variant && r )
-        noexcept( mp11::mp_all<std::is_nothrow_move_constructible<T>...>::value )
-    {
-        mp11::mp_with_index<sizeof...(T)>( r.index(), L4{ this, r } );
-        return *this;
-    }
+    // variant& operator=( variant const& ) = default;
+    // variant& operator=( variant && ) = default;

    template<class U,
        class E1 = typename std::enable_if<!std::is_same<typename std::decay<U>::type, variant>::value>::type,
@@ -1598,6 +1961,25 @@ namespace detail

 template<class T> using remove_cv_ref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;

+template<class... T> variant<T...> const & extract_variant_base_( variant<T...> const & );
+
+#if BOOST_WORKAROUND( BOOST_MSVC, < 1930 )
+
+template<class V> struct extract_vbase_impl
+{
+    using type = decltype( extract_variant_base_( std::declval<V>() ) );
+};
+
+template<class V> using extract_variant_base = remove_cv_ref_t< typename extract_vbase_impl<V>::type >;
+
+#else
+
+template<class V> using extract_variant_base = remove_cv_ref_t< decltype( extract_variant_base_( std::declval<V>() ) ) >;
+
+#endif
+
+template<class V> using variant_base_size = variant_size< extract_variant_base<V> >;
+
 template<class T, class U> struct copy_cv_ref
 {
    using type = T;
@@ -1637,13 +2019,28 @@ template<class F> struct Qret

 template<class L> using front_if_same = mp11::mp_if<mp11::mp_apply<mp11::mp_same, L>, mp11::mp_front<L>>;

-template<class V> using apply_cv_ref = mp11::mp_product<copy_cv_ref_t, remove_cv_ref_t<V>, mp11::mp_list<V>>;
+template<class V> using apply_cv_ref = mp11::mp_product<copy_cv_ref_t, extract_variant_base<V>, mp11::mp_list<V>>;

-template<class F, class... V> using Vret = front_if_same<mp11::mp_product_q<Qret<F>, apply_cv_ref<V>...>>;
+struct deduced {};
+
+#if !BOOST_WORKAROUND( BOOST_MSVC, < 1920 )
+
+template<class R, class F, class... V> using Vret = mp11::mp_eval_if_not< std::is_same<R, deduced>, R, front_if_same, mp11::mp_product_q<Qret<F>, apply_cv_ref<V>...> >;
+
+#else
+
+template<class R, class F, class... V> struct Vret_impl
+{
+    using type = mp11::mp_eval_if_not< std::is_same<R, deduced>, R, front_if_same, mp11::mp_product_q<Qret<F>, apply_cv_ref<V>...> >;
+};
+
+template<class R, class F, class... V> using Vret = typename Vret_impl<R, F, V...>::type;
+
+#endif

 } // namespace detail

-template<class F> constexpr auto visit( F&& f ) -> decltype(std::forward<F>(f)())
+template<class R = detail::deduced, class F> constexpr auto visit( F&& f ) -> detail::Vret<R, F>
 {
    return std::forward<F>(f)();
 }
@@ -1651,12 +2048,12 @@ template<class F> constexpr auto visit( F&& f ) -> decltype(std::forward<F>(f)()
 namespace detail
 {

-template<class F, class V1> struct visit_L1
+template<class R, class F, class V1> struct visit_L1
 {
    F&& f;
    V1&& v1;

-    template<class I> auto operator()( I ) const -> Vret<F, V1>
+    template<class I> auto operator()( I ) const -> Vret<R, F, V1>
    {
        return std::forward<F>(f)( unsafe_get<I::value>( std::forward<V1>(v1) ) );
    }
@@ -1664,9 +2061,9 @@ template<class F, class V1> struct visit_L1

 } // namespace detail

-template<class F, class V1> constexpr auto visit( F&& f, V1&& v1 ) -> detail::Vret<F, V1>
+template<class R = detail::deduced, class F, class V1> constexpr auto visit( F&& f, V1&& v1 ) -> detail::Vret<R, F, V1>
 {
-    return mp11::mp_with_index<variant_size<V1>>( v1.index(), detail::visit_L1<F, V1>{ std::forward<F>(f), std::forward<V1>(v1) } );
+    return mp11::mp_with_index<detail::variant_base_size<V1>>( v1.index(), detail::visit_L1<R, F, V1>{ std::forward<F>(f), std::forward<V1>(v1) } );
 }

 #if defined(BOOST_NO_CXX14_GENERIC_LAMBDAS) || BOOST_WORKAROUND( BOOST_MSVC, < 1920 )
@@ -1690,31 +2087,31 @@ template<class F, class A> bind_front_<F, A> bind_front( F&& f, A&& a )
    return bind_front_<F, A>{ std::forward<F>(f), std::forward<A>(a) };
 }

-template<class F, class V1, class V2> struct visit_L2
+template<class R, class F, class V1, class V2> struct visit_L2
 {
    F&& f;

    V1&& v1;
    V2&& v2;

-    template<class I> auto operator()( I ) const -> Vret<F, V1, V2>
+    template<class I> auto operator()( I ) const -> Vret<R, F, V1, V2>
    {
        auto f2 = bind_front( std::forward<F>(f), unsafe_get<I::value>( std::forward<V1>(v1) ) );
-        return visit( f2, std::forward<V2>(v2) );
+        return visit<R>( f2, std::forward<V2>(v2) );
    }
 };

 } // namespace detail

-template<class F, class V1, class V2> constexpr auto visit( F&& f, V1&& v1, V2&& v2 ) -> detail::Vret<F, V1, V2>
+template<class R = detail::deduced, class F, class V1, class V2> constexpr auto visit( F&& f, V1&& v1, V2&& v2 ) -> detail::Vret<R, F, V1, V2>
 {
-    return mp11::mp_with_index<variant_size<V1>>( v1.index(), detail::visit_L2<F, V1, V2>{ std::forward<F>(f), std::forward<V1>(v1), std::forward<V2>(v2) } );
+    return mp11::mp_with_index<detail::variant_base_size<V1>>( v1.index(), detail::visit_L2<R, F, V1, V2>{ std::forward<F>(f), std::forward<V1>(v1), std::forward<V2>(v2) } );
 }

 namespace detail
 {

-template<class F, class V1, class V2, class V3> struct visit_L3
+template<class R, class F, class V1, class V2, class V3> struct visit_L3
 {
    F&& f;

@@ -1722,24 +2119,24 @@ template<class F, class V1, class V2, class V3> struct visit_L3
    V2&& v2;
    V3&& v3;

-    template<class I> auto operator()( I ) const -> Vret<F, V1, V2, V3>
+    template<class I> auto operator()( I ) const -> Vret<R, F, V1, V2, V3>
    {
        auto f2 = bind_front( std::forward<F>(f), unsafe_get<I::value>( std::forward<V1>(v1) ) );
-        return visit( f2, std::forward<V2>(v2), std::forward<V3>(v3) );
+        return visit<R>( f2, std::forward<V2>(v2), std::forward<V3>(v3) );
    }
 };

 } // namespace detail

-template<class F, class V1, class V2, class V3> constexpr auto visit( F&& f, V1&& v1, V2&& v2, V3&& v3 ) -> detail::Vret<F, V1, V2, V3>
+template<class R = detail::deduced, class F, class V1, class V2, class V3> constexpr auto visit( F&& f, V1&& v1, V2&& v2, V3&& v3 ) -> detail::Vret<R, F, V1, V2, V3>
 {
-    return mp11::mp_with_index<variant_size<V1>>( v1.index(), detail::visit_L3<F, V1, V2, V3>{ std::forward<F>(f), std::forward<V1>(v1), std::forward<V2>(v2), std::forward<V3>(v3) } );
+    return mp11::mp_with_index<detail::variant_base_size<V1>>( v1.index(), detail::visit_L3<R, F, V1, V2, V3>{ std::forward<F>(f), std::forward<V1>(v1), std::forward<V2>(v2), std::forward<V3>(v3) } );
 }

 namespace detail
 {

-template<class F, class V1, class V2, class V3, class V4> struct visit_L4
+template<class R, class F, class V1, class V2, class V3, class V4> struct visit_L4
 {
    F&& f;

@@ -1748,28 +2145,28 @@ template<class F, class V1, class V2, class V3, class V4> struct visit_L4
    V3&& v3;
    V4&& v4;

-    template<class I> auto operator()( I ) const -> Vret<F, V1, V2, V3, V4>
+    template<class I> auto operator()( I ) const -> Vret<R, F, V1, V2, V3, V4>
    {
        auto f2 = bind_front( std::forward<F>(f), unsafe_get<I::value>( std::forward<V1>(v1) ) );
-        return visit( f2, std::forward<V2>(v2), std::forward<V3>(v3), std::forward<V4>(v4) );
+        return visit<R>( f2, std::forward<V2>(v2), std::forward<V3>(v3), std::forward<V4>(v4) );
    }
 };

 } // namespace detail

-template<class F, class V1, class V2, class V3, class V4> constexpr auto visit( F&& f, V1&& v1, V2&& v2, V3&& v3, V4&& v4 ) -> detail::Vret<F, V1, V2, V3, V4>
+template<class R = detail::deduced, class F, class V1, class V2, class V3, class V4> constexpr auto visit( F&& f, V1&& v1, V2&& v2, V3&& v3, V4&& v4 ) -> detail::Vret<R, F, V1, V2, V3, V4>
 {
-    return mp11::mp_with_index<variant_size<V1>>( v1.index(), detail::visit_L4<F, V1, V2, V3, V4>{ std::forward<F>(f), std::forward<V1>(v1), std::forward<V2>(v2), std::forward<V3>(v3), std::forward<V4>(v4) } );
+    return mp11::mp_with_index<detail::variant_base_size<V1>>( v1.index(), detail::visit_L4<R, F, V1, V2, V3, V4>{ std::forward<F>(f), std::forward<V1>(v1), std::forward<V2>(v2), std::forward<V3>(v3), std::forward<V4>(v4) } );
 }

 #else

-template<class F, class V1, class V2, class... V> constexpr auto visit( F&& f, V1&& v1, V2&& v2, V&&... v ) -> detail::Vret<F, V1, V2, V...>
+template<class R = detail::deduced, class F, class V1, class V2, class... V> constexpr auto visit( F&& f, V1&& v1, V2&& v2, V&&... v ) -> detail::Vret<R, F, V1, V2, V...>
 {
-    return mp11::mp_with_index<variant_size<V1>>( v1.index(), [&]( auto I ){
+    return mp11::mp_with_index<detail::variant_base_size<V1>>( v1.index(), [&]( auto I ){

        auto f2 = [&]( auto&&... a ){ return std::forward<F>(f)( detail::unsafe_get<I.value>( std::forward<V1>(v1) ), std::forward<decltype(a)>(a)... ); };
-        return visit( f2, std::forward<V2>(v2), std::forward<V>(v)... );
+        return visit<R>( f2, std::forward<V2>(v2), std::forward<V>(v)... );

    });
 }
@@ -1785,9 +2182,92 @@ void swap( variant<T...> & v, variant<T...> & w )
    v.swap( w );
 }

+// hashing support
+
+namespace detail
+{
+
+template<class V> struct hash_value_L
+{
+    V const & v;
+
+    template<class I> std::size_t operator()( I ) const
+    {
+        boost::ulong_long_type hv = ( boost::ulong_long_type( 0xCBF29CE4 ) << 32 ) + 0x84222325;
+        boost::ulong_long_type const prime = ( boost::ulong_long_type( 0x00000100 ) << 32 ) + 0x000001B3;
+
+        // index
+
+        hv ^= I::value;
+        hv *= prime;
+
+        // value
+
+        auto const & t = unsafe_get<I::value>( v );
+
+        hv ^= std::hash<remove_cv_ref_t<decltype(t)>>()( t );
+        hv *= prime;
+
+        return static_cast<std::size_t>( hv );
+    }
+};
+
+} // namespace detail
+
+inline std::size_t hash_value( monostate const & )
+{
+    return 0xA7EE4757u;
+}
+
+template<class... T> std::size_t hash_value( variant<T...> const & v )
+{
+    return mp11::mp_with_index<sizeof...(T)>( v.index(), detail::hash_value_L< variant<T...> >{ v } );
+}
+
+namespace detail
+{
+
+template<class T> using is_hash_enabled = std::is_default_constructible< std::hash<typename std::remove_const<T>::type> >;
+
+template<class V, bool E = mp11::mp_all_of<V, is_hash_enabled>::value> struct std_hash_impl;
+
+template<class V> struct std_hash_impl<V, false>
+{
+    std_hash_impl() = delete;
+    std_hash_impl( std_hash_impl const& ) = delete;
+    std_hash_impl& operator=( std_hash_impl const& ) = delete;
+};
+
+template<class V> struct std_hash_impl<V, true>
+{
+    std::size_t operator()( V const & v ) const
+    {
+        return hash_value( v );
+    }
+};
+
+} // namespace detail
+
 } // namespace variant2
 } // namespace boost

+namespace std
+{
+
+template<class... T> struct hash< ::boost::variant2::variant<T...> >: public ::boost::variant2::detail::std_hash_impl< ::boost::variant2::variant<T...> >
+{
+};
+
+template<> struct hash< ::boost::variant2::monostate >
+{
+    std::size_t operator()( ::boost::variant2::monostate const & v ) const
+    {
+        return hash_value( v );
+    }
+};
+
+} // namespace std
+
 #if defined(_MSC_VER) && _MSC_VER < 1910
 # pragma warning( pop )
 #endif
--- a/meta/libraries.json
+++ b/meta/libraries.json
@@ -5,10 +5,11 @@
        "Peter Dimov"
    ],
    "maintainers": [
-        "Peter Dimov <pdimov -at- pdimov.com>"
+        "Peter Dimov <pdimov -at- gmail.com>"
    ],
    "description": "A never-valueless, strong guarantee implementation of std::variant.",
    "category": [
        "Containers", "Data"
-    ]
+    ],
+    "cxxstd": "11"
 }
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -0,0 +1,11 @@
+# Copyright 2018, 2019 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(BoostTestJamfile OPTIONAL RESULT_VARIABLE HAVE_BOOST_TEST)
+
+if(HAVE_BOOST_TEST)
+
+boost_test_jamfile(FILE Jamfile LINK_LIBRARIES Boost::variant2 Boost::core Boost::container_hash)
+
+endif()
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -12,7 +12,7 @@ import ../../config/checks/config : requires ;
 project
  : default-build

-    <warnings>all
+    <warnings>extra

  : requirements

@@ -23,20 +23,22 @@ project
    <toolset>clang:<warnings-as-errors>on
  ;

+run quick.cpp ;
+
 run variant_size.cpp ;
 run variant_alternative.cpp ;

 run variant_holds_alternative.cpp ;
-compile variant_holds_alternative_cx.cpp ;
+compile variant_holds_alternative_cx.cpp : <toolset>msvc-14.0:<build>no ;

 run variant_get_by_index.cpp ;
-compile variant_get_by_index_cx.cpp ;
+compile variant_get_by_index_cx.cpp : <toolset>msvc-14.0:<build>no ;

 run variant_get_by_type.cpp ;
-compile variant_get_by_type_cx.cpp ;
+compile variant_get_by_type_cx.cpp : <toolset>msvc-14.0:<build>no ;

 run variant_default_construct.cpp ;
-compile variant_default_construct_cx.cpp ;
+compile variant_default_construct_cx.cpp : <toolset>msvc-14.0:<build>no ;

 run variant_copy_construct.cpp ;
 compile variant_copy_construct_cx.cpp : <toolset>msvc-14.0:<build>no ;
@@ -45,13 +47,13 @@ run variant_move_construct.cpp ;
 compile variant_move_construct_cx.cpp : [ requires cxx14_constexpr ] ;

 run variant_value_construct.cpp ;
-compile variant_value_construct_cx.cpp ;
+compile variant_value_construct_cx.cpp : <toolset>msvc-14.0:<build>no ;

 run variant_in_place_index_construct.cpp ;
-compile variant_in_place_index_construct_cx.cpp ;
+compile variant_in_place_index_construct_cx.cpp : <toolset>msvc-14.0:<build>no ;

 run variant_in_place_type_construct.cpp ;
-compile variant_in_place_type_construct_cx.cpp ;
+compile variant_in_place_type_construct_cx.cpp : <toolset>msvc-14.0:<build>no ;

 run variant_copy_assign.cpp ;
 compile variant_copy_assign_cx.cpp : [ requires cxx14_constexpr ] ;
@@ -97,9 +99,23 @@ local NX =
    ;

 run variant_get_by_index.cpp throw_exception.cpp : : : $(NX) : variant_get_by_index_nx ;
-compile variant_get_by_index_cx.cpp : $(NX) : variant_get_by_index_cx_nx ;
+compile variant_get_by_index_cx.cpp : $(NX) <toolset>msvc-14.0:<build>no : variant_get_by_index_cx_nx ;

 run variant_get_by_type.cpp throw_exception.cpp : : : $(NX) : variant_get_by_type_nx ;
-compile variant_get_by_type_cx.cpp : $(NX) : variant_get_by_type_cx_nx ;
+compile variant_get_by_type_cx.cpp : $(NX) <toolset>msvc-14.0:<build>no : variant_get_by_type_cx_nx ;

 run variant_subset.cpp throw_exception.cpp : : : $(NX) : variant_subset_nx ;
+
+run variant_hash.cpp ;
+
+run variant_trivial.cpp ;
+run variant_special.cpp ;
+
+run variant_visit_derived.cpp ;
+
+run variant_many_types.cpp ;
+
+run variant_visit_r.cpp : : :
+    <toolset>gcc,<target-os>windows:<variant>release
+    <toolset>gcc,<target-os>cygwin:<variant>release
+    ;
--- a/test/cmake_install_test/CMakeLists.txt
+++ b/test/cmake_install_test/CMakeLists.txt
@@ -0,0 +1,17 @@
+# Copyright 2018, 2019 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
+
+cmake_minimum_required(VERSION 3.5...3.16)
+
+project(cmake_install_test LANGUAGES CXX)
+
+find_package(boost_variant2 REQUIRED)
+
+add_executable(quick ../quick.cpp)
+target_link_libraries(quick Boost::variant2)
+
+enable_testing()
+add_test(quick quick)
+
+add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)
--- a/test/cmake_subdir_test/CMakeLists.txt
+++ b/test/cmake_subdir_test/CMakeLists.txt
@@ -2,7 +2,7 @@
 # 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

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

 project(cmake_subdir_test LANGUAGES CXX)

@@ -10,7 +10,7 @@ add_subdirectory(../.. boostorg/variant2)
 add_subdirectory(../../../config boostorg/config)
 add_subdirectory(../../../mp11 boostorg/mp11)

-add_executable(quick quick.cpp)
+add_executable(quick ../quick.cpp)
 target_link_libraries(quick Boost::variant2)

 enable_testing()
--- a/test/cmake_subdir_test/quick.cpp
+++ b/test/cmake_subdir_test/quick.cpp
--- a/test/variant_copy_construct.cpp
+++ b/test/variant_copy_construct.cpp
@@ -9,6 +9,8 @@
 #include <boost/variant2/variant.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/lightweight_test_trait.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
 #include <type_traits>
 #include <utility>
 #include <string>
@@ -48,12 +50,21 @@ struct Y
    Y( Y const& ) = delete;
 };

+struct D
+{
+    ~D() {}
+};
+
+inline bool operator==( D, D ) { return true; }
+
 template<class V> static void test( V const & v )
 {
    V v2( v );

    BOOST_TEST_EQ( v.index(), v2.index() );
    BOOST_TEST( v == v2 );
+
+    BOOST_TEST_TRAIT_TRUE((std::is_copy_constructible<V>));
 }

 int main()
@@ -115,6 +126,12 @@ int main()
        test( v );
    }

+#if !BOOST_WORKAROUND( __GNUC__, < 5 )
+
+    test( variant<D>() );
+
+#endif
+
    {
        BOOST_TEST_TRAIT_TRUE((std::is_nothrow_copy_constructible<variant<int>>));
        BOOST_TEST_TRAIT_TRUE((std::is_nothrow_copy_constructible<variant<int const>>));
--- a/test/variant_emplace_index.cpp
+++ b/test/variant_emplace_index.cpp
@@ -57,6 +57,60 @@ STATIC_ASSERT( !std::is_nothrow_move_constructible<X2>::value );
 STATIC_ASSERT( !std::is_nothrow_copy_assignable<X2>::value );
 STATIC_ASSERT( !std::is_nothrow_move_assignable<X2>::value );

+struct Y1
+{
+    int v = 1;
+
+    Y1() = default;
+    Y1(Y1 const&) = delete;
+    Y1(Y1&&) = delete;
+};
+
+STATIC_ASSERT( !std::is_copy_constructible<Y1>::value );
+STATIC_ASSERT( !std::is_move_constructible<Y1>::value );
+
+struct Y2
+{
+    int v = 2;
+
+    Y2() = default;
+    Y2(Y2 const&) = delete;
+    Y2(Y2&&) = delete;
+};
+
+STATIC_ASSERT( !std::is_copy_constructible<Y2>::value );
+STATIC_ASSERT( !std::is_move_constructible<Y2>::value );
+
+struct Z1
+{
+    static int instances;
+
+    int v = 1;
+
+    Z1() { ++instances; }
+    ~Z1() { --instances; }
+
+    Z1(Z1 const&) = delete;
+    Z1(Z1&&) = delete;
+};
+
+int Z1::instances = 0;
+
+struct Z2
+{
+    static int instances;
+
+    int v = 2;
+
+    Z2() { ++instances; }
+    ~Z2() { --instances; }
+
+    Z2(Z2 const&) = delete;
+    Z2(Z2&&) = delete;
+};
+
+int Z2::instances = 0;
+
 int main()
 {
    {
@@ -177,5 +231,62 @@ int main()
        BOOST_TEST_EQ( get<0>(v).v, 4 );
    }

+    {
+        variant<Y1, Y2> v;
+        BOOST_TEST_EQ( v.index(), 0 );
+        BOOST_TEST_EQ( get<0>(v).v, 1 );
+
+        v.emplace<0>();
+        BOOST_TEST_EQ( v.index(), 0 );
+        BOOST_TEST_EQ( get<0>(v).v, 1 );
+
+        v.emplace<1>();
+        BOOST_TEST_EQ( v.index(), 1 );
+        BOOST_TEST_EQ( get<1>(v).v, 2 );
+
+        v.emplace<1>();
+        BOOST_TEST_EQ( v.index(), 1 );
+        BOOST_TEST_EQ( get<1>(v).v, 2 );
+
+        v.emplace<0>();
+        BOOST_TEST_EQ( v.index(), 0 );
+        BOOST_TEST_EQ( get<0>(v).v, 1 );
+    }
+
+    {
+        variant<Z1, Z2> v;
+        BOOST_TEST_EQ( v.index(), 0 );
+        BOOST_TEST_EQ( get<0>(v).v, 1 );
+        BOOST_TEST_EQ( Z1::instances, 1 );
+        BOOST_TEST_EQ( Z2::instances, 0 );
+
+        v.emplace<0>();
+        BOOST_TEST_EQ( v.index(), 0 );
+        BOOST_TEST_EQ( get<0>(v).v, 1 );
+        BOOST_TEST_EQ( Z1::instances, 1 );
+        BOOST_TEST_EQ( Z2::instances, 0 );
+
+        v.emplace<1>();
+        BOOST_TEST_EQ( v.index(), 1 );
+        BOOST_TEST_EQ( get<1>(v).v, 2 );
+        BOOST_TEST_EQ( Z1::instances, 0 );
+        BOOST_TEST_EQ( Z2::instances, 1 );
+
+        v.emplace<1>();
+        BOOST_TEST_EQ( v.index(), 1 );
+        BOOST_TEST_EQ( get<1>(v).v, 2 );
+        BOOST_TEST_EQ( Z1::instances, 0 );
+        BOOST_TEST_EQ( Z2::instances, 1 );
+
+        v.emplace<0>();
+        BOOST_TEST_EQ( v.index(), 0 );
+        BOOST_TEST_EQ( get<0>(v).v, 1 );
+        BOOST_TEST_EQ( Z1::instances, 1 );
+        BOOST_TEST_EQ( Z2::instances, 0 );
+    }
+
+    BOOST_TEST_EQ( Z1::instances, 0 );
+    BOOST_TEST_EQ( Z2::instances, 0 );
+
    return boost::report_errors();
 }
--- a/test/variant_get_by_index.cpp
+++ b/test/variant_get_by_index.cpp
@@ -6,6 +6,12 @@
 // See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt

+#if defined( __clang__ ) && defined( __has_warning )
+# if __has_warning( "-Wdeprecated-volatile" )
+#  pragma clang diagnostic ignored "-Wdeprecated-volatile"
+# endif
+#endif
+
 #include <boost/variant2/variant.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/lightweight_test_trait.hpp>
--- a/test/variant_get_by_type.cpp
+++ b/test/variant_get_by_type.cpp
@@ -6,6 +6,12 @@
 // See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt

+#if defined( __clang__ ) && defined( __has_warning )
+# if __has_warning( "-Wdeprecated-volatile" )
+#  pragma clang diagnostic ignored "-Wdeprecated-volatile"
+# endif
+#endif
+
 #include <boost/variant2/variant.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/lightweight_test_trait.hpp>
--- a/test/variant_hash.cpp
+++ b/test/variant_hash.cpp
@@ -0,0 +1,73 @@
+
+// Copyright 2020 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// http://www.boost.org/LICENSE_1_0.txt
+
+#if defined(_MSC_VER)
+# pragma warning( disable: 4244 ) // conversion from int to float, possible loss of data
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <boost/container_hash/hash.hpp>
+#include <boost/config/workaround.hpp>
+
+using namespace boost::variant2;
+
+template<template<class...> class Hash, class T1, class T2, class T3> void test()
+{
+    variant<T1, T2, T3> v1( in_place_index_t<0>{} );
+    std::size_t h1 = Hash<decltype(v1)>()( v1 );
+
+    variant<T1, T2, T3> v2( in_place_index_t<1>{} );
+    std::size_t h2 = Hash<decltype(v2)>()( v2 );
+
+    variant<T1, T2, T3> v3( in_place_index_t<2>{} );
+    std::size_t h3 = Hash<decltype(v3)>()( v3 );
+
+    BOOST_TEST_NE( h1, h2 );
+    BOOST_TEST_NE( h1, h3 );
+    BOOST_TEST_NE( h2, h3 );
+}
+
+template<template<class...> class Hash, class T> void test2()
+{
+    variant<T> v1( 0 );
+    std::size_t h1 = Hash<decltype(v1)>()( v1 );
+
+    variant<T> v2( 1 );
+    std::size_t h2 = Hash<decltype(v2)>()( v2 );
+
+    variant<T> v3( 2 );
+    std::size_t h3 = Hash<decltype(v3)>()( v3 );
+
+    BOOST_TEST_NE( h1, h2 );
+    BOOST_TEST_NE( h1, h3 );
+    BOOST_TEST_NE( h2, h3 );
+}
+
+struct X {};
+
+int main()
+{
+    test<std::hash, monostate, monostate, monostate>();
+    test<std::hash, int, int, float>();
+
+    test<boost::hash, monostate, monostate, monostate>();
+    test<boost::hash, int, int, float>();
+
+    test2<std::hash, int>();
+    test2<std::hash, float>();
+
+    test2<boost::hash, int>();
+    test2<boost::hash, float>();
+
+#if !BOOST_WORKAROUND(BOOST_MSVC, < 1910) && ( !defined(_LIBCPP_STD_VER) || _LIBCPP_STD_VER > 11 )
+
+    BOOST_TEST_TRAIT_FALSE(( detail::is_hash_enabled<X> ));
+
+#endif
+
+    return boost::report_errors();
+}
--- a/test/variant_in_place_index_construct_cx.cpp
+++ b/test/variant_in_place_index_construct_cx.cpp
@@ -7,11 +7,8 @@
 // http://www.boost.org/LICENSE_1_0.txt

 #include <boost/variant2/variant.hpp>
-#include <boost/core/lightweight_test.hpp>
-#include <boost/core/lightweight_test_trait.hpp>
-#include <type_traits>
-#include <utility>
-#include <string>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>

 using namespace boost::variant2;

@@ -108,9 +105,17 @@ int main()
        STATIC_ASSERT( v.index() == 4 );
    }

+#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 100200)
+
+    // no idea why this fails on g++ 10
+
+#else
+
    {
        constexpr variant<int, int, float, float, X, X> v( in_place_index_t<5>{}, 0, 0 );

        STATIC_ASSERT( v.index() == 5 );
    }
+
+#endif
 }
--- a/test/variant_in_place_type_construct_cx.cpp
+++ b/test/variant_in_place_type_construct_cx.cpp
@@ -7,6 +7,8 @@
 // http://www.boost.org/LICENSE_1_0.txt

 #include <boost/variant2/variant.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>

 using namespace boost::variant2;

@@ -100,6 +102,12 @@ int main()
        STATIC_ASSERT( holds_alternative<X>(v) );
    }

+#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 100200)
+
+    // no idea why this fails on g++ 10
+
+#else
+
    {
        constexpr variant<int, int, float, float, X> v( in_place_type_t<X>{}, 0, 0 );

@@ -107,4 +115,6 @@ int main()

        STATIC_ASSERT( holds_alternative<X>(v) );
    }
+
+#endif
 }
--- a/test/variant_many_types.cpp
+++ b/test/variant_many_types.cpp
@@ -0,0 +1,109 @@
+
+// Copyright 2020 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(_MSC_VER)
+# pragma warning( disable: 4503 ) // decorated name length exceeded
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/mp11.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+using namespace boost::mp11;
+
+template<class I> struct X
+{
+    static int const value = I::value;
+    int v_;
+};
+
+template<class I> int const X<I>::value;
+
+template<class I> struct Y
+{
+    static int const value = I::value;
+    int v_;
+
+    Y() = default;
+    Y( Y const& ) = default;
+
+    explicit Y( int v ): v_( v ) {}
+
+    Y& operator=( Y const& ) noexcept = default;
+
+    Y& operator=( Y&& r ) noexcept
+    {
+        v_ = r.v_;
+        return *this;
+    }
+};
+
+template<class I> int const Y<I>::value;
+
+template<class I> struct Z
+{
+    static int const value = I::value;
+    int v_;
+
+    ~Z() {}
+};
+
+template<class I> int const Z<I>::value;
+
+template<class V> struct F1
+{
+    template<class T> void operator()( T ) const
+    {
+        int const i = T::value;
+
+        T t{ i * 2 };
+
+        using boost::variant2::get;
+
+        {
+            V v( t );
+
+            BOOST_TEST_EQ( v.index(), i );
+            BOOST_TEST_EQ( get<i>( v ).v_, t.v_ );
+            BOOST_TEST_EQ( get<T>( v ).v_, t.v_ );
+        }
+
+        {
+            V const v( t );
+
+            BOOST_TEST_EQ( v.index(), i );
+            BOOST_TEST_EQ( get<i>( v ).v_, t.v_ );
+            BOOST_TEST_EQ( get<T>( v ).v_, t.v_ );
+        }
+
+        {
+            V v;
+
+            v = t;
+
+            BOOST_TEST_EQ( v.index(), i );
+            BOOST_TEST_EQ( get<i>( v ).v_, t.v_ );
+            BOOST_TEST_EQ( get<T>( v ).v_, t.v_ );
+        }
+    }
+};
+
+template<class V> void test()
+{
+    mp_for_each<V>( F1<V>() );
+}
+
+int main()
+{
+    int const N = 32;
+
+    using V = mp_rename<mp_iota_c<N>, boost::variant2::variant>;
+
+    test< mp_transform<X, V> >();
+    test< mp_transform<Y, V> >();
+    test< mp_transform<Z, V> >();
+
+    return boost::report_errors();
+}
--- a/test/variant_special.cpp
+++ b/test/variant_special.cpp
@@ -0,0 +1,103 @@
+// Copyright 2020 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(_MSC_VER) && _MSC_VER < 1910
+# pragma warning(disable: 4503) // decorated name length exceeded
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+#include <boost/mp11.hpp>
+using namespace boost::mp11;
+
+//
+
+using namespace boost::variant2;
+
+struct D
+{
+    ~D() noexcept {}
+};
+
+struct CC1
+{
+    CC1( CC1 const& ) {}
+};
+
+struct CC2
+{
+    CC2( CC2 const& ) = delete;
+};
+
+struct MC1
+{
+    MC1( MC1 && ) {}
+};
+
+struct MC2
+{
+    MC2( MC2 && ) = delete;
+};
+
+struct CA1
+{
+    CA1& operator=( CA1 const& ) { return *this; }
+};
+
+struct CA2
+{
+    CA2& operator=( CA2 const& ) = delete;
+};
+
+struct MA1
+{
+    MA1& operator=( MA1 && ) { return *this; }
+};
+
+struct MA2
+{
+    MA2& operator=( MA2 && ) = delete;
+};
+
+struct test
+{
+    template<class... T> void operator()( mp_list<T...> ) const noexcept
+    {
+        using U = mp_inherit<T...>;
+
+#if !BOOST_WORKAROUND( __GNUC__, < 5 )
+
+        BOOST_TEST_EQ( std::is_copy_constructible<variant<U>>::value, std::is_copy_constructible<U>::value );
+        BOOST_TEST_EQ( std::is_nothrow_copy_constructible<variant<U>>::value, std::is_nothrow_copy_constructible<U>::value );
+
+#endif
+
+#if !BOOST_WORKAROUND(BOOST_MSVC, < 1910)
+
+        BOOST_TEST_EQ( std::is_move_constructible<variant<U>>::value, std::is_move_constructible<U>::value );
+
+#else
+
+        BOOST_TEST_GE( std::is_move_constructible<variant<U>>::value, std::is_move_constructible<U>::value );
+
+#endif
+
+        BOOST_TEST_EQ( std::is_nothrow_move_constructible<variant<U>>::value, std::is_nothrow_move_constructible<U>::value );
+
+        BOOST_TEST_EQ( std::is_copy_assignable<variant<U>>::value, std::is_copy_constructible<U>::value && std::is_copy_assignable<U>::value );
+        BOOST_TEST_EQ( std::is_nothrow_copy_assignable<variant<U>>::value, std::is_nothrow_copy_constructible<U>::value && std::is_copy_assignable<U>::value );
+
+        BOOST_TEST_EQ( std::is_move_assignable<variant<U>>::value, std::is_move_constructible<U>::value && std::is_move_assignable<U>::value );
+        BOOST_TEST_EQ( std::is_nothrow_move_assignable<variant<U>>::value, std::is_nothrow_move_constructible<U>::value && std::is_move_assignable<U>::value );
+    }
+};
+
+int main()
+{
+    mp_for_each< mp_power_set< mp_list<D, CC1, CC2, MC1, MC2, CA1, CA2, MA1, MA2> > >( test() );
+    return boost::report_errors();
+}
--- a/test/variant_trivial.cpp
+++ b/test/variant_trivial.cpp
@@ -0,0 +1,95 @@
+// Copyright 2020 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(_MSC_VER) && _MSC_VER < 1910
+# pragma warning(disable: 4503) // decorated name length exceeded
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+#include <boost/mp11.hpp>
+using namespace boost::mp11;
+
+//
+
+struct D
+{
+    ~D() noexcept {}
+};
+
+struct CC1
+{
+    CC1( CC1 const& ) noexcept {}
+};
+
+struct CC2
+{
+    CC2( CC2 const& ) = delete;
+};
+
+struct MC1
+{
+    MC1( MC1 && ) noexcept {}
+};
+
+struct MC2
+{
+    MC2( MC2 && ) = delete;
+};
+
+struct CA1
+{
+    CA1& operator=( CA1 const& ) noexcept { return *this; }
+};
+
+struct CA2
+{
+    CA2& operator=( CA2 const& ) = delete;
+};
+
+struct MA1
+{
+    MA1& operator=( MA1 && ) noexcept { return *this; }
+};
+
+struct MA2
+{
+    MA2& operator=( MA2 && ) = delete;
+};
+
+using namespace boost::variant2;
+namespace v2d = boost::variant2::detail;
+
+struct test
+{
+    template<class... T> void operator()( mp_list<T...> ) const noexcept
+    {
+        using U = mp_inherit<T...>;
+
+#if !BOOST_WORKAROUND( __GNUC__, < 5 )
+
+        BOOST_TEST_EQ( v2d::is_trivially_copy_constructible<variant<U>>::value, v2d::is_trivially_copy_constructible<U>::value );
+        BOOST_TEST_EQ( v2d::is_trivially_copy_assignable<variant<U>>::value, std::is_trivially_destructible<U>::value && v2d::is_trivially_copy_constructible<U>::value && v2d::is_trivially_copy_assignable<U>::value );
+
+#endif
+
+        BOOST_TEST_EQ( std::is_trivially_destructible<variant<U>>::value, std::is_trivially_destructible<U>::value );
+
+#if !BOOST_WORKAROUND(BOOST_LIBSTDCXX_VERSION, < 50000)
+
+        BOOST_TEST_EQ( v2d::is_trivially_move_constructible<variant<U>>::value, v2d::is_trivially_move_constructible<U>::value );
+        BOOST_TEST_EQ( v2d::is_trivially_move_assignable<variant<U>>::value, std::is_trivially_destructible<U>::value && v2d::is_trivially_move_constructible<U>::value && v2d::is_trivially_move_assignable<U>::value );
+
+#endif
+    }
+};
+
+int main()
+{
+    mp_for_each< mp_power_set< mp_list<D, CC1, CC2, MC1, MC2, CA1, CA2, MA1, MA2> > >( test() );
+    return boost::report_errors();
+}
--- a/test/variant_visit.cpp
+++ b/test/variant_visit.cpp
@@ -37,6 +37,10 @@ struct F

 int main()
 {
+    {
+        BOOST_TEST_EQ( (visit( []{ return 5; } )), 5 );
+    }
+
    {
        variant<int> v( 1 );

--- a/test/variant_visit_derived.cpp
+++ b/test/variant_visit_derived.cpp
@@ -0,0 +1,57 @@
+
+// Copyright 2017, 2020 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(_MSC_VER)
+# pragma warning( disable: 4244 ) // conversion from float to int, possible loss of data
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+#include <utility>
+
+struct X: boost::variant2::variant<int, float>
+{
+#if BOOST_WORKAROUND( BOOST_MSVC, < 1930 )
+
+    template<class T> explicit X( T&& t ): variant( std::forward<T>( t ) ) {};
+
+#else
+
+    using variant::variant;
+
+#endif
+};
+
+template<class... T> struct Y: boost::variant2::variant<T...>
+{
+    using boost::variant2::variant<T...>::variant;
+};
+
+int main()
+{
+    {
+        X v1( 1 );
+        X const v2( 3.14f );
+
+        BOOST_TEST_EQ( (visit( []( int x1, float x2 ){ return (int)(x1 * 1000) + (int)(x2 * 100); }, v1, v2 )), 1314 );
+
+        visit( []( int x1, float x2 ){ BOOST_TEST_EQ( x1, 1 ); BOOST_TEST_EQ( x2, 3.14f ); }, v1, v2 );
+        visit( []( int x1, float x2 ){ BOOST_TEST_EQ( x1, 1 ); BOOST_TEST_EQ( x2, 3.14f ); }, std::move(v1), std::move(v2) );
+    }
+
+    {
+        Y<int, float> v1( 1 );
+        Y<int, float> const v2( 3.14f );
+
+        BOOST_TEST_EQ( (visit( []( int x1, float x2 ){ return (int)(x1 * 1000) + (int)(x2 * 100); }, v1, v2 )), 1314 );
+
+        visit( []( int x1, float x2 ){ BOOST_TEST_EQ( x1, 1 ); BOOST_TEST_EQ( x2, 3.14f ); }, v1, v2 );
+        visit( []( int x1, float x2 ){ BOOST_TEST_EQ( x1, 1 ); BOOST_TEST_EQ( x2, 3.14f ); }, std::move(v1), std::move(v2) );
+    }
+
+    return boost::report_errors();
+}
--- a/test/variant_visit_r.cpp
+++ b/test/variant_visit_r.cpp
@@ -0,0 +1,98 @@
+
+// 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
+
+#if defined(_MSC_VER)
+# pragma warning( disable: 4244 ) // conversion from float to int, possible loss of data
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+using namespace boost::variant2;
+
+struct F1
+{
+    template<class T1> T1 operator()( T1 t1 ) const
+    {
+        return t1;
+    }
+};
+
+struct F2
+{
+    template<class T1, class T2> auto operator()( T1 t1, T2 t2 ) const -> decltype( t1 + t2 )
+    {
+        return t1 + t2;
+    }
+};
+
+struct F3
+{
+    template<class T1, class T2, class T3> auto operator()( T1 t1, T2 t2, T3 t3 ) const -> decltype( t1 + t2 + t3 )
+    {
+        return t1 + t2 + t3;
+    }
+};
+
+struct F4
+{
+    template<class T1, class T2, class T3, class T4> auto operator()( T1 t1, T2 t2, T3 t3, T4 t4 ) const -> decltype( t1 + t2 + t3 + t4 )
+    {
+        return t1 + t2 + t3 + t4;
+    }
+};
+
+int main()
+{
+    {
+        BOOST_TEST_EQ( (visit<int>( []{ return 3.14f; } )), 3 );
+    }
+
+    {
+        variant<int, float> v( 1 );
+
+        BOOST_TEST_EQ( visit<int>( F1(), v ), 1 );
+        BOOST_TEST_EQ( visit<float>( F1(), v ), 1.0f );
+    }
+
+    {
+        variant<int, float> const v( 3.14f );
+
+        BOOST_TEST_EQ( visit<int>( F1(), v ), 3 );
+        BOOST_TEST_EQ( visit<float>( F1(), v ), 3.14f );
+    }
+
+    {
+        variant<int, float> v1( 1 );
+        variant<int, float> const v2( 3.14f );
+
+        BOOST_TEST_EQ( visit<int>( F2(), v1, v2 ), 4 );
+        BOOST_TEST_EQ( visit<float>( F2(), v1, v2 ), 1 + 3.14f );
+    }
+
+    {
+        variant<int, float, double> v1( 1 );
+        variant<int, float, double> const v2( 3.14f );
+        variant<int, float, double> v3( 6.28 );
+
+        BOOST_TEST_EQ( visit<int>( F3(), v1, v2, v3 ), 10 );
+        BOOST_TEST_EQ( visit<float>( F3(), v1, v2, v3 ), static_cast<float>( 1 + 3.14f + 6.28 ) );
+    }
+
+    {
+        variant<int, float, double, char> v1( 1 );
+        variant<int, float, double, char> const v2( 3.14f );
+        variant<int, float, double, char> v3( 6.28 );
+        variant<int, float, double, char> const v4( 'A' );
+
+        BOOST_TEST_EQ( visit<int>( F4(), v1, v2, v3, v4 ), 10 + 'A' );
+        BOOST_TEST_EQ( visit<float>( F4(), v1, v2, v3, v4 ), static_cast<float>( 1 + 3.14f + 6.28 + 'A' ) );
+    }
+
+    return boost::report_errors();
+}
Author	SHA1	Message	Date
Peter Dimov	a3d35e61fe	g++ 4.7 doesn't have std::is_trivially_destructible	2021-01-13 04:51:27 +02:00
Peter Dimov	84a2c175d0	Use variant=release for variant_visit_r under g++/windows	2021-01-13 04:44:56 +02:00
Peter Dimov	ea3268feb4	Add .github/workflows	2021-01-13 04:19:15 +02:00
Peter Dimov	efc1d5acca	Add more tests to variant_emplace_index.cpp	2021-01-13 02:32:05 +02:00
Peter Dimov	c6186e0a95	Merge pull request #22 from eldiener/develop Add "cxxstd" json field. The "cxxstd" json field is being added to ea…	2020-12-16 18:45:01 +02:00
Edward Diener	24ccee2104	Add "cxxstd" json field. The "cxxstd" json field is being added to each Boost library's meta json information for libraries whose minumum C++ standard compilation level is C++11 on up. The value of this field matches one of the values for 'cxxstd' in Boost.Build. The purpose of doing this is to provide information for the Boost website documentation for each library which will specify the minimum C++ standard compilation that an end-user must employ in order to use the particular library. This will aid end-users who want to know if they can successfully use a Boost library based on their C++ compiler's compilation level, without having to search the library's documentation to find this out.	2020-12-16 01:45:24 -05:00
Peter Dimov	93b8618e94	Update maintainer e-mail	2020-12-12 01:08:09 +02:00
Peter Dimov	1ebc29aa02	Remove boost_install call from CMakeLists.txt	2020-06-11 17:21:57 +03:00
Peter Dimov	d3db874762	Document visit<R>	2020-06-03 18:01:57 +03:00
Peter Dimov	5586ebaa64	Add support for visit<R>	2020-06-03 17:00:13 +03:00
Peter Dimov	bede3777a8	Add test for nullary visit	2020-06-03 14:29:24 +03:00
Peter Dimov	b302dd5912	Update changelog	2020-05-22 17:57:29 +03:00
Peter Dimov	2ad6fed07a	Update revision history	2020-05-10 19:34:12 +03:00
Peter Dimov	84ea994325	Add specialization for variant_storage_impl<mp_false, ...>	2020-05-09 19:56:27 +03:00
Peter Dimov	465e5bac3d	Add specialization for variant_storage_impl<mp_true, ...> to reduce instantiations	2020-05-09 18:14:12 +03:00
Peter Dimov	41829b0fb1	test/variant_many_types: cosmetic fixes	2020-05-09 17:55:42 +03:00
Peter Dimov	b57d75ff80	Merge branch 'develop' into feature/many-types	2020-05-09 14:41:29 +03:00
Peter Dimov	03019860df	Fix gcc-10 version check	2020-05-09 05:10:28 +03:00
Peter Dimov	8ec4720d2d	Merge branch 'feature/clang-10' into feature/gcc-10	2020-05-09 05:09:11 +03:00
Peter Dimov	75f574fc48	Move warning suppression before the includes	2020-05-09 04:42:27 +03:00
Peter Dimov	1d79adfca0	Add gcc-10 to Travis	2020-05-09 04:32:11 +03:00
Peter Dimov	fa92e40b35	Disable failing constexpr tests on g++ 10.1	2020-05-09 04:31:26 +03:00
Peter Dimov	a403f82691	Disable -Wdeprecated-volatile	2020-05-09 03:57:27 +03:00
Peter Dimov	a7d0da59ad	Add clang-10 to Travis	2020-05-09 03:50:20 +03:00
Peter Dimov	fa872cb835	test/variant_many_types: add a constructor to Y	2020-05-08 23:23:19 +03:00
Peter Dimov	93204676f5	Add test/variant_many_types	2020-05-08 22:22:49 +03:00
Peter Dimov	772ef0d312	Support derived types in visit	2020-05-06 20:11:03 +03:00
Peter Dimov	f3b3b533aa	Remove local mp_power_set implementation, as it's now in mp11	2020-03-20 02:26:01 +02:00
Peter Dimov	4b60dee4b6	Avoid gcc warning 'base class should be explicitly initialized in copy constructor'	2020-02-01 01:18:40 +02:00
Peter Dimov	76c67c9b21	Use <warnings>extra instead of `all`	2020-01-31 23:59:00 +02:00
Peter Dimov	308bd731a5	Update documentation	2020-01-23 21:17:49 +02:00
Peter Dimov	719c43316f	Disable is_copy_constructible tests on gcc 4.x	2020-01-23 19:13:11 +02:00
Peter Dimov	d6680df4e5	Add a test case to test/variant_copy_construct	2020-01-23 18:33:39 +02:00
Peter Dimov	8cf72527a6	Revert incorrect changes in test/variant_trivial	2020-01-23 18:09:01 +02:00
Peter Dimov	b649a39776	Check std::is_copy_constructible in test/variant_copy_construct	2020-01-23 17:38:03 +02:00
Peter Dimov	37f6efab5d	Fix typo	2020-01-23 17:34:36 +02:00
Peter Dimov	5259bdd5fc	Disable move triviality tests on libstdc++ 4.x	2020-01-23 17:22:45 +02:00
Peter Dimov	9964e77dd2	Add clang++/trusty to Travis (libstdc++ 4.8)	2020-01-23 15:50:45 +02:00
Peter Dimov	57ab36bd95	Add test/variant_special	2020-01-23 15:24:32 +02:00
Peter Dimov	fac5992e45	Add test/variant_trivial	2020-01-23 03:53:05 +02:00
Peter Dimov	972280e59f	Remove commented-out variant_copy_base	2020-01-23 01:08:32 +02:00
Peter Dimov	ef2ef292b9	The msvc-14.0 workarounds are no longer needed	2020-01-22 20:14:11 +02:00
Peter Dimov	3b2fb1a48a	Split variant_copy_base into separate cc/ca/mc/ma bases; avoids multiple inheritance, which is a penalty in the MS ABI	2020-01-22 19:59:59 +02:00
Peter Dimov	4f81882bfd	Explicitly disable move constructor when needed	2020-01-22 18:30:36 +02:00
Peter Dimov	17bc06b090	Apply msvc-14.0 workarounds	2020-01-22 17:38:45 +02:00
Peter Dimov	c4cad3e96a	Use an intermediate trivial base for trivial variants	2020-01-22 17:09:15 +02:00
Peter Dimov	83ff667813	Remove stray `compiler: g++`	2020-01-21 02:22:17 +02:00
Peter Dimov	5e76451843	Use BOOST_INCLUDE_LIBRARIES=variant2 in the CMake install test	2020-01-21 00:43:15 +02:00
Peter Dimov	c2b5d101eb	Update revision history	2020-01-11 15:22:13 +02:00
Peter Dimov	a92185a86d	Add Boost::container_hash to LINK_LIBRARIES	2020-01-11 06:54:23 +02:00
Peter Dimov	a795f9cf01	Add missing inline	2020-01-11 06:41:21 +02:00
Peter Dimov	f6e2e78d7d	Libc++ doesn't implement a primary std::hash template under C++11	2020-01-11 06:31:45 +02:00
Peter Dimov	1f05cdfb17	Include <functional>, for g++ trunk (10.0)	2020-01-11 06:06:54 +02:00
Peter Dimov	1203aa97c0	Add g++ 4.8 to Travis	2020-01-11 05:29:07 +02:00
Peter Dimov	b3229d48b7	gcc < 7 doesn't like specializing std::hash in a different namespace	2020-01-11 05:27:57 +02:00
Peter Dimov	be11d94adc	Update appveyor.yml	2020-01-11 05:10:28 +02:00
Peter Dimov	fece11142c	Add hashing support	2020-01-11 04:51:30 +02:00
Peter Dimov	58b4a21deb	Add CMake tests	2020-01-09 17:43:54 +02:00
Peter Dimov	5192a345ab	Fix .travis.yml	2019-12-28 22:13:37 +02:00
Peter Dimov	74e6a04a60	Update .travis.yml	2019-12-28 21:35:20 +02:00
Peter Dimov	2af66dd815	Add CMake install support	2019-12-28 18:52:32 +02:00