Document uses_double_storage(). Refs #37 .

Update ci.yml
Use the exact 3.125f in variant_visit_r.cpp
2023-06-29 18:32:58 +03:00 · 2023-06-29 16:44:47 +03:00 · 2023-06-29 12:05:55 +03:00 · 2023-06-29 10:46:54 +03:00 · 2023-06-29 09:54:49 +03:00 · 2023-06-29 09:33:44 +03:00
39 changed files with 2109 additions and 307 deletions
--- a/.drone.jsonnet
+++ b/.drone.jsonnet
@ -0,0 +1,383 @@
+# Copyright 2022 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# https://www.boost.org/LICENSE_1_0.txt
+
+local library = "variant2";
+
+local triggers =
+{
+    branch: [ "master", "develop", "feature/*" ]
+};
+
+local ubsan = { UBSAN: '1', UBSAN_OPTIONS: 'print_stacktrace=1' };
+local asan = { ASAN: '1' };
+
+local linux_pipeline(name, image, environment, packages = "", sources = [], arch = "amd64") =
+{
+    name: name,
+    kind: "pipeline",
+    type: "docker",
+    trigger: triggers,
+    platform:
+    {
+        os: "linux",
+        arch: arch
+    },
+    steps:
+    [
+        {
+            name: "everything",
+            image: image,
+            environment: environment,
+            commands:
+            [
+                'set -e',
+                'wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -',
+            ] +
+            (if sources != [] then [ ('apt-add-repository "' + source + '"') for source in sources ] else []) +
+            (if packages != "" then [ 'apt-get update', 'apt-get -y install ' + packages ] else []) +
+            [
+                'export LIBRARY=' + library,
+                './.drone/drone.sh',
+            ]
+        }
+    ]
+};
+
+local macos_pipeline(name, environment, xcode_version = "12.2", osx_version = "catalina", arch = "amd64") =
+{
+    name: name,
+    kind: "pipeline",
+    type: "exec",
+    trigger: triggers,
+    platform: {
+        "os": "darwin",
+        "arch": arch
+    },
+    node: {
+        "os": osx_version
+    },
+    steps: [
+        {
+            name: "everything",
+            environment: environment + { "DEVELOPER_DIR": "/Applications/Xcode-" + xcode_version + ".app/Contents/Developer" },
+            commands:
+            [
+                'export LIBRARY=' + library,
+                './.drone/drone.sh',
+            ]
+        }
+    ]
+};
+
+local windows_pipeline(name, image, environment, arch = "amd64") =
+{
+    name: name,
+    kind: "pipeline",
+    type: "docker",
+    trigger: triggers,
+    platform:
+    {
+        os: "windows",
+        arch: arch
+    },
+    "steps":
+    [
+        {
+            name: "everything",
+            image: image,
+            environment: environment,
+            commands:
+            [
+                'cmd /C .drone\\\\drone.bat ' + library,
+            ]
+        }
+    ]
+};
+
+[
+    linux_pipeline(
+        "Linux 14.04 GCC 4.8* 32/64",
+        "cppalliance/droneubuntu1404:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11', ADDRMD: '32,64' },
+    ),
+
+    linux_pipeline(
+        "Linux 14.04 GCC 4.9 32/64",
+        "cppalliance/droneubuntu1404:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-4.9', CXXSTD: '03,11', ADDRMD: '32,64' },
+        "g++-4.9-multilib",
+        [ "ppa:ubuntu-toolchain-r/test" ],
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 GCC 5* 32/64",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14', ADDRMD: '32,64' },
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 GCC 6 32/64",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-6', CXXSTD: '03,11,14', ADDRMD: '32,64' },
+        "g++-6-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 GCC 7* 32/64",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17', ADDRMD: '32,64' },
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 GCC 8 32/64",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-8', CXXSTD: '03,11,14,17', ADDRMD: '32,64' },
+        "g++-8-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 GCC 9* 32/64",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17,2a', ADDRMD: '32,64' },
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 GCC 9* ARM64",
+        "cppalliance/droneubuntu2004:multiarch",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17,2a' },
+        arch="arm64",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 GCC 9* S390x",
+        "cppalliance/droneubuntu2004:multiarch",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17,2a' },
+        arch="s390x",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 GCC 10 32/64",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-10', CXXSTD: '03,11,14,17,20', ADDRMD: '32,64' },
+        "g++-10-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 GCC 11* 32/64",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11,14,17,2a', ADDRMD: '32,64' },
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 GCC 12 32 ASAN",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-12', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '32' } + asan,
+        "g++-12-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 GCC 12 64 ASAN",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-12', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '64' } + asan,
+        "g++-12-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 23.04 GCC 13 32/64",
+        "cppalliance/droneubuntu2304:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-13', CXXSTD: '03,11,14,17,20,2b', ADDRMD: '32,64' },
+        "g++-13-multilib",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 Clang 3.5",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.5', CXXSTD: '03,11' },
+        "clang-3.5",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 Clang 3.6",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.6', CXXSTD: '03,11,14' },
+        "clang-3.6",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 Clang 3.7",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.7', CXXSTD: '03,11,14' },
+        "clang-3.7",
+    ),
+
+    linux_pipeline(
+        "Linux 16.04 Clang 3.8",
+        "cppalliance/droneubuntu1604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.8', CXXSTD: '03,11,14' },
+        "clang-3.8",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 3.9",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.9', CXXSTD: '03,11,14' },
+        "clang-3.9",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 4.0",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-4.0', CXXSTD: '03,11,14' },
+        "clang-4.0",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 5.0",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-5.0', CXXSTD: '03,11,14,1z' },
+        "clang-5.0",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 6.0",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-6.0', CXXSTD: '03,11,14,17' },
+        "clang-6.0",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 7",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-7', CXXSTD: '03,11,14,17' },
+        "clang-7",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 8",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-8', CXXSTD: '03,11,14,17' },
+        "clang-8",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 9",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-9', CXXSTD: '03,11,14,17,2a' },
+        "clang-9",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 10",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-10', CXXSTD: '03,11,14,17,2a' },
+        "clang-10",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 11",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-11', CXXSTD: '03,11,14,17,2a' },
+        "clang-11",
+    ),
+
+    linux_pipeline(
+        "Linux 20.04 Clang 12",
+        "cppalliance/droneubuntu2004:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-12', CXXSTD: '03,11,14,17,2a' },
+        "clang-12",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 Clang 13",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-13', CXXSTD: '03,11,14,17,20,2b' },
+        "clang-13",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 Clang 14",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-14', CXXSTD: '03,11,14,17,20,2b' },
+        "clang-14",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 Clang 15 UBSAN",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-15', CXXSTD: '03,11,14,17,20,2b' } + ubsan,
+        "clang-15",
+    ),
+
+    linux_pipeline(
+        "Linux 22.04 Clang 15 ASAN",
+        "cppalliance/droneubuntu2204:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-15', CXXSTD: '03,11,14,17,20,2b' } + asan,
+        "clang-15",
+    ),
+
+    linux_pipeline(
+        "Linux 23.04 Clang 16",
+        "cppalliance/droneubuntu2304:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-16', CXXSTD: '03,11,14,17,20,2b' },
+        "clang-16",
+    ),
+
+    macos_pipeline(
+        "MacOS 10.15 Xcode 12.2 UBSAN",
+        { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,1z' } + ubsan,
+    ),
+
+    macos_pipeline(
+        "MacOS 10.15 Xcode 12.2 ASAN",
+        { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,1z' } + asan,
+    ),
+
+    macos_pipeline(
+        "MacOS 12.4 Xcode 13.4.1 UBSAN",
+        { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,17,20,2b' } + ubsan,
+        xcode_version = "13.4.1", osx_version = "monterey", arch = "arm64",
+    ),
+
+    macos_pipeline(
+        "MacOS 12.4 Xcode 13.4.1 ASAN",
+        { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,17,20,2b' } + asan,
+        xcode_version = "13.4.1", osx_version = "monterey", arch = "arm64",
+    ),
+
+    windows_pipeline(
+        "Windows VS2015 msvc-14.0",
+        "cppalliance/dronevs2015",
+        { TOOLSET: 'msvc-14.0', CXXSTD: '14,latest' },
+    ),
+
+    windows_pipeline(
+        "Windows VS2017 msvc-14.1",
+        "cppalliance/dronevs2017",
+        { TOOLSET: 'msvc-14.1', CXXSTD: '14,17,latest' },
+    ),
+
+    windows_pipeline(
+        "Windows VS2017 msvc-14.1 Strict",
+        "cppalliance/dronevs2017",
+        { TOOLSET: 'msvc-14.1', CXXSTD: '14,17,latest', CXXFLAGS: '/permissive-' },
+    ),
+
+    windows_pipeline(
+        "Windows VS2019 msvc-14.2",
+        "cppalliance/dronevs2019",
+        { TOOLSET: 'msvc-14.2', CXXSTD: '14,17,20,latest' },
+    ),
+
+    windows_pipeline(
+        "Windows VS2019 msvc-14.2 Strict",
+        "cppalliance/dronevs2019",
+        { TOOLSET: 'msvc-14.2', CXXSTD: '14,17,20,latest', CXXFLAGS: '/permissive-' },
+    ),
+
+    windows_pipeline(
+        "Windows VS2022 msvc-14.3",
+        "cppalliance/dronevs2022:1",
+        { TOOLSET: 'msvc-14.3', CXXSTD: '14,17,20,latest' },
+    ),
+]
--- a/.drone/drone.bat
+++ b/.drone/drone.bat
@ -0,0 +1,24 @@
+@REM Copyright 2022 Peter Dimov
+@REM Distributed under the Boost Software License, Version 1.0.
+@REM https://www.boost.org/LICENSE_1_0.txt
+
+@ECHO ON
+
+set LIBRARY=%1
+set DRONE_BUILD_DIR=%CD%
+
+set BOOST_BRANCH=develop
+if "%DRONE_BRANCH%" == "master" set BOOST_BRANCH=master
+cd ..
+git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule update --init tools/boostdep
+xcopy /s /e /q %DRONE_BUILD_DIR% libs\%LIBRARY%\
+python tools/boostdep/depinst/depinst.py %LIBRARY%
+cmd /c bootstrap
+b2 -d0 headers
+
+if not "%CXXSTD%" == "" set CXXSTD=cxxstd=%CXXSTD%
+if not "%ADDRMD%" == "" set ADDRMD=address-model=%ADDRMD%
+if not "%CXXFLAGS%" == "" set CXXFLAGS=cxxflags=%CXXFLAGS%
+b2 -j3 libs/%LIBRARY%/test toolset=%TOOLSET% %CXXSTD% %ADDRMD% %CXXFLAGS% variant=debug,release embed-manifest-via=linker
--- a/.drone/drone.sh
+++ b/.drone/drone.sh
@ -0,0 +1,25 @@
+#!/bin/bash
+
+# Copyright 2022 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# https://www.boost.org/LICENSE_1_0.txt
+
+set -ex
+export PATH=~/.local/bin:/usr/local/bin:$PATH
+
+DRONE_BUILD_DIR=$(pwd)
+
+BOOST_BRANCH=develop
+if [ "$DRONE_BRANCH" = "master" ]; then BOOST_BRANCH=master; fi
+
+cd ..
+git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule update --init tools/boostdep
+cp -r $DRONE_BUILD_DIR/* libs/$LIBRARY
+python tools/boostdep/depinst/depinst.py $LIBRARY
+./bootstrap.sh
+./b2 -d0 headers
+
+echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
+./b2 -j3 libs/$LIBRARY/test toolset=$TOOLSET cxxstd=$CXXSTD variant=debug,release ${ADDRMD:+address-model=$ADDRMD} ${UBSAN:+undefined-sanitizer=norecover debug-symbols=on} ${ASAN:+address-sanitizer=norecover debug-symbols=on} ${LINKFLAGS:+linkflags=$LINKFLAGS}
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@ -17,105 +17,154 @@ jobs:
      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
+            os: ubuntu-latest
+            container: ubuntu:18.04
            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
+            os: ubuntu-latest
+            container: ubuntu:18.04
+            install: g++-5
          - toolset: gcc-6
            cxxstd: "03,11,14,1z"
-            os: ubuntu-16.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
            install: g++-6
          - toolset: gcc-7
            cxxstd: "03,11,14,17"
-            os: ubuntu-18.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
          - toolset: gcc-8
            cxxstd: "03,11,14,17,2a"
-            os: ubuntu-18.04
+            os: ubuntu-20.04
+            install: g++-8
          - toolset: gcc-9
            cxxstd: "03,11,14,17,2a"
-            os: ubuntu-18.04
+            os: ubuntu-20.04
          - 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
+            os: ubuntu-20.04
+            install: g++-10
+          - toolset: gcc-11
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-20.04
+            install: g++-11
+          - toolset: gcc-12
+            cxxstd: "03,11,14,17,20,2b"
+            os: ubuntu-22.04
+            install: g++-12
+          - toolset: gcc-13
+            cxxstd: "03,11,14,17,20,2b"
+            os: ubuntu-latest
+            container: ubuntu:23.04
+            install: g++-13
          - toolset: clang
            compiler: clang++-3.9
            cxxstd: "03,11,14"
-            os: ubuntu-16.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
            install: clang-3.9
          - toolset: clang
            compiler: clang++-4.0
            cxxstd: "03,11,14"
-            os: ubuntu-16.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
            install: clang-4.0
          - toolset: clang
            compiler: clang++-5.0
            cxxstd: "03,11,14,1z"
-            os: ubuntu-16.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
            install: clang-5.0
          - toolset: clang
            compiler: clang++-6.0
            cxxstd: "03,11,14,17"
-            os: ubuntu-18.04
+            os: ubuntu-20.04
+            install: clang-6.0
          - toolset: clang
            compiler: clang++-7
            cxxstd: "03,11,14,17"
-            os: ubuntu-18.04
+            os: ubuntu-20.04
            install: clang-7
          - toolset: clang
            compiler: clang++-8
-            cxxstd: "03,11,14,17,2a"
+            cxxstd: "03,11,14,17"
            os: ubuntu-20.04
+            install: clang-8
          - toolset: clang
            compiler: clang++-9
            cxxstd: "03,11,14,17,2a"
            os: ubuntu-20.04
+            install: clang-9
          - toolset: clang
            compiler: clang++-10
            cxxstd: "03,11,14,17,2a"
            os: ubuntu-20.04
+            install: clang-10
+          - toolset: clang
+            compiler: clang++-11
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-20.04
+            install: clang-11
+          - toolset: clang
+            compiler: clang++-12
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-20.04
+            install: clang-12
+          - toolset: clang
+            compiler: clang++-13
+            cxxstd: "03,11,14,17,20,2b"
+            os: ubuntu-22.04
+            install: clang-13
+          - toolset: clang
+            compiler: clang++-14
+            cxxstd: "03,11,14,17,20,2b"
+            os: ubuntu-22.04
+            install: clang-14
+          - toolset: clang
+            compiler: clang++-15
+            cxxstd: "03,11,14,17,20,2b"
+            os: ubuntu-22.04
+            install: clang-15
+          - toolset: clang
+            compiler: clang++-16
+            cxxstd: "03,11,14,17,20,2b"
+            os: ubuntu-latest
+            container: ubuntu:23.04
+            install: clang-16
          - toolset: clang
            cxxstd: "03,11,14,17,2a"
-            os: macos-10.15
+            os: macos-11
+          - toolset: clang
+            cxxstd: "03,11,14,17,20,2b"
+            os: macos-12
+          - toolset: clang
+            cxxstd: "03,11,14,17,20,2b"
+            os: macos-13

    runs-on: ${{matrix.os}}
+    container: ${{matrix.container}}
+
+    defaults:
+      run:
+        shell: bash

    steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
+
+      - name: Setup container environment
+        if: matrix.container
+        run: |
+          apt-get update
+          apt-get -y install sudo python3 git g++

      - name: Install packages
        if: matrix.install
-        run: sudo apt install ${{matrix.install}}
+        run: |
+          sudo apt-get update
+          sudo apt-get -y install ${{matrix.install}}

      - name: Setup Boost
        run: |
@ -135,7 +184,7 @@ jobs:
          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
+          python3 tools/boostdep/depinst/depinst.py --git_args "--jobs 3" $LIBRARY
          ./bootstrap.sh
          ./b2 -d0 headers

@ -154,14 +203,22 @@ jobs:
      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"
+          - toolset: msvc-14.0
+            cxxstd: "14,latest"
            addrmd: 32,64
            os: windows-2019
+          - toolset: msvc-14.2
+            cxxstd: "14,17,20,latest"
+            addrmd: 32,64
+            os: windows-2019
+          - toolset: msvc-14.3
+            cxxstd: "14,17,20,latest"
+            addrmd: 32,64
+            os: windows-2022
+          - toolset: clang-win
+            cxxstd: "14,17,latest"
+            addrmd: 32,64
+            os: windows-2022
          - toolset: gcc
            cxxstd: "03,11,14,17,2a"
            addrmd: 64
@ -170,7 +227,7 @@ jobs:
    runs-on: ${{matrix.os}}

    steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3

      - name: Setup Boost
        shell: cmd
@ -198,4 +255,346 @@ jobs:
        shell: cmd
        run: |
          cd ../boost-root
-          b2 -j3 libs/%LIBRARY%/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} variant=debug,release
+          b2 -j3 libs/%LIBRARY%/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} variant=debug,release embed-manifest-via=linker
+
+  posix-cmake-subdir:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-20.04
+          - os: ubuntu-22.04
+          - os: macos-11
+          - os: macos-12
+          - os: macos-13
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install packages
+        if: matrix.install
+        run: sudo apt-get -y 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" $LIBRARY
+
+      - name: Use library with add_subdirectory
+        run: |
+          cd ../boost-root/libs/$LIBRARY/test/cmake_subdir_test
+          mkdir __build__ && cd __build__
+          cmake ..
+          cmake --build .
+          ctest --output-on-failure --no-tests=error
+
+  posix-cmake-install:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-20.04
+          - os: ubuntu-22.04
+          - os: macos-11
+          - os: macos-12
+          - os: macos-13
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install packages
+        if: matrix.install
+        run: sudo apt-get -y 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" $LIBRARY
+
+      - name: Configure
+        run: |
+          cd ../boost-root
+          mkdir __build__ && cd __build__
+          cmake -DBOOST_INCLUDE_LIBRARIES=$LIBRARY -DCMAKE_INSTALL_PREFIX=~/.local ..
+
+      - name: Install
+        run: |
+          cd ../boost-root/__build__
+          cmake --build . --target install
+
+      - name: Use the installed library
+        run: |
+          cd ../boost-root/libs/$LIBRARY/test/cmake_install_test && mkdir __build__ && cd __build__
+          cmake -DCMAKE_INSTALL_PREFIX=~/.local ..
+          cmake --build .
+          ctest --output-on-failure --no-tests=error
+
+  posix-cmake-test:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-20.04
+          - os: ubuntu-22.04
+          - os: macos-11
+          - os: macos-12
+          - os: macos-13
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install packages
+        if: matrix.install
+        run: sudo apt-get -y 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" $LIBRARY
+
+      - name: Configure
+        run: |
+          cd ../boost-root
+          mkdir __build__ && cd __build__
+          cmake -DBOOST_INCLUDE_LIBRARIES=$LIBRARY -DBUILD_TESTING=ON ..
+
+      - name: Build tests
+        run: |
+          cd ../boost-root/__build__
+          cmake --build . --target tests
+
+      - name: Run tests
+        run: |
+          cd ../boost-root/__build__
+          ctest --output-on-failure --no-tests=error
+
+  windows-cmake-subdir:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: windows-2019
+          - os: windows-2022
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - 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%
+
+      - name: Use library with add_subdirectory (Debug)
+        shell: cmd
+        run: |
+          cd ../boost-root/libs/%LIBRARY%/test/cmake_subdir_test
+          mkdir __build__ && cd __build__
+          cmake ..
+          cmake --build . --config Debug
+          ctest --output-on-failure --no-tests=error -C Debug
+
+      - name: Use library with add_subdirectory (Release)
+        shell: cmd
+        run: |
+          cd ../boost-root/libs/%LIBRARY%/test/cmake_subdir_test/__build__
+          cmake --build . --config Release
+          ctest --output-on-failure --no-tests=error -C Release
+
+  windows-cmake-install:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: windows-2019
+          - os: windows-2022
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - 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%
+
+      - name: Configure
+        shell: cmd
+        run: |
+          cd ../boost-root
+          mkdir __build__ && cd __build__
+          cmake -DBOOST_INCLUDE_LIBRARIES=%LIBRARY% -DCMAKE_INSTALL_PREFIX=C:/cmake-prefix ..
+
+      - name: Install (Debug)
+        shell: cmd
+        run: |
+          cd ../boost-root/__build__
+          cmake --build . --target install --config Debug
+
+      - name: Install (Release)
+        shell: cmd
+        run: |
+          cd ../boost-root/__build__
+          cmake --build . --target install --config Release
+
+      - name: Use the installed library (Debug)
+        shell: cmd
+        run: |
+          cd ../boost-root/libs/%LIBRARY%/test/cmake_install_test && mkdir __build__ && cd __build__
+          cmake -DCMAKE_INSTALL_PREFIX=C:/cmake-prefix ..
+          cmake --build . --config Debug
+          ctest --output-on-failure --no-tests=error -C Debug
+
+      - name: Use the installed library (Release)
+        shell: cmd
+        run: |
+          cd ../boost-root/libs/%LIBRARY%/test/cmake_install_test/__build__
+          cmake --build . --config Release
+          ctest --output-on-failure --no-tests=error -C Release
+
+  windows-cmake-test:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: windows-2019
+          - os: windows-2022
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - 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%
+
+      - name: Configure
+        shell: cmd
+        run: |
+          cd ../boost-root
+          mkdir __build__ && cd __build__
+          cmake -DBOOST_INCLUDE_LIBRARIES=%LIBRARY% -DBUILD_TESTING=ON ..
+
+      - name: Build tests (Debug)
+        shell: cmd
+        run: |
+          cd ../boost-root/__build__
+          cmake --build . --target tests --config Debug
+
+      - name: Run tests (Debug)
+        shell: cmd
+        run: |
+          cd ../boost-root/__build__
+          ctest --output-on-failure --no-tests=error -C Debug
+
+      - name: Build tests (Release)
+        shell: cmd
+        run: |
+          cd ../boost-root/__build__
+          cmake --build . --target tests --config Release
+
+      - name: Run tests (Release)
+        shell: cmd
+        run: |
+          cd ../boost-root/__build__
+          ctest --output-on-failure --no-tests=error -C Release
--- a/.travis.yml
+++ b/.travis.yml
@ -1,4 +1,4 @@
-# Copyright 2016-2019 Peter Dimov
+# Copyright 2016-2021 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)

@ -95,7 +95,7 @@ matrix:
    - os: linux
      dist: bionic
      compiler: g++-10
-      env: TOOLSET=gcc COMPILER=g++-10 CXXSTD=11,14,17,2a
+      env: UBSAN=1 TOOLSET=gcc COMPILER=g++-10 CXXSTD=11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1 LINKFLAGS=-fuse-ld=gold
      addons:
        apt:
          packages:
@ -103,21 +103,6 @@ matrix:
          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
-      addons:
-        apt:
-          packages:
-            - g++-8
-          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
@ -180,6 +165,7 @@ matrix:
            - ubuntu-toolchain-r-test

    - os: linux
+      dist: bionic
      compiler: clang++-5.0
      env: TOOLSET=clang COMPILER=clang++-5.0 CXXSTD=11,14,1z
      addons:
@ -190,6 +176,7 @@ matrix:
            - ubuntu-toolchain-r-test

    - os: linux
+      dist: bionic
      compiler: clang++-6.0
      env: TOOLSET=clang COMPILER=clang++-6.0 CXXSTD=11,14,17
      addons:
@ -200,6 +187,7 @@ matrix:
            - ubuntu-toolchain-r-test

    - os: linux
+      dist: bionic
      compiler: clang++-7
      env: TOOLSET=clang COMPILER=clang++-7 CXXSTD=11,14,17,2a
      addons:
@ -208,9 +196,10 @@ matrix:
            - clang-7
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-xenial-7
+            - llvm-toolchain-bionic-7

    - os: linux
+      dist: bionic
      compiler: clang++-8
      env: TOOLSET=clang COMPILER=clang++-8 CXXSTD=11,14,17,2a
      addons:
@ -219,10 +208,10 @@ matrix:
            - clang-8
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-xenial-8
+            - llvm-toolchain-bionic-8

    - os: linux
-      dist: xenial
+      dist: bionic
      compiler: clang++-9
      env: TOOLSET=clang COMPILER=clang++-9 CXXSTD=11,14,17,2a
      addons:
@ -231,11 +220,11 @@ matrix:
            - clang-9
          sources:
            - ubuntu-toolchain-r-test
-            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main'
+            - sourceline: 'deb https://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main'
              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'

    - os: linux
-      dist: xenial
+      dist: bionic
      compiler: clang++-10
      env: TOOLSET=clang COMPILER=clang++-10 CXXSTD=11,14,17,2a
      addons:
@ -244,19 +233,34 @@ matrix:
            - clang-10
          sources:
            - ubuntu-toolchain-r-test
-            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-10 main'
+            - sourceline: 'deb https://apt.llvm.org/bionic/ llvm-toolchain-bionic-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
+      dist: bionic
+      compiler: clang++-11
+      env: TOOLSET=clang COMPILER=clang++-11 CXXSTD=11,14,17,2a
      addons:
        apt:
          packages:
-            - clang-8
+            - clang-11
          sources:
            - ubuntu-toolchain-r-test
-            - llvm-toolchain-xenial-8
+            - sourceline: 'deb https://apt.llvm.org/bionic/ llvm-toolchain-bionic-11 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+
+    - os: linux
+      dist: bionic
+      compiler: clang++-12
+      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-12 CXXSTD=11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1
+      addons:
+        apt:
+          packages:
+            - clang-12
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: 'deb https://apt.llvm.org/bionic/ llvm-toolchain-bionic-12 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'

    - os: linux
      dist: trusty
@ -268,18 +272,14 @@ matrix:
            - libc++-dev

    - os: linux
-      dist: trusty
+      dist: bionic
      compiler: clang++-libc++
-      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=11,14,1z UBSAN_OPTIONS=print_stacktrace=1
+      env: TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=11,14,17,2a
      addons:
        apt:
          packages:
            - libc++-dev

-    - os: osx
-      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
@ -288,7 +288,7 @@ matrix:
      env: CMAKE_TEST=1
      script:
        - mkdir __build__ && cd __build__
-        - cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=variant2 ..
+        - cmake -DBOOST_ENABLE_CMAKE=1 -DBUILD_TESTING=ON -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=variant2 ..
        - ctest --output-on-failure -R boost_variant2

    - os: linux
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -1,8 +1,9 @@
-# Copyright 2018, 2019 Peter Dimov
+# Generated by `boostdep --cmake variant2`
+# Copyright 2020, 2021 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
-# http://www.boost.org/LICENSE_1_0.txt
+# https://www.boost.org/LICENSE_1_0.txt

-cmake_minimum_required(VERSION 3.5...3.16)
+cmake_minimum_required(VERSION 3.8...3.20)

 project(boost_variant2 VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)

@ -13,11 +14,23 @@ target_include_directories(boost_variant2 INTERFACE include)

 target_link_libraries(boost_variant2
  INTERFACE
+    Boost::assert
    Boost::config
    Boost::mp11
 )

-if(BUILD_TESTING)
+if(CMAKE_VERSION VERSION_GREATER 3.18 AND CMAKE_GENERATOR MATCHES "Visual Studio")
+
+  file(GLOB_RECURSE boost_variant2_IDEFILES CONFIGURE_DEPENDS include/*.hpp)
+  source_group(TREE ${PROJECT_SOURCE_DIR}/include FILES ${boost_variant2_IDEFILES} PREFIX "Header Files")
+  list(APPEND boost_variant2_IDEFILES extra/boost_variant2.natvis)
+  target_sources(boost_variant2 PRIVATE ${boost_variant2_IDEFILES})
+
+endif()
+
+target_compile_features(boost_variant2 INTERFACE cxx_std_11)
+
+if(BUILD_TESTING AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/test/CMakeLists.txt")

  add_subdirectory(test)

--- a/README.md
+++ b/README.md
@ -1,21 +1,18 @@
-# variant2
+# Boost.Variant2

 This repository contains a never-valueless, strong guarantee, C++11/14/17
 implementation of [std::variant](http://en.cppreference.com/w/cpp/utility/variant).
 See [the documentation](https://www.boost.org/libs/variant2)
 for more information.

-The code requires [Boost.Mp11](https://github.com/boostorg/mp11) and
-Boost.Config.
-
-The library is part of Boost, starting from release 1.71, but the header
-`variant.hpp` will also work [standalone](https://godbolt.org/z/nVUNKX).
+The library is part of Boost, starting from release 1.71. It depends on
+Boost.Mp11, Boost.Config, and Boost.Assert.

 Supported compilers:

 * g++ 4.8 or later with `-std=c++11` or above
-* clang++ 3.5 or later with `-std=c++11` or above
-* Visual Studio 2015, 2017, 2019
+* clang++ 3.9 or later with `-std=c++11` or above
+* Visual Studio 2015 or later

-Tested on [Travis](https://travis-ci.org/boostorg/variant2/) and
+Tested on [Github Actions](https://github.com/boostorg/variant2/actions) and
 [Appveyor](https://ci.appveyor.com/project/pdimov/variant2-fkab9).
--- a/appveyor.yml
+++ b/appveyor.yml
@ -1,4 +1,4 @@
-# Copyright 2016-2020 Peter Dimov
+# Copyright 2016-2021 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)

@ -20,15 +20,26 @@ environment:
    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
      TOOLSET: msvc-14.1
      ADDRMD: 32,64
-      CXXSTD: 14,17
+      CXXSTD: 14,17,latest
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      TOOLSET: msvc-14.1
+      ADDRMD: 32,64
+      CXXSTD: 14,17,latest
+      CXXFLAGS: /permissive-
    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
      TOOLSET: clang-win
      ADDRMD: 64
-      CXXSTD: 14,17
+      CXXSTD: 14,17,latest
    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
-      TOOLSET: msvc-14.2
-      ADDRMD: 32,64
-      CXXSTD: 14,17
+      TOOLSET: clang-win
+      ADDRMD: 64
+      CXXSTD: 14,17,latest
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      CMAKE: 1
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      CMAKE_SUBDIR: 1
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      CMAKE_INSTALL: 1

 install:
  - set BOOST_BRANCH=develop
@ -47,4 +58,28 @@ build: off
 test_script:
  - if not "%CXXSTD%" == "" set CXXSTD=cxxstd=%CXXSTD%
  - if not "%ADDRMD%" == "" set ADDRMD=address-model=%ADDRMD%
-  - b2 -j3 libs/variant2/test toolset=%TOOLSET% %CXXSTD% %ADDRMD% variant=debug,release
+  - if not "%CXXFLAGS%" == "" set CXXFLAGS=cxxflags=%CXXFLAGS%
+  - if "%CMAKE%%CMAKE_SUBDIR%%CMAKE_INSTALL%" == ""  b2 -j3 libs/variant2/test toolset=%TOOLSET% %CXXSTD% %ADDRMD% %CXXFLAGS% variant=debug,release embed-manifest-via=linker
+
+  - if not "%CMAKE%" == ""  mkdir __build__ && cd __build__
+  - if not "%CMAKE%" == ""  cmake -DBUILD_TESTING=ON -DBOOST_INCLUDE_LIBRARIES=variant2 -DBoost_VERBOSE=ON ..
+  - if not "%CMAKE%" == ""  cmake --build . --target tests -j 3 --config Debug & ctest --output-on-failure --no-tests=error -j 3 -C Debug
+  - if not "%CMAKE%" == ""  cmake --build . --target tests -j 3 --config Release & ctest --output-on-failure --no-tests=error -j 3 -C Release
+  - if not "%CMAKE%" == ""  cmake --build . --target tests -j 3 --config MinSizeRel & ctest --output-on-failure --no-tests=error -j 3 -C MinSizeRel
+  - if not "%CMAKE%" == ""  cmake --build . --target tests -j 3 --config RelWithDebInfo & ctest --output-on-failure --no-tests=error -j 3 -C RelWithDebInfo
+
+  - if not "%CMAKE_SUBDIR%" == ""  cd libs/variant2/test/cmake_subdir_test && mkdir __build__ && cd __build__
+  - if not "%CMAKE_SUBDIR%" == ""  cmake ..
+  - if not "%CMAKE_SUBDIR%" == ""  cmake --build . --config Debug && cmake --build . --target check --config Debug
+  - if not "%CMAKE_SUBDIR%" == ""  cmake --build . --config Release && cmake --build . --target check --config Release
+  - if not "%CMAKE_SUBDIR%" == ""  cmake --build . --config MinSizeRel && cmake --build . --target check --config MinSizeRel
+  - if not "%CMAKE_SUBDIR%" == ""  cmake --build . --config RelWithDebInfo && cmake --build . --target check --config RelWithDebInfo
+
+  - if not "%CMAKE_INSTALL%" == ""  mkdir __build__ && cd __build__
+  - if not "%CMAKE_INSTALL%" == ""  cmake -DBOOST_INCLUDE_LIBRARIES=variant2 -DCMAKE_INSTALL_PREFIX=C:/cmake-prefix ..
+  - if not "%CMAKE_INSTALL%" == ""  cmake --build . --target install --config Debug
+  - if not "%CMAKE_INSTALL%" == ""  cmake --build . --target install --config Release
+  - if not "%CMAKE_INSTALL%" == ""  cd ../libs/variant2/test/cmake_install_test && mkdir __build__ && cd __build__
+  - if not "%CMAKE_INSTALL%" == ""  cmake -DCMAKE_INSTALL_PREFIX=C:/cmake-prefix ..
+  - if not "%CMAKE_INSTALL%" == ""  cmake --build . --config Debug && cmake --build . --target check --config Debug
+  - if not "%CMAKE_INSTALL%" == ""  cmake --build . --config Release && cmake --build . --target check --config Release
--- a/doc/variant2.adoc
+++ b/doc/variant2.adoc
@ -13,6 +13,8 @@ Peter Dimov
 :toclevels: 4
 :idprefix:
 :docinfo: private-footer
+:source-highlighter: rouge
+:source-language: c++

 :leveloffset: +1

--- a/doc/variant2/changelog.adoc
+++ b/doc/variant2/changelog.adoc
@ -1,16 +1,36 @@
 ////
-Copyright 2019, 2020 Peter Dimov
-
+Copyright 2019-2022 Peter Dimov
 Distributed under the Boost Software License, Version 1.0.
-
-See accompanying file LICENSE_1_0.txt or copy at
-http://www.boost.org/LICENSE_1_0.txt
+https://www.boost.org/LICENSE_1_0.txt
 ////

 [#changelog]
 # Revision History
 :idprefix: changelog_

+## Changes in 1.83.0
+
+* Added `uses_double_storage()`.
+
+## Changes in 1.81.0
+
+* Added support for `boost::json::value_from` and `boost::json::value_to`.
+
+## Changes in 1.79.0
+
+* Added `operator<<` for `monostate`.
+
+## Changes in 1.78.0
+
+* Added `<boost/variant2.hpp>`.
+* Added `unsafe_get<I>`.
+* Added `visit_by_index`.
+* Added `operator<<`.
+
+## Changes in 1.76.0
+
+* Improved generated code for the double buffered case.
+
 ## Changes in 1.74.0

 * Added support for derived types in `visit`
--- a/doc/variant2/design.adoc
+++ b/doc/variant2/design.adoc
@ -169,6 +169,10 @@ 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.)
+* `unsafe_get`, an unchecked alternative to `get` and `get_if`, is provided
+  as an extension.
+* `visit_by_index`, a visitation function that takes a single variant and a
+  number of function objects, one per alternative, is provided as an extension.
 * The {cpp}20 additions and changes to `std::variant` have not yet been
  implemented.

--- a/doc/variant2/implementation.adoc
+++ b/doc/variant2/implementation.adoc
@ -1,10 +1,7 @@
 ////
 Copyright 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
+https://www.boost.org/LICENSE_1_0.txt
 ////

 [#implementation]
@ -13,13 +10,13 @@ http://www.boost.org/LICENSE_1_0.txt

 ## Dependencies

-This implementation only depends on Boost.Config and Boost.Mp11.
+This implementation only depends on Boost.Config, Boost.Assert, and Boost.Mp11.

 ## Supported Compilers

 * GCC 4.8 or later with `-std=c++11` or above
-* Clang 3.5 or later with `-std=c++11` or above
-* Visual Studio 2015, 2017, 2019
+* Clang 3.9 or later with `-std=c++11` or above
+* Visual Studio 2015 or later

-Tested on https://travis-ci.org/boostorg/variant2/[Travis] and
+Tested on https://github.com/boostorg/variant2/actions[Github Actions] and
 https://ci.appveyor.com/project/pdimov/variant2-fkab9[Appveyor].
--- a/doc/variant2/reference.adoc
+++ b/doc/variant2/reference.adoc
@ -1,10 +1,7 @@
 ////
-Copyright 2018, 2019 Peter Dimov
-
+Copyright 2018-2021 Peter Dimov
 Distributed under the Boost Software License, Version 1.0.
-
-See accompanying file LICENSE_1_0.txt or copy at
-http://www.boost.org/LICENSE_1_0.txt
+https://www.boost.org/LICENSE_1_0.txt
 ////

 [#reference]
@ -117,6 +114,21 @@ template<class U, class... T>
  constexpr add_pointer_t<const U>
    get_if(const variant<T...>* v) noexcept;

+// unsafe_get (extension)
+
+template<size_t I, class... T>
+  constexpr variant_alternative_t<I, variant<T...>>&
+    unsafe_get(variant<T...>& v);
+template<size_t I, class... T>
+  constexpr variant_alternative_t<I, variant<T...>>&&
+    unsafe_get(variant<T...>&& v);
+template<size_t I, class... T>
+  constexpr const variant_alternative_t<I, variant<T...>>&
+    unsafe_get(const variant<T...>& v);
+template<size_t I, class... T>
+  constexpr const variant_alternative_t<I, variant<T...>>&&
+    unsafe_get(const variant<T...>&& v);
+
 // relational operators

 template<class... T>
@ -132,11 +144,21 @@ template<class... T>
 template<class... T>
  constexpr bool operator>=(const variant<T...>& v, const variant<T...>& w);

+// swap
+
+template<class... T>
+  void swap(variant<T...>& v, variant<T...>& w) noexcept( /*see below*/ );
+
 // visit

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

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

 struct monostate {};
@ -148,10 +170,15 @@ constexpr bool operator>(monostate, monostate) noexcept { return false; }
 constexpr bool operator<=(monostate, monostate) noexcept { return true; }
 constexpr bool operator>=(monostate, monostate) noexcept { return true; }

-// swap
+// stream insertion (extension)

-template<class... T>
-  void swap(variant<T...>& v, variant<T...>& w) noexcept( /*see below*/ );
+template<class Ch, class Tr, class... T>
+  std::basic_ostream<Ch, Tr>&
+    operator<<( std::basic_ostream<Ch, Tr>& os, variant<T...> const& v );
+
+template<class Ch, class Tr>
+  std::basic_ostream<Ch, Tr>&
+    operator<<( std::basic_ostream<Ch, Tr>& os, monostate const& v );

 // bad_variant_access

@ -223,6 +250,8 @@ public:
  constexpr bool valueless_by_exception() const noexcept;
  constexpr size_t index() const noexcept;

+  static constexpr bool uses_double_storage() noexcept;
+
  // swap

  void swap( variant& r ) noexcept( /*see below*/ );
@ -490,8 +519,8 @@ template<size_t I, class... A>
 +
 Requires: :: `I < sizeof...(T)`.
 Effects:  ::
-  Destroys the currently contained value, then initializes a new contained
-  value as if using the expression `Ti(std::forward<A>(a)...)`.
+  Initializes a new contained value as if using the expression
+  `Ti(std::forward<A>(a)...)`, then destroys the currently contained value.
 Ensures:  :: `index() == I`.
 Returns:  :: A reference to the new contained value.
 Throws:   ::
@ -511,8 +540,8 @@ template<size_t I, class V, class... A>
 +
 Requires: :: `I < sizeof...(T)`.
 Effects:  ::
-  Destroys the currently contained value, then initializes a new contained
-  value as if using the expression `Ti(il, std::forward<A>(a)...)`.
+  Initializes a new contained value as if using the expression
+  `Ti(il, std::forward<A>(a)...)`, then destroys the currently contained value.
 Ensures:  :: `index() == I`.
 Returns:  :: A reference to the new contained value.
 Throws:   ::
@ -543,6 +572,18 @@ constexpr size_t index() const noexcept;
 Returns:  ::
  The zero-based index of the active alternative.

+```
+static constexpr bool uses_double_storage() noexcept;
+```
+[none]
+* {blank}
+
+Returns:  ::
+  `true` if the variant uses double storage to meet the never valueless
+  guarantee because one of the alternatives is not nothrow move constructible,
+  and `false` otherwise.
+
+
 #### Swap

 ```
@ -775,6 +816,34 @@ Requires: :: The type `U` occurs exactly once in `T...`. Otherwise, the
 Effects:  :: Equivalent to: `return get_if<I>(v);` with `I` being
  the zero-based index of `U` in `T...`.

+### unsafe_get (extension)
+
+```
+template<size_t I, class... T>
+  constexpr variant_alternative_t<I, variant<T...>>&
+    unsafe_get(variant<T...>& v);
+```
+```
+template<size_t I, class... T>
+  constexpr variant_alternative_t<I, variant<T...>>&&
+    unsafe_get(variant<T...>&& v);
+```
+```
+template<size_t I, class... T>
+  constexpr const variant_alternative_t<I, variant<T...>>&
+    unsafe_get(const variant<T...>& v);
+```
+```
+template<size_t I, class... T>
+  constexpr const variant_alternative_t<I, variant<T...>>&&
+    unsafe_get(const variant<T...>&& v);
+```
+[none]
+* {blank}
+
+Requires: :: `v.index() == I`.
+Returns: :: a reference to the object stored in the variant.
+
 ### Relational Operators

 ```
@ -835,6 +904,18 @@ template<class... T>
 Returns: ::
  `w \<= v`.

+### swap
+
+```
+template<class... T>
+  void swap(variant<T...>& v, variant<T...>& w) noexcept( /*see below*/ );
+```
+[none]
+* {blank}
+
+Effects: ::
+  Equivalent to `v.swap(w)`.
+
 ### visit

 ```
@ -851,17 +932,50 @@ Remarks: :: If `R` is given explicitly, as in `visit<int>`, the return
  of `F` to the variant alternatives must have the same return type for
  this deduction to succeed.

-### swap
+### visit_by_index (extension)

 ```
-template<class... T>
-  void swap(variant<T...>& v, variant<T...>& w) noexcept( /*see below*/ );
+template<class R = /*unspecified*/, class V, class... F>
+  constexpr /*see below*/ visit_by_index(V&& v, F&&.. f);
+```
+[none]
+* {blank}
+
+Requires: :: `variant_size<V>::value == sizeof...(F)`, or the program is ill-formed.
+Returns: :: `std::forward<Fi>(fi)(get<i>(std::forward<V>(v)))`, where
+  `i` is `v.index()` and `Fi` and `fi` are the `i`-th element of `F...` and `f...`
+  accordingly.
+Remarks: :: If `R` is given explicitly, as in `visit_by_index<int>`, the return
+  type is `R`. Otherwise, it's deduced from `F...` and `V`. All the applications
+  of `Fi` to the corresponding variant alternatives must have the same return type
+  for this deduction to succeed.
+
+### Stream Insertion (extension)
+```
+template<class Ch, class Tr, class... T>
+  std::basic_ostream<Ch, Tr>&
+    operator<<( std::basic_ostream<Ch, Tr>& os, variant<T...> const& v );
+```
+[none]
+* {blank}
+
+Requires: ::
+  `sizeof...(T) != 0`.
+Returns: ::
+  `os << get<I>(v)`, where `I` is `v.index()`.
+
+```
+template<class Ch, class Tr>
+  std::basic_ostream<Ch, Tr>&
+    operator<<( std::basic_ostream<Ch, Tr>& os, monostate const& v );
 ```
 [none]
 * {blank}
 +
 Effects: ::
-  Equivalent to `v.swap(w)`.
+  `os << "monostate"`.
+Returns: ::
+  `os`.

 ### bad_variant_access

@ -878,3 +992,7 @@ public:
    }
 };
 ```
+
+## <boost/variant2.hpp>
+
+This convenience header includes `<boost/variant2/variant.hpp>`.
--- a/extra/boost_variant2.natvis
+++ b/extra/boost_variant2.natvis
@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?>
+<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+
+    <Type Name="boost::variant2::detail::variant_ma_base_impl&lt;*&gt;" Inheritable="true">
+        <Intrinsic Name="index" Expression="$T2==1?((int)ix_-1):((int)((ix_-2)/2))"/>
+        <DisplayString Condition="index()==0&amp;&amp;$T2==1" Optional="true">{st_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==1&amp;&amp;$T2==1" Optional="true">{st_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==2&amp;&amp;$T2==1" Optional="true">{st_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==3&amp;&amp;$T2==1" Optional="true">{st_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==4&amp;&amp;$T2==1" Optional="true">{st_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==5&amp;&amp;$T2==1" Optional="true">{st_.rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==6&amp;&amp;$T2==1" Optional="true">{st_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==7&amp;&amp;$T2==1" Optional="true">{st_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==8&amp;&amp;$T2==1" Optional="true">{st_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==9&amp;&amp;$T2==1" Optional="true">{st_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==0&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==1&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==2&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==3&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==4&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==5&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==6&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==7&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==8&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <DisplayString Condition="index()==9&amp;&amp;$T2==0" Optional="true">{st_[ix_%2].rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.rest_.first_} ({index()})</DisplayString>
+        <Expand>
+            <Item Name="[index]">index()</Item>
+            <Item Name="ix_">ix_</Item>
+        </Expand>
+    </Type>
+
+</AutoVisualizer>
--- a/include/boost/variant2.hpp
+++ b/include/boost/variant2.hpp
@ -0,0 +1,10 @@
+#ifndef BOOST_VARIANT2_HPP_INCLUDED
+#define BOOST_VARIANT2_HPP_INCLUDED
+
+// Copyright 2021 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+
+#endif // #ifndef BOOST_VARIANT2_HPP_INCLUDED
--- a/include/boost/variant2/variant.hpp
+++ b/include/boost/variant2/variant.hpp
@ -13,19 +13,21 @@
 # pragma warning( disable: 4521 4522 ) // multiple copy operators
 #endif

-#ifndef BOOST_MP11_HPP_INCLUDED
 #include <boost/mp11.hpp>
-#endif
+#include <boost/assert.hpp>
+#include <boost/assert/source_location.hpp>
 #include <boost/config.hpp>
-#include <boost/detail/workaround.hpp>
+#include <boost/config/workaround.hpp>
 #include <boost/cstdint.hpp>
 #include <cstddef>
 #include <type_traits>
 #include <exception>
-#include <cassert>
 #include <initializer_list>
 #include <utility>
 #include <functional> // std::hash
+#include <iosfwd>
+#include <cstdint>
+#include <cerrno>

 //

@ -38,6 +40,8 @@ BOOST_NORETURN void throw_exception( std::exception const & e ); // user defined

 #endif

+template<class T> struct hash;
+
 namespace variant2
 {

@ -81,6 +85,8 @@ struct monostate
 {
 };

+#if !BOOST_WORKAROUND(BOOST_MSVC, < 1940)
+
 constexpr bool operator<(monostate, monostate) noexcept { return false; }
 constexpr bool operator>(monostate, monostate) noexcept { return false; }
 constexpr bool operator<=(monostate, monostate) noexcept { return true; }
@ -88,6 +94,17 @@ constexpr bool operator>=(monostate, monostate) noexcept { return true; }
 constexpr bool operator==(monostate, monostate) noexcept { return true; }
 constexpr bool operator!=(monostate, monostate) noexcept { return false; }

+#else
+
+constexpr bool operator<(monostate const&, monostate const&) noexcept { return false; }
+constexpr bool operator>(monostate const&, monostate const&) noexcept { return false; }
+constexpr bool operator<=(monostate const&, monostate const&) noexcept { return true; }
+constexpr bool operator>=(monostate const&, monostate const&) noexcept { return true; }
+constexpr bool operator==(monostate const&, monostate const&) noexcept { return true; }
+constexpr bool operator!=(monostate const&, monostate const&) noexcept { return false; }
+
+#endif
+
 // variant forward declaration

 template<class... T> class variant;
@ -351,37 +368,50 @@ template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T
 #endif
 }

-// detail::unsafe_get (for visit)
+// unsafe_get

-namespace detail
-{
+#if !defined(BOOST_NO_CXX14_CONSTEXPR)
+# define BOOST_VARIANT2_CX14_ASSERT(expr) BOOST_ASSERT(expr);
+#else
+# define BOOST_VARIANT2_CX14_ASSERT(expr)
+#endif

 template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>>& unsafe_get(variant<T...>& v)
 {
    static_assert( I < sizeof...(T), "Index out of bounds" );
+
+    BOOST_VARIANT2_CX14_ASSERT( v.index() == I )
+
    return v._get_impl( mp11::mp_size_t<I>() );
 }

 template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>>&& unsafe_get(variant<T...>&& v)
 {
    static_assert( I < sizeof...(T), "Index out of bounds" );
+
+    BOOST_VARIANT2_CX14_ASSERT( v.index() == I )
+
    return std::move( v._get_impl( mp11::mp_size_t<I>() ) );
 }

 template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>> const& unsafe_get(variant<T...> const& v)
 {
    static_assert( I < sizeof...(T), "Index out of bounds" );
+
+    BOOST_VARIANT2_CX14_ASSERT( v.index() == I )
+
    return v._get_impl( mp11::mp_size_t<I>() );
 }

 template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>> const&& unsafe_get(variant<T...> const&& v)
 {
    static_assert( I < sizeof...(T), "Index out of bounds" );
+
+    BOOST_VARIANT2_CX14_ASSERT( v.index() == I )
+
    return std::move( v._get_impl( mp11::mp_size_t<I>() ) );
 }

-} // namespace detail
-
 // get (type)

 template<class U, class... T> constexpr U& get(variant<T...>& v)
@ -520,11 +550,11 @@ template<class T1, class... T> union variant_storage_impl<mp11::mp_false, T1, T.
    T1 first_;
    variant_storage<T...> rest_;

-    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<0>, A&&... a ): first_( std::forward<A>(a)... )
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<0>, A&&... a ): first_( 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-1>(), std::forward<A>(a)... )
+    template<std::size_t I, class... A> constexpr variant_storage_impl( mp11::mp_size_t<I>, A&&... a ): rest_( mp11::mp_size_t<I-1>(), std::forward<A>(a)... )
    {
    }

@ -564,18 +594,18 @@ template<class T0, class T1, class T2, class T3, class T4, class T5, class T6, c

    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<class... A> constexpr variant_storage_impl( mp11::mp_size_t<0>, A&&... a ): t0_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<1>, A&&... a ): t1_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<2>, A&&... a ): t2_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<3>, A&&... a ): t3_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<4>, A&&... a ): t4_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<5>, A&&... a ): t5_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<6>, A&&... a ): t6_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<7>, A&&... a ): t7_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<8>, A&&... a ): t8_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr 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<std::size_t I, class... A> constexpr variant_storage_impl( mp11::mp_size_t<I>, A&&... a ): rest_( mp11::mp_size_t<I-10>(), std::forward<A>(a)... ) {}

    ~variant_storage_impl()
    {
@ -637,11 +667,11 @@ template<class T1, class... T> union variant_storage_impl<mp11::mp_true, T1, T..
    T1 first_;
    variant_storage<T...> rest_;

-    template<class... A> constexpr explicit variant_storage_impl( mp11::mp_size_t<0>, A&&... a ): first_( std::forward<A>(a)... )
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<0>, A&&... a ): first_( 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-1>(), std::forward<A>(a)... )
+    template<std::size_t I, class... A> constexpr variant_storage_impl( mp11::mp_size_t<I>, A&&... a ): rest_( mp11::mp_size_t<I-1>(), std::forward<A>(a)... )
    {
    }

@ -657,7 +687,17 @@ template<class T1, class... T> union variant_storage_impl<mp11::mp_true, T1, T..

    template<std::size_t I, class... A> BOOST_CXX14_CONSTEXPR void emplace_impl( mp11::mp_true, mp11::mp_size_t<I>, A&&... a )
    {
+#if defined(BOOST_GCC) && (__GNUC__ >= 7)
+# pragma GCC diagnostic push
+// False positive in at least GCC 7 and GCC 10 ASAN triggered by monostate (via result<void>)
+# pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
+
        *this = variant_storage_impl( mp11::mp_size_t<I>(), std::forward<A>(a)... );
+
+#if defined(BOOST_GCC) && (__GNUC__ >= 7)
+# pragma GCC diagnostic pop
+#endif
    }

    template<std::size_t I, class... A> BOOST_CXX14_CONSTEXPR void emplace( mp11::mp_size_t<I>, A&&... a )
@ -687,18 +727,18 @@ template<class T0, class T1, class T2, class T3, class T4, class T5, class T6, c

    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<class... A> constexpr variant_storage_impl( mp11::mp_size_t<0>, A&&... a ): t0_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<1>, A&&... a ): t1_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<2>, A&&... a ): t2_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<3>, A&&... a ): t3_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<4>, A&&... a ): t4_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<5>, A&&... a ): t5_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<6>, A&&... a ): t6_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<7>, A&&... a ): t7_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr variant_storage_impl( mp11::mp_size_t<8>, A&&... a ): t8_( std::forward<A>(a)... ) {}
+    template<class... A> constexpr 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<std::size_t I, class... A> constexpr 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)... ); }
@ -814,21 +854,21 @@ struct none {};
 // trivially destructible, single buffered
 template<class... T> struct variant_base_impl<true, true, T...>
 {
-    int ix_;
-    variant_storage<none, T...> st1_;
+    variant_storage<none, T...> st_;
+    unsigned ix_;

-    constexpr variant_base_impl(): ix_( 0 ), st1_( mp11::mp_size_t<0>() )
+    constexpr variant_base_impl(): st_( mp11::mp_size_t<0>() ), ix_( 0 )
    {
    }

-    template<class I, class... A> constexpr explicit variant_base_impl( I, A&&... a ): ix_( I::value + 1 ), st1_( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... )
+    template<class I, class... A> constexpr explicit variant_base_impl( I, A&&... a ): st_( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... ), ix_( I::value + 1 )
    {
    }

    // requires: ix_ == 0
    template<class I, class... A> void _replace( I, A&&... a )
    {
-        ::new( &st1_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
+        ::new( &st_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
        ix_ = I::value + 1;
    }

@ -841,24 +881,25 @@ template<class... T> struct variant_base_impl<true, true, T...>
    {
        size_t const J = I+1;

-        assert( ix_ == J );
+        BOOST_ASSERT( ix_ == J );

-        return st1_.get( mp11::mp_size_t<J>() );
+        return st_.get( mp11::mp_size_t<J>() );
    }

    template<std::size_t I> constexpr mp11::mp_at_c<variant<T...>, I> const& _get_impl( mp11::mp_size_t<I> ) const noexcept
    {
        // size_t const J = I+1;
-        // assert( ix_ == I+1 );

-        return st1_.get( mp11::mp_size_t<I+1>() );
+        BOOST_VARIANT2_CX14_ASSERT( ix_ == I+1 )
+
+        return st_.get( mp11::mp_size_t<I+1>() );
    }

    template<std::size_t J, class U, class... A> BOOST_CXX14_CONSTEXPR void emplace_impl( mp11::mp_true, A&&... a )
    {
        static_assert( std::is_nothrow_constructible<U, A&&...>::value, "Logic error: U must be nothrow constructible from A&&..." );

-        st1_.emplace( mp11::mp_size_t<J>(), std::forward<A>(a)... );
+        st_.emplace( mp11::mp_size_t<J>(), std::forward<A>(a)... );
        ix_ = J;
    }

@ -868,7 +909,7 @@ template<class... T> struct variant_base_impl<true, true, T...>

        U tmp( std::forward<A>(a)... );

-        st1_.emplace( mp11::mp_size_t<J>(), std::move(tmp) );
+        st_.emplace( mp11::mp_size_t<J>(), std::move(tmp) );
        ix_ = J;
    }

@ -879,89 +920,94 @@ template<class... T> struct variant_base_impl<true, true, T...>

        this->emplace_impl<J, U>( std::is_nothrow_constructible<U, A&&...>(), std::forward<A>(a)... );
    }
+
+    static constexpr bool uses_double_storage() noexcept
+    {
+        return false;
+    }
 };

 // trivially destructible, double buffered
 template<class... T> struct variant_base_impl<true, false, T...>
 {
-    int ix_;
-    variant_storage<none, T...> st1_;
-    variant_storage<none, T...> st2_;
+    variant_storage<none, T...> st_[ 2 ];
+    unsigned ix_;

-    constexpr variant_base_impl(): ix_( 0 ), st1_( mp11::mp_size_t<0>() ), st2_( mp11::mp_size_t<0>() )
+    constexpr variant_base_impl(): st_{ { mp11::mp_size_t<0>() }, { mp11::mp_size_t<0>() } }, ix_( 0 )
    {
    }

-    template<class I, class... A> constexpr explicit variant_base_impl( I, A&&... a ): ix_( I::value + 1 ), st1_( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... ), st2_( mp11::mp_size_t<0>() )
+    template<class I, class... A> constexpr explicit variant_base_impl( I, A&&... a ): st_{ { mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... }, { mp11::mp_size_t<0>() } }, ix_( ( I::value + 1 ) * 2 )
    {
    }

    // requires: ix_ == 0
    template<class I, class... A> void _replace( I, A&&... a )
    {
-        ::new( &st1_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
-        ix_ = I::value + 1;
+        ::new( &st_[ 0 ] ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
+        ix_ = ( I::value + 1 ) * 2;
    }

    constexpr std::size_t index() const noexcept
    {
-        return ix_ >= 0? ix_ - 1: -ix_ - 1;
+        return ix_ / 2 - 1;
    }

    template<std::size_t I> BOOST_CXX14_CONSTEXPR mp11::mp_at_c<variant<T...>, I>& _get_impl( mp11::mp_size_t<I> ) noexcept
    {
+        BOOST_ASSERT( index() == I );
+
        size_t const J = I+1;

-        assert( ix_ == J || -ix_ == J );
-
        constexpr mp11::mp_size_t<J> j{};
-        return ix_ >= 0? st1_.get( j ): st2_.get( j );
+        return st_[ ix_ & 1 ].get( j );
    }

    template<std::size_t I> constexpr mp11::mp_at_c<variant<T...>, I> const& _get_impl( mp11::mp_size_t<I> ) const noexcept
    {
+        BOOST_VARIANT2_CX14_ASSERT( index() == I )
+
        // size_t const J = I+1;
-        // assert( ix_ == J || -ix_ == J );
        // constexpr mp_size_t<J> j{};

-        return ix_ >= 0? st1_.get( mp11::mp_size_t<I+1>() ): st2_.get( mp11::mp_size_t<I+1>() );
+        return st_[ ix_ & 1 ].get( mp11::mp_size_t<I+1>() );
    }

    template<std::size_t I, class... A> BOOST_CXX14_CONSTEXPR void emplace( A&&... a )
    {
        size_t const J = I+1;

-        if( ix_ >= 0 )
-        {
-            st2_.emplace( mp11::mp_size_t<J>(), std::forward<A>(a)... );
-            ix_ = -static_cast<int>( J );
-        }
-        else
-        {
-            st1_.emplace( mp11::mp_size_t<J>(), std::forward<A>(a)... );
-            ix_ = J;
-        }
+        unsigned i2 = 1 - ( ix_ & 1 );
+
+        st_[ i2 ].emplace( mp11::mp_size_t<J>(), std::forward<A>(a)... );
+
+        ix_ = J * 2 + i2;
+    }
+
+    static constexpr bool uses_double_storage() noexcept
+    {
+        return true;
    }
 };

 // not trivially destructible, single buffered
 template<class... T> struct variant_base_impl<false, true, T...>
 {
-    int ix_;
-    variant_storage<none, T...> st1_;
+    variant_storage<none, T...> st_;
+    unsigned ix_;

-    constexpr variant_base_impl(): ix_( 0 ), st1_( mp11::mp_size_t<0>() )
+    constexpr variant_base_impl(): st_( mp11::mp_size_t<0>() ), ix_( 0 )
    {
    }

-    template<class I, class... A> constexpr explicit variant_base_impl( I, A&&... a ): ix_( I::value + 1 ), st1_( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... )
+    template<class I, class... A> constexpr explicit variant_base_impl( I, A&&... a ): st_( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... ), ix_( I::value + 1 )
    {
    }

    // requires: ix_ == 0
    template<class I, class... A> void _replace( I, A&&... a )
    {
-        ::new( &st1_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
+        ::new( &st_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
        ix_ = I::value + 1;
    }

@ -977,7 +1023,7 @@ template<class... T> struct variant_base_impl<false, true, T...>
        template<class I> void operator()( I ) const noexcept
        {
            using U = mp11::mp_at<mp11::mp_list<none, T...>, I>;
-            this_->st1_.get( I() ).~U();
+            this_->st_.get( I() ).~U();
        }
    };

@ -1003,17 +1049,18 @@ template<class... T> struct variant_base_impl<false, true, T...>
    {
        size_t const J = I+1;

-        assert( ix_ == J );
+        BOOST_ASSERT( ix_ == J );

-        return st1_.get( mp11::mp_size_t<J>() );
+        return st_.get( mp11::mp_size_t<J>() );
    }

    template<std::size_t I> constexpr mp11::mp_at_c<variant<T...>, I> const& _get_impl( mp11::mp_size_t<I> ) const noexcept
    {
        // size_t const J = I+1;
-        // assert( ix_ == J );

-        return st1_.get( mp11::mp_size_t<I+1>() );
+        BOOST_VARIANT2_CX14_ASSERT( ix_ == I+1 )
+
+        return st_.get( mp11::mp_size_t<I+1>() );
    }

    template<std::size_t I, class... A> void emplace( A&&... a )
@ -1028,31 +1075,74 @@ template<class... T> struct variant_base_impl<false, true, T...>

        _destroy();

-        st1_.emplace( mp11::mp_size_t<J>(), std::move(tmp) );
+        st_.emplace( mp11::mp_size_t<J>(), std::move(tmp) );
        ix_ = J;
    }
+
+    static constexpr bool uses_double_storage() noexcept
+    {
+        return false;
+    }
 };

 // not trivially destructible, double buffered
 template<class... T> struct variant_base_impl<false, false, T...>
 {
-    int ix_;
-    variant_storage<none, T...> st1_;
-    variant_storage<none, T...> st2_;
+#if defined(__GNUC__) && __GNUC__ < 11 && !defined(__clang__) && !defined(__INTEL_COMPILER)

-    constexpr variant_base_impl(): ix_( 0 ), st1_( mp11::mp_size_t<0>() ), st2_( mp11::mp_size_t<0>() )
+    // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63707 :-(
+
+    variant_storage<none, T...> st1_, st2_;
+    unsigned ix_;
+
+    constexpr variant_base_impl(): st1_( mp11::mp_size_t<0>() ), st2_( mp11::mp_size_t<0>() ), ix_( 0 )
    {
    }

-    template<class I, class... A> constexpr explicit variant_base_impl( I, A&&... a ): ix_( I::value + 1 ), st1_( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... ), st2_( mp11::mp_size_t<0>() )
+    template<class I, class... A> constexpr explicit variant_base_impl( I, A&&... a ): st1_( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... ), st2_( mp11::mp_size_t<0>() ), ix_( ( I::value + 1 ) * 2 )
    {
    }

+    BOOST_CXX14_CONSTEXPR variant_storage<none, T...>& storage( unsigned i2 ) noexcept
+    {
+        return i2 == 0? st1_: st2_;
+    }
+
+    constexpr variant_storage<none, T...> const& storage( unsigned i2 ) const noexcept
+    {
+        return i2 == 0? st1_: st2_;
+    }
+
+#else
+
+    variant_storage<none, T...> st_[ 2 ];
+    unsigned ix_;
+
+    constexpr variant_base_impl(): st_{ { mp11::mp_size_t<0>() }, { mp11::mp_size_t<0>() } }, ix_( 0 )
+    {
+    }
+
+    template<class I, class... A> constexpr explicit variant_base_impl( I, A&&... a ): st_{ { mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... }, { mp11::mp_size_t<0>() } }, ix_( ( I::value + 1 ) * 2 )
+    {
+    }
+
+    BOOST_CXX14_CONSTEXPR variant_storage<none, T...>& storage( unsigned i2 ) noexcept
+    {
+        return st_[ i2 ];
+    }
+
+    constexpr variant_storage<none, T...> const& storage( unsigned i2 ) const noexcept
+    {
+        return st_[ i2 ];
+    }
+
+#endif
+
    // requires: ix_ == 0
    template<class I, class... A> void _replace( I, A&&... a )
    {
-        ::new( &st1_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
-        ix_ = I::value + 1;
+        ::new( &storage( 0 ) ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
+        ix_ = ( I::value + 1 ) * 2;
    }

    //[&]( auto I ){
@ -1063,35 +1153,18 @@ template<class... T> struct variant_base_impl<false, false, T...>
    struct _destroy_L1
    {
        variant_base_impl * this_;
+        unsigned i2_;

        template<class I> void operator()( I ) const noexcept
        {
            using U = mp11::mp_at<mp11::mp_list<none, T...>, I>;
-            this_->st1_.get( I() ).~U();
-        }
-    };
-
-    struct _destroy_L2
-    {
-        variant_base_impl * this_;
-
-        template<class I> void operator()( I ) const noexcept
-        {
-            using U = mp11::mp_at<mp11::mp_list<none, T...>, I>;
-            this_->st2_.get( I() ).~U();
+            this_->storage( i2_ ).get( I() ).~U();
        }
    };

    void _destroy() noexcept
    {
-        if( ix_ > 0 )
-        {
-            mp11::mp_with_index<1 + sizeof...(T)>( ix_, _destroy_L1{ this } );
-        }
-        else if( ix_ < 0 )
-        {
-            mp11::mp_with_index<1 + sizeof...(T)>( -ix_, _destroy_L2{ this } );
-        }
+        mp11::mp_with_index<1 + sizeof...(T)>( ix_ / 2, _destroy_L1{ this, ix_ & 1 } );
    }

    ~variant_base_impl() noexcept
@ -1101,46 +1174,44 @@ template<class... T> struct variant_base_impl<false, false, T...>

    constexpr std::size_t index() const noexcept
    {
-        return ix_ >= 0? ix_ - 1: -ix_ - 1;
+        return ix_ / 2 - 1;
    }

    template<std::size_t I> BOOST_CXX14_CONSTEXPR mp11::mp_at_c<variant<T...>, I>& _get_impl( mp11::mp_size_t<I> ) noexcept
    {
+        BOOST_ASSERT( index() == I );
+
        size_t const J = I+1;

-        assert( ix_ == J || -ix_ == J );
-
        constexpr mp11::mp_size_t<J> j{};
-        return ix_ >= 0? st1_.get( j ): st2_.get( j );
+        return storage( ix_ & 1 ).get( j );
    }

    template<std::size_t I> constexpr mp11::mp_at_c<variant<T...>, I> const& _get_impl( mp11::mp_size_t<I> ) const noexcept
    {
+        BOOST_VARIANT2_CX14_ASSERT( index() == I )
+
        // size_t const J = I+1;
-        // assert( ix_ == J || -ix_ == J );
        // constexpr mp_size_t<J> j{};

-        return ix_ >= 0? st1_.get( mp11::mp_size_t<I+1>() ): st2_.get( mp11::mp_size_t<I+1>() );
+        return storage( ix_ & 1 ).get( mp11::mp_size_t<I+1>() );
    }

    template<std::size_t I, class... A> void emplace( A&&... a )
    {
        size_t const J = I+1;

-        if( ix_ >= 0 )
-        {
-            st2_.emplace( mp11::mp_size_t<J>(), std::forward<A>(a)... );
-            _destroy();
+        unsigned i2 = 1 - ( ix_ & 1 );

-            ix_ = -static_cast<int>( J );
-        }
-        else
-        {
-            st1_.emplace( mp11::mp_size_t<J>(), std::forward<A>(a)... );
-            _destroy();
+        storage( i2 ).emplace( mp11::mp_size_t<J>(), std::forward<A>(a)... );
+        _destroy();

-            ix_ = J;
-        }
+        ix_ = J * 2 + i2;
+    }
+
+    static constexpr bool uses_double_storage() noexcept
+    {
+        return true;
    }
 };

@ -1561,7 +1632,7 @@ public:

    template<class U,
        class Ud = typename std::decay<U>::type,
-        class E1 = typename std::enable_if< !std::is_same<Ud, variant>::value && !detail::is_in_place_index<Ud>::value && !detail::is_in_place_type<Ud>::value >::type,
+        class E1 = typename std::enable_if< !std::is_same<Ud, variant>::value && !std::is_base_of<variant, Ud>::value && !detail::is_in_place_index<Ud>::value && !detail::is_in_place_type<Ud>::value >::type,
        class V = detail::resolve_overload_type<U&&, T...>,
        class E2 = typename std::enable_if<std::is_constructible<V, U&&>::value>::type
        >
@ -1652,6 +1723,8 @@ public:

    using variant_base::index;

+    using variant_base::uses_double_storage;
+
    // swap

 private:
@ -2085,7 +2158,7 @@ template<class R, class F, class V1, class V2> struct visit_L2
    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<R>( f2, std::forward<V2>(v2) );
+        return visit<R>( f2, std::forward<V2>(v2) );
    }
 };

@ -2153,7 +2226,7 @@ template<class R = detail::deduced, class F, class V1, class V2, class... V> con
 {
    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)... ); };
+        auto f2 = [&]( auto&&... a ){ return std::forward<F>(f)( unsafe_get<I.value>( std::forward<V1>(v1) ), std::forward<decltype(a)>(a)... ); };
        return visit<R>( f2, std::forward<V2>(v2), std::forward<V>(v)... );

    });
@ -2170,36 +2243,133 @@ void swap( variant<T...> & v, variant<T...> & w )
    v.swap( w );
 }

+// visit_by_index
+
+namespace detail
+{
+
+template<class R, class V, class... F> using Vret2 = mp11::mp_eval_if_not< std::is_same<R, deduced>, R, front_if_same, mp11::mp_transform<mp11::mp_invoke_q, mp11::mp_list<Qret<F>...>, apply_cv_ref<V>> >;
+
+template<class R, class V, class... F> struct visit_by_index_L
+{
+    V&& v;
+    std::tuple<F&&...> tp;
+
+    template<class I> constexpr detail::Vret2<R, V, F...> operator()( I ) const
+    {
+        return std::get<I::value>( std::move(tp) )( unsafe_get<I::value>( std::forward<V>(v) ) );
+    }
+};
+
+} // namespace detail
+
+template<class R = detail::deduced, class V, class... F> constexpr auto visit_by_index( V&& v, F&&... f ) -> detail::Vret2<R, V, F...>
+{
+    static_assert( variant_size<V>::value == sizeof...(F), "Incorrect number of function objects" );
+
+    return mp11::mp_with_index<variant_size<V>::value>( v.index(),
+        detail::visit_by_index_L<R, V, F...>{ std::forward<V>(v), std::tuple<F&&...>( std::forward<F>(f)... ) } );
+}
+
+// output streaming
+
+namespace detail
+{
+
+template<class Ch, class Tr, class... T> struct ostream_insert_L
+{
+    std::basic_ostream<Ch, Tr>& os;
+    variant<T...> const& v;
+
+    template<class I> std::basic_ostream<Ch, Tr>& operator()( I ) const
+    {
+        return os << unsafe_get<I::value>( v );
+    }
+};
+
+template<class Os, class T, class E = void> struct is_output_streamable: std::false_type
+{
+};
+
+template<class Os, class T> struct is_output_streamable<Os, T, decltype( std::declval<Os&>() << std::declval<T const&>(), (void)0 )>: std::true_type
+{
+};
+
+} // namespace detail
+
+template<class Ch, class Tr>
+std::basic_ostream<Ch, Tr>& operator<<( std::basic_ostream<Ch, Tr>& os, monostate const& )
+{
+    os << "monostate";
+    return os;
+}
+
+template<class Ch, class Tr, class T1, class... T,
+    class E = typename std::enable_if< mp11::mp_all< detail::is_output_streamable<std::basic_ostream<Ch, Tr>, T>... >::value >::type >
+std::basic_ostream<Ch, Tr>& operator<<( std::basic_ostream<Ch, Tr>& os, variant<T1, T...> const& v )
+{
+    return mp11::mp_with_index<1 + sizeof...(T)>( v.index(),
+        detail::ostream_insert_L<Ch, Tr, T1, T...>{ os, v } );
+}
+
 // hashing support

 namespace detail
 {

-template<class V> struct hash_value_L
+inline std::size_t hash_value_impl_( mp11::mp_true, std::size_t index, std::size_t value )
+{
+    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;
+
+    hv ^= index;
+    hv *= prime;
+
+    hv ^= value;
+    hv *= prime;
+
+    return static_cast<std::size_t>( hv );
+}
+
+inline std::size_t hash_value_impl_( mp11::mp_false, std::size_t index, std::size_t value )
+{
+    std::size_t hv = 0x811C9DC5;
+    std::size_t const prime = 0x01000193;
+
+    hv ^= index;
+    hv *= prime;
+
+    hv ^= value;
+    hv *= prime;
+
+    return hv;
+}
+
+inline std::size_t hash_value_impl( std::size_t index, std::size_t value )
+{
+    return hash_value_impl_( mp11::mp_bool< (SIZE_MAX > UINT32_MAX) >(), index, value );
+}
+
+template<template<class> class H, 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;
+        std::size_t index = I::value;
+        std::size_t value = H<remove_cv_ref_t<decltype(t)>>()( t );

-        return static_cast<std::size_t>( hv );
+        return hash_value_impl( index, value );
    }
 };

+template<class... T> std::size_t hash_value_std( variant<T...> const & v )
+{
+    return mp11::mp_with_index<sizeof...(T)>( v.index(), detail::hash_value_L< std::hash, variant<T...> >{ v } );
+}
+
 } // namespace detail

 inline std::size_t hash_value( monostate const & )
@ -2209,7 +2379,7 @@ inline std::size_t hash_value( monostate const & )

 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 } );
+    return mp11::mp_with_index<sizeof...(T)>( v.index(), detail::hash_value_L< boost::hash, variant<T...> >{ v } );
 }

 namespace detail
@ -2230,7 +2400,7 @@ template<class V> struct std_hash_impl<V, true>
 {
    std::size_t operator()( V const & v ) const
    {
-        return hash_value( v );
+        return detail::hash_value_std( v );
    }
 };

@ -2256,6 +2426,111 @@ template<> struct hash< ::boost::variant2::monostate >

 } // namespace std

+// JSON support
+
+namespace boost
+{
+namespace json
+{
+
+class value;
+
+struct value_from_tag;
+
+template<class T>
+void value_from( T&& t, value& jv );
+
+template<class T>
+struct try_value_to_tag;
+
+template<class T1, class T2>
+struct result_for;
+
+template<class T>
+typename result_for<T, value>::type
+try_value_to( value const & jv );
+
+template<class T>
+typename result_for<T, value>::type
+result_from_errno( int e, boost::source_location const* loc ) noexcept;
+
+template<class T> struct is_null_like;
+
+template<> struct is_null_like<variant2::monostate>: std::true_type {};
+
+} // namespace json
+
+namespace variant2
+{
+
+namespace detail
+{
+
+struct tag_invoke_L1
+{
+    boost::json::value& v;
+
+#if defined(BOOST_MSVC) && BOOST_MSVC / 10 == 191
+    // msvc-14.1 with /permissive- needs this
+    explicit tag_invoke_L1( boost::json::value& v_ ): v( v_ ) {}
+#endif
+
+    template<class T> void operator()( T const& t ) const
+    {
+        boost::json::value_from( t, v );
+    }
+};
+
+} // namespace detail
+
+template<class... T>
+    void tag_invoke( boost::json::value_from_tag const&, boost::json::value& v, variant<T...> const & w )
+{
+    visit( detail::tag_invoke_L1{ v }, w );
+}
+
+namespace detail
+{
+
+template<class V> struct tag_invoke_L2
+{
+    boost::json::value const& v;
+    typename boost::json::result_for<V, boost::json::value>::type& r;
+
+    template<class I> void operator()( I i ) const
+    {
+        if( !r )
+        {
+            using Ti = mp11::mp_at_c<V, i>;
+            auto r2 = boost::json::try_value_to<Ti>( v );
+
+            if( r2 )
+            {
+                r.emplace( in_place_index_t<i>{}, std::move( *r2 ) );
+            }
+        }
+    }
+};
+
+} // namespace detail
+
+template<class... T>
+    typename boost::json::result_for<variant<T...>, boost::json::value>::type
+    tag_invoke( boost::json::try_value_to_tag<variant<T...>> const&, boost::json::value const& v )
+{
+    static constexpr boost::source_location loc = BOOST_CURRENT_LOCATION;
+    auto r = boost::json::result_from_errno< variant<T...> >( EINVAL, &loc );
+
+    mp11::mp_for_each<mp11::mp_iota_c<sizeof...(T)>>( detail::tag_invoke_L2< variant<T...> >{ v, r } );
+
+    return r;
+}
+
+} // namespace variant2
+} // namespace boost
+
+#undef BOOST_VARIANT2_CX14_ASSERT
+
 #if defined(_MSC_VER) && _MSC_VER < 1910
 # pragma warning( pop )
 #endif
--- a/test/Jamfile
+++ b/test/Jamfile
@ -119,3 +119,17 @@ run variant_visit_r.cpp : : :
    <toolset>gcc,<target-os>windows:<variant>release
    <toolset>gcc,<target-os>cygwin:<variant>release
    ;
+
+compile variant_derived_construct.cpp ;
+
+run variant_visit_by_index.cpp ;
+
+run variant_ostream_insert.cpp ;
+run is_output_streamable.cpp ;
+
+local JSON = <library>/boost//json/<warnings>off "<toolset>msvc-14.0:<build>no" "<toolset>msvc-14.2:<cxxflags>-wd5104" "<undefined-sanitizer>norecover:<link>static" ;
+
+run variant_json_value_from.cpp : : : $(JSON) ;
+run variant_json_value_to.cpp : : : $(JSON) ;
+
+compile variant_uses_double_storage.cpp ;
--- a/test/cmake_subdir_test/CMakeLists.txt
+++ b/test/cmake_subdir_test/CMakeLists.txt
@ -7,6 +7,8 @@ cmake_minimum_required(VERSION 3.5...3.16)
 project(cmake_subdir_test LANGUAGES CXX)

 add_subdirectory(../.. boostorg/variant2)
+
+add_subdirectory(../../../assert boostorg/assert)
 add_subdirectory(../../../config boostorg/config)
 add_subdirectory(../../../mp11 boostorg/mp11)

--- a/test/is_output_streamable.cpp
+++ b/test/is_output_streamable.cpp
@ -0,0 +1,41 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <ostream>
+#include <string>
+
+struct X
+{
+};
+
+struct Y
+{
+};
+
+std::ostream& operator<<( std::ostream& os, Y const& /*y*/ )
+{
+    os << "Y()";
+    return os;
+}
+
+int main()
+{
+    BOOST_TEST_TRAIT_TRUE((boost::variant2::detail::is_output_streamable<std::ostream, int>));
+    BOOST_TEST_TRAIT_TRUE((boost::variant2::detail::is_output_streamable<std::ostream, float>));
+    BOOST_TEST_TRAIT_TRUE((boost::variant2::detail::is_output_streamable<std::ostream, std::string>));
+    BOOST_TEST_TRAIT_FALSE((boost::variant2::detail::is_output_streamable<std::ostream, void>));
+    BOOST_TEST_TRAIT_FALSE((boost::variant2::detail::is_output_streamable<std::ostream, X>));
+    BOOST_TEST_TRAIT_TRUE((boost::variant2::detail::is_output_streamable<std::ostream, Y>));
+
+    BOOST_TEST_TRAIT_TRUE((boost::variant2::detail::is_output_streamable<std::ostream, boost::variant2::monostate>));
+
+    BOOST_TEST_TRAIT_TRUE((boost::variant2::detail::is_output_streamable<std::ostream, boost::variant2::variant<int, float, std::string>>));
+    BOOST_TEST_TRAIT_FALSE((boost::variant2::detail::is_output_streamable<std::ostream, boost::variant2::variant<int, float, X>>));
+    BOOST_TEST_TRAIT_TRUE((boost::variant2::detail::is_output_streamable<std::ostream, boost::variant2::variant<int, float, Y>>));
+    BOOST_TEST_TRAIT_TRUE((boost::variant2::detail::is_output_streamable<std::ostream, boost::variant2::variant<boost::variant2::monostate, int, float>>));
+
+    return boost::report_errors();
+}
--- a/test/quick.cpp
+++ b/test/quick.cpp
@ -1,10 +1,8 @@
-
 // Copyright 2019 Peter Dimov.
-//
 // Distributed under the Boost Software License, Version 1.0.
-// http://www.boost.org/LICENSE_1_0.txt
+// https://www.boost.org/LICENSE_1_0.txt

-#include <boost/variant2/variant.hpp>
+#include <boost/variant2.hpp>

 using namespace boost::variant2;

--- a/test/variant_derived_construct.cpp
+++ b/test/variant_derived_construct.cpp
@ -0,0 +1,33 @@
+// Copyright 2021 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+
+using namespace boost::variant2;
+
+template<class... T> class X: variant<T...>
+{
+    using base = variant<T...>;
+    using base::base;
+};
+
+struct Y
+{
+    Y( Y const& rhs ) = default;
+
+    template<class T> Y( T const& t )
+    {
+        t.bar();
+    }
+};
+
+int main()
+{
+    using W = X<int, double, Y>;
+
+    W a( 1 );
+    W b( a );
+
+    (void)b;
+}
--- a/test/variant_emplace_index.cpp
+++ b/test/variant_emplace_index.cpp
@ -288,5 +288,39 @@ int main()
    BOOST_TEST_EQ( Z1::instances, 0 );
    BOOST_TEST_EQ( Z2::instances, 0 );

+    {
+        variant<monostate, monostate> v;
+        BOOST_TEST_EQ( v.index(), 0 );
+
+        v.emplace<0>();
+        BOOST_TEST_EQ( v.index(), 0 );
+
+        v.emplace<1>();
+        BOOST_TEST_EQ( v.index(), 1 );
+
+        v.emplace<1>();
+        BOOST_TEST_EQ( v.index(), 1 );
+
+        v.emplace<0>();
+        BOOST_TEST_EQ( v.index(), 0 );
+    }
+
+    {
+        variant<monostate, int> v;
+        BOOST_TEST_EQ( v.index(), 0 );
+
+        v.emplace<0>();
+        BOOST_TEST_EQ( v.index(), 0 );
+
+        v.emplace<1>();
+        BOOST_TEST_EQ( v.index(), 1 );
+
+        v.emplace<1>();
+        BOOST_TEST_EQ( v.index(), 1 );
+
+        v.emplace<0>();
+        BOOST_TEST_EQ( v.index(), 0 );
+    }
+
    return boost::report_errors();
 }
--- a/test/variant_eq_ne.cpp
+++ b/test/variant_eq_ne.cpp
@ -88,5 +88,12 @@ int main()
        BOOST_TEST_NOT( v1 != v2 );
    }

+    {
+        variant<monostate> v1, v2;
+
+        BOOST_TEST( v1 == v2 );
+        BOOST_TEST_NOT( v1 != v2 );
+    }
+
    return boost::report_errors();
 }
--- a/test/variant_eq_ne_cx.cpp
+++ b/test/variant_eq_ne_cx.cpp
@ -93,6 +93,13 @@ int main()
        STATIC_ASSERT( !(v1 == v2) );
        STATIC_ASSERT( !(v1 != v2) );
    }
+
+    {
+        constexpr variant<monostate> v1, v2;
+
+        STATIC_ASSERT( v1 == v2 );
+        STATIC_ASSERT( !(v1 != v2) );
+    }
 }

 #endif
--- a/test/variant_get_by_index_cx.cpp
+++ b/test/variant_get_by_index_cx.cpp
@ -58,7 +58,7 @@ int main()
    {
        constexpr variant<int, float> v( 3.14f );

-        STATIC_ASSERT( get<1>(v) == 3.14f );
+        STATIC_ASSERT( get<1>(v) == (float)3.14f ); // see FLT_EVAL_METHOD

        STATIC_ASSERT_IF( get_if<0>(&v) == nullptr );
        STATIC_ASSERT_IF( get_if<1>(&v) == &get<1>(v) );
@ -87,7 +87,7 @@ int main()
    {
        constexpr variant<int, int, float> v( 3.14f );

-        STATIC_ASSERT( get<2>(v) == 3.14f );
+        STATIC_ASSERT( get<2>(v) == (float)3.14f );

        STATIC_ASSERT_IF( get_if<0>(&v) == nullptr );
        STATIC_ASSERT_IF( get_if<1>(&v) == nullptr );
--- a/test/variant_get_by_type_cx.cpp
+++ b/test/variant_get_by_type_cx.cpp
@ -58,7 +58,7 @@ int main()
    {
        constexpr variant<int, float> v( 3.14f );

-        STATIC_ASSERT( get<float>(v) == 3.14f );
+        STATIC_ASSERT( get<float>(v) == (float)3.14f ); // see FLT_EVAL_METHOD

        STATIC_ASSERT_IF( get_if<int>(&v) == nullptr );
        STATIC_ASSERT_IF( get_if<float>(&v) == &get<float>(v) );
@ -83,7 +83,7 @@ int main()
    {
        constexpr variant<int, int, float> v( 3.14f );

-        STATIC_ASSERT( get<float>(v) == 3.14f );
+        STATIC_ASSERT( get<float>(v) == (float)3.14f );

        STATIC_ASSERT_IF( get_if<float>(&v) == &get<float>(v) );
    }
--- a/test/variant_hash.cpp
+++ b/test/variant_hash.cpp
@ -12,6 +12,7 @@
 #include <boost/core/lightweight_test_trait.hpp>
 #include <boost/container_hash/hash.hpp>
 #include <boost/config/workaround.hpp>
+#include <vector>

 using namespace boost::variant2;

@ -47,7 +48,17 @@ template<template<class...> class Hash, class T> void test2()
    BOOST_TEST_NE( h2, h3 );
 }

-struct X {};
+struct X
+{
+    int m = 0;
+};
+
+std::size_t hash_value( X const& x )
+{
+    return boost::hash<int>()( x.m );
+}
+
+struct Y {}; // no hash support

 int main()
 {
@ -57,6 +68,8 @@ int main()
    test<boost::hash, monostate, monostate, monostate>();
    test<boost::hash, int, int, float>();

+    test<boost::hash, monostate, X, std::vector<X>>();
+
    test2<std::hash, int>();
    test2<std::hash, float>();

@ -65,7 +78,7 @@ int main()

 #if !BOOST_WORKAROUND(BOOST_MSVC, < 1910) && ( !defined(_LIBCPP_STD_VER) || _LIBCPP_STD_VER > 11 )

-    BOOST_TEST_TRAIT_FALSE(( detail::is_hash_enabled<X> ));
+    BOOST_TEST_TRAIT_FALSE(( detail::is_hash_enabled<Y> ));

 #endif

--- a/test/variant_in_place_index_construct_cx.cpp
+++ b/test/variant_in_place_index_construct_cx.cpp
@ -68,7 +68,7 @@ int main()
        constexpr variant<int, float> v( in_place_index_t<1>{}, 3.14f );

        STATIC_ASSERT( v.index() == 1 );
-        STATIC_ASSERT( get<1>(v) == 3.14f );
+        STATIC_ASSERT( get<1>(v) == (float)3.14f ); // see FLT_EVAL_METHOD
    }

    {
@ -89,14 +89,14 @@ int main()
        constexpr variant<int, int, float, float, X, X> v( in_place_index_t<2>{}, 3.14f );

        STATIC_ASSERT( v.index() == 2 );
-        STATIC_ASSERT( get<2>(v) == 3.14f );
+        STATIC_ASSERT( get<2>(v) == (float)3.14f );
    }

    {
        constexpr variant<int, int, float, float, X, X> v( in_place_index_t<3>{}, 3.14f );

        STATIC_ASSERT( v.index() == 3 );
-        STATIC_ASSERT( get<3>(v) == 3.14f );
+        STATIC_ASSERT( get<3>(v) == (float)3.14f );
    }

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

-#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 100200)
+#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 120000)

-    // no idea why this fails on g++ 10
+    // no idea why this fails on g++ 10/11

 #else

--- a/test/variant_in_place_type_construct_cx.cpp
+++ b/test/variant_in_place_type_construct_cx.cpp
@ -80,7 +80,7 @@ int main()
        constexpr variant<int, float> v( in_place_type_t<float>{}, 3.14f );

        STATIC_ASSERT( v.index() == 1 );
-        STATIC_ASSERT( get<1>(v) == 3.14f );
+        STATIC_ASSERT( get<1>(v) == (float)3.14f ); // see FLT_EVAL_METHOD

        STATIC_ASSERT( holds_alternative<float>(v) );
    }
@ -89,7 +89,7 @@ int main()
        constexpr variant<int, int, float, X> v( in_place_type_t<float>{}, 3.14f );

        STATIC_ASSERT( v.index() == 2 );
-        STATIC_ASSERT( get<2>(v) == 3.14f );
+        STATIC_ASSERT( get<2>(v) == (float)3.14f );

        STATIC_ASSERT( holds_alternative<float>(v) );
    }
@ -102,9 +102,9 @@ int main()
        STATIC_ASSERT( holds_alternative<X>(v) );
    }

-#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 100200)
+#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 120000)

-    // no idea why this fails on g++ 10
+    // no idea why this fails on g++ 10/11

 #else

--- a/test/variant_json_value_from.cpp
+++ b/test/variant_json_value_from.cpp
@ -0,0 +1,41 @@
+// Copyright 2022 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+#include <boost/json/value_from.hpp>
+#include <boost/json/serialize.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <string>
+
+using namespace boost::variant2;
+namespace json = boost::json;
+
+int main()
+{
+    {
+        monostate m;
+        json::value w = json::value_from( m );
+        BOOST_TEST_EQ( w, json::value( nullptr ) );
+    }
+
+    {
+        variant<monostate, int, std::string> v;
+        json::value w = json::value_from( v );
+        BOOST_TEST_EQ( w, json::value( nullptr ) );
+    }
+
+    {
+        variant<monostate, int, std::string> v( 17 );
+        json::value w = json::value_from( v );
+        BOOST_TEST_EQ( w, json::value( 17 ) );
+    }
+
+    {
+        variant<monostate, int, std::string> v( "test" );
+        json::value w = json::value_from( v );
+        BOOST_TEST_EQ( w, json::value( "test" ) );
+    }
+
+    return boost::report_errors();
+}
--- a/test/variant_json_value_to.cpp
+++ b/test/variant_json_value_to.cpp
@ -0,0 +1,42 @@
+// Copyright 2022 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+#include <boost/json/value_to.hpp>
+#include <boost/json/serialize.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+using namespace boost::variant2;
+namespace json = boost::json;
+
+int main()
+{
+    {
+        json::value v;
+        auto r = json::try_value_to<monostate>( v );
+        BOOST_TEST( r.has_value() );
+    }
+
+    using V = variant<monostate, int, std::string>;
+
+    {
+        json::value v;
+        auto r = json::try_value_to<V>( v );
+        BOOST_TEST( r.has_value() ) && BOOST_TEST_EQ( *r, V() );
+    }
+
+    {
+        json::value v( 12 );
+        auto r = json::try_value_to<V>( v );
+        BOOST_TEST( r.has_value() ) && BOOST_TEST_EQ( *r, V(12) );
+    }
+
+    {
+        json::value v( "test" );
+        auto r = json::try_value_to<V>( v );
+        BOOST_TEST( r.has_value() ) && BOOST_TEST_EQ( *r, V("test") );
+    }
+
+    return boost::report_errors();
+}
--- a/test/variant_lt_gt.cpp
+++ b/test/variant_lt_gt.cpp
@ -81,5 +81,14 @@ int main()
        BOOST_TEST_NOT( v1 >= v2 );
    }

+    {
+        variant<monostate> v1, v2;
+
+        BOOST_TEST_NOT( v1 < v2 );
+        BOOST_TEST_NOT( v1 > v2 );
+        BOOST_TEST( v1 <= v2 );
+        BOOST_TEST( v1 >= v2 );
+    }
+
    return boost::report_errors();
 }
--- a/test/variant_lt_gt_cx.cpp
+++ b/test/variant_lt_gt_cx.cpp
@ -86,6 +86,15 @@ int main()
        STATIC_ASSERT( !(v1 <= v2) );
        STATIC_ASSERT( !(v1 >= v2) );
    }
+
+    {
+        constexpr variant<monostate> v1, v2;
+
+        STATIC_ASSERT( !(v1 < v2) );
+        STATIC_ASSERT( !(v1 > v2) );
+        STATIC_ASSERT( v1 <= v2 );
+        STATIC_ASSERT( v1 >= v2 );
+    }
 }

 #endif
--- a/test/variant_ostream_insert.cpp
+++ b/test/variant_ostream_insert.cpp
@ -0,0 +1,43 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <sstream>
+#include <string>
+
+using namespace boost::variant2;
+
+template<class T> std::string to_string( T const& t )
+{
+    std::ostringstream os;
+
+    os << t;
+
+    return os.str();
+}
+
+int main()
+{
+    {
+        BOOST_TEST_EQ( to_string( monostate() ), "monostate" );
+    }
+
+    {
+        variant<monostate, int, float, std::string> v;
+
+        BOOST_TEST_EQ( to_string( v ), to_string( monostate() ) );
+
+        v = 1;
+        BOOST_TEST_EQ( to_string( v ), to_string( 1 ) );
+
+        v = 3.14f;
+        BOOST_TEST_EQ( to_string( v ), to_string( 3.14f ) );
+
+        v = "test";
+        BOOST_TEST_EQ( to_string( v ), to_string( "test" ) );
+    }
+
+    return boost::report_errors();
+}
--- a/test/variant_uses_double_storage.cpp
+++ b/test/variant_uses_double_storage.cpp
@ -0,0 +1,50 @@
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+#include <type_traits>
+
+using namespace boost::variant2;
+
+#define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
+
+struct X1
+{
+};
+
+STATIC_ASSERT( std::is_nothrow_move_constructible<X1>::value );
+STATIC_ASSERT( std::is_trivially_destructible<X1>::value );
+
+struct X2
+{
+    ~X2() {}
+};
+
+STATIC_ASSERT( std::is_nothrow_move_constructible<X2>::value );
+STATIC_ASSERT( !std::is_trivially_destructible<X2>::value );
+
+struct X3
+{
+    X3( X3&& ) {}
+};
+
+STATIC_ASSERT( !std::is_nothrow_move_constructible<X3>::value );
+STATIC_ASSERT( std::is_trivially_destructible<X3>::value );
+
+struct X4
+{
+    ~X4() {}
+    X4( X4&& ) {}
+};
+
+STATIC_ASSERT( !std::is_nothrow_move_constructible<X4>::value );
+STATIC_ASSERT( !std::is_trivially_destructible<X4>::value );
+
+//
+
+STATIC_ASSERT( !variant<int, float>::uses_double_storage() );
+STATIC_ASSERT( !variant<int, float, X1>::uses_double_storage() );
+STATIC_ASSERT( !variant<int, float, X2>::uses_double_storage() );
+STATIC_ASSERT( variant<int, float, X3>::uses_double_storage() );
+STATIC_ASSERT( variant<int, float, X4>::uses_double_storage() );
--- a/test/variant_value_construct_cx.cpp
+++ b/test/variant_value_construct_cx.cpp
@ -82,7 +82,7 @@ int main()

        STATIC_ASSERT( v.index() == 1 );
        STATIC_ASSERT( holds_alternative<float>(v) );
-        STATIC_ASSERT( get<1>(v) == 3.14f );
+        STATIC_ASSERT( get<1>(v) == (float)3.14f ); // see FLT_EVAL_METHOD
    }

    {
@ -97,7 +97,7 @@ int main()

        STATIC_ASSERT( v.index() == 2 );
        STATIC_ASSERT( holds_alternative<float>(v) );
-        STATIC_ASSERT( get<2>(v) == 3.14f );
+        STATIC_ASSERT( get<2>(v) == (float)3.14f );
    }

    {
--- a/test/variant_visit_by_index.cpp
+++ b/test/variant_visit_by_index.cpp
@ -0,0 +1,126 @@
+// Copyright 2017, 2021 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://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 <boost/mp11.hpp>
+#include <boost/config.hpp>
+
+using namespace boost::variant2;
+using boost::mp11::mp_int;
+
+struct X
+{
+};
+
+struct F1
+{
+    int operator()( X& ) const { return 1; }
+    int operator()( X const& ) const { return 2; }
+    int operator()( X&& ) const { return 3; }
+    int operator()( X const&& ) const { return 4; }
+};
+
+struct F2
+{
+    mp_int<1> operator()( X& ) const { return {}; }
+    mp_int<2> operator()( X const& ) const { return {}; }
+    mp_int<3> operator()( X&& ) const { return {}; }
+    mp_int<4> operator()( X const&& ) const { return {}; }
+};
+
+int main()
+{
+    {
+        variant<int, int, float> v;
+
+        visit_by_index( v,
+            []( int& x ){ BOOST_TEST_EQ( x, 0 ); },
+            []( int&   ){ BOOST_ERROR( "incorrect alternative" ); },
+            []( float& ){ BOOST_ERROR( "incorrect alternative" ); } );
+    }
+
+    {
+        variant<int const, int, float const> v( in_place_index_t<0>(), 1 );
+
+        visit_by_index( v,
+            []( int const& x ){ BOOST_TEST_EQ( x, 1 ); },
+            []( int&         ){ BOOST_ERROR( "incorrect alternative" ); },
+            []( float const& ){ BOOST_ERROR( "incorrect alternative" ); } );
+    }
+
+    {
+        variant<int, int, float> const v( in_place_index_t<1>(), 2 );
+
+        visit_by_index( v,
+            []( int const&   ){ BOOST_ERROR( "incorrect alternative" ); },
+            []( int const& x ){ BOOST_TEST_EQ( x, 2 ); },
+            []( float const& ){ BOOST_ERROR( "incorrect alternative" ); } );
+    }
+
+    {
+        variant<int const, int, float const> const v( 3.14f );
+
+        visit_by_index( v,
+            []( int const&     ){ BOOST_ERROR( "incorrect alternative" ); },
+            []( int const&     ){ BOOST_ERROR( "incorrect alternative" ); },
+            []( float const& x ){ BOOST_TEST_EQ( x, 3.14f ); } );
+    }
+
+    {
+        variant<int, float> const v( 7 );
+
+        auto r = visit_by_index( v,
+            []( int const& x   ) -> double { return x; },
+            []( float const& x ) -> double { return x; } );
+
+        BOOST_TEST_TRAIT_SAME( decltype(r), double );
+        BOOST_TEST_EQ( r, 7.0 );
+    }
+
+    {
+        variant<int, float> const v( 2.0f );
+
+        auto r = visit_by_index( v,
+            []( int const& x   ) { return x + 0.0; },
+            []( float const& x ) { return x + 0.0; } );
+
+        BOOST_TEST_TRAIT_SAME( decltype(r), double );
+        BOOST_TEST_EQ( r, 2.0 );
+    }
+
+    {
+        variant<int, float, double> const v( 3.0 );
+
+        auto r = visit_by_index<double>( v,
+            []( int const& x    ) { return x; },
+            []( float const& x  ) { return x; },
+            []( double const& x ) { return x; } );
+
+        BOOST_TEST_TRAIT_SAME( decltype(r), double );
+        BOOST_TEST_EQ( r, 3.0 );
+    }
+
+    {
+        variant<X> v;
+        variant<X> const cv;
+
+        F1 f1;
+
+        BOOST_TEST_EQ( visit_by_index( v, f1 ), 1 );
+        BOOST_TEST_EQ( visit_by_index( cv, f1 ), 2 );
+        BOOST_TEST_EQ( visit_by_index( std::move( v ), f1 ), 3 );
+        BOOST_TEST_EQ( visit_by_index( std::move( cv ), f1 ), 4 );
+
+        F2 f2;
+
+        BOOST_TEST_EQ( visit_by_index<int>( v, f2 ), 1 );
+        BOOST_TEST_EQ( visit_by_index<int>( cv, f2 ), 2 );
+        BOOST_TEST_EQ( visit_by_index<int>( std::move( v ), f2 ), 3 );
+        BOOST_TEST_EQ( visit_by_index<int>( std::move( cv ), f2 ), 4 );
+    }
+
+    return boost::report_errors();
+}
--- a/test/variant_visit_derived.cpp
+++ b/test/variant_visit_derived.cpp
@ -1,4 +1,3 @@
-
 // Copyright 2017, 2020 Peter Dimov.
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
@ -15,7 +14,7 @@

 struct X: boost::variant2::variant<int, float>
 {
-#if BOOST_WORKAROUND( BOOST_MSVC, < 1930 )
+#if BOOST_WORKAROUND( BOOST_MSVC, < 1940 )

    template<class T> explicit X( T&& t ): variant( std::forward<T>( t ) ) {};

--- a/test/variant_visit_r.cpp
+++ b/test/variant_visit_r.cpp
@ -61,18 +61,18 @@ int main()
    }

    {
-        variant<int, float> const v( 3.14f );
+        variant<int, float> const v( 3.125f );

        BOOST_TEST_EQ( visit<int>( F1(), v ), 3 );
-        BOOST_TEST_EQ( visit<float>( F1(), v ), 3.14f );
+        BOOST_TEST_EQ( visit<float>( F1(), v ), 3.125f );
    }

    {
        variant<int, float> v1( 1 );
-        variant<int, float> const v2( 3.14f );
+        variant<int, float> const v2( 3.125f );

        BOOST_TEST_EQ( visit<int>( F2(), v1, v2 ), 4 );
-        BOOST_TEST_EQ( visit<float>( F2(), v1, v2 ), 1 + 3.14f );
+        BOOST_TEST_EQ( visit<float>( F2(), v1, v2 ), 1 + 3.125f );
    }

    {
Author	SHA1	Message	Date
Peter Dimov	e2546b70ca	Document uses_double_storage(). Refs #37 .	2023-06-29 18:32:58 +03:00
Peter Dimov	362224a009	Update ci.yml	2023-06-29 16:44:47 +03:00
Peter Dimov	2c590716ab	Use the exact 3.125f in variant_visit_r.cpp	2023-06-29 12:05:55 +03:00
Peter Dimov	82b98fb757	Cast 3.14f to float because FLT_EVAL_METHOD (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108742 ) for discussion	2023-06-29 10:46:54 +03:00
Peter Dimov	30afb9e183	Update test/Jamfile to fix Drone issues	2023-06-29 09:54:49 +03:00
Peter Dimov	129e27ce09	Update Drone files	2023-06-29 09:33:44 +03:00
Peter Dimov	26595285d3	Add variant<>::uses_double_storage(). Refs #37 .	2023-06-28 22:14:56 +03:00
Peter Dimov	95a8c5ffec	Update .drone.jsonnet	2023-01-23 03:53:25 +02:00
Peter Dimov	ec2819a05e	Update CMakeLists.txt	2023-01-13 00:56:45 +02:00
Peter Dimov	fcf9746a2d	Merge branch 'develop' of https://github.com/vinniefalco/boost-variant2 into feature/pr-36	2023-01-13 00:55:17 +02:00
Peter Dimov	a74ebd34dc	Update appveyor.yml	2023-01-12 21:12:17 +02:00
Peter Dimov	1b34c20685	Update appveyor.yml	2023-01-12 18:38:10 +02:00
Peter Dimov	604d3700ad	Add CMake tests to Appveyor	2023-01-12 10:49:41 +02:00
Peter Dimov	4d1fd43d72	Update supported compilers in documentation and README	2022-10-27 21:25:57 +03:00
Peter Dimov	376925a209	Work around msvc-14.1 /permissive- failure	2022-10-24 15:47:09 +03:00
Peter Dimov	bcb8796225	Add /permissive- jobs to Drone and Appveyor	2022-10-24 15:27:05 +03:00
Peter Dimov	a948b85c74	Update revision history	2022-10-18 17:38:59 +03:00
Peter Dimov	32862d6db7	Add missing std::move	2022-10-18 16:02:33 +03:00
Peter Dimov	423d350ff1	Remove unneeded forward declarations	2022-10-18 16:01:31 +03:00
Peter Dimov	aad1f86fae	Reflect the change in is_null_like	2022-10-18 16:00:14 +03:00
Peter Dimov	1f8c4a1900	Replace polymorphic lambdas with function objects for C++11	2022-10-18 06:29:57 +03:00
Peter Dimov	67a12199e6	Add JSON support (refs #28 )	2022-10-18 06:08:18 +03:00
Peter Dimov	457147d1b0	Suppress -Wmaybe-uninitialized in emplace_impl	2022-10-18 03:20:36 +03:00
Peter Dimov	4a5f3dc498	Add variant<monostate, T>::emplace tests to fish out -Wmaybe-uninitialized warnings	2022-10-18 02:56:15 +03:00
Peter Dimov	6fe1c69bc8	Add Drone support	2022-10-18 02:16:59 +03:00
Peter Dimov	78a974429a	Update ci.yml	2022-10-15 19:39:32 +03:00
Vinnie Falco	4c5f254b9c	add boost_variant2.natvis and interface source files	2022-08-19 12:13:08 -07:00
Peter Dimov	c633a953de	Change macos-10.15 to macos-11 in ci.yml	2022-08-15 19:26:35 +03:00
Peter Dimov	8ee7c5aad0	Update ci.yml	2022-07-14 14:47:06 +03:00
Peter Dimov	d34658f4c8	Document operator<< for monostate	2022-01-31 19:19:49 +02:00
Peter Dimov	5e2bce1baa	Add operator<< for monostate	2022-01-31 17:55:26 +02:00
Peter Dimov	573ef77382	Move unsigned ix_ after the elements to avoid need to adjust rdi (closes #30 )	2021-12-09 21:28:35 +02:00
Peter Dimov	f6cad272d4	Add msvc-14.0 to GHA	2021-12-09 19:59:01 +02:00
Peter Dimov	3fc7540733	Only define operator<< when all contained types are streamable (refs #31 )	2021-12-09 18:39:03 +02:00
Peter Dimov	e4b4b3f02b	Extend msvc-14.2 workaround to 14.3	2021-10-29 02:18:23 +03:00
Peter Dimov	44d38c4111	Enable syntax highlighting	2021-10-28 23:23:13 +03:00
Peter Dimov	1ebfb3b689	Add msvc-14.3 to ci.yml	2021-10-28 23:22:20 +03:00
Peter Dimov	8af1fbde8e	Update cmake_subdir_test/CMakeLists.txt	2021-09-21 14:52:38 +03:00
Peter Dimov	26ce33597d	Regenerate CMakeLists.txt	2021-09-21 14:45:20 +03:00
Peter Dimov	c89713b978	Add CMake tests to ci.yml	2021-09-21 14:31:47 +03:00
Peter Dimov	10c441c8d7	Update appveyor.yml	2021-09-15 15:11:54 +03:00
Peter Dimov	09ec260780	Document operator<<	2021-09-15 03:53:13 +03:00
Peter Dimov	2da13befd7	Work around mysterious errors with gcc, msvc-14.1, and clang-cl	2021-09-15 03:28:29 +03:00
Peter Dimov	e668c099ce	Add operator<< for variant	2021-09-15 02:51:11 +03:00
Peter Dimov	aebcb9792d	Update documentation of visit_by_index	2021-09-15 02:00:33 +03:00
Peter Dimov	8fd9f830a9	Add proper type deduction to visit_by_index	2021-09-15 01:30:09 +03:00
Peter Dimov	ed4bebff3d	Document visit_by_index	2021-09-14 21:32:57 +03:00
Peter Dimov	ad06c9b923	Add visit_by_index	2021-09-14 21:06:01 +03:00
Peter Dimov	de4eb8b6d2	Update README.md	2021-09-11 19:47:34 +03:00
Peter Dimov	4d69db1441	Extend g++-10 workarounds to 11	2021-09-11 19:23:39 +03:00
Peter Dimov	095d9770c4	Update ci.yml	2021-09-11 18:36:43 +03:00
Peter Dimov	cca476fbbc	Update documentation	2021-09-11 18:29:17 +03:00
Peter Dimov	c76af4d3cf	Update README.md	2021-09-11 18:26:28 +03:00
Peter Dimov	1af7b165cf	BOOST_VARIANT2_CX14_ASSERT must be empty under C++11	2021-09-11 18:22:46 +03:00
Peter Dimov	49bff72be0	Define and use a helper macro BOOST_VARIANT2_CX14_ASSERT in constexpr functions	2021-09-11 18:11:17 +03:00
Peter Dimov	59780ba08e	Only assert when C++14	2021-09-11 18:00:29 +03:00
Peter Dimov	edd70cfd66	Update ci.yml	2021-09-11 17:43:05 +03:00
Peter Dimov	86c2782dff	Update documentation	2021-09-11 17:39:55 +03:00
Peter Dimov	dce8174550	Make unsafe_get public	2021-09-11 17:29:21 +03:00
Peter Dimov	9d40bc80f1	Use BOOST_ASSERT instead of assert	2021-09-11 17:23:29 +03:00
Peter Dimov	be6ddf9fdc	Add boost/variant2.hpp	2021-09-11 17:19:09 +03:00
Peter Dimov	4153a535a0	Update .github/workflows	2021-04-19 20:37:12 +03:00
Peter Dimov	f374ad68a3	Add -DBUILD_TESTING=ON to .yml files; it's not default anymore	2021-03-19 04:18:08 +02:00
Peter Dimov	3bc9a57c9b	Merge branch 'feature/issue-26' into develop	2021-03-13 18:23:39 +02:00
Peter Dimov	3ca95a65df	Use boost::hash in hash_value, not std::hash (closes #27 )	2021-03-13 05:08:03 +02:00
Peter Dimov	ae1f72671e	Add test for types supported by boost::hash, but not by std::hash	2021-03-13 04:50:01 +02:00
Peter Dimov	a2dab8c7d3	Refactor detail::hash_value_L	2021-03-13 04:10:41 +02:00
Peter Dimov	f39a71ed2f	Merge branch 'feature/issue-26-nofix' into feature/issue-26	2021-03-13 01:09:46 +02:00
Peter Dimov	06dde96400	Merge branch 'develop' into feature/issue-26-nofix	2021-03-13 01:09:17 +02:00
Peter Dimov	8be0a4a5fe	Update copyright	2021-03-12 23:42:32 +02:00
Peter Dimov	90cda5339f	Disable U&& constructor for derived types	2021-03-12 23:40:14 +02:00
Peter Dimov	afb0aafd64	Change clangs to bionic	2021-03-12 20:18:24 +02:00
Peter Dimov	f586dc8848	Add test for inherited constructors (refs #26 )	2021-03-12 20:15:09 +02:00
Peter Dimov	20b9175932	Add cxxstd=latest to Appveyor	2021-03-08 04:04:35 +02:00
Peter Dimov	fb3ce863ff	Add MSVC workaround for monospace constexpr (refs #25 )	2021-03-08 03:26:40 +02:00
Peter Dimov	8ec0bf448a	Add monospace relational tests (refs #25 )	2021-03-08 03:01:21 +02:00
Peter Dimov	6d19e6be68	Update revision history	2021-03-07 00:51:28 +02:00
Peter Dimov	d8552b23ae	UBSan on clang 7 is broken on Ubuntu	2021-03-01 06:35:38 +02:00
Peter Dimov	f44aba09a2	Update .travis.yml	2021-03-01 00:26:43 +02:00
Peter Dimov	99cc1db385	Fix documentation for emplace effects	2021-01-25 03:49:42 +02:00
Peter Dimov	6d848c5af6	Update GCC workarounds in constexpr in-place construct tests	2021-01-25 03:44:24 +02:00
Peter Dimov	3c9f4e56bf	Fix visit codegen regression when NDEBUG is not defined	2021-01-24 17:27:24 +02:00
Peter Dimov	3015e56bcb	GCC bug 63707 has been fixed for GCC 11	2021-01-23 20:36:12 +02:00
Peter Dimov	7c37053950	Merge branch 'develop' into feature/double-opt	2021-01-13 05:06:00 +02:00
Peter Dimov	60995edb41	Remove g++ 4.7 from GHA	2021-01-13 05:01:44 +02:00
Peter Dimov	6de876954a	Merge branch 'develop' into feature/double-opt	2021-01-13 02:32:32 +02:00
Peter Dimov	453b00dec8	Use (i+1)*2+j for the internal index in the double-buffered case, to avoid branches	2021-01-13 02:10:12 +02:00