Fix unwrap_and_invoke for functions returning void. Fixes #145.

.drone.jsonnet

@@ -239,19 +239,26 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
     ),
 
     linux_pipeline(
-        "Linux 25.04 GCC 15 UBSAN",
-        "cppalliance/droneubuntu2504:1",
+        "Linux 26.04 GCC 15 UBSAN",
+        "cppalliance/droneubuntu2604:1",
         { TOOLSET: 'gcc', COMPILER: 'g++-15', CXXSTD: '11,14,17,20,23,2c' } + ubsan,
         "g++-15-multilib",
     ),
 
     linux_pipeline(
-        "Linux 25.04 GCC 15 ASAN",
-        "cppalliance/droneubuntu2504:1",
+        "Linux 26.04 GCC 15 ASAN",
+        "cppalliance/droneubuntu2604:1",
         { TOOLSET: 'gcc', COMPILER: 'g++-15', CXXSTD: '11,14,17,20,23,2c' } + asan,
         "g++-15-multilib",
     ),
 
+    linux_pipeline(
+        "Linux 26.04 GCC 16",
+        "cppalliance/droneubuntu2604:1",
+        { TOOLSET: 'gcc', COMPILER: 'g++-16', CXXSTD: '11,14,17,20,23,2c' },
+        "g++-16-multilib",
+    ),
+
     linux_pipeline(
         "Linux 16.04 Clang 3.5",
         "cppalliance/droneubuntu1604:1",
@@ -280,6 +287,27 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
         "clang-3.8",
     ),
 
+    linux_pipeline(
+        "Linux 18.04 Clang 3.9",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-3.9', CXXSTD: '11,14' },
+        "clang-3.9",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 4.0",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-4.0', CXXSTD: '11,14' },
+        "clang-4.0",
+    ),
+
+    linux_pipeline(
+        "Linux 18.04 Clang 5.0",
+        "cppalliance/droneubuntu1804:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-5.0', CXXSTD: '11,14' },
+        "clang-5.0",
+    ),
+
     linux_pipeline(
         "Linux 22.04 Clang 13",
         "cppalliance/droneubuntu2204:1",
@@ -316,54 +344,47 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
     ),
 
     linux_pipeline(
-        "Linux 24.04 Clang 18 UBSAN",
+        "Linux 24.04 Clang 18",
         "cppalliance/droneubuntu2404:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-18', CXXSTD: '11,14,17,20,2b' } + ubsan,
+        { TOOLSET: 'clang', COMPILER: 'clang++-18', CXXSTD: '11,14,17,20,2b' },
         "clang-18",
     ),
 
     linux_pipeline(
-        "Linux 24.04 Clang 18 ASAN",
+        "Linux 24.04 Clang 19",
         "cppalliance/droneubuntu2404:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-18', CXXSTD: '11,14,17,20,2b' } + asan,
-        "clang-18",
-    ),
-
-    linux_pipeline(
-        "Linux 24.04 Clang 19 UBSAN",
-        "cppalliance/droneubuntu2404:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-19', CXXSTD: '11,14,17,20,2b' } + ubsan,
+        { TOOLSET: 'clang', COMPILER: 'clang++-19', CXXSTD: '11,14,17,20,2b' },
         "clang-19",
     ),
 
     linux_pipeline(
-        "Linux 24.04 Clang 19 ASAN",
+        "Linux 24.04 Clang 20",
         "cppalliance/droneubuntu2404:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-19', CXXSTD: '11,14,17,20,2b' } + asan,
-        "clang-19",
-    ),
-
-    linux_pipeline(
-        "Linux 24.04 Clang 20 UBSAN",
-        "cppalliance/droneubuntu2404:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-20', CXXSTD: '11,14,17,20,23,2c' } + ubsan,
+        { TOOLSET: 'clang', COMPILER: 'clang++-20', CXXSTD: '11,14,17,20,23,2c' },
         "clang-20",
     ),
 
     linux_pipeline(
-        "Linux 24.04 Clang 20 ASAN",
-        "cppalliance/droneubuntu2404:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-20', CXXSTD: '11,14,17,20,23,2c' } + asan,
-        "clang-20",
-    ),
-
-    linux_pipeline(
-        "Linux 25.10 Clang 21",
-        "cppalliance/droneubuntu2510:1",
+        "Linux 26.04 Clang 21",
+        "cppalliance/droneubuntu2604:1",
         { TOOLSET: 'clang', COMPILER: 'clang++-21', CXXSTD: '11,14,17,20,23,2c' },
         "clang-21",
     ),
 
+    linux_pipeline(
+        "Linux 26.04 Clang 22 UBSAN",
+        "cppalliance/droneubuntu2604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-22', CXXSTD: '11,14,17,20,23,2c' } + ubsan,
+        "clang-22",
+    ),
+
+    linux_pipeline(
+        "Linux 26.04 Clang 22 ASAN",
+        "cppalliance/droneubuntu2604:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-22', CXXSTD: '11,14,17,20,23,2c' } + asan,
+        "clang-22",
+    ),
+
     macos_pipeline(
         "MacOS 10.15 Xcode 12.2 UBSAN",
         { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '11,14,1z' } + ubsan,

.github/workflows/ci.yml

@@ -17,25 +17,11 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - toolset: gcc-4.8
-            cxxstd: "11"
-            container: ubuntu:18.04
-            os: ubuntu-latest
-            install: g++-4.8
-          - toolset: gcc-5
-            cxxstd: "11,14,1z"
-            container: ubuntu:18.04
-            os: ubuntu-latest
-            install: g++-5
-          - toolset: gcc-6
-            cxxstd: "11,14,1z"
-            container: ubuntu:18.04
-            os: ubuntu-latest
-            install: g++-6
           - toolset: gcc-7
             cxxstd: "11,14,17"
-            container: ubuntu:18.04
+            container: ubuntu:20.04
             os: ubuntu-latest
+            install: g++-7
           - toolset: gcc-8
             cxxstd: "11,14,17,2a"
             container: ubuntu:20.04
@@ -52,10 +38,12 @@ jobs:
             install: g++-10
           - toolset: gcc-11
             cxxstd: "11,14,17,2a"
-            os: ubuntu-22.04
+            container: ubuntu:22.04
+            os: ubuntu-latest
           - toolset: gcc-12
             cxxstd: "11,14,17,20,2b"
-            os: ubuntu-22.04
+            container: ubuntu:22.04
+            os: ubuntu-latest
             install: g++-12
           - toolset: gcc-13
             cxxstd: "11,14,17,20,2b"
@@ -69,27 +57,14 @@ jobs:
             install: g++-14
           - toolset: gcc-15
             cxxstd: "11,14,17,20,23,2c"
-            container: ubuntu:25.04
+            container: ubuntu:26.04
             os: ubuntu-latest
             install: g++-15
-          - toolset: clang
-            compiler: clang++-3.9
-            cxxstd: "11,14"
-            container: ubuntu:18.04
+          - toolset: gcc-16
+            cxxstd: "11,14,17,20,23,2c"
+            container: ubuntu:26.04
             os: ubuntu-latest
-            install: clang-3.9
-          - toolset: clang
-            compiler: clang++-4.0
-            cxxstd: "11,14"
-            container: ubuntu:18.04
-            os: ubuntu-latest
-            install: clang-4.0
-          - toolset: clang
-            compiler: clang++-5.0
-            cxxstd: "11,14,1z"
-            container: ubuntu:18.04
-            os: ubuntu-latest
-            install: clang-5.0
+            install: g++-16
           - toolset: clang
             compiler: clang++-6.0
             cxxstd: "11,14,17"
@@ -198,9 +173,16 @@ jobs:
             compiler: clang++-21
             cxxstd: "11,14,17,20,23,2c"
             stdlib: "native,libc++"
-            container: ubuntu:25.10
+            container: ubuntu:26.04
             os: ubuntu-latest
             install: clang-21 libc++-21-dev libc++abi-21-dev
+          - toolset: clang
+            compiler: clang++-22
+            cxxstd: "11,14,17,20,23,2c"
+            stdlib: "native,libc++"
+            container: ubuntu:26.04
+            os: ubuntu-latest
+            install: clang-22 libc++-22-dev libc++abi-22-dev
           - toolset: clang
             cxxstd: "11,14,17,20,2b"
             os: macos-14
@@ -212,12 +194,7 @@ jobs:
             os: macos-26
 
     runs-on: ${{matrix.os}}
-
-    container:
-      image: ${{matrix.container}}
-      volumes:
-        - /node20217:/node20217:rw,rshared
-        - ${{ startsWith(matrix.container, 'ubuntu:1') && '/node20217:/__e/node20:ro,rshared' || ' ' }}
+    container: ${{matrix.container}}
 
     defaults:
       run:
@@ -230,14 +207,7 @@ jobs:
           apt-get update
           apt-get -y install sudo python3 git g++ curl xz-utils
 
-      - name: Install nodejs20glibc2.17
-        if: ${{ startsWith( matrix.container, 'ubuntu:1' ) }}
-        run: |
-          curl -LO https://archives.boost.io/misc/node/node-v20.9.0-linux-x64-glibc-217.tar.xz
-          tar -xf node-v20.9.0-linux-x64-glibc-217.tar.xz --strip-components 1 -C /node20217
-          ldd /__e/node20/bin/node
-
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install packages
         if: matrix.install
@@ -286,19 +256,23 @@ jobs:
             cxxstd: "14,17,20,latest"
             addrmd: 32,64
             os: windows-2022
+          - toolset: msvc-14.5
+            cxxstd: "14,17,20,latest"
+            addrmd: 32,64
+            os: windows-2025-vs2026
           - toolset: clang-win
             cxxstd: "14,17,20,latest"
             addrmd: 32,64
-            os: windows-2022
+            os: windows-latest
           - toolset: gcc
             cxxstd: "11,14,17,2a"
             addrmd: 64
-            os: windows-2022
+            os: windows-latest
 
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup Boost
         shell: cmd
@@ -339,7 +313,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install packages
         if: matrix.install
@@ -384,7 +358,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install packages
         if: matrix.install
@@ -439,7 +413,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install packages
         if: matrix.install
@@ -481,6 +455,57 @@ jobs:
           cd ../boost-root/__build__
           ctest --output-on-failure --no-tests=error
 
+  posix-cmake-use:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-latest
+          - os: macos-latest
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v6
+
+      - 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" $LIBRARY
+          ./bootstrap.sh
+          ./b2 -d0 headers
+
+      - name: Install Boost --with-library
+        run: |
+          cd ../boost-root
+          ./b2 -j3 --with-$LIBRARY --prefix=$HOME/.local install
+
+      - name: Use the installed library
+        run: |
+          cd ../boost-root/libs/$LIBRARY/test/cmake_install_test && mkdir __build__ && cd __build__
+          cmake -DCMAKE_INSTALL_PREFIX=~/.local ..
+          cmake --build .
+          ctest --output-on-failure --no-tests=error
+
   windows-cmake-subdir:
     strategy:
       fail-fast: false
@@ -491,7 +516,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup Boost
         shell: cmd
@@ -539,7 +564,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup Boost
         shell: cmd
@@ -605,7 +630,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup Boost
         shell: cmd
@@ -657,3 +682,58 @@ jobs:
         run: |
           cd ../boost-root/__build__
           ctest --output-on-failure --no-tests=error -C Release
+
+  windows-cmake-use:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: windows-latest
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Setup Boost
+        shell: cmd
+        run: |
+          echo GITHUB_REPOSITORY: %GITHUB_REPOSITORY%
+          for /f %%i in ("%GITHUB_REPOSITORY%") do set LIBRARY=%%~nxi
+          echo LIBRARY: %LIBRARY%
+          echo LIBRARY=%LIBRARY%>>%GITHUB_ENV%
+          echo GITHUB_BASE_REF: %GITHUB_BASE_REF%
+          echo GITHUB_REF: %GITHUB_REF%
+          if "%GITHUB_BASE_REF%" == "" set GITHUB_BASE_REF=%GITHUB_REF%
+          set BOOST_BRANCH=develop
+          for /f %%i in ("%GITHUB_BASE_REF%") do if "%%~nxi" == "master" set BOOST_BRANCH=master
+          echo BOOST_BRANCH: %BOOST_BRANCH%
+          cd ..
+          git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          xcopy /s /e /q %GITHUB_WORKSPACE% libs\%LIBRARY%\
+          git submodule update --init tools/boostdep
+          python tools/boostdep/depinst/depinst.py --git_args "--jobs 3" %LIBRARY%
+          cmd /c bootstrap
+          b2 -d0 headers
+
+      - name: Install Boost --with-library
+        shell: cmd
+        run: |
+          cd ../boost-root
+          b2 -j3 --with-%LIBRARY% install
+
+      - name: Use the installed library (Debug)
+        shell: cmd
+        run: |
+          cd ../boost-root/libs/%LIBRARY%/test/cmake_install_test && mkdir __build__ && cd __build__
+          cmake -DBoost_ROOT=C:/Boost ..
+          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

include/boost/system/unwrap_and_invoke.hpp

@@ -66,7 +66,8 @@ template<class R, class T, class E> int invoke_test( R& r, result<T, E> const& r
 
 template<class F, class... A,
     class R = decltype( compat::invoke( std::declval<F>(), detail::invoke_unwrap( std::declval<A>() )... ) ),
-    class E = detail::get_error_type<compat::remove_cvref_t<A>...>
+    class E = detail::get_error_type<compat::remove_cvref_t<A>...>,
+    class En = typename std::enable_if< !std::is_void<R>::value >::type
 >
 auto unwrap_and_invoke( F&& f, A&&... a ) -> result<R, E>
 {
@@ -82,6 +83,28 @@ auto unwrap_and_invoke( F&& f, A&&... a ) -> result<R, E>
     return compat::invoke( std::forward<F>(f), detail::invoke_unwrap( std::forward<A>(a) )... );
 }
 
+template<class F, class... A,
+    class R = decltype( compat::invoke( std::declval<F>(), detail::invoke_unwrap( std::declval<A>() )... ) ),
+    class E = detail::get_error_type<compat::remove_cvref_t<A>...>,
+    class En1 = void,
+    class En2 = typename std::enable_if< std::is_void<R>::value >::type
+>
+auto unwrap_and_invoke( F&& f, A&&... a ) -> result<R, E>
+{
+    {
+        result<void, E> r;
+
+        using Q = int[];
+        (void)Q{ detail::invoke_test( r, a )... };
+
+        if( !r ) return r.error();
+    }
+
+    compat::invoke( std::forward<F>(f), detail::invoke_unwrap( std::forward<A>(a) )... );
+
+    return {};
+}
+
 // unwrap_and_construct
 
 namespace detail

test/Jamfile.v2

@@ -228,3 +228,5 @@ run unwrap_and_construct.cpp ;
 run unwrap_and_construct2.cpp ;
 
 run detail_is_aggregate_test.cpp ;
+
+run unwrap_and_invoke3.cpp ;

test/cmake_install_test/CMakeLists.txt

@@ -2,11 +2,11 @@
 # Distributed under the Boost Software License, Version 1.0.
 # See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
 
-cmake_minimum_required(VERSION 3.5...3.16)
+cmake_minimum_required(VERSION 3.5...3.31)
 
 project(cmake_install_test LANGUAGES CXX)
 
-find_package(boost_system REQUIRED)
+find_package(Boost COMPONENTS system REQUIRED)
 
 add_executable(main main.cpp)
 target_link_libraries(main Boost::system)

test/error_category_test.cpp

@@ -8,6 +8,10 @@
 
 // See library home page at http://www.boost.org/libs/system
 
+#if defined(__GNUC__) && __GNUC__ >= 16
+# pragma GCC diagnostic ignored "-Wformat-truncation"
+#endif
+
 #include <boost/system/error_code.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/snprintf.hpp>

test/error_category_test2.cpp

@@ -8,6 +8,10 @@
 
 // See library home page at http://www.boost.org/libs/system
 
+#if defined(__GNUC__) && __GNUC__ >= 16
+# pragma GCC diagnostic ignored "-Wformat-truncation"
+#endif
+
 #include <boost/system/error_category.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/snprintf.hpp>

test/unwrap_and_invoke3.cpp

@@ -0,0 +1,40 @@
+// Copyright 2026 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/system/unwrap_and_invoke.hpp>
+#include <boost/system/result.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+using namespace boost::system;
+
+int g_x;
+
+void f( int x )
+{
+    g_x += x;
+}
+
+int main()
+{
+    {
+        g_x = 0;
+
+        result<int> a1( 1 );
+        result<void> r = unwrap_and_invoke( f, a1 );
+
+        BOOST_TEST( r );
+        BOOST_TEST_EQ( g_x, 1 );
+    }
+
+    {
+        auto ec = make_error_code( errc::invalid_argument );
+
+        result<int> a1( ec );
+        result<void> r = unwrap_and_invoke( f, a1 );
+
+        BOOST_TEST( r.has_error() ) && BOOST_TEST_EQ( r.error(), ec );
+    }
+
+    return boost::report_errors();
+}