Add .github/workflows

.github/workflows/posix.yml

@@ -0,0 +1,84 @@
+name: POSIX
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - develop
+      - feature/**
+
+env:
+  LIBRARY: core
+  UBSAN_OPTIONS: print_stacktrace=1
+
+jobs:
+  CI:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - toolset: gcc-4.7
+            cxxstd: "03,11"
+            os: ubuntu-16.04
+            install: g++-4.7
+          - toolset: gcc-4.8
+            cxxstd: "03,11"
+            os: ubuntu-16.04
+            install: g++-4.8
+          - toolset: gcc-4.9
+            cxxstd: "03,11"
+            os: ubuntu-16.04
+            install: g++-4.9
+          - toolset: gcc-5
+            cxxstd: "03,11,14,1z"
+            os: ubuntu-16.04
+          - toolset: gcc-6
+            cxxstd: "03,11,14,1z"
+            os: ubuntu-16.04
+            install: g++-6
+          - toolset: gcc-7
+            cxxstd: "03,11,14,17"
+            os: ubuntu-18.04
+          - toolset: gcc-8
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-18.04
+          - toolset: gcc-9
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-18.04
+          - toolset: gcc-10
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-18.04
+          - toolset: clang
+            cxxstd: "03,11,14,17,2a"
+            os: ubuntu-18.04
+          - toolset: clang
+            cxxstd: "03,11,14,17,2a"
+            os: macos-10.15
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install packages
+        if: matrix.install
+        run: sudo apt install ${{matrix.install}}
+
+      - name: Setup Boost
+        run: |
+          REF=${GITHUB_BASE_REF:-$GITHUB_REF}
+          BOOST_BRANCH=develop && [ "$REF" == "master" ] && BOOST_BRANCH=master || true
+          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" $LIBRARY
+          ./bootstrap.sh
+          ./b2 -d0 headers
+
+      - name: Run tests
+        run: |
+          cd ../boost-root
+          ./b2 -j3 libs/$LIBRARY/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} variant=debug,release

.github/workflows/windows.yml

@@ -0,0 +1,51 @@
+name: Windows
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - develop
+      - feature/**
+
+env:
+  LIBRARY: core
+
+jobs:
+  CI:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - toolset: msvc-14.1
+            cxxstd: "14,17,latest"
+            os: windows-2016
+          - toolset: msvc-14.2
+            cxxstd: "14,17,latest"
+            os: windows-2019
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Setup Boost
+        shell: cmd
+        run: |
+          if "%GITHUB_BASE_REF%" == "" set GITHUB_BASE_REF=%GITHUB_REF%
+          set BOOST_BRANCH=develop
+          if "%GITHUB_BASE_REF%" == "master" set BOOST_BRANCH=master
+          cd ..
+          git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          xcopy /s /e /q %GITHUB_WORKSPACE% libs\%LIBRARY%\
+          git submodule update --init tools/boostdep
+          python tools/boostdep/depinst/depinst.py --git_args "--jobs 3" %LIBRARY%
+          cmd /c bootstrap
+          b2 -d0 headers
+
+      - name: Run tests
+        shell: cmd
+        run: |
+          cd ../boost-root
+          b2 -j3 libs/%LIBRARY%/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} variant=debug,release address-model=32,64

appveyor.yml

@@ -16,6 +16,7 @@ environment:
   matrix:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       TOOLSET: msvc-9.0,msvc-10.0,msvc-11.0
+      ADDRMD: 32
 
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       TOOLSET: msvc-12.0,msvc-14.0
@@ -36,7 +37,7 @@ environment:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       TOOLSET: msvc-14.2
       ADDRMD: 32,64
-      CXXSTD: 14,17
+      CXXSTD: 14,17,latest
 
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       ADDPATH: C:\cygwin\bin;

include/boost/core/ref.hpp

@@ -10,6 +10,7 @@
 #include <boost/config.hpp>
 #include <boost/config/workaround.hpp>
 #include <boost/core/addressof.hpp>
+#include <boost/core/enable_if.hpp>
 
 //
 //  ref.hpp - ref/cref, useful helper functions
@@ -46,6 +47,26 @@ namespace boost
 
 #endif
 
+namespace detail
+{
+
+template< class Y, class T > struct ref_convertible
+{
+    typedef char (&yes) [1];
+    typedef char (&no)  [2];
+
+    static yes f( T* );
+    static no  f( ... );
+
+    enum _vt { value = sizeof( (f)( static_cast<Y*>(0) ) ) == sizeof(yes) };
+};
+
+struct ref_empty
+{
+};
+
+} // namespace detail
+
 // reference_wrapper
 
 /**
@@ -87,6 +108,14 @@ public:
 public:
 #endif
 
+    template<class Y> friend class reference_wrapper;
+
+    template<class Y> reference_wrapper( reference_wrapper<Y> r,
+        typename enable_if_c<boost::detail::ref_convertible<Y, T>::value,
+            boost::detail::ref_empty>::type = boost::detail::ref_empty() ): t_( r.t_ )
+    {
+    }
+
     /**
      @return The stored reference.
      @remark Does not throw.

test/Jamfile.v2

@@ -35,7 +35,10 @@ compile-fail ref_rv_fail4.cpp ;
 compile-fail ref_rv_fail5.cpp ;
 compile-fail ref_implicit_fail.cpp ;
 compile-fail ref_implicit_fail2.cpp ;
+compile-fail ref_implicit_fail3.cpp ;
+compile-fail ref_implicit_fail4.cpp ;
 run ref_cv_test.cpp ;
+run ref_conversion_test.cpp ;
 
 run eif_constructors.cpp ;
 run eif_dummy_arg_disambiguation.cpp ;

test/ref_conversion_test.cpp

@@ -0,0 +1,39 @@
+//  Implicit conversions between compatible reference wrappers
+//
+//  Copyright 2020 Peter Dimov
+//
+//  Distributed under the Boost Software License, Version 1.0.
+//  See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/ref.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+struct X
+{
+};
+
+struct Y: public X
+{
+};
+
+void f1( boost::reference_wrapper<X> r, Y * p )
+{
+    BOOST_TEST_EQ( r.get_pointer(), p );
+}
+
+void f2( boost::reference_wrapper<int const> r, int * p )
+{
+    BOOST_TEST_EQ( r.get_pointer(), p );
+}
+
+int main()
+{
+    Y y;
+    f1( boost::ref(y), &y );
+
+    int i = 0;
+    f2( boost::ref(i), &i );
+
+    return boost::report_errors();
+}

test/ref_implicit_fail3.cpp

@@ -0,0 +1,29 @@
+//
+// Incompatible reference_wrappers must not implicitly convert to each other
+//
+// Copyright 2020 Peter Dimov
+//
+// Distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+//
+
+#include <boost/ref.hpp>
+
+struct X
+{
+};
+
+struct Y
+{
+};
+
+void f( boost::reference_wrapper<X> )
+{
+}
+
+int main()
+{
+    Y y;
+    f( boost::ref(y) ); // should fail
+}

test/ref_implicit_fail4.cpp

@@ -0,0 +1,21 @@
+//
+// Incompatible reference_wrappers must not implicitly convert to each other
+//
+// Copyright 2020 Peter Dimov
+//
+// Distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+//
+
+#include <boost/ref.hpp>
+
+void f( boost::reference_wrapper< int const > )
+{
+}
+
+int main()
+{
+    long y = 0;
+    f( boost::ref(y) ); // should fail
+}