Update std_interop_test12.cpp

Drone config

.drone.star

@@ -0,0 +1,32 @@
+# Copyright 2020 Rene Rivera
+# Copyright 2022 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# https://www.boost.org/LICENSE_1_0.txt
+
+globalenv={ 'UBSAN_OPTIONS': 'print_stacktrace=1' }
+
+def main(ctx):
+  return [
+  linux_cxx("GCC 4.4 14.04", "", packages="g++-4.4", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.4', 'CXXSTD': '98,0x'}, globalenv=globalenv),
+  linux_cxx("GCC 4.6 14.04", "", packages="g++-4.6", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.6', 'CXXSTD': '03,0x'}, globalenv=globalenv),
+  linux_cxx("GCC 4.8* 14.04", "", packages="g++-multilib", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11', 'ADDRMD': '32,64'}, globalenv=globalenv),
+  linux_cxx("GCC 4.9 14.04", "", packages="g++-4.9", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.9', 'CXXSTD': '03,11'}, globalenv=globalenv),
+  linux_cxx("GCC 5* 16.04", "", packages="g++-multilib", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11,14', 'ADDRMD': '32,64'}, globalenv=globalenv),
+  linux_cxx("GCC 6 16.04", "", packages="g++-6", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-6', 'CXXSTD': '03,11'}, globalenv=globalenv),
+  linux_cxx("GCC 7* 18.04", "", packages="g++-multilib", buildscript="drone", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11,14,1z', 'ADDRMD': '32,64'}, globalenv=globalenv),
+  #linux_cxx("GCC 8 18.04", "", packages="g++-8", buildscript="drone", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-8', 'CXXSTD': '03,11,14,1z', 'ADDRMD': '32,64'}, globalenv=globalenv),
+  linux_cxx("GCC 9* 20.04", "", packages="g++-multilib", buildscript="drone", image="cppalliance/droneubuntu2004:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11,14,17,2a', 'ADDRMD': '32,64'}, globalenv=globalenv),
+  linux_cxx("GCC 9* 20.04 UBSAN", "", packages="", buildscript="drone", image="cppalliance/droneubuntu2004:1", environment={'UBSAN': 1, 'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11,14,17,2a', 'LINKFLAGS': '-fuse-ld=gold'}, globalenv=globalenv),
+  linux_cxx("GCC 9* 20.04 ARM64", "", packages="", buildscript="drone", image="cppalliance/droneubuntu2004:multiarch", arch="arm64", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11,14,17,2a', 'ADDRMD': '32,64'}, globalenv=globalenv),
+  linux_cxx("Clang 3.4 14.04", "", packages="clang-3.4", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'clang', 'COMPILER': '/usr/bin/clang++', 'CXXSTD': '03,11'}, globalenv=globalenv),
+  linux_cxx("Clang 13 20.04 UBSAN", "", packages="clang-13", llvm_os="focal", llvm_ver="13", buildscript="drone", image="cppalliance/droneubuntu2004:1", environment={'UBSAN': '1', 'TOOLSET': 'clang', 'COMPILER': 'clang++-13', 'CXXSTD': '03,11,14,17,20'}, globalenv=globalenv),
+  linux_cxx("Clang 14 20.04 UBSAN", "", packages="clang-14", llvm_os="focal", llvm_ver="14", buildscript="drone", image="cppalliance/droneubuntu2004:1", environment={'UBSAN': '1', 'TOOLSET': 'clang', 'COMPILER': 'clang++-14', 'CXXSTD': '03,11,14,17,20'}, globalenv=globalenv),
+  osx_cxx("Xcode 12.2 UBSAN", "", packages="", buildtype="boost", buildscript="drone", xcode_version="12.2", environment={'UBSAN': '1', 'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '03,11,14,1z'}, globalenv=globalenv),
+  windows_cxx("msvc-14.0", "", image="cppalliance/dronevs2015", buildscript="drone", environment={"TOOLSET": "msvc-14.0", "CXXSTD": "14,latest"}, globalenv=globalenv),
+  windows_cxx("msvc-14.1", "", image="cppalliance/dronevs2017", buildscript="drone", environment={"TOOLSET": "msvc-14.1", "CXXSTD": "14,17,latest"}, globalenv=globalenv),
+  windows_cxx("msvc-14.2", "", image="cppalliance/dronevs2019", buildscript="drone", environment={"TOOLSET": "msvc-14.2", "CXXSTD": "14,17,20,latest"}, globalenv=globalenv),
+  windows_cxx("msvc-14.3", "", image="cppalliance/dronevs2022:1", buildscript="drone", environment={"TOOLSET": "msvc-14.3", "CXXSTD": "14,17,20,latest"}, globalenv=globalenv)
+    ]
+
+# from https://github.com/boostorg/boost-ci
+load("@boost_ci//ci/drone/:functions.star", "linux_cxx", "windows_cxx", "osx_cxx")

.drone/drone.bat

@@ -0,0 +1,24 @@
+@ECHO ON
+
+set DRONE_BUILD_DIR=%CD%
+
+IF "%DRONE_BRANCH%" == "" (
+  for /F %%i in ("%GITHUB_REF%") do @set DRONE_BRANCH=%%~nxi
+)
+
+for /F %%i in ("%DRONE_REPO%") do @set SELF=%%~nxi
+
+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\%SELF%\
+python tools/boostdep/depinst/depinst.py %SELF%
+cmd /c bootstrap
+b2 -d0 headers
+
+if not "%CXXSTD%" == "" set CXXSTD=cxxstd=%CXXSTD%
+if not "%ADDRMD%" == "" set ADDRMD=address-model=%ADDRMD%
+b2 -j3 libs/%SELF%/test toolset=%TOOLSET% %CXXSTD% %ADDRMD% variant=debug,release embed-manifest-via=linker

.drone/drone.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+# Copyright 2020 Rene Rivera, Sam Darwin
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE.txt or copy at http://boost.org/LICENSE_1_0.txt)
+
+set -e
+export TRAVIS_BUILD_DIR=$(pwd)
+export DRONE_BUILD_DIR=$(pwd)
+export TRAVIS_BRANCH=$DRONE_BRANCH
+export VCS_COMMIT_ID=$DRONE_COMMIT
+export GIT_COMMIT=$DRONE_COMMIT
+export REPO_NAME=$DRONE_REPO
+export PATH=~/.local/bin:/usr/local/bin:$PATH
+
+echo '==================================> INSTALL'
+
+BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+cd ..
+git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule update --init tools/boostdep
+cp -r $TRAVIS_BUILD_DIR/* libs/system
+python tools/boostdep/depinst/depinst.py system
+./bootstrap.sh
+./b2 -d0 headers
+
+echo '==================================> SCRIPT'
+
+echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
+./b2 -j3 libs/system/test toolset=$TOOLSET cxxstd=$CXXSTD variant=debug,release ${ADDRMD:+address-model=$ADDRMD} ${UBSAN:+cxxflags=-fsanitize=undefined cxxflags=-fno-sanitize-recover=undefined linkflags=-fsanitize=undefined define=UBSAN=1 debug-symbols=on} ${LINKFLAGS:+linkflags=$LINKFLAGS}

.github/workflows/ci.yml

@@ -153,10 +153,14 @@ jobs:
             addrmd: 32,64
             os: windows-2016
           - toolset: msvc-14.2
-            cxxstd: "14,17,latest"
+            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
@@ -196,7 +200,7 @@ 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:

doc/system/changes.adoc

@@ -1,5 +1,5 @@
 ////
-Copyright 2018-2021 Peter Dimov
+Copyright 2018-2022 Peter Dimov
 Distributed under the Boost Software License, Version 1.0.
 https://www.boost.org/LICENSE_1_0.txt
 ////
@@ -8,6 +8,13 @@ https://www.boost.org/LICENSE_1_0.txt
 # Revision History
 :idprefix:
 
+## Changes in Boost 1.79
+
+* Added a `throw_exception_from_error` overload for `std::error_code`.
+* Added a `boost::source_location` parameter to `throw_exception_from_error`.
+* `result<T>::value` now automatically supplies `BOOST_CURRENT_LOCATION` to
+  `throw_exception_from_error` via a default argument.
+
 ## Changes in Boost 1.78
 
 * Added support for source locations to `error_code`.

doc/system/copyright.adoc

@@ -14,6 +14,6 @@ http://www.boost.org/LICENSE_1_0.txt
 This documentation is
 
 * Copyright 2003-2017 Beman Dawes
-* Copyright 2018-2021 Peter Dimov
+* Copyright 2018-2022 Peter Dimov
 
 and is distributed under the http://www.boost.org/LICENSE_1_0.txt[Boost Software License, Version 1.0].

doc/system/reference.adoc

@@ -1,6 +1,6 @@
 ////
 Copyright 2003-2017 Beman Dawes
-Copyright 2018-2021 Peter Dimov
+Copyright 2018-2022 Peter Dimov
 
 Distributed under the Boost Software License, Version 1.0.
 
@@ -1454,7 +1454,11 @@ namespace system {
 
 // throw_exception_from_error
 
-BOOST_NORETURN inline void throw_exception_from_error( error_code const & e );
+BOOST_NORETURN inline void throw_exception_from_error( error_code const & e,
+  boost::source_location const & loc );
+
+BOOST_NORETURN inline void throw_exception_from_error( std::error_code const & e,
+  boost::source_location const & loc );
 
 // in_place_*
 
@@ -1486,13 +1490,24 @@ If `result<T, E>` is used with other error types, the user is expected to provid
 an appropriate overload of `throw_exception_from_error` in the namespace of `E`.
 
 ```
-BOOST_NORETURN inline void throw_exception_from_error( error_code const & e );
+BOOST_NORETURN inline void throw_exception_from_error( error_code const & e,
+  boost::source_location const & loc );
 ```
 [none]
 * {blank}
 +
 Effects: ::
-  `boost::throw_exception( system_error( e ) )`.
+  `boost::throw_exception( system_error( e ), loc )`.
+
+```
+BOOST_NORETURN inline void throw_exception_from_error( std::error_code const & e,
+  boost::source_location const & loc );
+```
+[none]
+* {blank}
++
+Effects: ::
+  `boost::throw_exception( std::system_error( e ), loc )`.
 
 ### result<T, E>
 
@@ -1528,10 +1543,17 @@ public:
 
     // checked value access
 
-    constexpr T& value() & ;
-    constexpr T const& value() const& ;
-    constexpr T&& value() && ;
-    constexpr T const&& value() const&& ;
+    constexpr T& value( boost::source_location const & loc =
+      BOOST_CURRENT_LOCATION ) & ;
+
+    constexpr T const& value( boost::source_location const & loc =
+      BOOST_CURRENT_LOCATION ) const& ;
+
+    constexpr T&& value( boost::source_location const & loc =
+      BOOST_CURRENT_LOCATION ) && ;
+
+    constexpr T const&& value( boost::source_location const & loc =
+      BOOST_CURRENT_LOCATION ) const&& ;
 
     // unchecked value access
 
@@ -1653,10 +1675,17 @@ Returns: ::
 #### Checked Value Access
 
 ```
-constexpr T& value() & ;
-constexpr T const& value() const& ;
-constexpr T&& value() && ;
-constexpr T const&& value() const&& ;
+constexpr T& value(
+  boost::source_location const & loc = BOOST_CURRENT_LOCATION ) & ;
+
+constexpr T const& value(
+  boost::source_location const & loc = BOOST_CURRENT_LOCATION ) const& ;
+
+constexpr T&& value(
+  boost::source_location const & loc = BOOST_CURRENT_LOCATION ) && ;
+
+constexpr T const&& value(
+  boost::source_location const & loc = BOOST_CURRENT_LOCATION ) const&& ;
 ```
 [none]
 * {blank}
@@ -1664,7 +1693,7 @@ constexpr T const&& value() const&& ;
 Effects: ::
   If `*this` holds a value, returns a reference to it. Otherwise,
   calls `throw_exception_from_error`, passing it a reference to
-  the held error.
+  the held error, and `loc`.
 
 #### Unchecked Value Access
 
@@ -1799,7 +1828,8 @@ public:
 
     // checked value access
 
-    constexpr void value() const;
+    constexpr void value( boost::source_location const & loc =
+      BOOST_CURRENT_LOCATION ) const;
 
     // unchecked value access
 
@@ -1912,14 +1942,15 @@ Returns: ::
 #### Checked Value Access
 
 ```
-constexpr void value() const;
+constexpr void value(
+  boost::source_location const & loc = BOOST_CURRENT_LOCATION ) const;
 ```
 [none]
 * {blank}
 +
 Effects: ::
   If `*this` doesn't hold a value, calls `throw_exception_from_error`,
-  passing it a reference to the held error.
+  passing it a reference to the held error, and `loc`.
 
 #### Unchecked Value Access
 

include/boost/system/detail/config.hpp

@@ -1,7 +1,7 @@
 #ifndef BOOST_SYSTEM_DETAIL_CONFIG_HPP_INCLUDED
 #define BOOST_SYSTEM_DETAIL_CONFIG_HPP_INCLUDED
 
-// Copyright 2018 Peter Dimov
+// Copyright 2018-2022 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)
@@ -62,4 +62,20 @@
 # define BOOST_SYSTEM_CLANG_6
 #endif
 
+//
+
+#if defined(BOOST_LIBSTDCXX_VERSION) && BOOST_LIBSTDCXX_VERSION < 50000
+# define BOOST_SYSTEM_AVOID_STD_GENERIC_CATEGORY
+#endif
+
+#if defined(__CYGWIN__) || defined(__MINGW32__) || (defined(_MSC_VER) && _MSC_VER == 1800) || (defined(BOOST_LIBSTDCXX_VERSION) && BOOST_LIBSTDCXX_VERSION < 90000)
+
+// Under Cygwin (and MinGW!), std::system_category() is POSIX
+// Under VS2013, std::system_category() isn't quite right
+// Under libstdc++ before 7.4, before 8.3, before 9.1, default_error_condition
+// for the system category returns a condition from the system category
+
+# define BOOST_SYSTEM_AVOID_STD_SYSTEM_CATEGORY
+#endif
+
 #endif // BOOST_SYSTEM_DETAIL_CONFIG_HPP_INCLUDED

include/boost/system/detail/error_category_impl.hpp

@@ -14,6 +14,7 @@
 #include <boost/system/detail/error_condition.hpp>
 #include <boost/system/detail/error_code.hpp>
 #include <boost/system/detail/snprintf.hpp>
+#include <boost/system/detail/config.hpp>
 #include <boost/config.hpp>
 #include <string>
 #include <cstring>
@@ -108,7 +109,7 @@ inline error_category::operator std::error_category const & () const
     if( id_ == detail::generic_category_id )
     {
 // This condition must be the same as the one in error_condition.hpp
-#if defined(BOOST_GCC) && BOOST_GCC < 50000
+#if defined(BOOST_SYSTEM_AVOID_STD_GENERIC_CATEGORY)
 
     static const boost::system::detail::std_category generic_instance( this, 0x1F4D3 );
     return generic_instance;
@@ -123,10 +124,7 @@ inline error_category::operator std::error_category const & () const
     if( id_ == detail::system_category_id )
     {
 // This condition must be the same as the one in error_code.hpp
-#if defined(__CYGWIN__) || defined(__MINGW32__) || (defined(_MSC_VER) && _MSC_VER == 1800) || (defined(BOOST_GCC) && BOOST_GCC < 50000)
-
-    // Under Cygwin (and MinGW!), std::system_category() is POSIX
-    // Under VS2013, std::system_category() isn't quite right
+#if defined(BOOST_SYSTEM_AVOID_STD_SYSTEM_CATEGORY)
 
     static const boost::system::detail::std_category system_instance( this, 0x1F4D7 );
     return system_instance;

include/boost/system/detail/error_code.hpp

@@ -575,7 +575,7 @@ public:
         else if( lc_flags_ == 0 )
         {
 // This condition must be the same as the one in error_category_impl.hpp
-#if defined(__CYGWIN__) || defined(__MINGW32__) || (defined(_MSC_VER) && _MSC_VER == 1800) || (defined(BOOST_GCC) && BOOST_GCC < 50000)
+#if defined(BOOST_SYSTEM_AVOID_STD_SYSTEM_CATEGORY)
 
             return std::error_code( 0, boost::system::system_category() );
 

include/boost/system/detail/error_condition.hpp

@@ -223,7 +223,7 @@ public:
     operator std::error_condition () const
     {
 // This condition must be the same as the one in error_category_impl.hpp
-#if defined(BOOST_GCC) && BOOST_GCC < 50000
+#if defined(BOOST_SYSTEM_AVOID_STD_GENERIC_CATEGORY)
 
         return std::error_condition( value(), category() );
 

include/boost/system/result.hpp

@@ -1,7 +1,7 @@
 #ifndef BOOST_SYSTEM_RESULT_HPP_INCLUDED
 #define BOOST_SYSTEM_RESULT_HPP_INCLUDED
 
-// Copyright 2017, 2021 Peter Dimov.
+// Copyright 2017, 2021, 2022 Peter Dimov.
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
@@ -11,11 +11,13 @@
 #include <boost/system/detail/error_category_impl.hpp>
 #include <boost/variant2/variant.hpp>
 #include <boost/throw_exception.hpp>
+#include <boost/assert/source_location.hpp>
 #include <boost/assert.hpp>
 #include <boost/config.hpp>
 #include <type_traits>
 #include <utility>
 #include <iosfwd>
+#include <system_error>
 
 //
 
@@ -26,11 +28,25 @@ namespace system
 
 // throw_exception_from_error
 
-BOOST_NORETURN inline void throw_exception_from_error( error_code const & e )
+#if defined(__GNUC__) && __GNUC__ >= 7 && __GNUC__ <= 8
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wattributes"
+#endif
+
+BOOST_NORETURN BOOST_NOINLINE inline void throw_exception_from_error( error_code const & e, boost::source_location const& loc )
 {
-    boost::throw_exception( system_error( e ) );
+    boost::throw_exception( system_error( e ), loc );
 }
 
+BOOST_NORETURN BOOST_NOINLINE inline void throw_exception_from_error( std::error_code const & e, boost::source_location const& loc )
+{
+    boost::throw_exception( std::system_error( e ), loc );
+}
+
+#if defined(__GNUC__) && __GNUC__ >= 7 && __GNUC__ <= 8
+# pragma GCC diagnostic pop
+#endif
+
 // in_place_*
 
 using in_place_value_t = variant2::in_place_index_t<0>;
@@ -155,7 +171,7 @@ public:
     // checked value access
 #if defined( BOOST_NO_CXX11_REF_QUALIFIERS )
 
-    BOOST_CXX14_CONSTEXPR T value() const
+    BOOST_CXX14_CONSTEXPR T value( boost::source_location const& loc = BOOST_CURRENT_LOCATION ) const
     {
         if( has_value() )
         {
@@ -163,13 +179,13 @@ public:
         }
         else
         {
-            throw_exception_from_error( variant2::unsafe_get<1>( v_ ) );
+            throw_exception_from_error( variant2::unsafe_get<1>( v_ ), loc );
         }
     }
 
 #else
 
-    BOOST_CXX14_CONSTEXPR T& value() &
+    BOOST_CXX14_CONSTEXPR T& value( boost::source_location const& loc = BOOST_CURRENT_LOCATION ) &
     {
         if( has_value() )
         {
@@ -177,11 +193,11 @@ public:
         }
         else
         {
-            throw_exception_from_error( variant2::unsafe_get<1>( v_ ) );
+            throw_exception_from_error( variant2::unsafe_get<1>( v_ ), loc );
         }
     }
 
-    BOOST_CXX14_CONSTEXPR T const& value() const&
+    BOOST_CXX14_CONSTEXPR T const& value( boost::source_location const& loc = BOOST_CURRENT_LOCATION ) const&
     {
         if( has_value() )
         {
@@ -189,24 +205,24 @@ public:
         }
         else
         {
-            throw_exception_from_error( variant2::unsafe_get<1>( v_ ) );
+            throw_exception_from_error( variant2::unsafe_get<1>( v_ ), loc );
         }
     }
 
     template<class U = T>
         BOOST_CXX14_CONSTEXPR
         typename std::enable_if<std::is_move_constructible<U>::value, T>::type
-        value() &&
+        value( boost::source_location const& loc = BOOST_CURRENT_LOCATION ) &&
     {
-        return std::move( value() );
+        return std::move( value( loc ) );
     }
 
     template<class U = T>
         BOOST_CXX14_CONSTEXPR
         typename std::enable_if<!std::is_move_constructible<U>::value, T&&>::type
-        value() &&
+        value( boost::source_location const& loc = BOOST_CURRENT_LOCATION ) &&
     {
-        return std::move( value() );
+        return std::move( value( loc ) );
     }
 
     template<class U = T>
@@ -217,9 +233,9 @@ public:
     template<class U = T>
         BOOST_CXX14_CONSTEXPR
         typename std::enable_if<!std::is_move_constructible<U>::value, T const&&>::type
-        value() const &&
+        value( boost::source_location const& loc = BOOST_CURRENT_LOCATION ) const &&
     {
-        return std::move( value() );
+        return std::move( value( loc ) );
     }
 
 #endif
@@ -443,14 +459,14 @@ public:
 
     // checked value access
 
-    BOOST_CXX14_CONSTEXPR void value() const
+    BOOST_CXX14_CONSTEXPR void value( boost::source_location const& loc = BOOST_CURRENT_LOCATION ) const
     {
         if( has_value() )
         {
         }
         else
         {
-            throw_exception_from_error( variant2::unsafe_get<1>( v_ ) );
+            throw_exception_from_error( variant2::unsafe_get<1>( v_ ), loc );
         }
     }
 

include/boost/system/system_error.hpp

@@ -23,46 +23,25 @@ private:
 
     error_code code_;
 
-private:
-
-    static std::string build_message( char const * prefix, error_code const & ec )
-    {
-        std::string r;
-
-        if( prefix )
-        {
-            r += prefix;
-            r += ": ";
-        }
-
-        r += ec.what();
-        return r;
-    }
-
-    static std::string build_message( char const * prefix, int ev, error_category const & cat )
-    {
-        return build_message( prefix, error_code( ev, cat ) );
-    }
-
 public:
 
-    explicit system_error( error_code const & ec )
-      : std::runtime_error( build_message( 0, ec ) ), code_( ec ) {}
+    explicit system_error( error_code const & ec ):
+        std::runtime_error( ec.what() ), code_( ec ) {}
 
-    system_error( error_code const & ec, std::string const & prefix )
-      : std::runtime_error( build_message( prefix.c_str(), ec ) ), code_( ec ) {}
+    system_error( error_code const & ec, std::string const & prefix ):
+        std::runtime_error( prefix + ": " + ec.what() ), code_( ec ) {}
 
-    system_error( error_code const & ec, char const * prefix )
-      : std::runtime_error( build_message( prefix, ec ) ), code_( ec ) {}
+    system_error( error_code const & ec, char const * prefix ):
+        std::runtime_error( std::string( prefix ) + ": " + ec.what() ), code_( ec ) {}
 
-    system_error( int ev, error_category const & ecat )
-      : std::runtime_error( build_message( 0, ev, ecat ) ), code_( ev, ecat ) {}
+    system_error( int ev, error_category const & ecat ):
+        std::runtime_error( error_code( ev, ecat ).what() ), code_( ev, ecat ) {}
 
-    system_error( int ev, error_category const & ecat, std::string const & prefix )
-      : std::runtime_error( build_message( prefix.c_str(), ev, ecat ) ), code_( ev, ecat ) {}
+    system_error( int ev, error_category const & ecat, std::string const & prefix ):
+        std::runtime_error( prefix + ": " + error_code( ev, ecat ).what() ), code_( ev, ecat ) {}
 
-    system_error( int ev, error_category const & ecat, char const * prefix )
-      : std::runtime_error( build_message( prefix, ev, ecat ) ), code_( ev, ecat ) {}
+    system_error( int ev, error_category const & ecat, char const * prefix ):
+        std::runtime_error( std::string( prefix ) + ": " + error_code( ev, ecat ).what() ), code_( ev, ecat ) {}
 
     error_code code() const BOOST_NOEXCEPT
     {

test/CMakeLists.txt

@@ -114,6 +114,8 @@ boost_test(TYPE run SOURCES std_interop_test11.cpp)
 
 boost_test(TYPE run SOURCES ec_wstream_test.cpp)
 
+boost_test(TYPE run SOURCES std_interop_test12.cpp)
+
 # result
 
 set(BOOST_TEST_COMPILE_FEATURES cxx_std_11)

test/Jamfile.v2

@@ -20,6 +20,8 @@ project
     <toolset>msvc:<warnings-as-errors>on
     <toolset>gcc:<warnings-as-errors>on
     <toolset>clang:<warnings-as-errors>on
+
+    <toolset>gcc-4.4:<cxxflags>-Wno-sign-compare
   ;
 
 rule system-run ( sources + )
@@ -136,6 +138,8 @@ run std_interop_test11.cpp ;
 
 run ec_wstream_test.cpp ;
 
+run std_interop_test12.cpp ;
+
 # result
 
 import ../../config/checks/config : requires ;

test/result_value_access.cpp

@@ -1,10 +1,11 @@
-// Copyright 2017, 2021 Peter Dimov.
+// Copyright 2017, 2021, 2022 Peter Dimov.
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
 #include <boost/system/result.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/lightweight_test_trait.hpp>
+#include <system_error>
 
 using namespace boost::system;
 
@@ -26,7 +27,7 @@ struct E
 {
 };
 
-BOOST_NORETURN void throw_exception_from_error( Y const & )
+BOOST_NORETURN void throw_exception_from_error( Y const &, boost::source_location const& )
 {
     throw E();
 }
@@ -165,6 +166,22 @@ int main()
         BOOST_TEST_EQ( result<int>( ec ).operator->(), static_cast<int*>(0) );
     }
 
+    {
+        auto ec = make_error_code( std::errc::invalid_argument );
+
+        result<int, std::error_code> const r( ec );
+
+        BOOST_TEST( !r.has_value() );
+        BOOST_TEST( r.has_error() );
+
+        BOOST_TEST_NOT( r );
+        BOOST_TEST( !r );
+
+        BOOST_TEST_THROWS( r.value(), std::system_error );
+
+        BOOST_TEST_EQ( r.operator->(), static_cast<int*>(0) );
+    }
+
     {
         result<X> r( 1 );
 
@@ -341,5 +358,21 @@ int main()
         BOOST_TEST_EQ( result<void>( ec ).operator->(), static_cast<void*>(0) );
     }
 
+    {
+        auto ec = make_error_code( std::errc::invalid_argument );
+
+        result<void, std::error_code> const r( ec );
+
+        BOOST_TEST( !r.has_value() );
+        BOOST_TEST( r.has_error() );
+
+        BOOST_TEST_NOT( r );
+        BOOST_TEST( !r );
+
+        BOOST_TEST_THROWS( r.value(), std::system_error );
+
+        BOOST_TEST_EQ( r.operator->(), static_cast<void*>(0) );
+    }
+
     return boost::report_errors();
 }

test/std_interop_test12.cpp

@@ -0,0 +1,127 @@
+// Copyright 2021, 2022 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// http://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/system/error_code.hpp>
+#include <boost/system/error_category.hpp>
+#include <boost/system/errc.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config/pragma_message.hpp>
+#include <boost/config.hpp>
+#include <cerrno>
+
+#if !defined(BOOST_SYSTEM_HAS_SYSTEM_ERROR)
+
+BOOST_PRAGMA_MESSAGE( "BOOST_SYSTEM_HAS_SYSTEM_ERROR not defined, test will be skipped" )
+int main() {}
+
+#else
+
+#include <system_error>
+
+enum my_errc
+{
+    my_enoent = ENOENT
+};
+
+class my_category: public boost::system::error_category
+{
+public:
+
+    char const* name() const BOOST_NOEXCEPT
+    {
+        return "mycat";
+    }
+
+    boost::system::error_condition default_error_condition( int ev ) const BOOST_NOEXCEPT
+    {
+        switch( ev )
+        {
+        case my_enoent:
+
+            return boost::system::error_condition( ENOENT, boost::system::generic_category() );
+
+        default:
+
+            return boost::system::error_condition( ev, *this );
+        }
+    }
+
+    std::string message( int ev ) const
+    {
+        switch( ev )
+        {
+        case my_enoent:
+
+            return "No such entity";
+
+        default:
+
+            return "Unknown error";
+        }
+    }
+};
+
+#if defined(BOOST_GCC) && BOOST_GCC < 70000
+
+// g++ 6 and earlier do not allow specializations outside the namespace
+
+namespace boost
+{
+namespace system
+{
+
+template<> struct is_error_code_enum<my_errc>: std::true_type {};
+
+} // namespace system
+} // namespace boost
+
+namespace std
+{
+
+template<> struct is_error_code_enum<my_errc>: std::true_type {};
+
+} // namespace std
+
+#else
+
+template<> struct boost::system::is_error_code_enum<my_errc>: std::true_type {};
+template<> struct std::is_error_code_enum<my_errc>: std::true_type {};
+
+#endif
+
+boost::system::error_code make_error_code( my_errc e )
+{
+    // If `cat` is declared constexpr or const, msvc-14.1 and
+    // msvc-14.2 before 19.29 put it in read-only memory,
+    // despite the `ps_` member being mutable. So it crashes.
+
+    static /*BOOST_SYSTEM_CONSTEXPR*/ my_category cat;
+    return boost::system::error_code( e, cat );
+}
+
+int main()
+{
+    {
+        boost::system::error_code e1 = my_enoent;
+
+        BOOST_TEST( e1 == my_enoent );
+        BOOST_TEST_NOT( e1 != my_enoent );
+
+        BOOST_TEST( e1 == boost::system::errc::no_such_file_or_directory );
+        BOOST_TEST( e1 == std::errc::no_such_file_or_directory );
+    }
+
+    {
+        std::error_code e1 = my_enoent;
+
+        BOOST_TEST( e1 == my_enoent );
+        BOOST_TEST_NOT( e1 != my_enoent );
+
+        BOOST_TEST( e1 == std::errc::no_such_file_or_directory );
+    }
+
+    return boost::report_errors();
+}
+
+#endif

test/system_error_test3.cpp

@@ -1,4 +1,4 @@
-// Copyright 2021 Peter Dimov
+// Copyright 2021, 2022 Peter Dimov
 // Distributed under the Boost Software License, Version 1.0
 // https://www.boost.org/LICENSE_1_0.txt
 
@@ -14,22 +14,36 @@ int main()
         sys::error_code ec( 5, sys::generic_category() );
         sys::system_error x1( ec );
 
-		BOOST_TEST_EQ( std::string( x1.what() ), ec.what() );
+        BOOST_TEST_EQ( std::string( x1.what() ), ec.what() );
     }
 
     {
-        BOOST_STATIC_CONSTEXPR boost::source_location loc = BOOST_CURRENT_LOCATION;
-
-        sys::error_code ec( 5, sys::system_category(), &loc );
+        sys::error_code ec( 5, sys::generic_category() );
         sys::system_error x1( ec, "prefix" );
 
         BOOST_TEST_EQ( std::string( x1.what() ), "prefix: " + ec.what() );
     }
 
     {
-        sys::system_error x1( 5, sys::generic_category() );
+        sys::error_code ec( 5, sys::generic_category() );
+        sys::system_error x1( ec, std::string( "prefix2" ) );
 
-        BOOST_TEST_EQ( std::string( x1.what() ), sys::error_code( 5, sys::generic_category() ).what() );
+        BOOST_TEST_EQ( std::string( x1.what() ), "prefix2: " + ec.what() );
+    }
+
+    {
+        BOOST_STATIC_CONSTEXPR boost::source_location loc = BOOST_CURRENT_LOCATION;
+
+        sys::error_code ec( 5, sys::generic_category(), &loc );
+        sys::system_error x1( ec, "prefix3" );
+
+        BOOST_TEST_EQ( std::string( x1.what() ), "prefix3: " + ec.what() );
+    }
+
+    {
+        sys::system_error x1( 5, sys::system_category() );
+
+        BOOST_TEST_EQ( std::string( x1.what() ), sys::error_code( 5, sys::system_category() ).what() );
     }
 
     {
@@ -38,5 +52,11 @@ int main()
         BOOST_TEST_EQ( std::string( x1.what() ), "prefix: " + sys::error_code( 5, sys::system_category() ).what() );
     }
 
+    {
+        sys::system_error x1( 5, sys::system_category(), std::string( "prefix2" ) );
+
+        BOOST_TEST_EQ( std::string( x1.what() ), "prefix2: " + sys::error_code( 5, sys::system_category() ).what() );
+    }
+
     return boost::report_errors();
 }