Merge branch 'fix_error_code_wostream' of https://github.com/MarcelRaad/system into feature/pr-76

This fixes a regression from commit
a9b64a888a.
Calling `operator<<` with `std::string` only works for `std::ostream`.
Use `c_str()` to restore the previous behavior of using `const char*`,
which works for any `basic_ostream` specialization.

.github/workflows/ci.yml

@@ -144,6 +144,10 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          - toolset: msvc-14.0
+            cxxstd: "14"
+            addrmd: 32,64
+            os: windows-2019
           - toolset: msvc-14.1
             cxxstd: "14,17,latest"
             addrmd: 32,64

include/boost/system/detail/error_code.hpp

@@ -604,7 +604,7 @@ public:
         inline friend std::basic_ostream<Ch, Tr>&
         operator<< (std::basic_ostream<Ch, Tr>& os, error_code const & ec)
     {
-        return os << ec.to_string();
+        return os << ec.to_string().c_str();
     }
 
     std::string what() const

test/CMakeLists.txt

@@ -112,6 +112,8 @@ boost_test(TYPE run SOURCES system_error_test3.cpp)
 
 boost_test(TYPE run SOURCES std_interop_test11.cpp)
 
+boost_test(TYPE run SOURCES ec_wstream_test.cpp)
+
 # result
 
 set(BOOST_TEST_COMPILE_FEATURES cxx_std_11)

test/Jamfile.v2

@@ -134,6 +134,8 @@ run system_error_test3.cpp ;
 
 run std_interop_test11.cpp ;
 
+run ec_wstream_test.cpp ;
+
 # result
 
 import ../../config/checks/config : requires ;

test/ec_wstream_test.cpp

@@ -0,0 +1,21 @@
+// Copyright 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/core/lightweight_test.hpp>
+#include <sstream>
+
+namespace sys = boost::system;
+
+int main()
+{
+    {
+        std::wostringstream os;
+        os << sys::error_code();
+
+        BOOST_TEST( os.str() == L"system:0" );
+    }
+
+    return boost::report_errors();
+}