Older compilers do not support defaulted nothrow destructors

[Lastique]

It seems, https://github.com/boostorg/test/pull/375 broke compilation on MSVC-12, as seen in Boost.Log CI.

.\boost/test/utils/runtime/errors.hpp(42) : error C2610: 'boost::runtime::param_error::~param_error(void) throw()' : is not a special member function which can be defaulted
        exception specification is not allowed
.\boost/test/utils/runtime/errors.hpp(61) : error C2610: 'boost::runtime::init_error::~init_error(void) throw()' : is not a special member function which can be defaulted
        exception specification is not allowed
.\boost/test/utils/runtime/errors.hpp(67) : error C2610: 'boost::runtime::input_error::~input_error(void) throw()' : is not a special member function which can be defaulted
        exception specification is not allowed
.\boost/test/utils/runtime/errors.hpp(76) : error C2610: 'boost::runtime::specific_param_error<Derived,Base>::~specific_param_error(void) throw()' : is not a special member function which can be defaulted
        exception specification is not allowed
        .\boost/test/utils/runtime/errors.hpp(127) : see reference to class template instantiation 'boost::runtime::specific_param_error<Derived,Base>' being compiled
.\boost/test/utils/runtime/errors.hpp(169) : error C2610: 'boost::runtime::ambiguous_param::~ambiguous_param(void) throw()' : is not a special member function which can be defaulted
        exception specification is not allowed
.\boost/test/utils/runtime/errors.hpp(185) : error C2610: 'boost::runtime::unrecognized_param::~unrecognized_param(void) throw()' : is not a special member function which can be defaulted
        exception specification is not allowed
    call "bin.v2\standalone\msvc\msvc-12.0\msvc-setup.bat" amd64 >nul
 cl /Zm800 -nologo "libs\test\src\compiler_log_formatter.cpp" -c -Fo"bin.v2\libs\test\build\msvc-12.0\release\threading-multi\compiler_log_formatter.obj"     -TP /wd4675 /EHs /GR /O2 /Ob2 /W4 /MD /Zc:forScope /Zc:wchar_t /Zc:inline /Gw /favor:blend -wd4275 -wd4671 -wd4673 -DBOOST_ALL_NO_LIB=1 -DBOOST_TEST_DYN_LINK=1 -DNDEBUG "-I." 

CC @ecatmur.

[Lastique]

And the same issue is with gcc-4.6:

./boost/test/utils/runtime/errors.hpp:42:5: error: function 'boost::runtime::param_error::~param_error()' defaulted on its first declaration must not have an exception-specification
./boost/test/utils/runtime/errors.hpp:61:5: error: function 'boost::runtime::init_error::~init_error()' defaulted on its first declaration must not have an exception-specification
./boost/test/utils/runtime/errors.hpp:67:5: error: function 'boost::runtime::input_error::~input_error()' defaulted on its first declaration must not have an exception-specification
./boost/test/utils/runtime/errors.hpp:76:5: error: function 'boost::runtime::specific_param_error<Derived, Base>::~specific_param_error()' defaulted on its first declaration must not have an exception-specification
./boost/test/utils/runtime/errors.hpp:169:5: error: function 'boost::runtime::ambiguous_param::~ambiguous_param()' defaulted on its first declaration must not have an exception-specification
./boost/test/utils/runtime/errors.hpp:185:5: error: function 'boost::runtime::unrecognized_param::~unrecognized_param()' defaulted on its first declaration must not have an exception-specification

    "g++-4.6"  -ftemplate-depth-1024 -std=c++0x -fvisibility-inlines-hidden -fPIC -m64 -pthread -O0 -fno-inline -Wall -g -fvisibility=hidden -Wno-variadic-macros -DBOOST_ALL_NO_LIB=1 -DBOOST_TEST_DYN_LINK=1   -I"."  -c -o "bin.v2/libs/test/build/gcc-4.6/debug/cxxstd-0x-iso/threading-multi/visibility-hidden/compiler_log_formatter.o" "libs/test/src/compiler_log_formatter.cpp"

[ecatmur]

Ugh, sorry. I can't see an elegant (one-line) fix; would a multi-line compatibility change be OK? Something like

#ifdef BOOST_NO_CXX11
~param_error() BOOST_NOEXCEPT_OR_NOTHROW BOOST_OVERRIDE {}
#else
~param_error() noexcept override = default;
#endif

If so (or if you can suggest any other mechanism) I'll prepare a PR.

[mborland]

Ugh, sorry. I can't see an elegant (one-line) fix; would a multi-line compatibility change be OK? Something like

#ifdef BOOST_NO_CXX11

~param_error() BOOST_NOEXCEPT_OR_NOTHROW BOOST_OVERRIDE {}

#else

~param_error() noexcept override = default;

#endif

If so (or if you can suggest any other mechanism) I'll prepare a PR.

That looks fine to me, and a PR would be great. Thanks.

[Lastique]

Ugh, sorry. I can't see an elegant (one-line) fix; would a multi-line compatibility change be OK? Something like

#ifdef BOOST_NO_CXX11
~param_error() BOOST_NOEXCEPT_OR_NOTHROW BOOST_OVERRIDE {}
#else
~param_error() noexcept override = default;
#endif

If so (or if you can suggest any other mechanism) I'll prepare a PR.

You could define your own compatibility macro like BOOST_DEFAULTED_FUNCTION, which expands to func() = default only on compilers that fully support the use cases you need. That is, on gcc >= 4.7 and MSVC >= 14.0. Then the rest of the changes would be more clean.