Compilation error using clang

[barendgehrels]

Using clang, we can't compile Boost.Fiber because the compilation error listed below.
With gcc it's all fine.
Clang version: clang version 5.0.2 (tags/RELEASE_502/final)

As a workaround, or solution, we changed this line:
https://github.com/boostorg/fiber/blob/develop/include/boost/fiber/context.hpp#L120
into just fss_data() noexcept {}
and then it compiles and works fine, also with clang.

Minimal reproduction scenario:
clang -c -std=c++14 -I . -o /tmp/scheduler1.o libs/fiber/src/scheduler.cpp

Scenario using all the compilation flags used in Boost.Fiber itself, but with clang and c++14:
clang -std=c++14 -fvisibility-inlines-hidden -fPIC -m64 -pthread -O0 -fno-inline -Wall -g -fvisibility=hidden -DBOOST_ALL_NO_LIB=1 -DBOOST_CONTEXT_DYN_LINK=1 -DBOOST_FIBERS_DYN_LINK=1 -DBOOST_FIBERS_SOURCE -DBOOST_FILESYSTEM_DYN_LINK=1 -I . -c -o /tmp/scheduler3.o libs/fiber/src/scheduler.cpp

Both scenarios give the same error:

In file included from libs/fiber/src/scheduler.cpp:7:
In file included from ./boost/fiber/scheduler.hpp:23:
./boost/fiber/context.hpp:120:9: error: default member initializer for 'vp' needed within definition of enclosing class 'context' outside of member functions
        fss_data() noexcept = default;
        ^
./boost/intrusive/pack_options.hpp:109:6: note: in instantiation of template class 'boost::intrusive::build_number_seq<0, boost::intrusive::index_tuple<0, 1, 2> >' requested here
   : build_number_seq<Num - 1, index_tuple<Indexes..., sizeof...(Indexes)> >
     ^
./boost/intrusive/pack_options.hpp:109:6: note: in instantiation of template class 'boost::intrusive::build_number_seq<1, boost::intrusive::index_tuple<0, 1> >' requested here
./boost/intrusive/pack_options.hpp:109:6: note: in instantiation of template class 'boost::intrusive::build_number_seq<2, boost::intrusive::index_tuple<0> >' requested here
./boost/intrusive/pack_options.hpp:189:21: note: in instantiation of template class 'boost::intrusive::build_number_seq<3, boost::intrusive::index_tuple<> >' requested here
   typedef typename build_number_seq<sizeof...(Types)>::type indexes_t;
                    ^
./boost/intrusive/pack_options.hpp:230:21: note: in instantiation of template class 'boost::intrusive::invert_typelist<boost::intrusive::typelist<boost::intrusive::hook_defaults,
      boost::intrusive::tag<boost::fibers::detail::remote_ready_tag>, boost::intrusive::link_mode<boost::intrusive::link_mode_type::safe_link> > >' requested here
   typedef typename invert_typelist<typelist_t>::type inverted_typelist;
                    ^
./boost/intrusive/slist_hook.hpp:172:21: note: in instantiation of template class 'boost::intrusive::pack_options<boost::intrusive::hook_defaults, boost::intrusive::tag<boost::fibers::detail::remote_ready_tag>,
      boost::intrusive::link_mode<boost::intrusive::link_mode_type::safe_link> >' requested here
   typedef typename pack_options
                    ^
./boost/intrusive/slist_hook.hpp:210:14: note: in instantiation of template class 'boost::intrusive::make_slist_member_hook<boost::intrusive::tag<boost::fibers::detail::remote_ready_tag>,
      boost::intrusive::link_mode<boost::intrusive::link_mode_type::safe_link> >' requested here
   :  public make_slist_member_hook<
             ^
./boost/fiber/context.hpp:142:57: note: in instantiation of template class 'boost::intrusive::slist_member_hook<boost::intrusive::tag<boost::fibers::detail::remote_ready_tag>,
      boost::intrusive::link_mode<boost::intrusive::link_mode_type::safe_link> >' requested here
    detail::remote_ready_hook                           remote_ready_hook_{};
                                                        ^
./boost/fiber/context.hpp:117:49: note: default member initializer declared here
        void                                *   vp{ nullptr };
                                                ^
./boost/fiber/context.hpp:120:9: error: default member initializer for 'cleanup_function' needed within definition of enclosing class 'context' outside of member functions
        fss_data() noexcept = default;
        ^
./boost/fiber/context.hpp:118:49: note: default member initializer declared here
        detail::fss_cleanup_function::ptr_t     cleanup_function{};
                                                ^
2 errors generated.

[barendgehrels]

Any news?

[mohak6401]

not able to understand your problem sir

[bernhardmgruber]

Same problem here. Just compile

#include <boost/fiber/fiber.hpp>

with clang-5 -std=c++11. See: https://godbolt.org/z/rY89sMfaK

Error:

In file included from <source>:1:
In file included from /opt/compiler-explorer/libs/boost_1_77_0/boost/fiber/fiber.hpp:22:
/opt/compiler-explorer/libs/boost_1_77_0/boost/fiber/context.hpp:120:9: error: default member initializer for 'vp' needed within definition of enclosing class 'context' outside of member functions
        fss_data() noexcept = default;
        ^
....

Works with clang-6 and higher.

[muggenhor]

Using that same godbolt link ^^ I can verify that this is fixed by Boost 1.78.0.

Probably a result of df11967:

-        fss_data() noexcept = default;
+        fss_data() = default;

I guess Clang 5 didn't like the noexcept in that default constructor definition...

[olk]

fixed