Compiling on GCC 4.8

[The-EDev]

There are a couple issues that don't allow compiling, the most recent is this, but also the changes introduced in #327.

Here's an error log:

In file included from crow.h:19:0,
                 from main.cpp:1:
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
crow/routing.h:584:88: error: no matching function for call to ‘wrapped_handler_call(crow::request&, crow::response&, const main()::__lambda53&)’
                   detail::wrapped_handler_call(req, res, f, std::forward<Args>(args)...);
                                                                                        ^
crow/routing.h:584:88: note: candidates are:
In file included from crow/routing.h:18:0,
                 from crow.h:19,
                 from main.cpp:1:
./crow/middleware.h:206:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:206:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = main()::__lambda53; Args = {}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
./crow/middleware.h:206:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
./crow/middleware.h:216:11: note: template<class F, class ... Args> typename std::enable_if<(crow::black_magic::is_callable<F, crow::request&, crow::response&, Args ...>::value && (! crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value))>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:216:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<(crow::black_magic::is_callable<F, crow::request&, crow::response&, Args ...>::value && (! crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value))>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = main()::__lambda53; Args = {}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
./crow/middleware.h:216:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
./crow/middleware.h:226:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& /*req*/, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:226:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = main()::__lambda53; Args = {}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
./crow/middleware.h:226:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
./crow/middleware.h:236:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::request, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:236:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::request, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = main()::__lambda53; Args = {}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
./crow/middleware.h:236:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
./crow/middleware.h:247:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, Args>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& /*req*/, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:247:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, Args>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = main()::__lambda53; Args = {}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]’
main.cpp:10:6:   required from here
./crow/middleware.h:247:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
In file included from crow.h:19:0,
                 from main.cpp:1:
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
crow/routing.h:584:88: error: no matching function for call to ‘wrapped_handler_call(crow::request&, crow::response&, const crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50&, std::basic_string<char>)’
                   detail::wrapped_handler_call(req, res, f, std::forward<Args>(args)...);
                                                                                        ^
crow/routing.h:584:88: note: candidates are:
In file included from crow/routing.h:18:0,
                 from crow.h:19,
                 from main.cpp:1:
./crow/middleware.h:206:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:206:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:206:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:216:11: note: template<class F, class ... Args> typename std::enable_if<(crow::black_magic::is_callable<F, crow::request&, crow::response&, Args ...>::value && (! crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value))>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:216:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<(crow::black_magic::is_callable<F, crow::request&, crow::response&, Args ...>::value && (! crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value))>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:216:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:226:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& /*req*/, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:226:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:226:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:236:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::request, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:236:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::request, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:236:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:247:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, Args>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& /*req*/, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:247:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, Args>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:241:22:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:247:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
In file included from crow.h:19:0,
                 from main.cpp:1:
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
crow/routing.h:584:88: error: no matching function for call to ‘wrapped_handler_call(crow::request&, crow::response&, const crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51&, std::basic_string<char>)’
                   detail::wrapped_handler_call(req, res, f, std::forward<Args>(args)...);
                                                                                        ^
crow/routing.h:584:88: note: candidates are:
In file included from crow/routing.h:18:0,
                 from crow.h:19,
                 from main.cpp:1:
./crow/middleware.h:206:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:206:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:206:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:216:11: note: template<class F, class ... Args> typename std::enable_if<(crow::black_magic::is_callable<F, crow::request&, crow::response&, Args ...>::value && (! crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value))>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:216:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<(crow::black_magic::is_callable<F, crow::request&, crow::response&, Args ...>::value && (! crow::black_magic::is_callable<F, const crow::request, crow::response&, Args ...>::value))>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:216:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:226:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& /*req*/, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:226:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::response&, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:226:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:236:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::request, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:236:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, crow::request, Args ...>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:236:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
crow/routing.h: In instantiation of ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’:
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:247:11: note: template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, Args>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...)
           wrapped_handler_call(crow::request& /*req*/, crow::response& res, const F& f, Args&&... args)
           ^
./crow/middleware.h:247:11: note:   template argument deduction/substitution failed:
./crow/middleware.h: In substitution of ‘template<class F, class ... Args> typename std::enable_if<crow::black_magic::is_callable<F, Args>::value>::type crow::detail::wrapped_handler_call(crow::request&, crow::response&, const F&, Args&& ...) [with F = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’:
crow/routing.h:584:88:   required from ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:581:16:   required from ‘struct crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’
crow/routing.h:577:22:   required from ‘void crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]’
crow/app.h:254:129:   required from ‘void crow::Crow<Middlewares>::validate() [with Middlewares = {}]’
crow/app.h:280:22:   required from ‘void crow::Crow<Middlewares>::run() [with Middlewares = {}]’
main.cpp:12:25:   required from here
./crow/middleware.h:247:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
In file included from /usr/include/boost/utility/compare_pointees.hpp:15:0,
                 from /usr/include/boost/optional/optional.hpp:55,
                 from /usr/include/boost/optional.hpp:15,
                 from crow/query_string.h:9,
                 from crow.h:2,
                 from main.cpp:1:
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include/c++/functional:2334:2: error: ‘std::function<_Res(_ArgTypes ...)>::_Requires<std::__and_<std::__not_<std::is_same<typename std::decay<_Tp>::type, std::function<_Res(_ArgTypes ...)> > >, std::__or_<std::is_void<_Tp>, std::is_convertible<std::function<_Res(_ArgTypes ...)>::_Invoke<typename std::decay<_Tp>::type>, _Res> > >, std::function<_Res(_ArgTypes ...)>&> std::function<_Res(_ArgTypes ...)>::operator=(_Functor&&) [with _Functor = crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27; _Res = void; _ArgTypes = {crow::request&, crow::response&}; std::function<_Res(_ArgTypes ...)>::_Requires<std::__and_<std::__not_<std::is_same<typename std::decay<_Tp>::type, std::function<_Res(_ArgTypes ...)> > >, std::__or_<std::is_void<_Tp>, std::is_convertible<std::function<_Res(_ArgTypes ...)>::_Invoke<typename std::decay<_Tp>::type>, _Res> > >, std::function<_Res(_ArgTypes ...)>&> = std::function<void(crow::request&, crow::response&)>&]’, declared using local type ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = main()::__lambda53; Args = {}]::__lambda27’, is used but never defined [-fpermissive]
  operator=(_Functor&& __f)
  ^
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include/c++/functional:2334:2: error: ‘std::function<_Res(_ArgTypes ...)>::_Requires<std::__and_<std::__not_<std::is_same<typename std::decay<_Tp>::type, std::function<_Res(_ArgTypes ...)> > >, std::__or_<std::is_void<_Tp>, std::is_convertible<std::function<_Res(_ArgTypes ...)>::_Invoke<typename std::decay<_Tp>::type>, _Res> > >, std::function<_Res(_ArgTypes ...)>&> std::function<_Res(_ArgTypes ...)>::operator=(_Functor&&) [with _Functor = crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27; _Res = void; _ArgTypes = {crow::request&, crow::response&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >}; std::function<_Res(_ArgTypes ...)>::_Requires<std::__and_<std::__not_<std::is_same<typename std::decay<_Tp>::type, std::function<_Res(_ArgTypes ...)> > >, std::__or_<std::is_void<_Tp>, std::is_convertible<std::function<_Res(_ArgTypes ...)>::_Invoke<typename std::decay<_Tp>::type>, _Res> > >, std::function<_Res(_ArgTypes ...)>&> = std::function<void(crow::request&, crow::response&, std::basic_string<char>)>&]’, declared using local type ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda50; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’, is used but never defined [-fpermissive]
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include/c++/functional:2334:2: error: ‘std::function<_Res(_ArgTypes ...)>::_Requires<std::__and_<std::__not_<std::is_same<typename std::decay<_Tp>::type, std::function<_Res(_ArgTypes ...)> > >, std::__or_<std::is_void<_Tp>, std::is_convertible<std::function<_Res(_ArgTypes ...)>::_Invoke<typename std::decay<_Tp>::type>, _Res> > >, std::function<_Res(_ArgTypes ...)>&> std::function<_Res(_ArgTypes ...)>::operator=(_Functor&&) [with _Functor = crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27; _Res = void; _ArgTypes = {crow::request&, crow::response&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >}; std::function<_Res(_ArgTypes ...)>::_Requires<std::__and_<std::__not_<std::is_same<typename std::decay<_Tp>::type, std::function<_Res(_ArgTypes ...)> > >, std::__or_<std::is_void<_Tp>, std::is_convertible<std::function<_Res(_ArgTypes ...)>::_Invoke<typename std::decay<_Tp>::type>, _Res> > >, std::function<_Res(_ArgTypes ...)>&> = std::function<void(crow::request&, crow::response&, std::basic_string<char>)>&]’, declared using local type ‘crow::TaggedRule<Args>::operator()(Func&&) [with Func = crow::Crow<Middlewares>::validate() [with Middlewares = {}]::__lambda51; Args = {std::basic_string<char, std::char_traits<char>, std::allocator<char> >}]::__lambda27’, is used but never defined [-fpermissive]

@dranikpg would it be possible to have wrapped_handler_call compile under GCC 4.8 ? What do you think?

[The-EDev]

The candidate that should be considered seems to be the one in middleware.h : 247, that's the same one getting error: no type named ‘type’ in ‘struct std::enable_if<false, void>’

[The-EDev]

Update: the error occurs for all instances of std::enable_if<black_magic::is_callable... I'm going to attempt to use the old method (black_magic::CallHelper) which didn't have this error.
I'm not sure what specifically in is_callable is causing this error, hence the switching back..

[The-EDev]

Using CallHelper works, I haven't checked all the features or ran tests, but hello world compiled on g++ 4.8