c++ - What is causing deleted function error message? -

i have main program uses 2 templates classes trans , travel, , generates compilation error use of deleted function 'makecolor::makecolor(), , also: note: 'makecolor::makecolor()' implicitly deleted because default definition ill-formed. how can fix this?

class travel:

#include "trans.hpp" template<typename a, typename b, typename c> class travel {      public:       typedef trans<a, b> cartype;     typedef trans<c, int> boattype;      typedef typename cartype::newest newestcar;     typedef typename boattype::newest newestboat; }; 

class trans:

template<typename a, typename b> class trans {      public:       class newest; }; 

main program:

#include "travel.hpp" #include "trans.hpp"   travel<makecolor, makematerial, makesize>  struct makecolor {   cartype::newestcar model; // error };  int main(){ ... } 

makecolor not have default constructor because cartype::newestcar not have default constructor.

you'll need explicitly create constructor initializes model.

struct makecolor {   makecolor() : model( /* pass constructor parameters here */ ) {}   cartype::newestcar model; // error };