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#include <iostream>
#include <type_traits>
 
using namespace std;
 
template<typename Parser>
struct Module{
    using DType = typename Parser::DType;
    using OptionsType = int;
};
 
template<typename D, typename Derived = void >
struct Parser{
	using DType = D;
 
	using DerivedType = typename std::conditional< std::is_same<Derived,void>::value, Parser, Derived>::type;
    using ModuleType = Module<DerivedType>;
    using ModuleOptions = typename ModuleType::OptionsType; //uncomment this!!
};
 
template<typename D>
struct ParserDerived: Parser<D, ParserDerived<D> >{
 
	using Base = Parser<D, ParserDerived<D> >;
 
};
 
 
int main() {
	Parser<double> t;
 
	ParserDerived<double> d;
}

prog.cpp: In instantiation of ‘struct Module<ParserDerived<double> >’:
prog.cpp:18:59:   required from ‘struct Parser<double, ParserDerived<double> >’
prog.cpp:22:8:   required from ‘struct ParserDerived<double>’
prog.cpp:32:24:   required from here
prog.cpp:8:41: error: no type named ‘DType’ in ‘struct ParserDerived<double>’
     using DType = typename Parser::DType;
                                         ^
prog.cpp: In function ‘int main()’:
prog.cpp:30:17: warning: unused variable ‘t’ [-Wunused-variable]
  Parser<double> t;
                 ^
prog.cpp:32:24: warning: unused variable ‘d’ [-Wunused-variable]
  ParserDerived<double> d;
                        ^

Standard output is empty