c++ - GCC Templates: expected »(« before »>« token -

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• where , why have put “template” , “typename” keywords? 5 answers

i don't understand why following code doesn't compile:

template< typename typearg > class data { public:     struct selector1     {     };      template< typename selector >     void foo()     {     } };  template< typename typearg > class test { public:     void test(); };   template< typename typearg > void test< typearg >::test() {     data< typearg > data;     data.foo< typename data< typearg >::selector1 >(); } 

i have tested gcc 4.6 , gcc 4.9. both give me same error:

test.cpp: in member function »void test::test()«: test.cpp:28:51: error: expected »(« before »>« token test.cpp:28:53: error: expected primary-expression before »)« token

can tell me needs done code compile?

since type of data dependent, nature of data.foo not known , needs disambiguated:

data.template foo<typename data< typearg >::selector1>(); //   ^^^^^^^^