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  1.     #include <tuple>
  2.     #include <type_traits>
  3.     #include <vector>
  4.  
  5.     template<typename T>
  6.     struct innermost_impl
  7.     {
  8.         using type = T;
  9.     };
  10.  
  11.     template<template<typename...> class E, typename Head, typename... Tail>
  12.     struct innermost_impl<E<Head, Tail...>>
  13.     {
  14.         using type = typename innermost_impl<Head>::type;
  15.     };
  16.  
  17.     template<typename T>
  18.     using innermost = typename innermost_impl<T>::type;
  19.  
  20.     template<class>
  21.     struct X;
  22.  
  23.     static_assert(std::is_same<innermost<X<X<X<int>>>>, int>::value, "");
  24.  
  25.     static_assert(std::is_same<innermost<std::vector<X<std::vector<int>>>>, int>::value, "");
  26.  
  27.     int main()
  28.     {
  29.     }
Success #stdin #stdout 0s 3292KB
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https://ideone.com/5dOW1l
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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