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std::indirect_result_t(3)      C++ Standard Libary     std::indirect_result_t(3)

NAME
     std::indirect_result_t - std::indirect_result_t

Synopsis
	Defined in header <iterator>
	template< class F, class... Is >

	    requires (std::indirectly_readable<Is> && ...) &&
		      std::invocable<F, 	   std::iter_reference_t<Is>...>
     (since C++20)

	using indirect_result_t = std::invoke_result_t<F,
	std::iter_reference_t<Is>...>;

	The alias template indirect_result_t obtains the result type of invoking
     an
	invocable type F on  the  result  of  dereferencing  indirectly_readable
     types Is....

Template parameters
	F  - an invocable type
	Is - indirectly readable types that are dereferenced to arguments

Example
     // Run this code

      #include <iterator>
      #include <type_traits>

      struct Fn
      {
	  long operator()(const int&);
	  int operator()(int&&);
	  short operator()(int, int) const;
	  auto operator()(const float) -> int&;
	  void operator()(int[8]);
      };

      static_assert(
	  std::is_same_v<std::indirect_result_t<Fn, const int*>, long> and
	  std::is_same_v<std::indirect_result_t<Fn,   std::move_iterator<int*>>,
     int> and
	  std::is_same_v<std::indirect_result_t<const Fn,  int*,  int*>,  short>
     and
	  std::is_same_v<std::indirect_result_t<Fn, float*>, int&> and
	  std::is_same_v<std::indirect_result_t<Fn, int**>, void>
      );

      int main() {}

See also
	result_of		  deduces the result type of invoking a callable
     object with
	invoke_result		  a set of arguments
	(C++11)(removed in C++20) (class template)
	(C++17)

http://cppreference.com 	   2024.06.10	       std::indirect_result_t(3)
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