minor corrections suggested by Johan

Author: Alexandre Hoffmann

include/xtensor/containers/xscalar.hpp

@@ -318,7 +318,7 @@ namespace xt
     using is_xscalar = detail::is_xscalar_impl<E>;
 
     template <class E>
-    concept is_xscalar_concept = is_xscalar<std::decay_t<E>>::value;
+    concept xscalar_concept = is_xscalar<std::decay_t<E>>::value;
 
     namespace detail
     {

include/xtensor/containers/xstorage.hpp

@@ -56,7 +56,7 @@ namespace xt
         explicit uvector(size_type count, const allocator_type& alloc = allocator_type());
         uvector(size_type count, const_reference value, const allocator_type& alloc = allocator_type());
 
-        template <input_iterator_concept InputIt>
+        template <std::input_iterator InputIt>
         uvector(InputIt first, InputIt last, const allocator_type& alloc = allocator_type());
 
         uvector(std::initializer_list<T> init, const allocator_type& alloc = allocator_type());
@@ -269,7 +269,7 @@ namespace xt
     }
 
     template <class T, class A>
-    template <input_iterator_concept InputIt>
+    template <std::input_iterator InputIt>
     inline uvector<T, A>::uvector(InputIt first, InputIt last, const allocator_type& alloc)
         : m_allocator(alloc)
         , p_begin(nullptr)
@@ -667,7 +667,7 @@ namespace xt
 
         svector(const std::vector<T>& vec);
 
-        template <input_iterator_concept IT>
+        template <std::input_iterator IT>
         svector(IT begin, IT end, const allocator_type& alloc = allocator_type());
 
         template <std::size_t N2, bool I2>
@@ -803,7 +803,7 @@ namespace xt
     }
 
     template <class T, std::size_t N, class A, bool Init>
-    template <input_iterator_concept IT>
+    template <std::input_iterator IT>
     inline svector<T, N, A, Init>::svector(IT begin, IT end, const allocator_type& alloc)
         : m_allocator(alloc)
     {

include/xtensor/utils/xutils.hpp

@@ -632,9 +632,6 @@ namespace xt
 
     template <typename E>
     concept iterator_concept = is_iterator<E>::value;
-    template <typename E>
-    concept input_iterator_concept = std::
-        is_convertible<typename std::iterator_traits<E>::iterator_category, std::input_iterator_tag>::value;
 
     /********************************************
      * xtrivial_default_construct implemenation *

include/xtensor/views/xview.hpp

@@ -596,13 +596,13 @@ namespace xt
         inline const_container_iterator data_xend(layout_type l, size_type offset) const noexcept;
 
         // Conversion operator enabled for statically "scalar" views
-        template <is_xscalar_concept ST = self_type>
+        template <xscalar_concept ST = self_type>
         operator reference()
         {
             return (*this)();
         }
 
-        template <is_xscalar_concept ST = self_type>
+        template <xscalar_concept ST = self_type>
         operator const_reference() const
         {
             return (*this)();