change span from signed to unsigned to align to std

include/gsl/span

@@ -26,16 +26,18 @@
 #include <cstddef>   // for ptrdiff_t, size_t, nullptr_t
 #include <iterator>  // for reverse_iterator, distance, random_access_...
 #include <limits>
+#include <memory> // for std::addressof
 #include <stdexcept>
 #include <type_traits> // for enable_if_t, declval, is_convertible, inte...
 #include <utility>
-#include <memory> // for std::addressof
 
 #if defined(_MSC_VER) && !defined(__clang__)
 #pragma warning(push)
 
 // turn off some warnings that are noisy about our Expects statements
 #pragma warning(disable : 4127) // conditional expression is constant
+#pragma warning(                                                                                   \
+    disable : 4146) // unary minus operator applied to unsigned type, result still unsigned
 #pragma warning(disable : 4702) // unreachable code
 
 // Turn MSVC /analyze rules that generate too much noise. TODO: fix in the tool.
@@ -70,9 +72,9 @@ namespace gsl
 {
 
 // [views.constants], constants
-constexpr const std::ptrdiff_t dynamic_extent = -1;
+constexpr const std::size_t dynamic_extent = std::numeric_limits<std::size_t>::max();
 
-template <class ElementType, std::ptrdiff_t Extent = dynamic_extent>
+template <class ElementType, std::size_t Extent = dynamic_extent>
 class span;
 
 // implementation details
@@ -83,7 +85,7 @@ namespace details
     {
     };
 
-    template <class ElementType, std::ptrdiff_t Extent>
+    template <class ElementType, std::size_t Extent>
     struct is_span_oracle<gsl::span<ElementType, Extent>> : std::true_type
     {
     };
@@ -108,7 +110,7 @@ namespace details
     {
     };
 
-    template <std::ptrdiff_t From, std::ptrdiff_t To>
+    template <std::size_t From, std::size_t To>
     struct is_allowed_extent_conversion
         : public std::integral_constant<bool, From == To || From == gsl::dynamic_extent ||
                                                   To == gsl::dynamic_extent>
@@ -154,7 +156,7 @@ namespace details
         GSL_SUPPRESS(bounds .1) // NO-FORMAT: attribute
         constexpr reference operator*() const
         {
-            Expects(index_ != span_->size());
+            Expects(static_cast<size_t>(index_) != span_->size());
             return *(span_->data() + index_);
         }
 
@@ -166,7 +168,7 @@ namespace details
 
         constexpr span_iterator& operator++() noexcept
         {
-            Expects(0 <= index_ && index_ != span_->size());
+            Expects(0 <= index_ && static_cast<size_t>(index_) != span_->size());
             ++index_;
             return *this;
         }
@@ -180,7 +182,7 @@ namespace details
 
         constexpr span_iterator& operator--() noexcept
         {
-            Expects(index_ != 0 && index_ <= span_->size());
+            Expects(index_ != 0 && static_cast<size_t>(index_) <= span_->size());
             --index_;
             return *this;
         }
@@ -198,7 +200,8 @@ namespace details
             return ret += n;
         }
 
-        friend constexpr span_iterator operator+(difference_type n, span_iterator const& rhs) noexcept
+        friend constexpr span_iterator operator+(difference_type n,
+                                                 span_iterator const& rhs) noexcept
         {
             return rhs + n;
         }
@@ -300,11 +303,11 @@ namespace details
         std::ptrdiff_t index_ = 0;
     };
 
-    template <std::ptrdiff_t Ext>
+    template <std::size_t Ext>
     class extent_type
     {
     public:
-        using index_type = std::ptrdiff_t;
+        using index_type = std::size_t;
 
         static_assert(Ext >= 0, "A fixed-size span must be >= 0 in size.");
 
@@ -327,13 +330,16 @@ namespace details
     class extent_type<dynamic_extent>
     {
     public:
-        using index_type = std::ptrdiff_t;
+        using index_type = std::size_t;
 
         template <index_type Other>
         explicit constexpr extent_type(extent_type<Other> ext) : size_(ext.size())
         {}
 
-        explicit constexpr extent_type(index_type size) : size_(size) { Expects(size >= 0); }
+        explicit constexpr extent_type(index_type size) : size_(size)
+        {
+            Expects(size != dynamic_extent);
+        }
 
         constexpr index_type size() const noexcept { return size_; }
 
@@ -341,7 +347,7 @@ namespace details
         index_type size_;
     };
 
-    template <class ElementType, std::ptrdiff_t Extent, std::ptrdiff_t Offset, std::ptrdiff_t Count>
+    template <class ElementType, std::size_t Extent, std::size_t Offset, std::size_t Count>
     struct calculate_subspan_type
     {
         using type = span<ElementType, Count != dynamic_extent
@@ -351,16 +357,17 @@ namespace details
 } // namespace details
 
 // [span], class template span
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 class span
 {
 public:
     // constants and types
     using element_type = ElementType;
     using value_type = std::remove_cv_t<ElementType>;
-    using index_type = std::ptrdiff_t;
+    using index_type = std::size_t;
     using pointer = element_type*;
     using reference = element_type&;
+    using difference_type = std::ptrdiff_t;
 
     using iterator = details::span_iterator<span<ElementType, Extent>, false>;
     using const_iterator = details::span_iterator<span<ElementType, Extent>, true>;
@@ -379,7 +386,7 @@ public:
     template <bool Dependent = false,
               // "Dependent" is needed to make "std::enable_if_t<Dependent || Extent <= 0>" SFINAE,
               // since "std::enable_if_t<Extent <= 0>" is ill-formed when Extent is greater than 0.
-              class = std::enable_if_t<(Dependent || Extent <= 0)>>
+              class = std::enable_if_t<(Dependent || Extent == 0 || Extent == dynamic_extent)>>
     constexpr span() noexcept : storage_(nullptr, details::extent_type<0>())
     {}
 
@@ -397,24 +404,20 @@ public:
     template <std::size_t N, class = std::enable_if_t<(N > 0)>>
     constexpr span(std::array<std::remove_const_t<element_type>, N>& arr) noexcept
         : storage_(KnownNotNull{arr.data()}, details::extent_type<N>())
-    {
+    {}
-    }
 
     constexpr span(std::array<std::remove_const_t<element_type>, 0>&) noexcept
         : storage_(static_cast<pointer>(nullptr), details::extent_type<0>())
-    {
+    {}
-    }
 
     template <std::size_t N, class = std::enable_if_t<(N > 0)>>
     constexpr span(const std::array<std::remove_const_t<element_type>, N>& arr) noexcept
         : storage_(KnownNotNull{arr.data()}, details::extent_type<N>())
-    {
+    {}
-    }
 
     constexpr span(const std::array<std::remove_const_t<element_type>, 0>&) noexcept
         : storage_(static_cast<pointer>(nullptr), details::extent_type<0>())
-    {
+    {}
-    }
 
     // NB: the SFINAE here uses .data() as a incomplete/imperfect proxy for the requirement
     // on Container to be a contiguous sequence container.
@@ -433,13 +436,14 @@ public:
                   std::is_convertible<typename Container::pointer, pointer>::value &&
                   std::is_convertible<typename Container::pointer,
                                       decltype(std::declval<Container>().data())>::value>>
-    constexpr span(const Container& cont) noexcept : span(cont.data(), narrow<index_type>(cont.size()))
+    constexpr span(const Container& cont) noexcept
+        : span(cont.data(), narrow<index_type>(cont.size()))
     {}
 
     constexpr span(const span& other) noexcept = default;
 
     template <
-        class OtherElementType, std::ptrdiff_t OtherExtent,
+        class OtherElementType, std::size_t OtherExtent,
         class = std::enable_if_t<
             details::is_allowed_extent_conversion<OtherExtent, Extent>::value &&
             details::is_allowed_element_type_conversion<OtherElementType, element_type>::value>>
@@ -451,27 +455,27 @@ public:
     constexpr span& operator=(const span& other) noexcept = default;
 
     // [span.sub], span subviews
-    template <std::ptrdiff_t Count>
+    template <std::size_t Count>
     constexpr span<element_type, Count> first() const noexcept
     {
-        Expects(Count >= 0 && Count <= size());
+        Expects(Count <= size());
         return {data(), Count};
     }
 
-    template <std::ptrdiff_t Count>
+    template <std::size_t Count>
     GSL_SUPPRESS(bounds .1) // NO-FORMAT: attribute
     constexpr span<element_type, Count> last() const noexcept
     {
-        Expects(Count >= 0 && size() - Count >= 0);
+        Expects(size() >= Count);
         return {data() + (size() - Count), Count};
     }
 
-    template <std::ptrdiff_t Offset, std::ptrdiff_t Count = dynamic_extent>
+    template <std::size_t Offset, std::size_t Count = dynamic_extent>
     GSL_SUPPRESS(bounds .1) // NO-FORMAT: attribute
     constexpr auto subspan() const noexcept ->
         typename details::calculate_subspan_type<ElementType, Extent, Offset, Count>::type
     {
-        Expects((Offset >= 0 && size() - Offset >= 0) &&
+        Expects((size() >= Offset) &&
                 (Count == dynamic_extent || (Count >= 0 && Offset + Count <= size())));
 
         return {data() + Offset, Count == dynamic_extent ? size() - Offset : Count};
@@ -479,17 +483,19 @@ public:
 
     constexpr span<element_type, dynamic_extent> first(index_type count) const noexcept
     {
-        Expects(count >= 0 && count <= size());
+        Expects(count <= size());
         return {data(), count};
     }
 
     constexpr span<element_type, dynamic_extent> last(index_type count) const noexcept
     {
+        Expects(count <= size());
         return make_subspan(size() - count, dynamic_extent, subspan_selector<Extent>{});
     }
 
     constexpr span<element_type, dynamic_extent> subspan(index_type offset,
-                                                         index_type count = dynamic_extent) const noexcept
+                                                         index_type count = dynamic_extent) const
+        noexcept
     {
         return make_subspan(offset, count, subspan_selector<Extent>{});
     }
@@ -512,23 +518,25 @@ public:
 
     constexpr reference front() const noexcept
     {
-        Expects(size() > 0);
+        Expects(size() != dynamic_extent && size() > 0);
         return data()[0];
     }
 
     constexpr reference back() const noexcept
     {
-        Expects(size() > 0);
+        Expects(size() != dynamic_extent && size() > 0);
         return data()[size() - 1];
     }
 
     // at and operator() are deprecated to align to the public member functions of std::span
-    [[deprecated("Use operator[]")]]
+    [[deprecated("Use operator[]")]] constexpr reference at(index_type idx) const noexcept
-    constexpr reference at(index_type idx) const noexcept{ return this->operator[](idx); }
+    {
-    [[deprecated("Use operator[]")]]
+        return this->operator[](idx);
-    constexpr reference operator()(index_type idx) const noexcept{ return this->operator[](idx); }
+    }
-
+    [[deprecated("Use operator[]")]] constexpr reference operator()(index_type idx) const noexcept
-
+    {
+        return this->operator[](idx);
+    }
 
     constexpr pointer data() const noexcept { return storage_.data(); }
 
@@ -607,13 +615,13 @@ private:
         constexpr storage_type(KnownNotNull data, OtherExtentType ext)
             : ExtentType(ext), data_(data.p)
         {
-            Expects(ExtentType::size() >= 0);
+            Expects(ExtentType::size() != dynamic_extent);
         }
 
         template <class OtherExtentType>
         constexpr storage_type(pointer data, OtherExtentType ext) : ExtentType(ext), data_(data)
         {
-            Expects(ExtentType::size() >= 0);
+            Expects(ExtentType::size() != dynamic_extent);
             Expects(data || ExtentType::size() == 0);
         }
 
@@ -629,12 +637,12 @@ private:
     // in subspans and constructors from arrays
     constexpr span(KnownNotNull ptr, index_type count) : storage_(ptr, count) {}
 
-    template <std::ptrdiff_t CallerExtent>
+    template <std::size_t CallerExtent>
     class subspan_selector
     {
     };
 
-    template <std::ptrdiff_t CallerExtent>
+    template <std::size_t CallerExtent>
     span<element_type, dynamic_extent> make_subspan(index_type offset, index_type count,
                                                     subspan_selector<CallerExtent>) const
     {
@@ -646,52 +654,52 @@ private:
     span<element_type, dynamic_extent> make_subspan(index_type offset, index_type count,
                                                     subspan_selector<dynamic_extent>) const
     {
-        Expects(offset >= 0 && size() - offset >= 0);
+        Expects(offset >= 0 && size() >= offset && size() != dynamic_extent);
 
         if (count == dynamic_extent) { return {KnownNotNull{data() + offset}, size() - offset}; }
 
-        Expects(count >= 0 && size() - offset >= count);
+        Expects(size() - offset >= count);
         return {KnownNotNull{data() + offset}, count};
     }
 };
 
 #if defined(GSL_USE_STATIC_CONSTEXPR_WORKAROUND)
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 constexpr const typename span<ElementType, Extent>::index_type span<ElementType, Extent>::extent;
 #endif
 
 // [span.comparison], span comparison operators
-template <class ElementType, std::ptrdiff_t FirstExtent, std::ptrdiff_t SecondExtent>
+template <class ElementType, std::size_t FirstExtent, std::size_t SecondExtent>
 constexpr bool operator==(span<ElementType, FirstExtent> l, span<ElementType, SecondExtent> r)
 {
     return std::equal(l.begin(), l.end(), r.begin(), r.end());
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 constexpr bool operator!=(span<ElementType, Extent> l, span<ElementType, Extent> r)
 {
     return !(l == r);
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 constexpr bool operator<(span<ElementType, Extent> l, span<ElementType, Extent> r)
 {
     return std::lexicographical_compare(l.begin(), l.end(), r.begin(), r.end());
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 constexpr bool operator<=(span<ElementType, Extent> l, span<ElementType, Extent> r)
 {
     return !(l > r);
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 constexpr bool operator>(span<ElementType, Extent> l, span<ElementType, Extent> r)
 {
     return r < l;
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 constexpr bool operator>=(span<ElementType, Extent> l, span<ElementType, Extent> r)
 {
     return !(l < r);
@@ -705,23 +713,20 @@ namespace details
     // we should use a narrow_cast<> to go to std::size_t, but older compilers may not see it as
     // constexpr
     // and so will fail compilation of the template
-    template <class ElementType, std::ptrdiff_t Extent>
+    template <class ElementType, std::size_t Extent>
-    struct calculate_byte_size
+    struct calculate_byte_size : std::integral_constant<std::size_t, sizeof(ElementType) * Extent>
-        : std::integral_constant<std::ptrdiff_t,
-                                 static_cast<std::ptrdiff_t>(sizeof(ElementType) *
-                                                             static_cast<std::size_t>(Extent))>
     {
     };
 
     template <class ElementType>
     struct calculate_byte_size<ElementType, dynamic_extent>
-        : std::integral_constant<std::ptrdiff_t, dynamic_extent>
+        : std::integral_constant<std::size_t, dynamic_extent>
     {
     };
 } // namespace details
 
 // [span.objectrep], views of object representation
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 span<const byte, details::calculate_byte_size<ElementType, Extent>::value>
 as_bytes(span<ElementType, Extent> s) noexcept
 {
@@ -729,7 +734,7 @@ as_bytes(span<ElementType, Extent> s) noexcept
     return {reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
 }
 
-template <class ElementType, std::ptrdiff_t Extent,
+template <class ElementType, std::size_t Extent,
           class = std::enable_if_t<!std::is_const<ElementType>::value>>
 span<byte, details::calculate_byte_size<ElementType, Extent>::value>
 as_writeable_bytes(span<ElementType, Extent> s) noexcept
@@ -773,7 +778,7 @@ constexpr span<const typename Container::value_type> make_span(const Container&
 }
 
 template <class Ptr>
-constexpr span<typename Ptr::element_type> make_span(Ptr& cont, std::ptrdiff_t count)
+constexpr span<typename Ptr::element_type> make_span(Ptr& cont, std::size_t count)
 {
     return span<typename Ptr::element_type>(cont, count);
 }
@@ -785,7 +790,7 @@ constexpr span<typename Ptr::element_type> make_span(Ptr& cont)
 }
 
 // Specialization of gsl::at for span
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 constexpr ElementType& at(span<ElementType, Extent> s, index i)
 {
     // No bounds checking here because it is done in span::operator[] called below
@@ -793,57 +798,66 @@ constexpr ElementType& at(span<ElementType, Extent> s, index i)
 }
 
 // [span.obs] Free observer functions
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
-constexpr typename span<ElementType, Extent>::index_type ssize(const span<ElementType, Extent> &span) noexcept
+constexpr typename span<ElementType, Extent>::index_type
+ssize(const span<ElementType, Extent>& span) noexcept
 {
     return span.size();
 }
 
 // [span.iter] Free functions for begin/end functions
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
-constexpr typename span<ElementType, Extent>::iterator begin(const span<ElementType, Extent> &span) noexcept
+constexpr typename span<ElementType, Extent>::iterator
+begin(const span<ElementType, Extent>& span) noexcept
 {
     return span.begin();
 }
 
-template <class ElementType, std::ptrdiff_t Extent = dynamic_extent>
+template <class ElementType, std::size_t Extent = dynamic_extent>
-constexpr typename span<ElementType, Extent>::iterator end(const span<ElementType, Extent> &span) noexcept
+constexpr typename span<ElementType, Extent>::iterator
+end(const span<ElementType, Extent>& span) noexcept
 {
     return span.end();
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
-constexpr typename span<ElementType, Extent>::const_iterator cbegin(const span<ElementType, Extent> &span) noexcept
+constexpr typename span<ElementType, Extent>::const_iterator
+cbegin(const span<ElementType, Extent>& span) noexcept
 {
     return span.cbegin();
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
-constexpr typename span<ElementType, Extent>::const_iterator cend(const span<ElementType, Extent> &span) noexcept
+constexpr typename span<ElementType, Extent>::const_iterator
+cend(const span<ElementType, Extent>& span) noexcept
 {
     return span.cend();
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
-constexpr typename span<ElementType, Extent>::reverse_iterator rbegin(const span<ElementType, Extent> &span) noexcept
+constexpr typename span<ElementType, Extent>::reverse_iterator
+rbegin(const span<ElementType, Extent>& span) noexcept
 {
     return span.rbegin();
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
-constexpr typename span<ElementType, Extent>::reverse_iterator rend(const span<ElementType, Extent> &span) noexcept
+constexpr typename span<ElementType, Extent>::reverse_iterator
+rend(const span<ElementType, Extent>& span) noexcept
 {
     return span.rend();
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
-constexpr typename span<ElementType, Extent>::const_reverse_iterator crbegin(const span<ElementType, Extent> &span) noexcept
+constexpr typename span<ElementType, Extent>::const_reverse_iterator
+crbegin(const span<ElementType, Extent>& span) noexcept
 {
     return span.crbegin();
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
-constexpr typename span<ElementType, Extent>::const_reverse_iterator crend(const span<ElementType, Extent> &span) noexcept
+constexpr typename span<ElementType, Extent>::const_reverse_iterator
+crend(const span<ElementType, Extent>& span) noexcept
 {
     return span.crend();
 }

include/gsl/string_span

@@ -23,7 +23,7 @@
 
 #include <algorithm> // for equal, lexicographical_compare
 #include <array>     // for array
-#include <cstddef>   // for ptrdiff_t, size_t, nullptr_t
+#include <cstddef>   // for size_t, nullptr_t
 #include <cstdint>   // for PTRDIFF_MAX
 #include <cstring>
 #include <string>      // for basic_string, allocator, char_traits
@@ -56,43 +56,43 @@ namespace gsl
 // (sometimes needlessly) break existing programs when introduced.
 //
 
-template <typename CharT, std::ptrdiff_t Extent = dynamic_extent>
+template <typename CharT, std::size_t Extent = dynamic_extent>
 using basic_zstring = CharT*;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using czstring = basic_zstring<const char, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using cwzstring = basic_zstring<const wchar_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using cu16zstring = basic_zstring<const char16_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using cu32zstring = basic_zstring<const char32_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using zstring = basic_zstring<char, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using wzstring = basic_zstring<wchar_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using u16zstring = basic_zstring<char16_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using u32zstring = basic_zstring<char32_t, Extent>;
 
 namespace details
 {
     template <class CharT>
-    std::ptrdiff_t string_length(const CharT* str, std::ptrdiff_t n)
+    std::size_t string_length(const CharT* str, std::size_t n)
     {
-        if (str == nullptr || n <= 0) return 0;
+        if (str == nullptr || n == dynamic_extent) return 0;
 
         const span<const CharT> str_span{str, n};
 
-        std::ptrdiff_t len = 0;
+        std::size_t len = 0;
         while (len < n && str_span[len]) len++;
 
         return len;
@@ -108,18 +108,20 @@ namespace details
 // Will fail-fast if sentinel cannot be found before max elements are examined.
 //
 template <typename T, const T Sentinel>
-span<T, dynamic_extent> ensure_sentinel(T* seq, std::ptrdiff_t max = PTRDIFF_MAX)
+span<T, dynamic_extent> ensure_sentinel(T* seq,
+                                        std::size_t max = std::numeric_limits<std::size_t>::max())
 {
     Ensures(seq != nullptr);
 
-    GSL_SUPPRESS(f.23) // NO-FORMAT: attribute // TODO: false positive // TODO: suppress does not work
+    GSL_SUPPRESS(
+        f .23) // NO-FORMAT: attribute // TODO: false positive // TODO: suppress does not work
     auto cur = seq;
     Ensures(cur != nullptr); // workaround for removing the warning
 
     GSL_SUPPRESS(bounds .1) // NO-FORMAT: attribute // TODO: suppress does not work
-    while ((cur - seq) < max && *cur != Sentinel) ++cur;
+    while (static_cast<std::size_t>(cur - seq) < max && *cur != Sentinel) ++cur;
     Ensures(*cur == Sentinel);
-    return {seq, cur - seq};
+    return {seq, static_cast<std::size_t>(cur - seq)};
 }
 
 //
@@ -128,7 +130,8 @@ span<T, dynamic_extent> ensure_sentinel(T* seq, std::ptrdiff_t max = PTRDIFF_MAX
 // the limit of size_type.
 //
 template <typename CharT>
-span<CharT, dynamic_extent> ensure_z(CharT* const& sz, std::ptrdiff_t max = PTRDIFF_MAX)
+span<CharT, dynamic_extent> ensure_z(CharT* const& sz,
+                                     std::size_t max = std::numeric_limits<std::size_t>::max())
 {
     return ensure_sentinel<CharT, CharT(0)>(sz, max);
 }
@@ -136,26 +139,27 @@ span<CharT, dynamic_extent> ensure_z(CharT* const& sz, std::ptrdiff_t max = PTRD
 template <typename CharT, std::size_t N>
 span<CharT, dynamic_extent> ensure_z(CharT (&sz)[N])
 {
-    return ensure_z(&sz[0], narrow_cast<std::ptrdiff_t>(N));
+    return ensure_z(&sz[0], N);
 }
 
 template <class Cont>
 span<typename std::remove_pointer<typename Cont::pointer>::type, dynamic_extent>
 ensure_z(Cont& cont)
 {
-    return ensure_z(cont.data(), narrow_cast<std::ptrdiff_t>(cont.size()));
+    return ensure_z(cont.data(), cont.size());
 }
 
-template <typename CharT, std::ptrdiff_t>
+template <typename CharT, std::size_t>
 class basic_string_span;
 
-namespace details {
+namespace details
+{
     template <typename T>
     struct is_basic_string_span_oracle : std::false_type
     {
     };
 
-    template <typename CharT, std::ptrdiff_t Extent>
+    template <typename CharT, std::size_t Extent>
     struct is_basic_string_span_oracle<basic_string_span<CharT, Extent>> : std::true_type
     {
     };
@@ -169,7 +173,7 @@ namespace details {
 //
 // string_span and relatives
 //
-template <typename CharT, std::ptrdiff_t Extent = dynamic_extent>
+template <typename CharT, std::size_t Extent = dynamic_extent>
 class basic_string_span
 {
 public:
@@ -218,7 +222,7 @@ public:
     template <class Traits, class Allocator>
     // GSL_SUPPRESS(bounds.4) // NO-FORMAT: attribute // TODO: parser bug
     constexpr basic_string_span(std::basic_string<element_type, Traits, Allocator>& str)
-        : span_(&str[0], narrow_cast<std::ptrdiff_t>(str.length()))
+        : span_(&str[0], str.length())
     {}
 
     template <class Traits, class Allocator>
@@ -247,7 +251,7 @@ public:
 
     // from string_span
     template <
-        class OtherValueType, std::ptrdiff_t OtherExtent,
+        class OtherValueType, std::size_t OtherExtent,
         class = std::enable_if_t<std::is_convertible<
             typename basic_string_span<OtherValueType, OtherExtent>::impl_type, impl_type>::value>>
     constexpr basic_string_span(basic_string_span<OtherValueType, OtherExtent> other)
@@ -312,7 +316,7 @@ public:
     constexpr const_reverse_iterator crend() const noexcept { return span_.crend(); }
 
 private:
-    static impl_type remove_z(pointer const& sz, std::ptrdiff_t max)
+    static impl_type remove_z(pointer const& sz, std::size_t max)
     {
         return {sz, details::string_length(sz, max)};
     }
@@ -320,41 +324,41 @@ private:
     template <std::size_t N>
     static impl_type remove_z(element_type (&sz)[N])
     {
-        return remove_z(&sz[0], narrow_cast<std::ptrdiff_t>(N));
+        return remove_z(&sz[0], N);
     }
 
     impl_type span_;
 };
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using string_span = basic_string_span<char, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using cstring_span = basic_string_span<const char, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using wstring_span = basic_string_span<wchar_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using cwstring_span = basic_string_span<const wchar_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using u16string_span = basic_string_span<char16_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using cu16string_span = basic_string_span<const char16_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using u32string_span = basic_string_span<char32_t, Extent>;
 
-template <std::ptrdiff_t Extent = dynamic_extent>
+template <std::size_t Extent = dynamic_extent>
 using cu32string_span = basic_string_span<const char32_t, Extent>;
 
 //
 // to_string() allow (explicit) conversions from string_span to string
 //
 
-template <typename CharT, std::ptrdiff_t Extent>
+template <typename CharT, std::size_t Extent>
 std::basic_string<typename std::remove_const<CharT>::type>
 to_string(basic_string_span<CharT, Extent> view)
 {
@@ -362,13 +366,13 @@ to_string(basic_string_span<CharT, Extent> view)
 }
 
 template <typename CharT, typename Traits = typename std::char_traits<CharT>,
-          typename Allocator = std::allocator<CharT>, typename gCharT, std::ptrdiff_t Extent>
+          typename Allocator = std::allocator<CharT>, typename gCharT, std::size_t Extent>
 std::basic_string<CharT, Traits, Allocator> to_basic_string(basic_string_span<gCharT, Extent> view)
 {
     return {view.data(), narrow_cast<std::size_t>(view.length())};
 }
 
-template <class ElementType, std::ptrdiff_t Extent>
+template <class ElementType, std::size_t Extent>
 basic_string_span<const byte, details::calculate_byte_size<ElementType, Extent>::value>
 as_bytes(basic_string_span<ElementType, Extent> s) noexcept
 {
@@ -376,7 +380,7 @@ as_bytes(basic_string_span<ElementType, Extent> s) noexcept
     return {reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
 }
 
-template <class ElementType, std::ptrdiff_t Extent,
+template <class ElementType, std::size_t Extent,
           class = std::enable_if_t<!std::is_const<ElementType>::value>>
 basic_string_span<byte, details::calculate_byte_size<ElementType, Extent>::value>
 as_writeable_bytes(basic_string_span<ElementType, Extent> s) noexcept
@@ -387,8 +391,9 @@ as_writeable_bytes(basic_string_span<ElementType, Extent> s) noexcept
 
 // zero-terminated string span, used to convert
 // zero-terminated spans to legacy strings
-template <typename CharT, std::ptrdiff_t Extent = dynamic_extent>
+template <typename CharT, std::size_t Extent = dynamic_extent>
-class basic_zstring_span {
+class basic_zstring_span
+{
 public:
     using value_type = CharT;
     using const_value_type = std::add_const_t<CharT>;
@@ -435,32 +440,32 @@ private:
     impl_type span_;
 };
 
-template <std::ptrdiff_t Max = dynamic_extent>
+template <std::size_t Max = dynamic_extent>
 using zstring_span = basic_zstring_span<char, Max>;
 
-template <std::ptrdiff_t Max = dynamic_extent>
+template <std::size_t Max = dynamic_extent>
 using wzstring_span = basic_zstring_span<wchar_t, Max>;
 
-template <std::ptrdiff_t Max = dynamic_extent>
+template <std::size_t Max = dynamic_extent>
 using u16zstring_span = basic_zstring_span<char16_t, Max>;
 
-template <std::ptrdiff_t Max = dynamic_extent>
+template <std::size_t Max = dynamic_extent>
 using u32zstring_span = basic_zstring_span<char32_t, Max>;
 
-template <std::ptrdiff_t Max = dynamic_extent>
+template <std::size_t Max = dynamic_extent>
 using czstring_span = basic_zstring_span<const char, Max>;
 
-template <std::ptrdiff_t Max = dynamic_extent>
+template <std::size_t Max = dynamic_extent>
 using cwzstring_span = basic_zstring_span<const wchar_t, Max>;
 
-template <std::ptrdiff_t Max = dynamic_extent>
+template <std::size_t Max = dynamic_extent>
 using cu16zstring_span = basic_zstring_span<const char16_t, Max>;
 
-template <std::ptrdiff_t Max = dynamic_extent>
+template <std::size_t Max = dynamic_extent>
 using cu32zstring_span = basic_zstring_span<const char32_t, Max>;
 
 // operator ==
-template <class CharT, std::ptrdiff_t Extent, class T,
+template <class CharT, std::size_t Extent, class T,
           class = std::enable_if_t<
               details::is_basic_string_span<T>::value ||
               std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>>>::value>>
@@ -470,7 +475,7 @@ bool operator==(const gsl::basic_string_span<CharT, Extent>& one, const T& other
     return std::equal(one.begin(), one.end(), tmp.begin(), tmp.end());
 }
 
-template <class CharT, std::ptrdiff_t Extent, class T,
+template <class CharT, std::size_t Extent, class T,
           class = std::enable_if_t<
               !details::is_basic_string_span<T>::value &&
               std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>>>::value>>
@@ -481,7 +486,7 @@ bool operator==(const T& one, const gsl::basic_string_span<CharT, Extent>& other
 }
 
 // operator !=
-template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator!=(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -490,7 +495,7 @@ bool operator!=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -500,7 +505,7 @@ bool operator!=(const T& one, gsl::basic_string_span<CharT, Extent> other)
 }
 
 // operator<
-template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator<(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -510,7 +515,7 @@ bool operator<(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -526,7 +531,7 @@ bool operator<(const T& one, gsl::basic_string_span<CharT, Extent> other)
 // so the cases below are already covered by the previous operators
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -540,7 +545,7 @@ bool operator<(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -555,7 +560,7 @@ bool operator<(const T& one, gsl::basic_string_span<CharT, Extent> other)
 #endif
 
 // operator <=
-template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator<=(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -564,7 +569,7 @@ bool operator<=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -579,7 +584,7 @@ bool operator<=(const T& one, gsl::basic_string_span<CharT, Extent> other)
 // so the cases below are already covered by the previous operators
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -592,7 +597,7 @@ bool operator<=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -606,7 +611,7 @@ bool operator<=(const T& one, gsl::basic_string_span<CharT, Extent> other)
 #endif
 
 // operator>
-template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator>(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -615,7 +620,7 @@ bool operator>(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -630,7 +635,7 @@ bool operator>(const T& one, gsl::basic_string_span<CharT, Extent> other)
 // so the cases below are already covered by the previous operators
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -643,7 +648,7 @@ bool operator>(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -657,7 +662,7 @@ bool operator>(const T& one, gsl::basic_string_span<CharT, Extent> other)
 #endif
 
 // operator >=
-template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator>=(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -666,7 +671,7 @@ bool operator>=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -681,7 +686,7 @@ bool operator>=(const T& one, gsl::basic_string_span<CharT, Extent> other)
 // so the cases below are already covered by the previous operators
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -694,7 +699,7 @@ bool operator>=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::ptrdiff_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&

tests/span_tests.cpp

@@ -158,14 +158,14 @@ TEST(span_test, from_pointer_length_constructor)
     int arr[4] = {1, 2, 3, 4};
 
     {
-        for (int i = 0; i < 4; ++i)
+        for (std::size_t i = 0; i < 4; ++i)
         {
             {
                 span<int> s = {&arr[0], i};
                 EXPECT_TRUE(s.size() == i);
                 EXPECT_TRUE(s.data() == &arr[0]);
                 EXPECT_TRUE(s.empty() == (i == 0));
-                for (int j = 0; j < i; ++j)
+                for (std::size_t j = 0; j < i; ++j)
                 {
                     EXPECT_TRUE(arr[j] == s[j]);
                     EXPECT_TRUE(arr[j] == s.at(j));
@@ -173,12 +173,12 @@ TEST(span_test, from_pointer_length_constructor)
                 }
             }
             {
-                span<int> s = {&arr[i], 4 - narrow_cast<ptrdiff_t>(i)};
+                span<int> s = {&arr[i], 4 - i};
                 EXPECT_TRUE(s.size() == 4 - i);
                 EXPECT_TRUE(s.data() == &arr[i]);
                 EXPECT_TRUE(s.empty() == ((4 - i) == 0));
 
-                for (int j = 0; j < 4 - i; ++j)
+                for (std::size_t j = 0; j < 4 - i; ++j)
                 {
                     EXPECT_TRUE(arr[j + i] == s[j]);
                     EXPECT_TRUE(arr[j + i] == s.at(j));
@@ -457,21 +457,21 @@ TEST(span_test, from_array_constructor)
 
      {
          span<int> s{arr};
-         EXPECT_TRUE(s.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(s.size() == arr.size());
          EXPECT_TRUE(s.data() == arr.data());
 
          span<const int> cs{arr};
-         EXPECT_TRUE(cs.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(cs.size() == arr.size());
          EXPECT_TRUE(cs.data() == arr.data());
      }
 
      {
          span<int, 4> s{arr};
-         EXPECT_TRUE(s.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(s.size() == arr.size());
          EXPECT_TRUE(s.data() == arr.data());
 
          span<const int, 4> cs{arr};
-         EXPECT_TRUE(cs.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(cs.size() == arr.size());
          EXPECT_TRUE(cs.data() == arr.data());
      }
 
@@ -486,7 +486,7 @@ TEST(span_test, from_array_constructor)
 
      {
          span<AddressOverloaded, 4> fs{ao_arr};
-         EXPECT_TRUE(fs.size() == narrow_cast<ptrdiff_t>(ao_arr.size()));
+         EXPECT_TRUE(fs.size() == ao_arr.size());
          EXPECT_TRUE(ao_arr.data() == fs.data());
      }
 
@@ -532,7 +532,7 @@ TEST(span_test, from_array_constructor)
 
      {
          auto s = make_span(arr);
-         EXPECT_TRUE(s.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(s.size() == arr.size());
          EXPECT_TRUE(s.data() == arr.data());
      }
 
@@ -561,13 +561,13 @@ TEST(span_test, from_array_constructor)
 
      {
          span<const int> s{arr};
-         EXPECT_TRUE(s.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(s.size() == arr.size());
          EXPECT_TRUE(s.data() == arr.data());
      }
 
      {
          span<const int, 4> s{arr};
-         EXPECT_TRUE(s.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(s.size() == arr.size());
          EXPECT_TRUE(s.data() == arr.data());
      }
 
@@ -575,7 +575,7 @@ TEST(span_test, from_array_constructor)
 
      {
          span<const AddressOverloaded, 4> s{ao_arr};
-         EXPECT_TRUE(s.size() == narrow_cast<ptrdiff_t>(ao_arr.size()));
+         EXPECT_TRUE(s.size() == ao_arr.size());
          EXPECT_TRUE(s.data() == ao_arr.data());
      }
 
@@ -606,7 +606,7 @@ TEST(span_test, from_array_constructor)
 
      {
          auto s = make_span(arr);
-         EXPECT_TRUE(s.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(s.size() == arr.size());
          EXPECT_TRUE(s.data() == arr.data());
      }
  }
@@ -617,13 +617,13 @@ TEST(span_test, from_array_constructor)
 
      {
          span<const int> s{arr};
-         EXPECT_TRUE(s.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(s.size() == arr.size());
          EXPECT_TRUE(s.data() == arr.data());
      }
 
      {
          span<const int, 4> s{arr};
-         EXPECT_TRUE(s.size() ==  narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(s.size() ==  arr.size());
          EXPECT_TRUE(s.data() == arr.data());
      }
 
@@ -651,7 +651,7 @@ TEST(span_test, from_array_constructor)
 
      {
          auto s = make_span(arr);
-         EXPECT_TRUE(s.size() == narrow_cast<ptrdiff_t>(arr.size()));
+         EXPECT_TRUE(s.size() == arr.size());
          EXPECT_TRUE(s.data() == arr.data());
      }
  }
@@ -663,11 +663,11 @@ TEST(span_test, from_array_constructor)
 
      {
          span<int> s{v};
-         EXPECT_TRUE(s.size() == narrow_cast<std::ptrdiff_t>(v.size()));
+         EXPECT_TRUE(s.size() == v.size());
          EXPECT_TRUE(s.data() == v.data());
 
          span<const int> cs{v};
-         EXPECT_TRUE(cs.size() == narrow_cast<std::ptrdiff_t>(v.size()));
+         EXPECT_TRUE(cs.size() == v.size());
          EXPECT_TRUE(cs.data() == v.data());
      }
 
@@ -677,11 +677,11 @@ TEST(span_test, from_array_constructor)
      {
  #ifdef CONFIRM_COMPILATION_ERRORS
          span<char> s{str};
-         EXPECT_TRUE(s.size() == narrow_cast<std::ptrdiff_t>(str.size()));
+         EXPECT_TRUE(s.size() == str.size());
          EXPECT_TRUE(s.data() == str.data()));
  #endif
          span<const char> cs{str};
-         EXPECT_TRUE(cs.size() == narrow_cast<std::ptrdiff_t>(str.size()));
+         EXPECT_TRUE(cs.size() == str.size());
          EXPECT_TRUE(cs.data() == str.data());
      }
 
@@ -690,7 +690,7 @@ TEST(span_test, from_array_constructor)
          span<char> s{cstr};
  #endif
          span<const char> cs{cstr};
-         EXPECT_TRUE(cs.size() == narrow_cast<std::ptrdiff_t>(cstr.size()));
+         EXPECT_TRUE(cs.size() == cstr.size());
          EXPECT_TRUE(cs.data() == cstr.data());
      }
 
@@ -745,11 +745,11 @@ TEST(span_test, from_array_constructor)
 
      {
          auto s = make_span(v);
-         EXPECT_TRUE(s.size() == narrow_cast<std::ptrdiff_t>(v.size()));
+         EXPECT_TRUE(s.size() == v.size());
          EXPECT_TRUE(s.data() == v.data());
 
          auto cs = make_span(cv);
-         EXPECT_TRUE(cs.size() == narrow_cast<std::ptrdiff_t>(cv.size()));
+         EXPECT_TRUE(cs.size() == cv.size());
          EXPECT_TRUE(cs.data() == cv.data());
      }
  }