cmstd: Modernize CMake system headers

Provide a standardized way to handle the C++ "standard" headers
customized to be used with current CMake C++ standard constraints.
Offer under directory `cm` headers which can be used as direct
replacements of the standard ones.  For example:

    #include <cm/string_view>

can be used safely for CMake development in place of the `<string_view>`
standard header.

Fixes: #19491

1 files changed, 0 insertions, 77 deletions

diff --git a/Source/cmAlgorithms.h b/Source/cmAlgorithms.h
index 60b746c..06ea9f6 100644
--- a/Source/cmAlgorithms.h
+++ b/Source/cmAlgorithms.h
@@ -238,81 +238,4 @@ typename Range::const_iterator cmFindNot(Range const& r, T const& t)
   return std::find_if(r.begin(), r.end(), [&t](T const& i) { return i != t; });
 }
 
-template <class Iter>
-std::reverse_iterator<Iter> cmMakeReverseIterator(Iter it)
-{
-  return std::reverse_iterator<Iter>(it);
-}
-
-namespace cm {
-
-#if __cplusplus >= 201703L || defined(_MSVC_LANG) && _MSVC_LANG >= 201703L
-
-using std::size;
-
-#else
-
-// std::size backport from C++17.
-template <class C>
-#  if !defined(_MSC_VER) || _MSC_VER >= 1900
-constexpr
-#  endif
-  auto
-  size(C const& c) -> decltype(c.size())
-{
-  return c.size();
-}
-
-template <typename T, size_t N>
-#  if !defined(_MSC_VER) || _MSC_VER >= 1900
-constexpr
-#  endif
-  std::size_t
-  size(const T (&)[N]) throw()
-{
-  return N;
-}
-
-#endif
-
-template <typename T>
-int isize(const T& t)
-{
-  return static_cast<int>(cm::size(t));
-}
-
-#if __cplusplus >= 201402L || defined(_MSVC_LANG) && _MSVC_LANG >= 201402L
-
-using std::cbegin;
-using std::cend;
-
-#else
-
-// std::c{begin,end} backport from C++14
-template <class C>
-#  if defined(_MSC_VER) && _MSC_VER < 1900
-auto cbegin(C const& c)
-#  else
-constexpr auto cbegin(C const& c) noexcept(noexcept(std::begin(c)))
-#  endif
-  -> decltype(std::begin(c))
-{
-  return std::begin(c);
-}
-
-template <class C>
-#  if defined(_MSC_VER) && _MSC_VER < 1900
-auto cend(C const& c)
-#  else
-constexpr auto cend(C const& c) noexcept(noexcept(std::end(c)))
-#  endif
-  -> decltype(std::end(c))
-{
-  return std::end(c);
-}
-
-#endif
-
-} // namespace cm
-
 #endif