From 9cb376c0508475c8aa8be015ef266558232f9583 Mon Sep 17 00:00:00 2001
From: Jordan Maples <jomaples@microsoft.com>
Date: Tue, 14 Apr 2020 16:57:12 -0700
Subject: [PATCH] adding back free functions for [c|cr][begin|end]

---
 include/gsl/span_ext     | 28 ++++++++++++++++++++++++++++
 tests/span_ext_tests.cpp | 12 ++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/gsl/span_ext b/include/gsl/span_ext
index 0f8c4c9..1d375fd 100644
--- a/include/gsl/span_ext
+++ b/include/gsl/span_ext
@@ -165,6 +165,34 @@ rend(const span<ElementType, Extent>& s) noexcept
     return s.rend();
 }
 
+template <class ElementType, std::size_t Extent>
+constexpr typename span<ElementType, Extent>::iterator
+cbegin(const span<ElementType, Extent>& s) noexcept
+{
+    return s.begin();
+}
+
+template <class ElementType, std::size_t Extent = dynamic_extent>
+constexpr typename span<ElementType, Extent>::iterator
+cend(const span<ElementType, Extent>& s) noexcept
+{
+    return s.end();
+}
+
+template <class ElementType, std::size_t Extent>
+constexpr typename span<ElementType, Extent>::reverse_iterator
+crbegin(const span<ElementType, Extent>& s) noexcept
+{
+    return s.rbegin();
+}
+
+template <class ElementType, std::size_t Extent>
+constexpr typename span<ElementType, Extent>::reverse_iterator
+crend(const span<ElementType, Extent>& s) noexcept
+{
+    return s.rend();
+}
+
 } // namespace gsl
 
 #endif // GSL_SPAN_EXT_H
diff --git a/tests/span_ext_tests.cpp b/tests/span_ext_tests.cpp
index 74aba3e..d413e03 100644
--- a/tests/span_ext_tests.cpp
+++ b/tests/span_ext_tests.cpp
@@ -208,14 +208,26 @@ TEST(span_ext_test, make_span_from_array_constructor)
      EXPECT_TRUE((std::is_same<decltype(s.begin()), decltype(begin(s))>::value));
      EXPECT_TRUE((std::is_same<decltype(s.end()), decltype(end(s))>::value));
 
+     EXPECT_TRUE((std::is_same<decltype(std::cbegin(s)), decltype(cbegin(s))>::value));
+     EXPECT_TRUE((std::is_same<decltype(std::cend(s)), decltype(cend(s))>::value));
+
      EXPECT_TRUE((std::is_same<decltype(s.rbegin()), decltype(rbegin(s))>::value));
      EXPECT_TRUE((std::is_same<decltype(s.rend()), decltype(rend(s))>::value));
 
+     EXPECT_TRUE((std::is_same<decltype(std::crbegin(s)), decltype(crbegin(s))>::value));
+     EXPECT_TRUE((std::is_same<decltype(std::crend(s)), decltype(crend(s))>::value));
+
      EXPECT_TRUE(s.begin() == begin(s));
      EXPECT_TRUE(s.end() == end(s));
 
      EXPECT_TRUE(s.rbegin() == rbegin(s));
      EXPECT_TRUE(s.rend() == rend(s));
+
+     EXPECT_TRUE(s.begin() == cbegin(s));
+     EXPECT_TRUE(s.end() == cend(s));
+
+     EXPECT_TRUE(s.rbegin() == crbegin(s));
+     EXPECT_TRUE(s.rend() == crend(s));
  }
 
  TEST(span_ext_test, ssize_free_function)