1 files changed, 117 insertions, 0 deletions
diff --git a/test/std/containers/views/span.iterators/rbegin.pass.cpp b/test/std/containers/views/span.iterators/rbegin.pass.cpp
new file mode 100644
index 0000000000000..c0776c00a81bb
--- /dev/null
+++ b/test/std/containers/views/span.iterators/rbegin.pass.cpp
@@ -0,0 +1,117 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17 
+
+// <span>
+
+// constexpr       reverse_iterator  rbegin() const noexcept;
+// constexpr const_reverse_iterator crbegin() const noexcept;
+
+#include <span>
+#include <cassert>
+#include <string>
+
+#include "test_macros.h"
+
+template <class Span>
+constexpr bool testConstexprSpan(Span s)
+{
+    bool ret = true;
+    typename Span::reverse_iterator b        = s. rbegin();
+    typename Span::const_reverse_iterator cb = s.crbegin();
+    if (s.empty())
+    {
+        ret = ret &&  ( b ==  s.rend());
+        ret = ret &&  (cb == s.crend());
+    }
+    else
+    {
+        const typename Span::index_type last = s.size() - 1;
+        ret = ret &&  (  *b ==  s[last]);
+        ret = ret &&  ( &*b == &s[last]);
+        ret = ret &&  ( *cb ==  s[last]);
+        ret = ret &&  (&*cb == &s[last]);
+    }
+    ret = ret &&  (b == cb);
+    return ret;
+}
+
+
+template <class Span>
+void testRuntimeSpan(Span s)
+{
+    typename Span::reverse_iterator b        = s. rbegin();
+    typename Span::const_reverse_iterator cb = s.crbegin();
+    if (s.empty())
+    {
+        assert( b ==  s.rend());
+        assert(cb == s.crend());
+    }
+    else
+    {
+        const typename Span::index_type last = s.size() - 1;
+        assert(  *b ==  s[last]);
+        assert( &*b == &s[last]);
+        assert( *cb ==  s[last]);
+        assert(&*cb == &s[last]);
+    }
+    assert(b == cb);
+}
+
+
+struct A{};
+bool operator==(A, A) {return true;}
+
+constexpr int iArr1[] = { 0,  1,  2,  3,  4,  5,  6,  7,  8,  9};
+          int iArr2[] = {10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
+
+
+int main()
+{
+    static_assert(testConstexprSpan(std::span<int>()),            "");
+    static_assert(testConstexprSpan(std::span<long>()),           "");
+    static_assert(testConstexprSpan(std::span<double>()),         "");
+    static_assert(testConstexprSpan(std::span<A>()),              "");
+    static_assert(testConstexprSpan(std::span<std::string>()),    "");
+
+    static_assert(testConstexprSpan(std::span<int, 0>()),         "");
+    static_assert(testConstexprSpan(std::span<long, 0>()),        "");
+    static_assert(testConstexprSpan(std::span<double, 0>()),      "");
+    static_assert(testConstexprSpan(std::span<A, 0>()),           "");
+    static_assert(testConstexprSpan(std::span<std::string, 0>()), "");
+
+    static_assert(testConstexprSpan(std::span<const int>(iArr1, 1)),    "");
+    static_assert(testConstexprSpan(std::span<const int>(iArr1, 2)),    "");
+    static_assert(testConstexprSpan(std::span<const int>(iArr1, 3)),    "");
+    static_assert(testConstexprSpan(std::span<const int>(iArr1, 4)),    "");
+    static_assert(testConstexprSpan(std::span<const int>(iArr1, 5)),    "");
+
+
+    testRuntimeSpan(std::span<int>        ());
+    testRuntimeSpan(std::span<long>       ());
+    testRuntimeSpan(std::span<double>     ());
+    testRuntimeSpan(std::span<A>          ());
+    testRuntimeSpan(std::span<std::string>());
+
+    testRuntimeSpan(std::span<int, 0>        ());
+    testRuntimeSpan(std::span<long, 0>       ());
+    testRuntimeSpan(std::span<double, 0>     ());
+    testRuntimeSpan(std::span<A, 0>          ());
+    testRuntimeSpan(std::span<std::string, 0>());
+
+    testRuntimeSpan(std::span<int>(iArr2, 1));
+    testRuntimeSpan(std::span<int>(iArr2, 2));
+    testRuntimeSpan(std::span<int>(iArr2, 3));
+    testRuntimeSpan(std::span<int>(iArr2, 4));
+    testRuntimeSpan(std::span<int>(iArr2, 5));
+
+    std::string s;
+    testRuntimeSpan(std::span<std::string>(&s, static_cast<std::ptrdiff_t>(0)));
+    testRuntimeSpan(std::span<std::string>(&s, 1));
+}