From b279a9005bfda9f5837aadf22a61c9843eaa862b Mon Sep 17 00:00:00 2001
From: Marshall Clow <marshall@Triskaidekaphobia.local>
Date: Thu, 7 Feb 2019 07:52:11 -0800
Subject: [PATCH] Fix off-by-one error in range-checking for 'at()'. thanks to
 DHilbrich for the bug report.

---
 include/boost/array.hpp |  2 +-
 test/array6.cpp         | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/include/boost/array.hpp b/include/boost/array.hpp
index 210c072..99dc2c6 100644
--- a/include/boost/array.hpp
+++ b/include/boost/array.hpp
@@ -183,7 +183,7 @@ namespace boost {
 
         // check range (may be private because it is static)
         static BOOST_CONSTEXPR bool rangecheck (size_type i) {
-            return i > size() ? boost::throw_exception(std::out_of_range ("array<>: index out of range")), true : true;
+            return i >= size() ? boost::throw_exception(std::out_of_range ("array<>: index out of range")), true : true;
         }
 
     };
diff --git a/test/array6.cpp b/test/array6.cpp
index 3d737fd..b8bac55 100644
--- a/test/array6.cpp
+++ b/test/array6.cpp
@@ -27,6 +27,25 @@ namespace {
         const arr &caRef = get_c_array ( test_case );
         typename test_type::const_iterator iter = test_case.begin ();
         BOOST_CHECK ( &*iter == &caRef[0] );
+
+    //  Confirm at() throws the std lib defined exception
+        try {
+            test_case.at( test_case.size());
+            BOOST_CHECK(false);
+            }
+        catch ( const std::out_of_range & ) {}
+
+        try {
+            test_case.at( test_case.size() + 1);
+            BOOST_CHECK(false);
+            }
+        catch ( const std::out_of_range & ) {}
+
+        try {
+            test_case.at( test_case.size() + 100);
+            BOOST_CHECK(false);
+            }
+        catch ( const std::out_of_range & ) {}
     }
 }