Added basic compile support for MSVC 2013 to byte.

include/gsl_byte.h

@@ -19,6 +19,23 @@
 #ifndef GSL_BYTE_H
 #define GSL_BYTE_H
 
+#ifdef _MSC_VER
+
+// MSVC 2013 workarounds
+#if _MSC_VER <= 1800
+
+// constexpr is not understood
+#pragma push_macro("constexpr")
+#define constexpr 
+
+// noexcept is not understood 
+#pragma push_macro("noexcept")
+#define noexcept  
+
+#endif // _MSC_VER <= 1800
+
+#endif // _MSC_VER
+
 namespace gsl
 {
     // This is a simple definition for now that allows
@@ -68,4 +85,19 @@ namespace gsl
     
 } // namespace gsl
 
+
+#ifdef _MSC_VER
+
+#if _MSC_VER <= 1800
+
+#undef constexpr
+#pragma pop_macro("constexpr")
+
+#undef noexcept
+#pragma pop_macro("noexcept")
+
+#endif // _MSC_VER <= 1800
+
+#endif // _MSC_VER
+
 #endif // GSL_BYTE_H

tests/byte_tests.cpp

@@ -87,6 +87,7 @@ SUITE(byte_tests)
         CHECK(a == byte(0x0F));
     }
 }
+
 }
 
 int main(int, const char* []) { return UnitTest::RunAllTests(); }

tests/span_tests.cpp

@@ -794,6 +794,15 @@ SUITE(span_tests)
         CHECK(it1 == it2);
     }
 
+    TEST(const_iterator)
+    {
+        span<int>::const_iterator it1;
+        span<int>::const_iterator it2;
+        CHECK(it1 == it2);
+
+        
+    }
+
     TEST(begin_end)
     {
         {