From f38ee4fb5e58b6bb88b723578661e1ad3744e3a2 Mon Sep 17 00:00:00 2001
From: Pascal Menuet <pmenuet@libertysurf.fr>
Date: Sat, 12 Dec 2015 22:59:57 +0100
Subject: [PATCH] In VS2013, the std::equal does not have the overload that
 takes 4 iterators

---
 include/string_span.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/string_span.h b/include/string_span.h
index 01c56dc..03ef07a 100644
--- a/include/string_span.h
+++ b/include/string_span.h
@@ -35,6 +35,7 @@
 
 #define GSL_MSVC_HAS_TYPE_DEDUCTION_BUG
 #define GSL_MSVC2013_ICE_WHEN_USING_DUMMY_TEMPLATE_PARAMETER
+#define GSL_MSVC2013_EQUAL_ALGORITHM_IS_NOT_CPP14
 
 // noexcept is not understood
 #ifndef GSL_THROW_ON_CONTRACT_VIOLATION
@@ -611,7 +612,13 @@ using wzstring_builder = basic_zstring_builder<wchar_t, Max>;
 template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_range>
 bool operator==(const gsl::basic_string_span<CharT, Extent>& one, const gsl::basic_string_span<CharT, Extent>& other) noexcept
 {
+#ifdef GSL_MSVC2013_EQUAL_ALGORITHM_IS_NOT_CPP14
+    if (std::distance(one.begin(), one.end()) != std::distance(other.begin(), other.end()))
+        return false;
+    return std::equal(one.begin(), one.end(), other.begin());
+#else
     return std::equal(one.begin(), one.end(), other.begin(), other.end());
+#endif
 }
 
 template <typename CharT, std::ptrdiff_t Extent = gsl::dynamic_range>
@@ -651,6 +658,7 @@ bool operator>=(const gsl::basic_string_span<CharT, Extent>& one, const gsl::bas
 #pragma pop_macro("noexcept")
 #endif // GSL_THROW_ON_CONTRACT_VIOLATION
 
+#undef GSL_MSVC2013_EQUAL_ALGORITHM_IS_NOT_CPP14
 #undef GSL_MSVC2013_ICE_WHEN_USING_DUMMY_TEMPLATE_PARAMETER
 #undef GSL_MSVC_HAS_TYPE_DEDUCTION_BUG