Add Visual C++ info to hash_info

test/hash_info.cpp

@@ -7,8 +7,69 @@
 
 #include <boost/container_hash/hash.hpp>
 #include <iostream>
+#include <algorithm>
+
+#if defined(BOOST_MSVC)
+
+struct msvc_version {
+    std::size_t version;
+    char const* description;
+
+    bool operator<(std::size_t v) const {
+        return version < v;
+    }
+    friend bool operator<(std::size_t v1, msvc_version const& v2) {
+        return v1 < v2.version;
+    }
+};
+
+void write_compiler_info() {
+    // From:
+    // https://en.wikipedia.org/wiki/Microsoft_Visual_C%2B%2B
+    // https://blogs.msdn.microsoft.com/vcblog/2017/11/15/side-by-side-minor-version-msvc-toolsets-in-visual-studio-2017/
+    msvc_version versions[] = {
+        {0, "Old Visual C++"},
+        {1000, "Visual C++ 4.x, VS4.0?"},
+        {1100, "Visual C++ 5.0, VS97"},
+        {1200, "Visual C++ 6.0, VS6.0"},
+        {1300, "Visual C++ 7.0, VS.NET 2002"},
+        {1310, "Visual C++ 7.1, VS.NET 2003"},
+        {1400, "Visual C++ 8.0, VS2005"},
+        {1500, "Visual C++ 9.0, VS2008"},
+        {1600, "Visual C++ 10.0, VS2010"},
+        {1700, "Visual C++ 11.0, VS2012"},
+        {1800, "Visual C++ 12.0, VS2013"},
+        {1900, "Visual C++ 14.00, VS2015"},
+        {1910, "Visual C++ 14.10, VS2017 15.1/2"},
+        {1911, "Visual C++ 14.11, VS2017 15.3/4"},
+        {1912, "Visual C++ 14.12, VS2017 15.5"}
+    };
+
+    std::size_t msvc = BOOST_MSVC;
+    msvc_version* v = std::upper_bound(versions,
+        versions + sizeof(versions) / sizeof(*versions),
+        msvc) - 1;
+    std::size_t difference = BOOST_MSVC - v->version;
+
+    std::cout << v->description << std::endl;
+    if (difference) {
+        std::cout << "+" << difference << std::endl;
+    }
+#if defined(_HAS_CXX17) && _HAS_CXX17
+    std::cout << "C++17 mode" << std::endl;
+#endif
+}
+
+#else
+
+void write_compiler_info() {
+}
+
+#endif
 
 int main() {
+    write_compiler_info();
+
 #if defined(__cplusplus)
     std::cout << "__cplusplus: "
         << __cplusplus