Fix MinGW build

Summary:
snprintf is defined as _snprintf, which doesn't exist in the std
namespace.
Closes https://github.com/facebook/rocksdb/pull/2298

Differential Revision: D5070457

Pulled By: yiwu-arbug

fbshipit-source-id: 6e1659ac3e86170653b174578da5a8ed16812cbb

CMakeLists.txt

@@ -148,7 +148,7 @@ if(MSVC)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /FC /d2Zi+ /W3 /wd4127 /wd4800 /wd4996 /wd4351")
 else()
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -W -Wextra -Wall")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wsign-compare -Wshadow -Wno-unused-parameter -Wno-unused-variable -Woverloaded-virtual -Wnon-virtual-dtor -Wno-missing-field-initializers")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wsign-compare -Wshadow -Wno-unused-parameter -Wno-unused-variable -Woverloaded-virtual -Wnon-virtual-dtor -Wno-missing-field-initializers -Wno-strict-aliasing")
   if(MINGW)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-format")
   endif()

port/win/port_win.h

@@ -28,6 +28,7 @@
 #include <limits>
 #include <condition_variable>
 #include <malloc.h>
+#include <intrin.h>
 
 #include <stdint.h>
 
@@ -80,19 +81,8 @@ namespace rocksdb {
 
 namespace port {
 
-// VS 15
-#if (defined _MSC_VER) && (_MSC_VER >= 1900)
-
-#define ROCKSDB_NOEXCEPT noexcept
-
-// For use at db/file_indexer.h kLevelMaxIndex
-const int kMaxInt32 = std::numeric_limits<int>::max();
-const uint64_t kMaxUint64 = std::numeric_limits<uint64_t>::max();
-const int64_t kMaxInt64 = std::numeric_limits<int64_t>::max();
-
-const size_t kMaxSizet = std::numeric_limits<size_t>::max();
-
-#else //_MSC_VER
+// VS < 2015
+#if defined(_MSC_VER) && (_MSC_VER < 1900)
 
 // VS 15 has snprintf
 #define snprintf _snprintf
@@ -112,6 +102,17 @@ const size_t kMaxSizet = UINT64_MAX;
 const size_t kMaxSizet = UINT_MAX;
 #endif
 
+#else // VS >= 2015 or MinGW
+
+#define ROCKSDB_NOEXCEPT noexcept
+
+// For use at db/file_indexer.h kLevelMaxIndex
+const int kMaxInt32 = std::numeric_limits<int>::max();
+const uint64_t kMaxUint64 = std::numeric_limits<uint64_t>::max();
+const int64_t kMaxInt64 = std::numeric_limits<int64_t>::max();
+
+const size_t kMaxSizet = std::numeric_limits<size_t>::max();
+
 #endif //_MSC_VER
 
 const bool kLittleEndian = true;