Fix mingw compilation with -DNDEBUG

Summary:
This was exposed by a48a62d, which made NDEBUG the default for cmake
builds.
Closes https://github.com/facebook/rocksdb/pull/2315

Differential Revision: D5079583

Pulled By: sagar0

fbshipit-source-id: c614e96a40df016a834a62b6236852265e7ee4db

port/win/env_win.cc

@@ -1079,13 +1079,19 @@ std::string Env::GenerateUniqueId() {
   UuidCreateSequential(&uuid);
 
   RPC_CSTR rpc_str;
-  auto status = UuidToStringA(&uuid, &rpc_str);
-  assert(status == RPC_S_OK);
+#ifndef NDEBUG
+  assert(UuidToStringA(&uuid, &rpc_str) == RPC_S_OK);
+#else
+  UuidToStringA(&uuid, &rpc_str);
+#endif
 
   result = reinterpret_cast<char*>(rpc_str);
 
-  status = RpcStringFreeA(&rpc_str);
-  assert(status == RPC_S_OK);
+#ifndef NDEBUG
+  assert(RpcStringFreeA(&rpc_str) == RPC_S_OK);
+#else
+  RpcStringFreeA(&rpc_str);
+#endif
 
   return result;
 }

port/win/io_win.cc

@@ -194,11 +194,13 @@ WinMmapReadableFile::WinMmapReadableFile(const std::string& fileName,
       length_(length) {}
 
 WinMmapReadableFile::~WinMmapReadableFile() {
-  BOOL ret = ::UnmapViewOfFile(mapped_region_);
-  assert(ret);
-
-  ret = ::CloseHandle(hMap_);
-  assert(ret);
+#ifndef NDEBUG
+  assert(::UnmapViewOfFile(mapped_region_));
+  assert(::CloseHandle(hMap_));
+#else
+  ::UnmapViewOfFile(mapped_region_);
+  ::CloseHandle(hMap_);
+#endif
 }
 
 Status WinMmapReadableFile::Read(uint64_t offset, size_t n, Slice* result,
@@ -745,7 +747,9 @@ Status WinWritableImpl::AppendImpl(const Slice& data) {
 
   assert(data.size() < std::numeric_limits<DWORD>::max());
 
+#ifndef NDEBUG
   uint64_t written = 0;
+#endif
 
   if (file_data_->use_direct_io()) {
 
@@ -765,7 +769,9 @@ Status WinWritableImpl::AppendImpl(const Slice& data) {
         "Failed to pwrite for: " + file_data_->GetName(), lastError);
     }
     else {
+#ifndef NDEBUG
       written = ret;
+#endif
     }
 
   } else {
@@ -779,7 +785,9 @@ Status WinWritableImpl::AppendImpl(const Slice& data) {
         lastError);
     }
     else {
+#ifndef NDEBUG
       written = bytesWritten;
+#endif
     }
   }