Revert removing type traits assertions

Author: bugdea1er

src/file.cpp

@@ -4,27 +4,34 @@
 
 #include <tmp/file>
 
-#include <fcntl.h>
+#include <cstdio>
 #include <filesystem>
 #include <ios>
-#include <istream>
 #include <system_error>
-#include <utility>
+#include <type_traits>
 
 #ifdef __GLIBCXX__
 #include <ext/stdio_filebuf.h>
 #endif
 
 #ifdef _WIN32
 #include <Windows.h>
-#include <corecrt_io.h>
+#include <io.h>
 #endif
 
 namespace tmp {
 namespace {
 
 namespace fs = std::filesystem;
 
+// Confirm that native_handle_type matches `TriviallyCopyable` named requirement
+static_assert(std::is_trivially_copyable_v<file::native_handle_type>);
+
+#ifdef _WIN32
+// Confirm that `HANDLE` is as implemented in `file`
+static_assert(std::is_same_v<HANDLE, file::native_handle_type>);
+#endif
+
 #ifndef _MSC_VER
 /// Open mode for binary temporary files
 constexpr auto mode = std::ios::binary | std::ios::in | std::ios::out;