Resolve [-Wclass-memaccess]

Source/Core/VideoCommon/VertexLoaderManager.cpp

@@ -8,6 +8,7 @@
 #include <memory>
 #include <mutex>
 #include <string>
+#include <type_traits>
 #include <unordered_map>
 #include <utility>
 #include <vector>
@@ -153,14 +154,8 @@ NativeVertexFormat* GetUberVertexFormat(const PortableVertexDeclaration& decl)
   // The padding in the structs can cause the memcmp() in the map to create duplicates.
   // Avoid this by initializing the padding to zero.
   PortableVertexDeclaration new_decl;
-#ifdef __GNUC__
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wclass-memaccess"
-#endif
-  std::memset(&new_decl, 0, sizeof(new_decl));
-#ifdef __GNUC__
-#pragma GCC diagnostic pop
-#endif
+  static_assert(std::is_trivially_copyable_v<PortableVertexDeclaration>);
+  std::memset(static_cast<void*>(&new_decl), 0, sizeof(new_decl));
   new_decl.stride = decl.stride;
 
   auto MakeDummyAttribute = [](AttributeFormat& attr, ComponentFormat type, int components,