Error C2280 in a simple piece of C++ code

I’m trying to solve a "stupid" problem I got with Visual Studio Enterprise 2022.

I created a new MFC application from scratch, then I added this single line of code:

CFile testFile = CFile(_T("TEST STRING"), CFile::modeCreate);

When I try to build the solution, I get this error from the compiler:

error C2280: 'CFile::CFile(const CFile &)': attempting to reference a deleted function

I read lot of answers and also the official MS Guide about this error but I still cannot figure how to solve.

Any hint?

Thank you!

>Solution :

CFile objects can’t be copied, but that is exactly what you are trying to do – you are creating a temporary CFile object and then copy-constructing your testFile from it. ¹

Use this instead to avoid the copy and just construct testFile directly:

CFile testFile(_T("TEST STRING"), CFile::Attribute::normal);

¹: I would be very worried by the fact that the compiler is even complaining about this copy, instead of just optimizing the temporary away, as all modern C++ compilers are supposed to do.

This statement:

CFile testFile = CFile(_T("TEST STRING"), CFile::Attribute::normal);

Is effectively just syntax sugar for this (hence the delete‘d copy constructor being called):

CFile testFile(CFile(_T("TEST STRING"), CFile::Attribute::normal));

Which modern compilers since C++17 onward are supposed to optimize to this:

CFile testFile(_T("TEST STRING"), CFile::Attribute::normal);

However, at least according to MSDN, Visual Studio defaults to C++14 by default. So make sure you are compiling for a later C++ version instead.