Visual Studio warning about copies of files with different contents

Question

When I go to debug my C++ project in Visual Studio, up pops a little warning dialogue box that tells me:

A copy of datum.h was found in
c:/users/brad/desktop/sou         


        

Answer 1

This occurs if you rename an implementation file (*.c, *.cpp, etc.) to a header file.

This is because the Item Type still remains as C/C++ Source File, making it get compiled as a separate translation unit rather than as an actual header, preventing Visual Studio from recognizing its inclusion as a header elsewhere.

It took me quite a while to figure this out.

To fix this:

1. Right-click your header file in Solution Explorer and select Properties.

2. Select All Configurations, All Platforms.

3. Under General, change Item Type to C/C++ Header.

4. Press OK.

5. Force-recompile any file that #includes your header (or just Rebuild the solution).