Visual C++ 2008 Express - cpp filename conflict

Question

I'm developing application for GNU/Linux using gcc 4 and cmake to manage compilation process. I found that is has no problems when there are two files with the same name but in other directory and namespace like this:

.  
|-- gfx  
|   |-- Object.cpp  
|   `-- Object.h  
`-- logic  
    |-- Object.cpp  
    `-- Object.h  

First Object class is in Gfx namespace and second in Logic namespace.

Then I've tried to compile this project using Visual C++ 2008 Express Edition. Linker threw several errors about non-existing implementation of Gfx::Object class. After few checks I found out that:

• Visual C++ is tracking two of Object.cpp files
• When change occurs in first or second file the recompilation of Object unit is queued
• It always recompile only the second Object.cpp regardless of which file was actually modified

I also found out that Visual C++ don't allow to create two classes with same name.

Is there a solution for this? I don't really want to refactor quite big part of code.

Answer 1

The problem is that by default VC++2008 places all the object files into a single output folder, so the existence of the first object.obj file satisfies the dependency for the second so it is not compiled; and even if it were, it would overwrite the first one.

What you need to be able to do is make the intermediate directory setting dependent in the file being compiled. However I have tried setting it to $(InputDir) and various other combinations, but could not succeed in achieving a configuration that works, although it may be possible. The available macros are documented here.

Failing that you could use a "makefile" project, and manage the build with make, nmake, or cmake or whatever, since there is nothing fundamentally wrong with what you are doing (even if it is ill-advised), it is just that it is not easily supported by the IDE.

Answer 2

Both Object.cpp files will be compiled to Object.obj. Into the same directory. In other words, the last one that is compiled will overwrite the Object.obj of the first one. Yes, the linker isn't going to be thrilled by that, you'll get multiply defined symbols since it links the same Object.obj file twice.

The fix is easy, right-click one of the Object.cpp files, Properties, C/C++, Output Files. Change the Object File Name from $(IntDir)\ to, say, $(IntDir)\$(InputName)2.obj

Answer 3

This has already been answered, but I also want to add Visual Studio 2010 will automatically put the two .obj files into different directories if there is a conflict, based on my experience with Beta 2.

EDIT: Uh oh, this is wrong! The real answer is that CMake was automatically doing this for me.