Question

It often happens that a single C# solution contains some projects that are x86-specific (usually by having native dependencies) and others that are ‘Any CPU’.

Up until recently I’ve always gone into the configuration manager and made sure that the solution platform was ‘Any CPU’. This isn’t too much of a problem; it requires occasional tweaks like the ones mentioned here, but overall isn’t too bad.

However, I recently started wondering if these efforts are misguided. I’m clearly going against the way Visual Studio 2010 (and previously Visual Studio 2008) is designed to handle this. “Mixed Platforms” is actually an accurate description, and although it initially feels like there’s something wrong, upon further thought I have to conclude that it’s no more wrong than “Any CPU”.

So, lately I have been trying to choose between keeping “Mixed Platforms” or changing to “x86” as my Solution Platform in such cases. The latter reflects the intention: the final EXE file is x86, and runs in 32-bit mode on 64-bit OSes. The former however is what Visual Studio really wants it to be.

In your experience, is there a particular solution platform that is more suitable in any way than the others in this situation?

Note 1: in every case that I’ve encountered, ‘x86’ is justified by native dependencies and ‘Any CPU’ is justified by being an external library that is really platform-independent.

Note 2: if I understand correctly, the solution platform doesn’t make much of a difference; it’s just a name. It seems to change the default “to-build-or-not-to-build” checkbox state when new projects are added, but that’s about the only effect that it has. Right?

Answer 1

Having had some more experience with this, here’s what I now think:

• It doesn’t make any difference at all what the solution platform is called for a mixed-platform project. The behaviour of VS is exactly the same, requiring the exact same amount of clean-up after adding a project.
• “Mixed platforms” is slightly more accurate, so I have a slight preference for this one.

Changing everything to x86 is undesirable for two reasons:

• Some algorithms are almost twice as fast in x64 mode.
• Any shared library that is x86 cannot be used in a project that benefits a lot from x64 mode.
• Maintaining shared libraries in two platforms, x86+x64, is a lot more effort than keeping them “Any CPU” and cleaning up after Visual Studio every time it sprinkles unwanted solution configurations into a solution.