In my Visual Studio 2010 project I have files with .mm file extension, that need to be compiled as normal C++ files. Is there a way to make a build rule for new extensions or something like that? In VS 2008 there were options for that, but they are gone in 2010.
For an individual file: Right click on the file > Properties > Configuration Properties - General > Item Type : C/C++ compiler.
In general for a project: How to: Select the Files to Build, Walkthrough: Using MSBuild, Walkthrough: Creating an MSBuild Project File from Scratch.