I’m working on a solution where I have several different projects. Some of these projects are class libraries (DLLs) and some projects reference others. In some of them I have a number of extension methods.
I’ve noticed something strange happening occasionally. The extension methods in one of the class libraries stop functioning as extension methods for no apparent reason. This is even if they are called from within the same class library. It is usually after I have changed something, but not anything significant, and the namespace references all appear to be correct when I check. This isn’t just intellisense either – the build fails compilation.
The simple solution to this problem that I have found (which may solve other weird compilation bugs as well) is simply to clean the solution, close Visual Studio, reopen it and build again. This has worked every time that I’ve tried it so far.
This applies to Visual Studio 2010 Professional, and possibly 2008 as well, but I can’t remember if I had that problem then.