I hit a wall today with rcov + Rails3.
I am developing my Rails3 app using Ruby 1.9.2-preview3. rcov and relevance-rcov do not work with Ruby 1.9.2 yet. I can't find any fork of rcov that does yet either. It wasn't that big of a deal since I could easily switch over to Ruby 1.8.7 using rvm --default 1.8.7; rake test:coverage.
So then today I brought my app forward from beta4 to Rails 3.0.0-rc. That version requires linecache19. The problem is linecache19 doesn't compile with 1.8.7, only 1.9.2-preview3, it can't see my vm_core.h file no matter how I configure it's --include-* params. That means I lost my working rcov on my Ruby 1.8.7 setup and I now only have a barely working rcov with my 1.9.2-preview3 setup, and it creates terribly wrong coverage stats.
What's my short-term solution for a working, accurate rcov?