They have already implemented it in IDEA 12, if I'm reading their website correctly.
Which personally I think was a waste of development time, I cannot imagine how it could be useful to keep compilation errors in your code.
Which personally I think was a waste of development time, I cannot imagine how it could be useful to keep compilation errors in your code.
As for the merit of the technique - try it out. I've found it allows a level of experimentation not possible without the option; personally I've found that useful when it is not obvious what the right thing to do is upfront, I can try out a small change to a chunk of code, try it out via unit tests, then update all call sites appropriately; as opposed to attempting to "upgrade" call sites appropriately using a canned refactoring before I've validated whether or not I'm going to be able to achieve what I want for a few test cases.