DeriveFunctor and GeneralizedNewtypeDeriving instances never reporting as covered
When testing coverage of test cases, HPC does not report some instances as receiving coverage even though it seems they are. Particularly, when one hand derives the functions they show full coverage. The specific instances in question appear to be ones derived via DeriveFunctor and GeneralizedNewtypeDeriving. Problems have been observed with at least Functor, Applicative, and Monad.
A minimal example is attached, and available as a cabal project at https://code.xkrd.net/davean/minimal-coverage-test. To reproduce, run "cabal v2-test --enable-coverage" and view the resulting coverage HTML files.