5.0: .hi files should indicate origin
It would be nice if a .hi file indicated its origin. Otherwise, if you happen to have two different files with the same module name, GHC can get confused (or more importantly, the user can get confused!), because it has no way of knowing whether it's using the .hi file from the wrong source file. This seems a bit of a marginal case, but it shows up in things like test suites. In GHC's tests, tc056.hs and tc057.hs if run one after the other (as is intended), will fail on tc057.hs with a warning about something that comes from the .hi file of test056. % ghc -c tc056.hs tc056.hs:14: Warning: Duplicate class assertion `Eq' a' in the context: (Eq' a, Eq' a) => ... % ghc -c tc057.hs ./ShouldSucceed.hi:8: Warning: Duplicate class assertion `ShouldSucceed.Eq' a' in the context: (ShouldSucceed.Eq' a, ShouldSucceed.Eq' a) => ... As you might guess, there's no duplicate class assertion in tc057.hs.