OK, it looks like this goes wrong because of the way we interleave the building of packages when building GHC. GHC assumes that if we're building one package, then packages that it depends on have already been built and are complete. Therefore, even if a module in the other package has a `.hs- boot` file, the real `.hs` file will also have been compiled and there will be a full `.hi` file.
That seems like a reasonable assumption to make, and it doesn't look
#7373: When building GHC: Failed to load interface for `GHC.Fingerprint' -------------------------------+-------------------------------------------- Reporter: igloo | Owner: igloo Type: bug | Status: closed Priority: normal | Milestone: 7.8.1 Component: libraries/base | Version: 7.6.1 Resolution: wontfix | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Difficulty: Unknown Testcase: | Blockedby: Blocking: | Related: -------------------------------+-------------------------------------------- Comment(by simonpj): Replying to [comment:3 igloo]: like anything actually fails as a result of this, so I don't think we need to take any action. Ian I'm far from certain that your diagnosis here is correct, and indeed I don't really understand it. Yes, the assumption you describe seems a reasonable one. Does it not hold? Does not-holding have consequences of missing unfoldings? GHC is, I believe, happy to accept either a .hi file or a .hi-boot file. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7373#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler