On Tue, Apr 3, 2018 at 5:37 PM, Simon Peyton Jones via ghc-devs <ghc-devs@haskell.org> wrote:
It seems to be caused by some missing Makefile dependency
It may be significant that the dependency is a module in libraries/base
GHC/IO.hs-boot depending on one
GHC.Integer.Type in libraries/integer-gmp.
That's quite likely the case, either directly or indirectly. When changing the dependency graph, especially involving `.hs-boot` files, it happens quite easily that one needs to give the build-system a hint and make implicit module-graph dependencies more explicit by adding an explicit `import SomeModule ()` in the appropriate place. You may find commit of mine where I did things like that in the past.