Simplify ghc-boot database representation with new type class.

Previously, we had an 'OriginalModule' type in ghc-boot which
was basically identical to 'Module', and we had to do a bit of
gyrating to get it converted into the right form.  This commit
introduces a new typeclass, 'DbModuleRep' which represents types
which we know how to serialize to and from the (now renamed) 'DbModule'
type.

The upshot is that we can just store 'Module's DIRECTLY in
the 'InstalledPackageInfo', no conversion needed.

I took the opportunity to clean up ghc-pkg to make its use of
the 'BinaryStringRep' classes more type safe.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Test Plan: validate

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1811

1 files changed, 7 insertions, 3 deletions

diff --git a/compiler/main/Packages.hs b/compiler/main/Packages.hs
index 0a8b279374..3c646a5a5d 100644
--- a/compiler/main/Packages.hs
+++ b/compiler/main/Packages.hs
@@ -768,8 +768,12 @@ findWiredInPackages dflags pkgs vis_map = do
                   | otherwise
                   = pkg
                 upd_deps pkg = pkg {
-                      depends = map upd_wired_in (depends pkg)
+                      depends = map upd_wired_in (depends pkg),
+                      exposedModules
+                        = map (\(k,v) -> (k, fmap upd_wired_in_mod v))
+                              (exposedModules pkg)
                     }
+                upd_wired_in_mod (Module uid m) = Module (upd_wired_in uid) m
                 upd_wired_in key
                     | Just key' <- Map.lookup key wiredInMap = key'
                     | otherwise = key
@@ -1155,11 +1159,11 @@ mkModuleToPkgConfAll dflags pkg_db vis_map =
 
     es :: Bool -> [(ModuleName, Map Module ModuleOrigin)]
     es e = do
-     ExposedModule m exposedReexport <- exposed_mods
+     (m, exposedReexport) <- exposed_mods
      let (pk', m', pkg', origin') =
           case exposedReexport of
            Nothing -> (pk, m, pkg, fromExposedModules e)
-           Just (OriginalModule pk' m') ->
+           Just (Module pk' m') ->
             let pkg' = pkg_lookup pk'
             in (pk', m', pkg', fromReexportedModules e pkg')
      return (m, sing pk' m' pkg' origin')