Support installing multiple ghc-mod instances

Setup.hs

@@ -1,13 +1,18 @@
 #!/usr/bin/env runhaskell
-{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE RecordWildCards, NamedFieldPuns #-}
 import Distribution.Simple
+import Distribution.Simple.Utils
 import Distribution.Simple.Setup
 import Distribution.Simple.Install
 import Distribution.Simple.Register
-import Distribution.Simple.InstallDirs as ID
+import Distribution.Simple.BuildPaths
+import qualified Distribution.Simple.InstallDirs as ID
 import Distribution.Simple.LocalBuildInfo
 import Distribution.PackageDescription
 
+import qualified Data.Map as M
+import Data.Map (Map)
+
 import Control.Arrow
 import Control.Applicative
 import Control.Monad
@@ -18,37 +23,130 @@ import Data.Monoid
 import System.Process
 import System.Exit
 import System.FilePath
-
-import SetupCompat
+import System.Directory (renameFile)
 
 main :: IO ()
 main = defaultMainWithHooks $ simpleUserHooks {
+   instHook = inst,
+   copyHook = copy,
+
    confHook = \(gpd, hbi) cf ->
-              xBuildDependsLike <$> (confHook simpleUserHooks) (gpd, hbi) cf
+              xBuildDependsLike <$> (confHook simpleUserHooks) (gpd, hbi) cf,
+
+   buildHook = \pd lbi hooks flags -> (buildHook simpleUserHooks) pd (patchLibexecdir lbi) hooks flags
  }
 
+patchLibexecdir :: LocalBuildInfo -> LocalBuildInfo
+patchLibexecdir lbi = let
+    idirtpl     = installDirTemplates lbi
+    libexecdir' = toPathTemplate $ fromPathTemplate (libexecdir idirtpl) </> "$abi/$pkgid"
+    lbi' = lbi { installDirTemplates = idirtpl { libexecdir = libexecdir' } }
+  in
+    lbi'
+
+
 xBuildDependsLike :: LocalBuildInfo -> LocalBuildInfo
 xBuildDependsLike lbi =
   let
       cc = componentsConfigs lbi
       pd = localPkgDescr lbi
       deps = dependsMap lbi
-  in setComponentsConfigs lbi
-        [ (cn, updateClbi deps comp clbi, cdeps)
-        | (cn, clbi, cdeps) <- cc
-        , let comp = getComponent pd cn
-        ]
-
+  in lbi {
+          componentsConfigs =
+              [ (cn, updateClbi deps comp clbi, cdeps)
+              | (cn, clbi, cdeps) <- cc
+              , let comp = getComponent pd cn
+              ]
+         }
  where
    updateClbi deps comp clbi = setUnionDeps (otherDeps deps comp) clbi
 
    dependsMap ::
-    LocalBuildInfo -> [(ComponentName, Deps)]
+    LocalBuildInfo -> [(ComponentName, ([(UnitId, PackageId)], Map PackageName ModuleRenaming))]
    dependsMap lbi =
-       second getDeps <$> allComponentsInBuildOrder lbi
+       second (componentPackageDeps &&& componentPackageRenaming)
+           <$> allComponentsInBuildOrder lbi
 
-   otherDeps :: [(ComponentName, Deps)] -> Component -> Deps
-   otherDeps deps comp = fromMaybe noDeps $
+   otherDeps :: [(ComponentName, ([(UnitId, PackageId)], Map PackageName ModuleRenaming))] -> Component -> ([(UnitId, PackageId)], Map PackageName ModuleRenaming)
+   otherDeps deps comp = fromMaybe ([], M.empty) $
        flip lookup deps =<< read <$> lookup "x-build-depends-like" fields
       where
         fields = customFieldsBI (componentBuildInfo comp)
+
+   setComponentPackageRenaming clbi cprn =
+     clbi { componentPackageRenaming =
+                componentPackageRenaming clbi `M.union` cprn }
+
+   setUnionDeps :: ([(UnitId, PackageId)], Map PackageName ModuleRenaming) -> ComponentLocalBuildInfo -> ComponentLocalBuildInfo
+   setUnionDeps (deps, rns) clbi = let
+      clbi' = setComponentPackageRenaming clbi rns
+      cpdeps = componentPackageDeps clbi
+    in
+      clbi' {
+          componentPackageDeps = cpdeps `union` deps
+      }
+
+
+-- mostly copypasta from 'defaultInstallHook'
+inst ::
+    PackageDescription -> LocalBuildInfo -> UserHooks -> InstallFlags -> IO ()
+inst pd lbi _uf ifl = do
+  let copyFlags = defaultCopyFlags {
+                      copyDistPref   = installDistPref ifl,
+                      copyDest       = toFlag NoCopyDest,
+                      copyVerbosity  = installVerbosity ifl
+                  }
+  xInstallTarget pd lbi copyFlags (\pd' lbi' -> install pd' lbi' copyFlags)
+  let registerFlags = defaultRegisterFlags {
+                          regDistPref  = installDistPref ifl,
+                          regInPlace   = installInPlace ifl,
+                          regPackageDB = installPackageDB ifl,
+                          regVerbosity = installVerbosity ifl
+                      }
+  when (hasLibs pd) $ register pd lbi registerFlags
+
+copy :: PackageDescription -> LocalBuildInfo -> UserHooks -> CopyFlags -> IO ()
+copy pd lbi _uh cf =
+    xInstallTarget pd lbi cf (\pd' lbi' -> install pd' lbi' cf)
+
+xInstallTarget :: PackageDescription
+               -> LocalBuildInfo
+               -> CopyFlags
+               -> (PackageDescription -> LocalBuildInfo -> IO ())
+               -> IO ()
+xInstallTarget pd lbi cf fn = do
+  let (extended, regular) = partition isInternal (executables pd)
+
+  let pd_regular = pd { executables = regular }
+
+  _ <- flip mapM extended $ \exe -> do
+    let pd_extended = onlyExePackageDesc [exe] pd
+    fn pd_extended lbi
+
+    let lbi' = patchLibexecdir lbi
+        copydest  = fromFlag (copyDest cf)
+        verbosity = fromFlag (copyVerbosity cf)
+        InstallDirs { bindir, libexecdir } = absoluteInstallDirs pd lbi' copydest
+        progprefix = substPathTemplate (packageId pd) lbi (progPrefix lbi)
+        progsuffix = substPathTemplate (packageId pd) lbi (progSuffix lbi)
+        fixedExeBaseName = progprefix ++ exeName exe ++ progsuffix
+
+        fixedExeFileName = bindir </> fixedExeBaseName <.> exeExtension
+        newExeFileName   = libexecdir </> fixedExeBaseName <.> exeExtension
+
+    when (exeName exe == "ghc-mod-real") $ do
+        createDirectoryIfMissingVerbose verbosity True libexecdir
+        renameFile fixedExeFileName newExeFileName
+
+  fn pd_regular lbi
+
+ where
+   isInternal :: Executable -> Bool
+   isInternal exe =
+    fromMaybe False $ (=="True") <$> lookup "x-internal" (customFieldsBI $ buildInfo exe)
+
+onlyExePackageDesc :: [Executable] -> PackageDescription -> PackageDescription
+onlyExePackageDesc exes pd = emptyPackageDescription {
+                     package = package pd
+                   , executables = exes
+                   }