Include datadirs of a component's dependencies in the Paths_* module

The added constant is `dependencies_datadirs :: [(String, FilePath)]`,
which is a mapping from the dependency's package name to the data
directory of the installed depenency.

Cabal/src/Distribution/Simple/Build/PathsModule.hs

@@ -26,11 +26,16 @@ import Distribution.Package
 import Distribution.PackageDescription
 import Distribution.Simple.Compiler
 import Distribution.Simple.LocalBuildInfo
+import Distribution.Simple.PackageIndex (allPackagesForUnitIds)
 import Distribution.Simple.Utils (shortRelativePath)
 import Distribution.System
 import Distribution.Version
 
+import qualified Data.Set as Set
 import qualified Distribution.Simple.Build.PathsModule.Z as Z
+import qualified Distribution.Types.InstalledPackageInfo as InstalledPackageInfo
+import qualified Distribution.Types.LocalBuildConfig as LocalBuildConfig
+import qualified System.FilePath as FilePath
 
 -- ------------------------------------------------------------
 
@@ -61,6 +66,7 @@ generatePathsModule pkg_descr lbi clbi =
       , Z.zDatadir = zDatadir
       , Z.zLibexecdir = zLibexecdir
       , Z.zSysconfdir = zSysconfdir
+      , Z.zDependenciesDatadirs = zDependenciesDatadirs
       }
   where
     supports_cpp = supports_language_pragma
@@ -148,6 +154,29 @@ generatePathsModule pkg_descr lbi clbi =
     flat_libexecdir_reloc = shortRelativePath flat_prefix flat_libexecdir
     flat_sysconfdir_reloc = shortRelativePath flat_prefix flat_sysconfdir
 
+    zDependenciesDatadirs :: [(PackageName, FilePath)]
+    zDependenciesDatadirs =
+      [ (packageName info, directory)
+      | info <- dependenciesPackageInfos
+      , let directory = InstalledPackageInfo.dataDir info
+      , FilePath.isAbsolute directory
+      ]
+
+    dependenciesPackageInfos =
+      allPackagesForUnitIds dependenciesUnitIds installedPackageIndex
+
+    dependenciesUnitIds =
+      Set.fromList
+        . map fst
+        . componentPackageDeps
+        $ clbi
+
+    installedPackageIndex =
+        LocalBuildConfig.installedPkgs
+          . LocalBuildConfig.componentBuildDescr
+          . localBuildDescr
+          $ lbi
+
 -- | Generates the name of the environment variable controlling the path
 -- component of interest.
 --

Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs

@@ -1,7 +1,12 @@
 {- FOURMOLU_DISABLE -}
 {-# LANGUAGE DeriveGeneric #-}
+
 module Distribution.Simple.Build.PathsModule.Z (render, Z(..)) where
+
 import Distribution.ZinzaPrelude
+
+import qualified Data.List as List
+
 data Z
     = Z {zPackageName :: PackageName,
          zVersionDigits :: String,
@@ -20,9 +25,11 @@ data Z
          zDatadir :: FilePath,
          zLibexecdir :: FilePath,
          zSysconfdir :: FilePath,
+         zDependenciesDatadirs :: [(PackageName, FilePath)],
          zNot :: (Bool -> Bool),
          zManglePkgName :: (PackageName -> String)}
     deriving Generic
+
 render :: Z -> String
 render z_root = execWriter $ do
   if (zSupportsCpp z_root)
@@ -58,7 +65,7 @@ render z_root = execWriter $ do
   tell " (\n"
   tell "    version,\n"
   tell "    getBinDir, getLibDir, getDynLibDir, getDataDir, getLibexecDir,\n"
-  tell "    getDataFileName, getSysconfDir\n"
+  tell "    getDataFileName, getSysconfDir, dependencies_datadirs\n"
   tell "  ) where\n"
   tell "\n"
   if (zNot z_root (zAbsolute z_root))
@@ -111,6 +118,15 @@ render z_root = execWriter $ do
   tell "  dir <- getDataDir\n"
   tell "  return (dir `joinFileName` name)\n"
   tell "\n"
+  tell "dependencies_datadirs :: [(String, FilePath)]\n"
+  tell "dependencies_datadirs =\n"
+  tell "  [ "
+  tell
+    $ List.intercalate "  , "
+    $ map (\(name, directory) -> "(\"" ++ prettyShow name ++ "\", \"" ++ directory ++ "\")\n")
+    $ zDependenciesDatadirs z_root
+  tell "  ]\n"
+  tell "\n"
   tell "getBinDir, getLibDir, getDynLibDir, getDataDir, getLibexecDir, getSysconfDir :: IO FilePath\n"
   tell "\n"
   let

Cabal/src/Distribution/Simple/PackageIndex.hs

@@ -82,6 +82,7 @@ module Distribution.Simple.PackageIndex
   , allPackagesByName
   , allPackagesBySourcePackageId
   , allPackagesBySourcePackageIdAndLibName
+  , allPackagesForUnitIds
 
     -- ** Special queries
   , brokenPackages
@@ -424,6 +425,11 @@ allPackagesBySourcePackageIdAndLibName index =
   , ipkgs@(ipkg : _) <- Map.elems pvers
   ]
 
+-- | Get all packages from the index that match one of the provided `UnitId`s.
+allPackagesForUnitIds :: Set UnitId -> PackageIndex a -> [a]
+allPackagesForUnitIds unitIds (PackageIndex pids _pnames) =
+  Map.elems (Map.restrictKeys pids unitIds)
+
 --
 
 -- * Lookups