added extensionToGHCFlag (from bringert)

Distribution/Misc.hs

@@ -42,7 +42,7 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -}
 
-module Distribution.Misc(License(..), Dependency, Extension, Opt
+module Distribution.Misc(License(..), Dependency, Extension(..), Opt
 #ifdef DEBUG        
         ,hunitTests
 #endif
@@ -70,7 +70,11 @@ data Dependency = Dependency String VersionRange
 -- |This represents non-standard compiler extensions which each
 -- package might employ.  Not yet implemented.
 
-data Extension = Foo | Bar deriving Show
+data Extension = 
+	       OverlappingInstances
+	       | TypeSynonymInstances
+	       | TemplateHaskell
+	       deriving Show
 
 type Opt = String
 

Distribution/Simple/Build.hs

@@ -47,7 +47,7 @@ module Distribution.Simple.Build (
 #endif
   ) where
 
-import Distribution.Misc (Extension)
+import Distribution.Misc (Extension(..))
 import Distribution.Setup (CompilerFlavor(..), compilerFlavor, compilerPath)
 import Distribution.Package (PackageDescription(..), showPackageId)
 import Distribution.Simple.Configure (LocalBuildInfo, compiler)
@@ -59,7 +59,7 @@ import Distribution.Simple.Utils (rawSystemExit, setupMessage,
 
 
 import Control.Monad (when)
-import Data.List(intersperse)
+import Data.List(intersperse, nub)
 
 #ifdef DEBUG
 import HUnit (Test)
@@ -117,7 +117,11 @@ constructGHCCmdLine pref pkg_descr _ =
   ++ allModules pkg_descr
 
 extensionsToGHCFlag :: [ Extension ] -> [String]
-extensionsToGHCFlag _ = [] -- ToDo
+extensionsToGHCFlag = nub . map extensionToGHCFlag
+    where
+    extensionToGHCFlag OverlappingInstances = "-fallow-overlapping-instances"
+    extensionToGHCFlag TypeSynonymInstances = "-fglasgow-exts"
+    extensionToGHCFlag TemplateHaskell = "-fth"
 
 extensionsToNHCFlag :: [ Extension ] -> [String]
 extensionsToNHCFlag _ = [] -- ToDo