Display minimal complete definitions for type classes

This corresponds to the new {-# MINIMAL #-} pragma present in GHC 7.8+.
I also cleaned up some of the places in which ExportDecl is used to make
adding fields easier in the future.

Lots of test cases have been updated since they now render with
minimality information.

1 files changed, 10 insertions, 1 deletions

diff --git a/src/Haddock/GhcUtils.hs b/src/Haddock/GhcUtils.hs
index bf6436d1..c06b34a6 100644
--- a/src/Haddock/GhcUtils.hs
+++ b/src/Haddock/GhcUtils.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE FlexibleInstances, ViewPatterns #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 {-# OPTIONS_HADDOCK hide #-}
 -----------------------------------------------------------------------------
@@ -35,6 +35,7 @@ import GhcMonad (withSession)
 import HscTypes
 import UniqFM
 import GHC
+import Class
 
 
 moduleString :: Module -> String
@@ -114,6 +115,7 @@ filterSigNames :: (name -> Bool) -> Sig name -> Maybe (Sig name)
 filterSigNames p orig@(SpecSig n _ _)          = ifTrueJust (p $ unLoc n) orig
 filterSigNames p orig@(InlineSig n _)          = ifTrueJust (p $ unLoc n) orig
 filterSigNames p orig@(FixSig (FixitySig n _)) = ifTrueJust (p $ unLoc n) orig
+filterSigNames _ orig@(MinimalSig _)           = Just orig
 filterSigNames p (TypeSig ns ty)               =
   case filter (p . unLoc) ns of
     []       -> Nothing
@@ -279,6 +281,13 @@ modifySessionDynFlags f = do
 gbracket_ :: ExceptionMonad m => m a -> m b -> m c -> m c
 gbracket_ before_ after thing = gbracket before_ (const after) (const thing)
 
+-- Extract the minimal complete definition of a Name, if one exists
+minimalDef :: GhcMonad m => Name -> m (Maybe ClassMinimalDef)
+minimalDef n = do
+  mty <- lookupGlobalName n
+  case mty of
+    Just (ATyCon (tyConClass_maybe -> Just c)) -> return . Just $ classMinimalDef c
+    _ -> return Nothing
 
 -------------------------------------------------------------------------------
 -- * DynFlags