Render Haddocks for derived instances

Currently, one can document top-level instance declarations, but derived
instances (both those in `deriving` clauses and standalone `deriving`
instances) do not enjoy the same privilege. This makes the necessary
changes to the Haddock API to enable rendering Haddock comments for
derived instances.

This is part of a fix for Trac #11768.

1 files changed, 10 insertions, 0 deletions

diff --git a/haddock-api/src/Haddock/Interface/Rename.hs b/haddock-api/src/Haddock/Interface/Rename.hs
index 3054e2f9..1f3f2aab 100644
--- a/haddock-api/src/Haddock/Interface/Rename.hs
+++ b/haddock-api/src/Haddock/Interface/Rename.hs
@@ -328,6 +328,9 @@ renameDecl decl = case decl of
   InstD d -> do
     d' <- renameInstD d
     return (InstD d')
+  DerivD d -> do
+    d' <- renameDerivD d
+    return (DerivD d')
   _ -> error "renameDecl"
 
 renameLThing :: (a Name -> RnM (a DocName)) -> Located (a Name) -> RnM (Located (a DocName))
@@ -503,6 +506,13 @@ renameInstD (DataFamInstD { dfid_inst = d }) = do
   d' <- renameDataFamInstD d
   return (DataFamInstD { dfid_inst = d' })
 
+renameDerivD :: DerivDecl Name -> RnM (DerivDecl DocName)
+renameDerivD (DerivDecl { deriv_type = ty
+                        , deriv_overlap_mode = omode }) = do
+  ty' <- renameLSigType ty
+  return (DerivDecl { deriv_type = ty'
+                    , deriv_overlap_mode = omode })
+
 renameClsInstD :: ClsInstDecl Name -> RnM (ClsInstDecl DocName)
 renameClsInstD (ClsInstDecl { cid_overlap_mode = omode
                             , cid_poly_ty =ltype, cid_tyfam_insts = lATs