From cf7addb983bd2079b221199f8ec09c8edaeb8956 Mon Sep 17 00:00:00 2001
From: Alex Biehl <alexbiehl@gmail.com>
Date: Fri, 23 Jun 2017 14:44:41 +0200
Subject: [PATCH] Lookup fixities for reexports without subordinates (#642)
So we agree that reexported declarations which do not have subordinates (for example top-level functions) shouldn't have gotten fixities reexported according to the current logic. I wondered why for example Prelude.($) which is obviously reexported from GHC.Base has fixities attached (c.f. http://hackage.haskell.org/package/base-4.9.1.0/docs/Prelude.html#v:-36-).
The reason is this: In mkMaps we lookup all the subordinates of top-level declarations, of course top-level functions don't have subordinates so for them the resulting list is empty. In #644 I established the invariant that there won't be any empty lists in the subordinate map. Without the patch from #642 top-level functions now started to fail reexporting their fixities.
---
haddock-api/src/Haddock/Interface/AttachInstances.hs | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/haddock-api/src/Haddock/Interface/AttachInstances.hs b/haddock-api/src/Haddock/Interface/AttachInstances.hs
index 527c6bccdd..a2cdb7525f 100644
--- a/haddock-api/src/Haddock/Interface/AttachInstances.hs
+++ b/haddock-api/src/Haddock/Interface/AttachInstances.hs
@@ -18,6 +18,7 @@ import Haddock.Types
import Haddock.Convert
import Haddock.GhcUtils
+import Control.Applicative
import Control.Arrow hiding ((<+>))
import Data.List
import Data.Ord (comparing)
@@ -119,7 +120,7 @@ attachToExportItem index expInfo iface ifaceMap instIfaceMap export =
} = e { expItemFixities =
nubByName fst $ expItemFixities e ++
[ (n',f) | n <- getMainDeclBinder d
- , Just subs <- [instLookup instSubMap n iface ifaceMap instIfaceMap]
+ , Just subs <- [instLookup instSubMap n iface ifaceMap instIfaceMap <|> Just []]
, n' <- n : (subs ++ patsyn_names)
, Just f <- [instLookup instFixMap n' iface ifaceMap instIfaceMap]
] }
--
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