Refactor renamer datastructures

This patch significantly refactors key renamer datastructures (primarily Avail
and GlobalRdrElt) in order to treat DuplicateRecordFields in a more robust way.
In particular it allows the extension to be used with pattern synonyms (fixes
where mangled record selector names could be printed instead of field labels
(e.g. with -Wpartial-fields or hole fits, see new tests).

The key idea is the introduction of a new type GreName for names that may
represent either normal entities or field labels.  This is then used in
GlobalRdrElt and AvailInfo, in place of the old way of representing fields
using FldParent (yuck) and an extra list in AvailTC.

Updates the haddock submodule.

1 files changed, 9 insertions, 9 deletions

diff --git a/compiler/GHC/Iface/Load.hs b/compiler/GHC/Iface/Load.hs
index e7833d8145..8e5bcf9f4b 100644
--- a/compiler/GHC/Iface/Load.hs
+++ b/compiler/GHC/Iface/Load.hs
@@ -92,7 +92,6 @@ import GHC.Types.TypeEnv
 import GHC.Types.Unique.FM
 import GHC.Types.Unique.DSet
 import GHC.Types.SrcLoc
-import GHC.Types.FieldLabel
 import GHC.Types.TyThing
 
 import GHC.Unit.External
@@ -1134,15 +1133,16 @@ When printing export lists, we print like this:
 -}
 
 pprExport :: IfaceExport -> SDoc
-pprExport (Avail n)         = ppr n
-pprExport (AvailTC _ [] []) = Outputable.empty
-pprExport (AvailTC n ns0 fs)
-  = case ns0 of
-      (n':ns) | n==n' -> ppr n <> pp_export ns fs
-      _               -> ppr n <> vbar <> pp_export ns0 fs
+pprExport (Avail n)      = ppr n
+pprExport (AvailTC _ []) = Outputable.empty
+pprExport avail@(AvailTC n _) =
+    ppr n <> mark <> pp_export (availSubordinateGreNames avail)
   where
-    pp_export []    [] = Outputable.empty
-    pp_export names fs = braces (hsep (map ppr names ++ map (ppr . flLabel) fs))
+    mark | availExportsDecl avail = Outputable.empty
+         | otherwise              = vbar
+
+    pp_export []    = Outputable.empty
+    pp_export names = braces (hsep (map ppr names))
 
 pprUsage :: Usage -> SDoc
 pprUsage usage@UsagePackageModule{}