Simplify IfaceIdInfo type

IfaceIdInfo type is confusing: there's practically no difference between
`NoInfo` and `HasInfo []`. The comments say NoInfo is used when
-fomit-interface-pragmas is enabled, but we don't need to distinguish
`NoInfo` from `HasInfo []` in when reading the interface so the
distinction is not important.

This patch simplifies the type by removing NoInfo. When we have no info
we use an empty list.

With this change we no longer read the info list lazily when reading an
IfaceInfoItem, but when reading an IfaceId the ifIdInfo field is
read lazily, so I doubt this is going to be a problem.

1 files changed, 2 insertions, 4 deletions

diff --git a/compiler/GHC/IfaceToCore.hs b/compiler/GHC/IfaceToCore.hs
index a6fa7408b2..700d830c9d 100644
--- a/compiler/GHC/IfaceToCore.hs
+++ b/compiler/GHC/IfaceToCore.hs
@@ -1465,10 +1465,8 @@ tcIdInfo ignore_prags toplvl name ty info = do
     let init_info | if_boot lcl_env = vanillaIdInfo `setUnfoldingInfo` BootUnfolding
                   | otherwise       = vanillaIdInfo
 
-    case info of
-      NoInfo       -> return init_info
-      HasInfo info -> let needed = needed_prags info in
-                      foldlM tcPrag init_info needed
+    let needed = needed_prags info
+    foldlM tcPrag init_info needed
   where
     needed_prags :: [IfaceInfoItem] -> [IfaceInfoItem]
     needed_prags items