Accumulate explicitly which modules to load for 'attachInstances'

The old approach to fixing #469, while correct, consumes a lot of
memory. We ended up with a HUGE 'GblRdrEnv' in 'ic_rn_gbl_env'. However,
'getNameToInstancesIndex' takes that environment and compresses it down
to a much smaller 'ModuleSet'.

Now, we compute that 'ModuleSet' explicitly as we process modules. That
way we can just tell 'getNameToInstancesIndex' what modules to load
(instead of it trying to compute that information from the interactive
context).

(cherry picked from commit 5c7c596c51d69b92164e9ba920157b36ce2b2ec1)

1 files changed, 7 insertions, 4 deletions

diff --git a/haddock-api/src/Haddock/Interface/AttachInstances.hs b/haddock-api/src/Haddock/Interface/AttachInstances.hs
index bf50ded3..2d72d117 100644
--- a/haddock-api/src/Haddock/Interface/AttachInstances.hs
+++ b/haddock-api/src/Haddock/Interface/AttachInstances.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE CPP, MagicHash #-}
+{-# LANGUAGE CPP, MagicHash, BangPatterns #-}
 {-# LANGUAGE TypeFamilies #-}
 -----------------------------------------------------------------------------
 -- |
@@ -34,6 +34,7 @@ import FamInstEnv
 import FastString
 import GHC
 import InstEnv
+import Module ( ModuleSet, moduleSetElts )
 import MonadUtils (liftIO)
 import Name
 import NameEnv
@@ -51,11 +52,13 @@ type Modules = Set.Set Module
 type ExportInfo = (ExportedNames, Modules)
 
 -- Also attaches fixities
-attachInstances :: ExportInfo -> [Interface] -> InstIfaceMap -> Ghc [Interface]
-attachInstances expInfo ifaces instIfaceMap = do
-  (_msgs, mb_index) <- getNameToInstancesIndex (map ifaceMod ifaces)
+attachInstances :: ExportInfo -> [Interface] -> InstIfaceMap -> ModuleSet -> Ghc [Interface]
+attachInstances expInfo ifaces instIfaceMap mods = do
+  (_msgs, mb_index) <- getNameToInstancesIndex (map ifaceMod ifaces) mods'
   mapM (attach $ fromMaybe emptyNameEnv mb_index) ifaces
   where
+    mods' = Just (moduleSetElts mods)
+
     -- TODO: take an IfaceMap as input
     ifaceMap = Map.fromList [ (ifaceMod i, i) | i <- ifaces ]