[commit: ghc] : Garbage collect when determining stateAbsVars since we stopped doing it in reduceForMatch (f62af23)

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : 

http://hackage.haskell.org/trac/ghc/changeset/f62af232b59c5d58363f0d8ff5d51b73b12baa51

>---------------------------------------------------------------

commit f62af232b59c5d58363f0d8ff5d51b73b12baa51
Author: Max Bolingbroke <[email protected]>
Date:   Thu Mar 15 10:28:46 2012 +0000

    Garbage collect when determining stateAbsVars since we stopped doing it in reduceForMatch

>---------------------------------------------------------------

 .../supercompile/Supercompile/Drive/Process3.hs    |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/compiler/supercompile/Supercompile/Drive/Process3.hs b/compiler/supercompile/Supercompile/Drive/Process3.hs
index d343ea9..aa6a375 100644
--- a/compiler/supercompile/Supercompile/Drive/Process3.hs
+++ b/compiler/supercompile/Supercompile/Drive/Process3.hs
@@ -84,7 +84,13 @@ data MemoState = MS {
 
 promise :: MemoState -> (State, State) -> (MemoState, Promise)
 promise ms (state, reduced_state) = (ms', p)
-  where (vs_list, h_ty) = stateAbsVars (Just (stateLambdaBounders reduced_state)) state
+  where -- NB: because we stopped garbage-collecting in reduceForMatch, we need to garbage
+        -- collect here to ensure we mark as dead any lambda binders we won't be able to
+        -- determine a renaming for because they are dead.
+        --
+        -- If we don't do this then renameAbsVar will panic when it tries to lookup the renamed
+        -- version of a live variable.
+        (vs_list, h_ty) = stateAbsVars (Just (stateLambdaBounders (gc reduced_state))) state
         h_name :< h_names' = hNames ms
         x = mkLocalId h_name h_ty
         p = P {