Stuck when compiling XMonad.StackSet in xmonad 0.9 (hackage version)

This is the end of the -v output without -O2

Ready for upsweep
  [NONREC
      ModSummary {
         ms_hs_date = Fri Sep  5 21:53:18 CEST 2008
         ms_mod = main:XMonad.StackSet,
         ms_imps = [Data.Map, Data.List, Data.List, Data.Maybe, Prelude]
         ms_srcimps = []
      }]
compile: input file ./XMonad/StackSet.hs
Created temporary directory: /tmp/ghc14177_0
*** Checking old interface for main:XMonad.StackSet:
[1 of 1] Compiling XMonad.StackSet  ( XMonad/StackSet.hs, XMonad/StackSet.o )
*** Parser:
*** Renamer/typechecker:
*** Desugar:
    Result size = 7813
*** Simplify:
    Result size = 6756
    Result size = 6535
    Result size = 6511
    Result size = 6511
*** Tidy Core:
    Result size = 6511
*** CorePrep:

1. ..and then it stops, consuming full CPU and constant (~27MB) memory.

The output with -O2 is slightly different

Ready for upsweep
  [NONREC
      ModSummary {
         ms_hs_date = Fri Sep  5 21:53:18 CEST 2008
         ms_mod = main:XMonad.StackSet,
         ms_imps = [Data.Map, Data.List, Data.List, Data.Maybe, Prelude]
         ms_srcimps = []
      }]
compile: input file ./XMonad/StackSet.hs
Created temporary directory: /tmp/ghc14187_0
*** Checking old interface for main:XMonad.StackSet:
[1 of 1] Compiling XMonad.StackSet  ( XMonad/StackSet.hs, XMonad/StackSet.o )
*** Parser:
*** Renamer/typechecker:
*** Desugar:
    Result size = 7808
*** Simplify:
    Result size = 6281
    Result size = 6189
    Result size = 6189
*** Specialise:
    Result size = 6189
*** Float out (not lambdas, not constants):

I waited for about 30 minutes before killing it. This problem doesn't seem to be present in the 6.10 branch, so the culprit must be a relatively recent patch.

Trac metadata

Trac field	Value
Version	6.11
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture	Unknown/Multiple