STM with data invariants crashes GHC

Ben Franksen writes: my ghc(i) crashes when using STM data invariants. This little piece of code demonstrates the problem:

module Bug where

import Control.Concurrent.STM

test = do
  x <- atomically $ do
    v <- newTVar 0
    always $ return True -- remove this line and all is fine
    return v
  atomically (readTVar x) >>= print

This is what ghci makes of it:

ben@sarun> ghci Bug.hs
GHCi, version 6.10.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Bug              ( Bug.hs, interpreted )
Ok, modules loaded: Bug.
*Bug> test
Loading package syb ... linking ... done.
Loading package array-0.2.0.0 ... linking ... done.
Loading package stm-2.1.1.2 ... linking ... done.
zsh: segmentation fault  ghci Bug.hs

I am using ghc-6.10.1 freshly installed from source with just a 'cabal install stm' thrown after it.

BTW, the documentation for Control.Concurrent.STM.TVar lists... nothing. Similar with Control.Monad.STM. Well, at least the source link works, so one isn't completely lost... :-)

Trac metadata

Trac field	Value
Version	6.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
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Related
Blocking
CC	ben.franksen@online.de
Operating system
Architecture