Bug in STM with data invariants

[Simon Peyton-Jones]

Thank you for a nicely characterised bug report.  GHC should never crash! I've created a trac ticket http://hackage.haskell.org/trac/ghc/ticket/3049

Simon

| -----Original Message-----
| From: glasgow-haskell-users-bounces at haskell.org [mailto:glasgow-haskell-users-
| bounces at haskell.org] On Behalf Of Ben Franksen
| Sent: 24 February 2009 19:50
| To: glasgow-haskell-users at haskell.org
| Subject: Bug in STM with data invariants
|
| 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 at 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... :-)
|
| Cheers
| Ben
|
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