#7369: Simplifier bug(?)
------------------------------+---------------------------------------------
Reporter: sweirich | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.6.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Other | Testcase:
Blockedby: | Blocking:
Related: |
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Not sure if it is really a bug. I was playing around with the following
infinite loop in GHC 7.6:
{{{
{-# LANGUAGE GADTs, KindSignatures #-}
data False
data I (c :: * -> *)
data R (c :: *) where
R :: (a (I a) -> False) -> R (I a)
delta :: R (I R) -> False
delta = \ (R f) -> f (R f)
omega :: False
omega = delta (R delta)
main :: IO ()
main = seq omega (return ())
}}}
And I got the following result. It's supposed to be an infinite loop,
though, so maybe it is ok. GHC 7.4 just hangs on this example.
{{{
spaceman:haskell sweirich$ ghc inj4.hs
[1 of 1] Compiling Main ( inj4.hs, inj4.o )
ghc: panic! (the 'impossible' happened)
(GHC version 7.6.1 for i386-apple-darwin):
Simplifier ticks exhausted
When trying UnfoldingDone main:Main.$WR{v reV} [gid[DataConWrapper]]
To increase the limit, use -fsimpl-tick-factor=N (default 100)
If you need to do this, let GHC HQ know, and what factor you needed
To see detailed counts use -ddump-simpl-stats
Total ticks: 5160
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7369>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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