Simplifier bug(?)
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
Trac metadata
Trac field | Value |
---|---|
Version | 7.6.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |