One can play funny games with GHC-3.00 and the following program
(a small fragment of a Happy-generated parser):
--------------------------------------------------------------------------
module Foo ( happyParse ) where
action_0 1 = \j tk _ -> action_1 j j tk (HappyState action_1)
action_1 3 = error "Bar"
action_1 _ = \i tk st@(HappyState action) sts stk -> action (-1) (-1) tk st sts (Just
i : stk)
happyParse = action_0 2 2 '-' (HappyState action_0) [] [] 2
newtype HappyState b c =
HappyState (Int -> Int -> b -> HappyState b c -> [HappyState b c] -> c)
--------------------------------------------------------------------------
* Compiling it as-is with "ghc-3.00 -O -c Foo.hs" yields:
=> panic! (the `impossible' happened):
fun_result_ty: 6 PrelBase.Int{-3f-}
-> PrelBase.Int{-3f-}
-> b_tr74
-> Foo.HappyState{-r6P-} b_tr74 c_tr75
-> [Foo.HappyState{-r6P-} b_tr74 c_tr75]
-> c_tr75
Please report it as a compiler bug to [EMAIL PROTECTED]
* If newtype is changed to data or "( happyParse )" is deleted,
it compiles fine.
* GHC-2.10 doesn't complain in any way.
* If the first equation of action_1 is commented out, GHC seems to loop:
ghc-3.00 -O -c Foo.hs -H50M -K50M
=> GHC's heap exhausted;
while trying to allocate 20 bytes in a 50000000-byte heap;
use the `-H<size>' option to increase the total heap size.
Cheers,
Sven "Unhappy-too" Panne
--
Sven Panne Tel.: +49/89/2178-2235
LMU, Institut fuer Informatik FAX : +49/89/2178-2211
LFE Programmier- und Modellierungssprachen Oettingenstr. 67
mailto:[EMAIL PROTECTED] D-80538 Muenchen
http://www.pms.informatik.uni-muenchen.de/mitarbeiter/panne
