#2202: type error causes type checker stack overflow
-------------------------------------+--------------------------------------
Reporter: chiral | Owner: chak
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 6.8.2
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Architecture: Other
Os: Other |
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Changes (by simonpj):
* cc: [EMAIL PROTECTED] (added)
* difficulty: => Unknown
Comment:
I believe this bug from Bryan Donlan is closely related. (He sent the
report by email; I don't think there's a ticket for it.) I propose not to
chase it down until Manuel has fixed this ticket (he is on the job). Then
let's re-investigate.
Simon
I've found a case where GHC will hang (consuming more and more memory)
when it should report an occurs check error. The test case is at
[http://fushizen.net/~bd/kaos-ghc-loop.tgz] - the error in question is
that the arguments in the `StateT` instance for `HOLift` are reversed like
so:
{{{
diff --git a/src/Kaos/KaosM.hs b/src/Kaos/KaosM.hs
index ec4e69a..268250a 100644
--- a/src/Kaos/KaosM.hs
+++ b/src/Kaos/KaosM.hs
@@ -88,7 +88,7 @@ genlift' unbox box f m = box $ \s -> f (unbox m s)
class HOLift m b | m -> b where
genlift :: (forall r'. b r' -> b r') -> (forall r. m r -> m r)
-instance HOLift m (StateT s m) where
+instance HOLift (StateT s m) m where
genlift = genlift' runStateT StateT
instance (HOLift m b, KaosDiagM r b) => KaosDiagM r m where
}}}
I'm using GHC 6.8.2 on ubuntu hardy.
Bryan Donlan
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2202#comment:2>
GHC <http://www.haskell.org/ghc/>
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