#3787: GHC 6.12.1 panic
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Reporter: blamario | Owner: simonpj
Type: bug | Status: infoneeded
Priority: normal | Milestone: 7.0.1
Component: Compiler (Type checker) | Version: 6.12.1
Keywords: panic | Testcase:
indexed-types/should_compile/T3787
Blockedby: 4232 | Difficulty:
Os: Linux | Blocking:
Architecture: x86_64 (amd64) | Failure: Compile-time crash
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Comment(by blamario):
I've tested the original test case with HEAD from 2010-09-15, and there's
no panic any more. I guess the bug can be closed. The only thing I find
mildly alarming is that the module doesn't compile with HEAD, while it
compiles with GHC 6.12.1. Even the current version of SCC doesn't compile
with HEAD. Is this a known problem or should I be worried? Here is the
error message I get on the current version of SCC from Darcs repository at
http://code.haskell.org/SCC/:
{{{
Control/Concurrent/SCC/Streams.hs:387:28:
Couldn't match type `d' with `d1'
because this skolem type variable would escape: `d1'
This skolem is bound by
the polymorphic type
`forall (d :: * -> *).
AncestorFunctor a d =>
Int -> Coroutine d m [x]'
The following variables have types that mention d
repeat :: Int -> Coroutine d m [y]
(bound at Control/Concurrent/SCC/Streams.hs:388:10)
In the `getChunk' field of a record
In the expression: Source {getChunk = repeat}
In an equation for `retryWhileEmpty':
retryWhileEmpty f source
= Source {getChunk = repeat}
where
repeat n
= getChunk source n >>= apply
where
apply input = test input =<< f input
test (_ : _) [] = repeat n
test _ output = return output
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3787#comment:11>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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