#3692: TcTyFuns.flattenType: unexpected PredType
-------------------------------+--------------------------------------------
Reporter: cdfh | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.10.4 | Keywords: TcTyFuns PredType panic
Os: Linux | Testcase:
Architecture: x86_64 (amd64) | Failure: Compile-time crash
-------------------------------+--------------------------------------------
Hello,
I've found a bug, however it may be a duplicate of one of these: #2846,
#3272, #3592, #3125, #3102 (roughly in order of duplicate-likelihoodness).
Here's the code:
{{{
type Foo a b = () -> (Bar a => a)
class Bar a where {}
foo :: Foo a b
foo = id (undefined :: Foo a b)
}}}
And the result of compilation:
{{{
$ ghc -fglasgow-exts --make Bug.hs
[1 of 1] Compiling Bug ( Bug.hs, Bug.o )
ghc: panic! (the 'impossible' happened)
(GHC version 6.10.4 for x86_64-unknown-linux):
TcTyFuns.flattenType: unexpected PredType
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
I'm running Gentoo Linux, with dev-lang/ghc-6.10.4 (not dev-haskell
/haskell-platform)
{{{
Linux geneva 2.6.29-gentoo-r5 #1 SMP Sun Jul 12 03:16:58 BST 2009 x86_64
Intel(R) Core(TM)2 CPU 4300 @ 1.80GHz GenuineIntel GNU/Linux
}}}
I'm afraid I've not tested this against HEAD, since I couldn't get it to
build.
Note that `foo = undefined :: Foo a b` does not cause GHC to panic.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3692>
GHC <http://www.haskell.org/ghc/>
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