#2018: Interface file error with GADT and -O1
-------------------------------+--------------------------------------------
Reporter: Ashley Yakeley | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.8.2
Severity: normal | Keywords:
Difficulty: Unknown | Testcase:
Architecture: x86_64 (amd64) | Os: Linux
-------------------------------+--------------------------------------------
I've tried to simplify this as much as possible. In particular, the bug
goes away if -O1 is removed.
{{{
module Bug1 where
data A a where
MkA :: A ()
class C w where
f :: forall a . w a -> Maybe a
instance C A where
f MkA = Just ()
}}}
{{{
module Bug2 where
import Bug1
f' :: A a -> Maybe a
f' = f
}}}
Run with this:
{{{
#!/bin/sh
rm -f *.hi *.o
ghc --version
ghc -c -XGADTs -XRankNTypes -O1 Bug1.hs
ghc -c -XGADTs -XRankNTypes -O1 Bug2.hs
}}}
This is the result I get:
{{{
The Glorious Glasgow Haskell Compilation System, version 6.8.2
Bug1.hi
Declaration for a:
Iface type variable out of scope: a
Cannot continue after interface file error
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2018>
GHC <http://www.haskell.org/ghc/>
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