#1751: program with GADTs segfaults when compiled with -prof and -auto-all
-----------------------+----------------------------------------------------
Reporter: guest | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.6.1
Severity: normal | Keywords:
Difficulty: Unknown | Os: Unknown
Testcase: | Architecture: Unknown
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Consider the following modules Main.hs and M.hs:
{{{
module Main ( main )
where
import M
main :: IO ()
main = do let f = T [undefined, undefined]
[a] <- c f (\t -> return [r (UR undefined) t])
a
}}}
{{{
{-# OPTIONS_GHC -fglasgow-exts -fno-warn-incomplete-patterns #-}
module M ( R(..), U, r, T(..), c )
where
data T f where T :: [T f] -> T ()
data R t where
UR :: (T f -> ()) -> R (U f)
R :: R ()
data U f
c :: T f -> (T () -> a) -> a
c p@(T _) f = f p
r :: R (U f) -> T f -> IO ()
r a f = (fu a f) `seq` return ()
fu :: R (U f) -> T f -> ()
fu (UR f) = f
}}}
I get:
{{{
$ ghc --make -prof -auto-all Main
$ ./Main +RTS -p
Segmentation fault
$./Main
Segmentation fault
}}}
This is a boiled-down example taken from a large project. A couple of
observations:
* I haven't been able to reproduce it using only one module
* The R constructor from type R is not used, but if removed, the
segfault no longer happens
* If -auto-all is not used, the segfault does not happen
* I've been able to reproduce it both on linux and os x, using ghc 6.6.1
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1751>
GHC <http://www.haskell.org/ghc/>
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