#5587: Code using seq has wrong strictness (too lazy) when optimised
---------------------------------+------------------------------------------
Reporter: michal.palka | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.3 | Keywords: seq strictness strict lazy
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: Incorrect result at runtime
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Following program prints `[1]` instead of crashing when compiled with `-O
-fno-full-laziness`. Note that it's neccessary to use the extra definition
`hiddenError` instead of calling `error` directly. The problem might be
related to #5557, which, however, has already been fixed and optimisation
is needed to trigger the current bug.
{{{
hiddenError = error "hidden error"
main = do
print $ seq (head (map (\a -> \b -> hiddenError) (hiddenError::[]
Bool))) id [1]
}}}
I used GHC 7.3.20111022 for triggering this problem.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5587>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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