#5539: GHC panic - Simplifier ticks exhausted
---------------------------------+------------------------------------------
Reporter: hvr | Owner: simonpj
Type: bug | Status: new
Priority: high | Milestone: 7.6.1
Component: Compiler | Version: 7.3
Resolution: | Keywords:
Os: Linux | Architecture: x86_64 (amd64)
Failure: Compile-time crash | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related:
---------------------------------+------------------------------------------
Comment(by pcapriotti):
Here is a simple example (by kosmikus) which blows up the simplifier
without any INLINE pragma:
{{{
module TestCase where
import Control.Applicative
data X = X
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
mb :: (String -> Maybe a) -> String -> Maybe (Maybe a)
mb _ "" = Just Nothing
mb _ "-" = Just Nothing
mb p xs = Just <$> p xs
run :: [String] -> Maybe X
run
[ x1
, x2
, x3
, x4
, x5
, x6
, x7
, x8
, x9
] = X
<$> mb pure x1
<*> mb pure x2
<*> mb pure x3
<*> mb pure x4
<*> mb pure x5
<*> mb pure x6
<*> mb pure x7
<*> mb pure x8
<*> mb pure x9
}}}
Unless `mb` is marked as NOINLINE, it gets expanded in the body of `run` a
number of times that seems to grow exponentially with the size of the list
(9 in the example).
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5539#comment:45>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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