CgCase fails with strict data/functions
The following code results in a ghc panic when compiled with -O or above:
-- Test.hs
module Test where
import Data.List (foldl')
data SPair = SPair { pX, pY :: Double } deriving (Eq,Show)
data AList = AList
{ pairs :: [SPair] } deriving Show
rnf' :: AList -> ()
rnf' aList = foldl' (flip seq) () (pairs aList) `seq` ()
{- -- this works
rnf' :: AList -> ()
rnf' aList = foldl (flip seq) () (pairs aList) `seq` ()
-}
The resulting error is
{{{ $ ghc -O Test.hs [1 of 1] Compiling Test ( Test.hs, Test.o ) ghc: panic! (the 'impossible' happened)
(GHC version 7.6.1 for x86_64-unknown-linux):
compiler/codeGen/CgCase.lhs:572:15-61: Irrefutable pattern failed for pattern ((CoreSyn.DEFAULT,
Trac metadata
Trac field | Value |
---|---|
Version | 7.6.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |