#11702: Constant folding on 'mod/Word' - incorrect result -------------------------------------+------------------------------------- Reporter: ondrap | Owner: bgamari Type: bug | Status: closed Priority: highest | Milestone: 8.0.1 Component: Prelude | Version: 7.10.3 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D2004 Wiki Page: | -------------------------------------+------------------------------------- Comment (by hjarvi): On my x64 the given test case goes through without a problem on GHC7.10 and GHC8.0, but I find a more effective test case to be (produces "5 0" on GHC7.10.3 and GHC8.0.0.20160302. The correct result "0 0" is produced by GHC 7.6.3 and GHC 8.0.1.20160822): {{{ -- -*- haskell -*- module Main ( main ) where import Data.IORef import Data.Word main = do i <- newIORef (5 :: Word) >>= readIORef print $ i `mod` 1 print $ (5 :: Word) `mod` 1 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11702#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler