#8853: Surprising mention of unboxed integers in pattern exhaustiveness warning -------------------------------------+------------------------------------- Reporter: | Owner: MikolajKonarski | Status: new Type: bug | Milestone: Priority: normal | Version: 7.8.1-rc2 Component: Compiler | Keywords: Resolution: | Architecture: x86_64 (amd64) Operating System: Linux | Difficulty: Unknown Type of failure: Incorrect | Blocked By: warning at compile-time | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Old description:
The attached code produces this alarming warning:
{{{ ~/waste$ ghc --version The Glorious Glasgow Haskell Compilation System, version 7.8.0.20140228 ~/waste$ ghc -Wall --make AlarmingPattern.hs -fforce-recomp [1 of 1] Compiling Main ( AlarmingPattern.hs, AlarmingPattern.o )
AlarmingPattern.hs:6:7: Warning: Pattern match(es) are non-exhaustive In an equation for ‘takeFromInv’: Patterns not matched: (GHC.Types.I# _) (GHC.Types.I# (#x)) with #x `notElem` [0#] Linking AlarmingPattern ... ~/waste$ ./AlarmingPattern AlarmingPattern: AlarmingPattern.hs:(6,7)-(7,26): Non-exhaustive patterns in function takeFromInv }}}
New description: The attached code produces this alarming warning: {{{ ~/waste$ ghc -Wall --make AlarmingPattern.hs -fforce-recomp [1 of 1] Compiling Main ( AlarmingPattern.hs, AlarmingPattern.o ) AlarmingPattern.hs:6:7: Warning: Pattern match(es) are non-exhaustive In an equation for ‘takeFromInv’: Patterns not matched: (GHC.Types.I# _) (GHC.Types.I# (#x)) with #x `notElem` [0#] Linking AlarmingPattern ... }}} The error message is alarming because it refers to unboxed integers, but the source code does not. -- Comment (by thomie): Reproducable with version 7.9.20140802. This ticket is listed on [wiki:Status/SLPJ-Tickets]. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8853#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler