July 2013 - ghc-tickets

[GHC] #8098: Faulty Word64 arithmetic if optimized
by GHC 02 Dec '15

02 Dec '15

#8098: Faulty Word64 arithmetic if optimized ----------------------------+--------------------------------- Reporter: achp | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.4.2 Keywords: | Operating System: Windows Architecture: x86 | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------+--------------------------------- The following program produces different results depending on optimization: Checked.hs: {{{ module Checked ((.-.)) where (.-.) :: (Bounded a, Integral a) => a -> a -> Maybe a x .-. y | x >= 0 && y < 0 = if z > x then Just z else Nothing | x >= 0 = if z <= x then Just z else Nothing | x < 0 && y > 0 = if z < x then Just z else Nothing | otherwise = Just z where z = x - y }}} Main.hs: {{{ module Main (main) where import Data.Maybe import Data.Word import Numeric import Checked main :: IO () main = print $ showHex (fromJust ((0xFFFFFFFF00000000 :: Word64) .-. 0x00000000FFFFFFFF)) "" }}} {{{ D:\dev\haskell\ch1>ghc --make Checked.hs Main.hs [1 of 2] Compiling Checked ( Checked.hs, Checked.o ) [2 of 2] Compiling Main ( Main.hs, Main.o ) Linking Main.exe ... D:\dev\haskell\ch1>Main.exe "fffffffe00000001" D:\dev\haskell\ch1>del *.hi *.o *.exe D:\dev\haskell\ch1>ghc --make -O2 Checked.hs Main.hs [1 of 2] Compiling Checked ( Checked.hs, Checked.o ) [2 of 2] Compiling Main ( Main.hs, Main.o ) Linking Main.exe ... D:\dev\haskell\ch1>Main.exe "fffe00000001" D:\dev\haskell\ch1> }}} The bug disappears if definition and usage of (.-.) are in the same module. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8098> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8079: Redo T7919 with a cabal file
by GHC 21 Nov '15

21 Nov '15

#8079: Redo T7919 with a cabal file -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Compile-time Difficulty: Easy (less than 1 | crash hour) | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- Right now T7919 fails because the new dynamic-by-default GHC means that Template Haskell must be built with dynamic; of course, GHC isn't clever enough to figure this out. If we Cabalize the test, the example should start building again (and if they don't, well, that's a bug!) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8079> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8096: Add fudge-factor for performance tests run on non-validate builds
by GHC 27 Aug '15

27 Aug '15

#8096: Add fudge-factor for performance tests run on non-validate builds ------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Since I'm not going to get around to this immediately, Trac'ifying for posterity: These tests have been doing better than expected in the nightlies for some while. {{{ Unexpected failures: perf/compiler T3064 [stat too good] (normal) perf/compiler T3294 [stat too good] (normal) perf/compiler T5642 [stat too good] (normal) perf/haddock haddock.Cabal [stat too good] (normal) perf/haddock haddock.base [stat too good] (normal) }}} Unfortunately, fixing them is not a simple matter of shifting the ranges up, since the tests only exceed expectations on a /perf/ build, so on a normal build such as 'quick', these tests all pass normally. I could bump up the upper bounds so that the builder stops bleating about them; perhaps we could do something more complicated where the expected performance depends on what level of optimization GHC was built with (but I don't know how to implement this.) ---- The problem with just widening the bounds to cover 2 different types of build is that it increases the chance that performance changes won't actually be noticed by thge person responsible. Having different bounds for different build configurations is a pain, because (a) the testsuite has to work out which set of bounds to use, and (b) you now have even more wobbly values to keep up-to-date. I think perhaps the best thing would be to add some sort of (per-test?) fudge factor for non-validate builds. That way validate will still find performance regressions, like it does today, but other builds are less likely to give false positives. (Igloo) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8096> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8086: Minimal install for GHC
by GHC 04 May '15

04 May '15

#8086: Minimal install for GHC ------------------------------------+--------------------------------- Reporter: gidyn | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+--------------------------------- Installing GHC on a shared server requires a minimal footprint, without GHCi, profiling, debugging, documentation, or anything else not needed for regular building and installing. And anything stripable should be striped, if it isn't already. It would be great if the configuration script would support a --minimal option. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8086> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8085: Both GHC and its installer don't run on current Debian Stable
by GHC 04 May '15

04 May '15

#8085: Both GHC and its installer don't run on current Debian Stable -------------------------------------+------------------------------------- Reporter: ppetr | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: GHC doesn't work Difficulty: Easy (less than 1 | at all hour) | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- Currently it's not possible to run GHC or its installer. It fails with: {{{ ghc: error while loading shared libraries: libgmp.so.3: cannot open shared object file: No such file or directory }}} The problem is that the current Debian stable is Wheezy and it uses a newer version of libgmp. Proposed solution: Recompile on a recent Debian stable (Wheezy). Applies to x86_64 as well, most likely all architectures supported by Debian are affected. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8085> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8057: PackageImports with versions for ghci
by GHC 06 Apr '15

06 Apr '15

#8057: PackageImports with versions for ghci ------------------------------------+------------------------------------- Reporter: Lemming | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Imports with explicit package names and versions would be nice to have in GHCi, because you cannot use the -package and -hide-package options from within GHCi. This is what currently happens: {{{ $ ghci-7.6.3 -XPackageImports GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> import Control.Monad.Trans.List <no location info>: Ambiguous module name `Control.Monad.Trans.List': it was found in multiple packages: transformers-0.3.0.0 List-0.5.1 Prelude> import "transformers-0.3.0.0" Control.Monad.Trans.List <no location info>: Could not find module `Control.Monad.Trans.List' It is not a module in the current program, or in any known package. Prelude> :q Leaving GHCi. $ ghci-7.6.3 -hide-package List GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> import Control.Monad.Trans.List Prelude Control.Monad.Trans.List> }}} However, I now see that the import with explicit package name works, if I omit the package version. I think GHCi should at least warn that providing a version does not work. See also #2362 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8057> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8078: Core lint failure for profiled code
by GHC 23 Mar '15

23 Mar '15

#8078: Core lint failure for profiled code -----------------------------------+--------------------------------------- Reporter: ezyang | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: T4492 Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- Probably related to the cardinality changes. Here is the dump: =====> T4492(profasm) 3361 of 3686 [2, 51, 0] cd ./indexed-types/should_compile && '/srv/code/ghc-build- sandbox/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T4492.hs -O -prof -static -auto-all >T4492.comp.stderr 2>&1 Compile failed (status 256) errors were: *** Core Lint errors : in result of CorePrep *** {-# LINE 12 "T4492.hs #-}: Warning: [RHS of T4492.$fCMaybe_$cgo :: forall a_aex. T4492.C a_aex => forall b_ae0. (forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_ae0 -> a1_ae1) -> Data.Maybe.Maybe a_aex -> T4492.F (Data.Maybe.Maybe a_aex) b_ae0] Demand type has 4 arguments, rhs has 3 arguments, T4492.$fCMaybe_$cgo Binder's strictness signature: DmdType <C(C(S)),1*C1(C1(U))><L,U><L,U><L,U> *** Offending Program *** T4492.go [InlPrag=INLINE] :: forall a_adZ. T4492.C a_adZ => forall b_ae0. (forall a_ae1. Data.Maybe.Maybe a_ae1 -> b_ae0 -> a_ae1) -> a_adZ -> T4492.F a_adZ b_ae0 [GblId[ClassOp], Arity=1, Caf=NoCafRefs, Str=DmdType <S,U>, Unf=OtherCon []] T4492.go = \ (@ a_adZ) (tpl_sgH [Occ=Once] :: T4492.C a_adZ) -> tpl_sgH `cast` (T4492.NTCo:C[0] <a_adZ> :: T4492.C a_adZ ~# (forall b_ae0. (forall a_ae1. Data.Maybe.Maybe a_ae1 -> b_ae0 -> a_ae1) -> a_adZ -> T4492.F a_adZ b_ae0)) T4492.$fCMaybe1 :: forall a_aex. T4492.C a_aex => forall b_afH. (forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_afH -> a1_ae1) -> Data.Maybe.Maybe a_aex -> b_afH -> T4492.F a_aex b_afH [GblId, Arity=4, Caf=NoCafRefs, Str=DmdType <C(C(S)),1*C1(C1(U))><L,U><L,U><L,U>, Unf=OtherCon []] T4492.$fCMaybe1 = \ (@ a_aex) ($dC_sgI [Occ=OnceL] :: T4492.C a_aex) (@ b_afH) (f_sgJ :: forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_afH -> a1_ae1) (a1_sgK [Occ=OnceL] :: Data.Maybe.Maybe a_aex) (b1_sgL [Occ=OnceL] :: b_afH) -> scctick<go> let { sat_sgM [Occ=Once] :: a_aex [LclId, Str=DmdType] sat_sgM = f_sgJ @ a_aex a1_sgK b1_sgL } in ($dC_sgI `cast` (T4492.NTCo:C[0] <a_aex> :: T4492.C a_aex ~# (forall b_ae0. (forall a_ae1. Data.Maybe.Maybe a_ae1 -> b_ae0 -> a_ae1) -> a_aex -> T4492.F a_aex b_ae0))) @ b_afH f_sgJ sat_sgM T4492.$fCMaybe_$cgo :: forall a_aex. T4492.C a_aex => forall b_ae0. (forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_ae0 -> a1_ae1) -> Data.Maybe.Maybe a_aex -> T4492.F (Data.Maybe.Maybe a_aex) b_ae0 [GblId, Arity=3, Caf=NoCafRefs, Str=DmdType <C(C(S)),1*C1(C1(U))><L,U><L,U><L,U>, Unf=OtherCon []] T4492.$fCMaybe_$cgo = (\ (@ a_aex) (eta_B3 [Occ=Once] :: T4492.C a_aex) (@ b_afH) (eta_B2 [Occ=Once] :: forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_afH -> a1_ae1) (eta_B1 [Occ=Once] :: Data.Maybe.Maybe a_aex) -> T4492.$fCMaybe1 @ a_aex eta_B3 @ b_afH eta_B2 eta_B1) `cast` (forall a_aex. <T4492.C a_aex> -> forall b_afH. <forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_afH -> a1_ae1> -> <Data.Maybe.Maybe a_aex> -> Sym (T4492.TFCo:R:FMaybeb[0] <a_aex> <b_afH>) :: (forall a_aex. T4492.C a_aex => forall b_afH. (forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_afH -> a1_ae1) -> Data.Maybe.Maybe a_aex -> b_afH -> T4492.F a_aex b_afH) ~# (forall a_aex. T4492.C a_aex => forall b_afH. (forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_afH -> a1_ae1) -> Data.Maybe.Maybe a_aex -> T4492.F (Data.Maybe.Maybe a_aex) b_afH)) T4492.$fCMaybe [InlPrag=INLINE (sat-args=0)] :: forall a_aex. T4492.C a_aex => T4492.C (Data.Maybe.Maybe a_aex) [GblId[DFunId(nt)], Arity=3, Caf=NoCafRefs, Str=DmdType <C(C(S)),1*C1(C1(U))><L,U><L,U><L,U>, Unf=OtherCon []] T4492.$fCMaybe = (\ (@ a_aex) (eta_B3 [Occ=Once] :: T4492.C a_aex) (@ b_afH) (eta_B2 [Occ=Once] :: forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_afH -> a1_ae1) (eta_B1 [Occ=Once] :: Data.Maybe.Maybe a_aex) -> T4492.$fCMaybe1 @ a_aex eta_B3 @ b_afH eta_B2 eta_B1) `cast` (forall a_aex. <T4492.C a_aex> -> (forall b_afH. <forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_afH -> a1_ae1> -> <Data.Maybe.Maybe a_aex> -> Sym (T4492.TFCo:R:FMaybeb[0] <a_aex> <b_afH>)) ; Sym (T4492.NTCo:C[0] <Data.Maybe.Maybe a_aex>) :: (forall a_aex. T4492.C a_aex => forall b_afH. (forall a1_ae1. Data.Maybe.Maybe a1_ae1 -> b_afH -> a1_ae1) -> Data.Maybe.Maybe a_aex -> b_afH -> T4492.F a_aex b_afH) ~# (forall a_aex. T4492.C a_aex => T4492.C (Data.Maybe.Maybe a_aex))) *** End of Offense *** <no location info>: Compilation had errors *** unexpected failure for T4492(profasm) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8078> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8100: Standalone deriving using template haskell
by GHC 01 Dec '14

01 Dec '14

#8100: Standalone deriving using template haskell ------------------------------------+------------------------------------- Reporter: acube | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Template Haskell | Version: Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Currently, there seems to be no support for standalone deriving in TemplateHaskell: {{{ Prelude Data.Typeable Language.Haskell.TH> :set -XStandaloneDeriving Prelude Data.Typeable Language.Haskell.TH> data Weird a (b :: * -> * -> *) c = Weird Prelude Data.Typeable Language.Haskell.TH> runQ $ [d| deriving instance Typeable Weird |] [] }}} ''Use case'': The library [http://hackage.haskell.org/package/typeable-th typeable-th] can already generate Typeable instances using TH for GHC 7.4 and 7.6. To add support for GHC 7.8 in a way that the user doesn't have to care about the version, there has to be a way to make Typeable instances via TH in GHC 7.8. This is currently impossible, but with StandaloneDeriving support for TH, it would be possible. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8100> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8044: "Inaccessible code" error reported in wrong place
by GHC 24 Nov '14

24 Nov '14

#8044: "Inaccessible code" error reported in wrong place -------------------------------------------+------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.7 Keywords: GADTs | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------+------------------------------- Here is my file `Bug.hs`: {{{ {-# LANGUAGE GADTs, TypeFamilies #-} module Bug where data X a where XInt :: X Int XBool :: X Bool XChar :: X Char type family Frob a where Frob Int = Int Frob x = Char frob :: X a -> X (Frob a) frob XInt = XInt frob _ = XChar }}} Compiling this file produces the error {{{ Bug.hs:15:6: Couldn't match type ‛Int’ with ‛Char’ Inaccessible code in a pattern with constructor XInt :: X Int, in an equation for ‛frob’ In the pattern: XInt In an equation for ‛frob’: frob XInt = XInt }}} The line/column number single out the pattern `XInt` in the first clause of the function `frob`. But, the real problem (as I see it), is the right- hand side of the ''second'' clause of `frob`. Indeed, when I comment out the second line of the function, the error goes away, even though it was reported on the first line. I do not believe that this error is caused by closed type families, per se, because I have run across it without them, just in code that was too hard to pare down enough to make a bug report out of. This was tested on 7.7.20130702. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8044> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8046: Make the timer management scale better across multicore
by GHC 22 Nov '14

22 Nov '14

#8046: Make the timer management scale better across multicore ------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- A recent commit {{{ commit e843e73690f828498f6e33bb89f47a50c3ab2ac9 Author: Ian Lynagh <ian(a)well-typed.com> Date: Sat Jun 8 20:19:59 2013 +0100 IO manager: Edit the timeout queue directly, rather than using an edit list Fixes #7653. }}} undid an optimization to the management of timeouts (to fix a bug, which is good). We should check how much this hurt performance, but it might be better to rewrite the timeout management altogether. The current scheme scales poorly to several cores. We should probably have one priority queue per core and use an efficient mutable data structure. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8046> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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