July 2016 - ghc-tickets

[GHC] #12379: WARN pragma gives warning `warning: [-Wdeprecations]'
by GHC 22 Jun '17

22 Jun '17

#12379: WARN pragma gives warning `warning: [-Wdeprecations]' -------------------------------------+------------------------------------- Reporter: zilinc | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Incorrect (amd64) | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Example: {{{#!hs -- Warn.hs module Warn where __todo :: String -> a {-# WARNING __todo "TODO" #-} __todo msg = error $ "TODO: " ++ msg }}} {{{#!hs -- Main.hs {- OPTIONS_GHC -Wall #-} import Warn inc :: Int -> Int inc n | n >= 0 = n + 1 inc _ = __todo "what about negatives?" }}} When compile the files (or ghci), I get {{{ UseWarn.hs:9:9: warning: [-Wdeprecations] In the use of ‘__todo’ (imported from Warn): "TODO" }}} Should the flag be `-Wwarnings-deprecations`? And `-Wdeprecations` is not in the user guide, if it is a genuine flag. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12379> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11758: Drop x86_64 binutils <2.17 hack
by GHC 20 Jun '17

20 Jun '17

#11758: Drop x86_64 binutils <2.17 hack -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.0.1-rc2 (NCG) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- `X86.CodeGen.genSwitch` contains this comment, {{{ else -- HACK: On x86_64 binutils<2.17 is only able to generate -- PC32 relocations, hence we only get 32-bit offsets in -- the jump table. As these offsets are always negative -- we need to properly sign extend them to 64-bit. This -- hack should be removed in conjunction with the hack in -- PprMach.hs/pprDataItem once binutils 2.17 is standard. }}} binutils 2.17 is now quite standard; even CentOS 5 shipped with 2.17. I think it is likely safe to remove this hack at this point. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11758> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8697: Type rationals
by GHC 16 Jun '17

16 Jun '17

#8697: Type rationals ------------------------------------+------------------------------------- Reporter: MikeIzbicki | Owner: Type: feature request | 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: | ------------------------------------+------------------------------------- I've used GHC's Type Nats to implement my own type level rationals (code below). This works fine, but the syntax is a little funky because you have to write out the number as a fraction. For example, you must write 13/10 instead of 1.3; or even worse, 13/1 instead of 13. It would be nice to just write the decimal notation. I only see one potential problem with this feature: the dot in the decimal notation could interfere with the dot in forall statements. I guess this can be parsed unambiguously, but maybe not. {{{ data Frac = Frac Nat Nat data instance Sing (n::Frac) = SFrac Integer Integer instance (SingI a, SingI b) => SingI ('Frac a b) where sing = SFrac (fromSing (sing :: Sing a)) (fromSing (sing :: Sing b)) instance Fractional r => SingE (Kind :: Frac) r where fromSing (SFrac a b) = fromIntegral a/fromIntegral b type (/) a b = 'Frac a b }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8697> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12056: Too aggressive `-w` option
by GHC 12 Jun '17

12 Jun '17

#12056: Too aggressive `-w` option -------------------------------------+------------------------------------- Reporter: asr | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- By running {{{ ghc -w -Wunrecognised-warning-flags -Wfoo Main.hs }}} I would expect the warning {{{ on the commandline: warning: unrecognised warning flag: -Wfoo }}} however this warning isn't reported. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12056> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11501: Building nofib/fibon returns permission denied
by GHC 08 Jun '17

08 Jun '17

#11501: Building nofib/fibon returns permission denied -------------------------------------+------------------------------------- Reporter: rem | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: NoFib | Version: 7.10.3 benchmark suite | Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: None/Unknown (amd64) | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Building nofib/fibon returns permission denied: {{{ == make boot - --no-print-directory; in /h/ywang30/nofib/fibon/Hackage/Bzlib ------------------------------------------------------------------------ // Codec/Compression/BZip/Stream.hsc make[3]: execvp: //: Permission denied make[3]: *** [Codec/Compression/BZip/Stream.hs] Error 127 }}} Steps to reproduce: Edit nofib/mk/boilerplate.mk:35 to NoFibSubDirs = fibon make clean && make boot in nofib/ -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11501> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11317: Test prog003 fails with segfault on Windows (GHCi)
by GHC 07 Jun '17

07 Jun '17

#11317: Test prog003 fails with segfault on Windows (GHCi) --------------------------------------+------------------------------- Reporter: rdragon | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.11 Keywords: | Operating System: Windows Architecture: x86_64 (amd64) | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: #11234 Differential Rev(s): | Wiki Page: --------------------------------------+------------------------------- On my `x86_64` Windows machine test `prog003` fails with a segfault: {{{ cd ./ghci/prog003 && ghciWayFlags=-static HC="/home/Rik/ghc/inplace/bin /ghc-stage2.exe" HC_OPTS="-dcore-lint -dcmm-lint -dno-debug-output -no- user-package-db -rtsopts -fno-warn-tabs -fno-warn-missed-specialisations -fno-ghci-history " "/home/Rik/ghc/inplace/bin/ghc-stage2.exe" -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-warn-tabs -fno-warn-missed-specialisations -fno-ghci-history --interactive -v0 -ignore-dot-ghci +RTS -I0.1 -RTS <prog003.script > prog003.run.stdout 2> prog003.run.stderr >> prog003.run.stdout 2>> prog003.run.stderr Wrong exit code (expected 0 , actual 1 ) Stdout: Run 1 a :: Int -> Int 168 Run 2 (A.a,B.b,C.c,D.d) :: (Float -> Float, Float -> Float, Float -> Float, Float -> Float) 28.0 Run 3 (A.a,B.b,C.c,D.d) :: (Float -> Float, Float -> Float, Float -> Float, Float -> Float) 28.0 Run 4 (A.a,B.b,C.c,D.d) :: (Float -> Float, Float -> Float, Float -> Float, Float -> Float) 28.0 Run 5 (A.a,B.b,C.c,D.d) :: (Float -> Float, Float -> Float, Float -> Float, Float -> Float) 28.0 Run 6 (A.a,B.b,C.c,D.d) :: (Float -> Float, Float -> Float, Float -> Float, Float -> Float) 28.0 Run 7 (A.a,B.b,C.c,D.d) :: (Float -> Float, Float -> Float, Float -> Float, Float -> Float) 28.0 Run 8 Segmentation fault/access violation in generated code Stderr: *** unexpected failure for prog003(ghci) }}} (I do not think it is an access violation error since when I remove [https://github.com/ghc/ghc/blob/c2fab84239299176a8e72aa26ae894019d677bd9/te… line 65] and everything below line 70, the same stdout is generated.) This looks related to ticket #11234. The GHC version used was [http://git.haskell.org/ghc.git/commit/df6cb57b32d94b7f6f7c9a86207adfeee9712… df6cb57b32d94b7f6f7c9a86207adfeee9712ed6], although I already noticed the problem with a version a few days older. If someone could point me to information about how to install GDB suitable for debugging GHC on my Windows machine I will try to post the stack trace. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11317> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8703: Use guard pages rather than heap checks
by GHC 07 Jun '17

07 Jun '17

#8703: Use guard pages rather than heap checks ------------------------------------+------------------------------------- Reporter: schyler | Owner: simonmar Type: feature request | Status: new Priority: normal | Milestone: Component: Runtime System | Version: Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- By mmap'ing memory using MAP_ANONYMOUS (or /dev/zero) as PROT_NONE (Windows has an equivalent functionality with VirtualAlloc), it's possible to create a page that will fault when read or written to. It may be possible to remove the heap checks in the runtime, speeding up allocations, and instead expand the heap when a fault is raised. This is likely cheaper for large pages full of many small allocations than the cost of the heap checking branch. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8703> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10600: -fwarn-incomplete-patterns doesn't work with -fno-code
by GHC 05 Jun '17

05 Jun '17

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- `-fwarn-incomplete-patterns` doensn't seem to generate any warnings when `-fno-code` is specified. To reproduce, save this module as `foo.hs`. {{{#!hs module Foo where foo True = 4 }}} and compile with `-fwarn-incomplete-patterns`, with and without `-fno- code`. {{{ % ghc -fwarn-incomplete-patterns -fforce-recomp foo.hs [1 of 1] Compiling Foo ( foo.hs, foo.o ) foo.hs:2:1: Warning: Pattern match(es) are non-exhaustive In an equation for ‘foo’: Patterns not matched: False % ghc -fwarn-incomplete-patterns -fforce-recomp -fno-code foo.hs [1 of 1] Compiling Foo ( foo.hs, nothing ) % }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10600> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11032: Missing result type handling for State# s in foreign import prim.
by GHC 02 Jun '17

02 Jun '17

#11032: Missing result type handling for State# s in foreign import prim. -------------------------------------+------------------------------------- Reporter: ekmett | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 (FFI) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I've been using `foreign import prim` for a while now to craft custom primops on an as-needed basis. Attempting to write {{{#!hs {-# LANGUAGE MagicHash #-} {-# LANGUAGE UnboxedTuples #-} {-# LANGUAGE UnliftedFFITypes #-} {-# LANGUAGE GHCForeignImportPrim #-} {-# LANGUAGE ForeignFunctionInterface #-} foreign import prim "pinThreadzh" pinThread# :: State# s -> (# State# s, Int#, Int# #) foreign import prim "unpinThreadzh" unpinThread# :: State# s -> State# s }}} threw me for a loop when it didn't work. The former works fine. The latter complains that `State# s` isn't a valid result type! {{{ src/Concurrent/Internal/Thread.hs:23:1: Unacceptable result type in foreign declaration: ‘State# s’ cannot be marshalled in a foreign call When checking declaration: foreign import prim safe "static unpinThreadzh" unpinThread# :: State# s -> State# s }}} Builtin primitives work this way all the time, so I'm guessing we just missed it in a case statement somewhere inside the compiler when dealing with `foreign import prim` support. I can likely hack around it by giving back something like `(# State# s #)` for now but that is a rather unsatisfying solution. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11032> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12237: Constraint resolution vs. type family resolution vs. TypeErrors
by GHC 01 Jun '17

01 Jun '17

#12237: Constraint resolution vs. type family resolution vs. TypeErrors -------------------------------------+------------------------------------- Reporter: cactus | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple CustomTypeErrors | Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Via http://stackoverflow.com/q/37769351/477476, given the following setup: {{{#!hs {-# LANGUAGE DataKinds, TypeFamilies, TypeOperators #-} {-# LANGUAGE FlexibleContexts, MultiParamTypeClasses, UndecidableInstances #-} import Data.Proxy import GHC.TypeLits type family TEq a b where TEq a a = a TEq a b = TypeError (Text "TEq error") type family F a where F () = () F (a, b) = TEq (F a) (F b) F a = TypeError (Text "Unsupported type: " :<>: ShowType a) }}} and the following usages of `F` and `TEq`: {{{#!hs class (repr ~ F a) => C repr a foo :: (C (F a) a) => proxy a -> () foo _ = () main :: IO () main = print $ foo (Proxy :: Proxy (Int, ())) }}} This results in {{{ * No instance for (C (TEq (TypeError ...) ()) (Int, ())) arising from a use of `foo' * In the second argument of `($)', namely `foo (Proxy :: Proxy (Int, ()))' In the expression: print $ foo (Proxy :: Proxy (Int, ())) In an equation for `main': main = print $ foo (Proxy :: Proxy (Int, ())) }}} but it would be preferable to bail out earlier when `F Int` is resolved to `TypeError ...` instead of propagating that all the way to the `C` constraint. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12237> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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