January 2017 - ghc-tickets

Re: [GHC] #605: Optimisation: strict enumerations
by GHC 04 Jan '17

04 Jan '17

#605: Optimisation: strict enumerations -------------------------------------+------------------------------------- Reporter: simonmar | Owner: Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: None Resolution: None | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: N/A Blocked By: | Blocking: Related Tickets: #6135 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by dfeuer): * cc: dfeuer (added) * milestone: ⊥ => 8.2.1 Comment: Setting a milestone because osa1 is working actively in this area. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/605#comment:22> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13061: Incorrect constraints given single flexible undecidable instance
by GHC 03 Jan '17

03 Jan '17

#13061: Incorrect constraints given single flexible undecidable instance -------------------------------------+------------------------------------- Reporter: JCarr | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: Constraint, | Operating System: Unknown/Multiple UndecidableInstances, | FlexibleInstances | Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- If a class has an instance in the form F a => G a in its file, and no other instances, then the functions in G a will have the constraint F a, rather than G a. Example file {{{#!hs {-# LANGUAGE FlexibleInstances, UndecidableInstances #-} class A a where f :: a -> a instance {-# OVERLAPPABLE #-} Eq a => A a where f = id }}} f will have type Eq a => a -> a -> Bool If we add: {{{#!hs instance A Int where f = id }}} Then f will have the type A a => a -> a -> Bool. A function of type A a => ... will always be rejected unless Eq is also included -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13061> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13060: Visible type application doesn't work for functions with inferred types
by GHC 03 Jan '17

03 Jan '17

#13060: Visible type application doesn't work for functions with inferred types -------------------------------------+------------------------------------- Reporter: Feuerbach | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | 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: -------------------------------------+------------------------------------- {{{ GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/feuerbach/.ghci Prelude> :set -XTypeApplications -fprint-explicit-kinds -fprint-explicit- foralls Prelude> :t id id :: forall {a}. a -> a Prelude> :t id @Int id @Int :: Int -> Int Prelude> let foo :: a -> a; foo = id Prelude> :t foo foo :: forall {a}. a -> a Prelude> :t foo @Int foo @Int :: Int -> Int Prelude> let bar = id Prelude> :t bar bar :: forall {a}. a -> a Prelude> :t bar @Int <interactive>:1:1: error: • Cannot apply expression of type ‘a0 -> a0’ to a visible type argument ‘Int’ • In the expression: bar @Int }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13060> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13033: GHC Panics with "colorGraph: trivially colorable nodes didn't color!" on PPC
by GHC 03 Jan '17

03 Jan '17

#13033: GHC Panics with "colorGraph: trivially colorable nodes didn't color!" on PPC -------------------------------------+------------------------------------- Reporter: hvr | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 Component: Compiler | Version: 8.0.2-rc2 Keywords: | Operating System: AIX Architecture: powerpc | Type of failure: Compile-time | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I was finally able to build GHC 8.0.2rc2 (or rather, c5f375c53671130c79713800b13a1da53d070b84 + a minor buildsys fix) on AIX/PPC; most packages seem to work as they did with GHC 8.0.1, however, `unordered-containers` now panics with: {{{ $ cabal get unordered-containers && cd unordered-containers-0.2.7.1/ $ cabal new-build -j1 Resolving dependencies... In order, the following will be built (use -v for more details): - unordered-containers-0.2.7.1 (lib) (first run) Configuring component lib from unordered-containers-0.2.7.1... Preprocessing library unordered-containers-0.2.7.1... [1 of 8] Compiling Data.HashMap.UnsafeShift ( Data/HashMap/UnsafeShift.hs, /home/hvr/unordered-containers-0.2.7.1/dist-newstyle/build/ppc- aix/ghc-8.0.1.20161223/unordered- containers-0.2.7.1/build/Data/HashMap/UnsafeShift.o ) [2 of 8] Compiling Data.HashMap.Unsafe ( Data/HashMap/Unsafe.hs, /home/hvr /unordered-containers-0.2.7.1/dist-newstyle/build/ppc- aix/ghc-8.0.1.20161223/unordered- containers-0.2.7.1/build/Data/HashMap/Unsafe.o ) [3 of 8] Compiling Data.HashMap.PopCount ( Data/HashMap/PopCount.hs, /home/hvr/unordered-containers-0.2.7.1/dist-newstyle/build/ppc- aix/ghc-8.0.1.20161223/unordered- containers-0.2.7.1/build/Data/HashMap/PopCount.o ) [4 of 8] Compiling Data.HashMap.Array ( Data/HashMap/Array.hs, /home/hvr /unordered-containers-0.2.7.1/dist-newstyle/build/ppc- aix/ghc-8.0.1.20161223/unordered- containers-0.2.7.1/build/Data/HashMap/Array.o ) [5 of 8] Compiling Data.HashMap.Base ( Data/HashMap/Base.hs, /home/hvr /unordered-containers-0.2.7.1/dist-newstyle/build/ppc- aix/ghc-8.0.1.20161223/unordered- containers-0.2.7.1/build/Data/HashMap/Base.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1.20161223 for powerpc-ibm-aix): colorGraph: trivially colorable nodes didn't color! ksTriv = [%vHi_HCRu, %vHi_HCRA, %vI_nGN7, %vI_nGNh, %vI_sCRp, %vI_sCRr, %vHi_HCRt, %vHi_HGNi, %vHi_HGNj, %vI_nGN3, %vI_nGN4, %vI_nGN5, %vI_nGN6, %vI_nGN8, %vI_nGN9, %vI_nGNa, %vI_nGNb, %vI_nGNc, %vI_nGNd, %vI_nGNe, %vI_nGNf, %vI_nGNi, %vI_nGNj, %vI_nGNk, %vI_nGNl, %vI_nGNm, %vI_nGNn, %vI_nGNo, %vI_nGNp, %vI_nGNq, %vI_nGNr, %vI_nGNs, %vI_nGNt, %vI_sCRH, %vI_sCRM] ksNoTriv = [%vI_sCRr] colors = [L0 :-> [R3 :-> %r3, R4 :-> %r4, R5 :-> %r5, R6 :-> %r6, R7 :-> %r7, R8 :-> %r8, R9 :-> %r9, Ra :-> %r10, Rb :-> %r11, Rc :-> %r12, Rn :-> %r23, Rq :-> %r26, Rs :-> %r28, Rt :-> %r29, Rv :-> %r31], L2 :-> [Rw :-> %r32, Rx :-> %r33, Ry :-> %r34, Rz :-> %r35, RA :-> %r36, RB :-> %r37, RC :-> %r38, RD :-> %r39, RE :-> %r40, RF :-> %r41, RG :-> %r42, RH :-> %r43, RI :-> %r44, RJ :-> %r45, RQ :-> %r52, RR :-> %r53, RS :-> %r54, RT :-> %r55, RU :-> %r56, RV :-> %r57, RW :-> %r58, RX :-> %r59, RY :-> %r60, RZ :-> %r61, R10 :-> %r62, R11 :-> %r63]] graph G { node [label="%vHi_HCRt :: I\n(%r3)" style=filled fillcolor="white"] "%vHi_HCRt"; node [label="%vHi_HCRu :: I\n-%r3 -%r4 -%r5 -%r6 -%r7 -%r8 -%r9 -%r10 -%r11 -%r12 -%r32 -%r33 -%r34 -%r35 -%r36 -%r37 -%r38 -%r39 -%r40 -%r41 -%r42 -%r43 -%r44 -%r45 +%r3\n(%r23)" style=filled fillcolor="white"] "%vHi_HCRu"; node [label="%vHi_HCRA :: I\n-%r3 -%r4 -%r5 -%r6 -%r7 -%r8 -%r9 -%r10 -%r11 -%r12 -%r32 -%r33 -%r34 -%r35 -%r36 -%r37 -%r38 -%r39 -%r40 -%r41 -%r42 -%r43 -%r44 -%r45 +%r5\n(%r26)" style=filled fillcolor="white"] "%vHi_HCRA"; node [label="%vHi_HGNi :: I\n+%r3\n(%r3)" style=filled fillcolor="white"] "%vHi_HGNi"; node [label="%vHi_HGNj :: I\n-%r3 -%r4 +%r5\n(%r5)" style=filled fillcolor="white"] "%vHi_HGNj"; node [label="%vI_nGN3 :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGN3"; node [label="%vI_nGN4 :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGN4"; node [label="%vI_nGN5 :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGN5"; node [label="%vI_nGN6 :: I\n(%r4)" style=filled fillcolor="white"] "%vI_nGN6"; node [label="%vI_nGN7 :: I\n-%r3 -%r4 -%r5 -%r6 -%r7 -%r8 -%r9 -%r10 -%r11 -%r12 -%r32 -%r33 -%r34 -%r35 -%r36 -%r37 -%r38 -%r39 -%r40 -%r41 -%r42 -%r43 -%r44 -%r45 +%r4\n(%r28)" style=filled fillcolor="white"] "%vI_nGN7"; node [label="%vI_nGN8 :: I\n(%r5)" style=filled fillcolor="white"] "%vI_nGN8"; node [label="%vI_nGN9 :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGN9"; node [label="%vI_nGNa :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNa"; node [label="%vI_nGNb :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNb"; node [label="%vI_nGNc :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNc"; node [label="%vI_nGNd :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNd"; node [label="%vI_nGNe :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNe"; node [label="%vI_nGNf :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNf"; node [label="%vI_nGNh :: I\n-%r3 -%r4 -%r5 -%r6 -%r7 -%r8 -%r9 -%r10 -%r11 -%r12 -%r32 -%r33 -%r34 -%r35 -%r36 -%r37 -%r38 -%r39 -%r40 -%r41 -%r42 -%r43 -%r44 -%r45 +%r6\n(%r29)" style=filled fillcolor="white"] "%vI_nGNh"; node [label="%vI_nGNi :: I\n-%r3 +%r4\n(%r4)" style=filled fillcolor="white"] "%vI_nGNi"; node [label="%vI_nGNj :: I\n-%r3 -%r4 -%r5 +%r6\n(%r6)" style=filled fillcolor="white"] "%vI_nGNj"; node [label="%vI_nGNk :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNk"; node [label="%vI_nGNl :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNl"; node [label="%vI_nGNm :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNm"; node [label="%vI_nGNn :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNn"; node [label="%vI_nGNo :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNo"; node [label="%vI_nGNp :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNp"; node [label="%vI_nGNq :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNq"; node [label="%vI_nGNr :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNr"; node [label="%vI_nGNs :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNs"; node [label="%vI_nGNt :: I\n(%r3)" style=filled fillcolor="white"] "%vI_nGNt"; node [label="%vI_sCRo :: I\n-%r3 -%r4 -%r5 -%r6 -%r7 -%r8 -%r9 -%r10 -%r11 -%r12 -%r32 -%r33 -%r34 -%r35 -%r36 -%r37 -%r38 -%r39 -%r40 -%r41 -%r42 -%r43 -%r44 -%r45\n(spill?)" style=filled fillcolor=white] "%vI_sCRo"; node [label="%vI_sCRp :: I\n-%r3 -%r4 -%r5 -%r6 -%r7 -%r8 -%r9 -%r10 -%r11 -%r12 -%r32 -%r33 -%r34 -%r35 -%r36 -%r37 -%r38 -%r39 -%r40 -%r41 -%r42 -%r43 -%r44 -%r45\n(%r31)" style=filled fillcolor="white"] "%vI_sCRp"; node [label="%vI_sCRr :: I\n-%r3 -%r4 -%r5 -%r6 -%r7 -%r8 -%r9 -%r10 -%r11 -%r12 -%r32 -%r33 -%r34 -%r35 -%r36 -%r37 -%r38 -%r39 -%r40 -%r41 -%r42 -%r43 -%r44 -%r45\n(spill?)" style=filled fillcolor=white] "%vI_sCRr"; node [label="%vI_sCRH :: I\n+%r3\n(%r3)" style=filled fillcolor="white"] "%vI_sCRH"; node [label="%vI_sCRM :: I\n+%r3\n(%r3)" style=filled fillcolor="white"] "%vI_sCRM"; "%vHi_HCRt" -- "%vHi_HCRu"; "%vHi_HCRt" -- "%vI_nGN6"; "%vHi_HCRt" -- "%vI_nGN7"; "%vHi_HCRt" -- "%vI_nGN8"; "%vHi_HCRu" -- "%vHi_HCRA"; "%vHi_HCRu" -- "%vHi_HGNi"; "%vHi_HCRu" -- "%vHi_HGNj"; "%vHi_HCRu" -- "%vI_nGN6"; "%vHi_HCRu" -- "%vI_nGN7"; "%vHi_HCRu" -- "%vI_nGN8"; "%vHi_HCRu" -- "%vI_nGNh"; "%vHi_HCRu" -- "%vI_nGNi"; "%vHi_HCRu" -- "%vI_nGNj"; "%vHi_HCRu" -- "%vI_sCRo"; "%vHi_HCRu" -- "%vI_sCRp"; "%vHi_HCRu" -- "%vI_sCRr"; "%vHi_HCRu" -- "%vI_sCRH"; "%vHi_HCRA" -- "%vHi_HGNi"; "%vHi_HCRA" -- "%vHi_HGNj"; "%vHi_HCRA" -- "%vI_nGN7"; "%vHi_HCRA" -- "%vI_nGNh"; "%vHi_HCRA" -- "%vI_nGNi"; "%vHi_HCRA" -- "%vI_nGNj"; "%vHi_HCRA" -- "%vI_sCRo"; "%vHi_HCRA" -- "%vI_sCRp"; "%vHi_HCRA" -- "%vI_sCRr"; "%vHi_HCRA" -- "%vI_sCRH"; "%vHi_HGNi" -- "%vI_nGN7"; "%vHi_HGNi" -- "%vI_nGNh"; "%vHi_HGNi" -- "%vI_nGNi"; "%vHi_HGNi" -- "%vI_sCRo"; "%vHi_HGNi" -- "%vI_sCRp"; "%vHi_HGNi" -- "%vI_sCRr"; "%vHi_HGNj" -- "%vI_nGN7"; "%vHi_HGNj" -- "%vI_nGNh"; "%vHi_HGNj" -- "%vI_nGNj"; "%vHi_HGNj" -- "%vI_sCRo"; "%vHi_HGNj" -- "%vI_sCRp"; "%vHi_HGNj" -- "%vI_sCRr"; "%vI_nGN6" -- "%vI_nGN7"; "%vI_nGN6" -- "%vI_nGN8"; "%vI_nGN7" -- "%vI_nGN8"; "%vI_nGN7" -- "%vI_nGNh"; "%vI_nGN7" -- "%vI_nGNi"; "%vI_nGN7" -- "%vI_nGNj"; "%vI_nGN7" -- "%vI_sCRo"; "%vI_nGN7" -- "%vI_sCRp"; "%vI_nGN7" -- "%vI_sCRr"; "%vI_nGN7" -- "%vI_sCRH"; "%vI_nGNh" -- "%vI_nGNi"; "%vI_nGNh" -- "%vI_nGNj"; "%vI_nGNh" -- "%vI_sCRo"; "%vI_nGNh" -- "%vI_sCRp"; "%vI_nGNh" -- "%vI_sCRr"; "%vI_nGNh" -- "%vI_sCRH"; "%vI_nGNi" -- "%vI_sCRo"; "%vI_nGNi" -- "%vI_sCRp"; "%vI_nGNi" -- "%vI_sCRr"; "%vI_nGNj" -- "%vI_sCRo"; "%vI_nGNj" -- "%vI_sCRp"; "%vI_nGNj" -- "%vI_sCRr"; "%vI_nGNo" -- "%vI_sCRo"; "%vI_nGNo" -- "%vI_sCRp"; "%vI_nGNo" -- "%vI_sCRr"; "%vI_nGNp" -- "%vI_sCRo"; "%vI_nGNp" -- "%vI_sCRp"; "%vI_nGNp" -- "%vI_sCRr"; "%vI_sCRo" -- "%vI_sCRp"; "%vI_sCRo" -- "%vI_sCRr"; "%vI_sCRo" -- "%vI_sCRH"; "%vI_sCRo" -- "%vI_sCRM"; "%vI_sCRp" -- "%vI_sCRr"; "%vI_sCRp" -- "%vI_sCRH"; "%vI_sCRp" -- "%vI_sCRM"; "%vI_sCRr" -- "%vI_sCRH"; "%vI_sCRr" -- "%vI_sCRM"; } Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13033> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12940: ghc-8.0.2 RC1 libs installed under package dirs vs Cabal installing packages under abi dir
by GHC 03 Jan '17

03 Jan '17

#12940: ghc-8.0.2 RC1 libs installed under package dirs vs Cabal installing packages under abi dir ----------------------------------------+--------------------------------- Reporter: juhpetersen | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 Component: Build System | Version: 8.0.2-rc1 Keywords: | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- This may be more of an inconsistency than a bug: Under Linux, ghc-8.0.1.20161117 installs its dynlibs in package libdirs whereas Cabal-1.24.1.0 installs them under the abi dir: eg /usr/lib/ghc-8.0.2/pkg-version/libHSpkg-version-*.so vs /usr/lib/<arch>-linux-ghc-8.0.2/libHSpkg-version-*.so It would be more consistent for both to install in the same place. Personally I would even suggest just to install ghc dynlibs in /usr/lib itself but that is probably another discuss for Cabal... That would avoid the need for RPATH's entirely. :-) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12940> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13005: Mac OSX uses MAP_ANON in place of MAP_ANONYMOUS
by GHC 03 Jan '17

03 Jan '17

#13005: Mac OSX uses MAP_ANON in place of MAP_ANONYMOUS -------------------------------------+------------------------------------- Reporter: gracjan | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.0.1 (Linking) | Keywords: | Operating System: MacOS X Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Looks like Mac OS X has MAP_ANON instead of MAP_ANONYMOUS in /usr/include/sys/mman.h rts/linker/MachO.c needs fixed. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13005> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12784: Typechecker regression in GHC 8.0.2 involving DefaultSignatures
by GHC 03 Jan '17

03 Jan '17

#12784: Typechecker regression in GHC 8.0.2 involving DefaultSignatures -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: highest | Milestone: 8.0.2 Component: Compiler | Version: 8.1 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: -------------------------------------+------------------------------------- This code compiles without issue on GHC 8.0.1 and earlier, but not with GHC 8.0.2 or HEAD. This was adapted from the [https://github.com/kazu- yamamoto/logger/blob/master/monad-logger/Control/Monad/Logger.hs monad- logger] library (which fails to build with GHC 8.0.2 and HEAD due to the same issue): {{{#!hs {-# LANGUAGE DefaultSignatures #-} {-# LANGUAGE GADTs #-} module MonadLogger where import Control.Monad.IO.Class import qualified Control.Monad.Trans.Class as Trans import Control.Monad.Trans.Identity data Loc data LogSource data LogLevel data LogStr class ToLogStr msg class Monad m => MonadLogger m class (MonadLogger m, MonadIO m) => MonadLoggerIO m where askLoggerIO :: m (Loc -> LogSource -> LogLevel -> LogStr -> IO ()) default askLoggerIO :: (Trans.MonadTrans t, MonadLogger (t m), MonadIO (t m)) => t m (Loc -> LogSource -> LogLevel -> LogStr -> IO ()) askLoggerIO = Trans.lift askLoggerIO instance MonadLogger m => MonadLogger (IdentityT m) instance MonadLoggerIO m => MonadLoggerIO (IdentityT m) }}} On GHC HEAD, this fails with: {{{ [1 of 1] Compiling MonadLogger ( MonadLogger.hs, interpreted ) MonadLogger.hs:23:10: error: • Couldn't match type ‘m’ with ‘IdentityT m’ ‘m’ is a rigid type variable bound by the instance declaration at MonadLogger.hs:23:10-55 Expected type: IdentityT m (Loc -> LogSource -> LogLevel -> LogStr -> IO ()) Actual type: IdentityT (IdentityT m) (Loc -> LogSource -> LogLevel -> LogStr -> IO ()) • In the expression: MonadLogger.$dmaskLoggerIO @IdentityT m In an equation for ‘askLoggerIO’: askLoggerIO = MonadLogger.$dmaskLoggerIO @IdentityT m In the instance declaration for ‘MonadLoggerIO (IdentityT m)’ • Relevant bindings include askLoggerIO :: IdentityT m (Loc -> LogSource -> LogLevel -> LogStr -> IO ()) (bound at MonadLogger.hs:23:10) }}} This stopped typechecking after d2958bd08a049b61941f078e51809c7e63bc3354 (i.e, #12220). As a workaround, you can change the default signature to: {{{#!hs default askLoggerIO :: (Trans.MonadTrans t, MonadLoggerIO n, t n ~ m) => t n (Loc -> LogSource -> LogLevel -> LogStr -> IO ()) }}} And it'll work. Any thoughts on this, Simon? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12784> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13040: realToFrac into Complex Double has no specialization
by GHC 03 Jan '17

03 Jan '17

#13040: realToFrac into Complex Double has no specialization -------------------------------------+------------------------------------- Reporter: akio | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 8.0.1 libraries/base | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Runtime Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Example: {{{#!hs module Foo where import Data.Complex f :: Double -> Complex Double f x = realToFrac x }}} `ghc -O -ddump-simpl` gives: {{{ f = \ (w_s17v :: Double) -> case w_s17v of _ [Occ=Dead] { GHC.Types.D# ww1_s17y -> case GHC.Float.$w$ctoRational ww1_s17y of _ [Occ=Dead] { (# ww3_a152, ww4_a153 #) -> case GHC.Float.rationalToDouble ww3_a152 ww4_a153 of dt_a15c { GHC.Types.D# ipv_a15g -> Data.Complex.:+ @ Double dt_a15c Data.Complex.$fFloatingComplex1 } } } }}} This means the conversion goes through Rational. However, in this case, the conversion could be done much more efficiently with `(:+0)`. It would be nice if this happened automatically. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13040> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13057: Build failing
by GHC 03 Jan '17

03 Jan '17

#13057: Build failing -------------------------------------+------------------------------------- Reporter: salmon | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.0.1 Keywords: | Operating System: Windows Architecture: x86_64 | Type of failure: Building GHC (amd64) | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I pulled changes and ran make. Received this error message for compiling utils/ghc-pkg/Main.hs. {{{ utils\ghc-pkg\Main.hs:1110:43: error: Not in scope: data constructor ‘AbiDependency’ Perhaps you meant ‘Dependency’ (imported from Distribution.Package) make[1]: *** [utils/ghc-pkg/ghc.mk:60: utils/ghc-pkg/dist/build/Main.o] Error 1 make: *** [Makefile:125: all] Error 2 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13057> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12879: (xs -> xs) wrongly suggests TypeApplications
by GHC 03 Jan '17

03 Jan '17

#12879: (xs -> xs) wrongly suggests TypeApplications -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- `(xs -> xs)` and `map (xs -> xs)` wrongly suggest `TypeApplications` {{{ > map (xs -> xs) <interactive>:38:6: error: Pattern syntax in expression context: xs -> xs Did you mean to enable TypeApplications? }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12879> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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