June 2015 - ghc-tickets

[GHC] #9911: Pattern synonyms with no signatures should yield warnings
by GHC 15 Dec '15

15 Dec '15

#9911: Pattern synonyms with no signatures should yield warnings -------------------------------------+------------------------------------- Reporter: cactus | Owner: cactus Type: feature request | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler (Type | Version: 7.8.3 checker) | Operating System: Keywords: PatternSynonyms | Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Incorrect Difficulty: Unknown | warning at compile-time Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- When `-fwarn-missing-signatures` is turned on, GHC should emit warnings for pattern synonyms with no signatures -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9911> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9923: Offer copy-on-GC sliced arrays
by GHC 15 Dec '15

15 Dec '15

#9923: Offer copy-on-GC sliced arrays -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: simonmar Type: feature request | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.11 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- It's sometimes useful to split an array and send each part on to a different computation. Slicing works very well for this sort of thing, as long as both computations run to completion or become garbage at about the same time. It can work badly, however, if one computation is completed or abandoned and the other is retained—it may only hold a tiny slice, but that's enough to keep the entire array alive. The alternative, currently, is to copy the array to form two new arrays. This gets rid of the retention problem, but introduces a performance problem. One way to solve these problems might be to offer sliced arrays supported by the RTS. On collection, the garbage collector would copy each slice separately, turning it into an independent (and independently collectible) array. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9923> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9931: Option to truncate Show output in ghci REPL
by GHC 15 Dec '15

15 Dec '15

#9931: Option to truncate Show output in ghci REPL -------------------------------------+------------------------------------- Reporter: pumpkin | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Perhaps a configurable limit, with a :more (or :all) that would give you more if you ask for it. Seems pretty harmless and could help usability a bit. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9931> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9974: Allow more general structural recursion without UndecidableInstances
by GHC 15 Dec '15

15 Dec '15

#9974: Allow more general structural recursion without UndecidableInstances -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.11 Component: Compiler | Operating System: Unknown/Multiple (Type checker) | Type of failure: None/Unknown Keywords: | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- I bet this is a duplicate, but I couldn't find it. A simple example from the `HList` package: {{{#!hs type family HRevApp (l1 :: [k]) (l2 :: [k]) :: [k] type instance HRevApp '[] l = l type instance HRevApp (e ': l) l' = HRevApp l (e ': l') }}} GHC 7.8.3 and 7.11 both complain about the second instance if `UndecidableInstances` is turned off, because the application is no smaller than the index head. Moreover, the same error occurs when the type family is closed. However, GHC already knows how to separate term-level definitions into recursive groups; applying this same analysis to the type family above would reveal that `HRevApp` is structurally recursive, and therefore decidable. It is key, in this case, that the instance for `[]` is visible from the instance declaration for `e ': l`, so such an analysis could only be done in module dependency order for open type families. Side note: there is a (nasty) workaround available for the problem in this case: {{{#!hs type family HRevApp' (l1 :: [k]) (l1' :: [k]) (l2 :: [k]) :: [k] type instance HRevApp' t '[] l = l type instance HRevApp' (e ': l) (e' ': l') l'' = HRevApp' l l' (e ': l'') type HRevApp l1 l2 = HRevApp' l1 l1 l2 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9974> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9981: Potential typechecker regression in GHC 7.10.1RC
by GHC 15 Dec '15

15 Dec '15

#9981: Potential typechecker regression in GHC 7.10.1RC -------------------------------------+------------------------------------- Reporter: hvr | Owner: simonpj Type: bug | Status: new Priority: highest | Milestone: 7.10.1 Component: Compiler | Version: 7.10.1-rc1 (Type checker) | Operating System: Unknown/Multiple Keywords: | Type of failure: GHC rejects Architecture: | valid program Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The following snippet (extracted from hackage:index-core) is accepted by GHCs prior to GHC 7.10: {{{#!hs {-# LANGUAGE Rank2Types, TypeOperators #-} module Foo where type a :-> b = forall i . a i -> b i class IFunctor f where fmapI :: (a :-> b) -> (f a :-> f b) class (IFunctor m) => IMonad m where returnI :: a :-> m a bindI :: (a :-> m b) -> (m a :-> m b) (?>=) :: (IMonad m) => m a i -> (a :-> m b) -> m b i (?>=) = flip bindI }}} {{{ $ ghci-7.8.4 -Wall Foo.hs GHCi, version 7.8.4: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. [1 of 1] Compiling Control.IMonad.Core ( Foo.hs, interpreted ) Ok, modules loaded: Control.IMonad.Core. λ:2> :browse type (:->) (a :: * -> *) (b :: * -> *) = forall i. a i -> b i class IFunctor (f :: (* -> *) -> * -> *) where fmapI :: (a :-> b) -> f a :-> f b class IFunctor m => IMonad (m :: (* -> *) -> * -> *) where returnI :: a i -> m a i bindI :: (a :-> m b) -> m a :-> m b (?>=) :: IMonad m => m a i -> (a :-> m b) -> m b i }}} vs. {{{ $ ghci-7.10.0.20141227 -Wall Foo.hs GHCi, version 7.10.0.20141227: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Control.IMonad.Core ( Foo.hs, interpreted ) Foo.hs:15:14: Couldn't match type ‘a i0 -> m b i0’ with ‘forall i1. a i1 -> m b i1’ Expected type: (a i0 -> m b i0) -> m a i -> m b i Actual type: a :-> m b -> m a i -> m b i Relevant bindings include (?>=) :: m a i -> a :-> m b -> m b i (bound at Foo.hs:15:1) In the first argument of ‘flip’, namely ‘bindI’ In the expression: flip bindI Failed, modules loaded: none. λ:2> }}} I'm not sure though whether that module was valid to begin with... -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9981> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9996: Support symbols in GHCi tab completion
by GHC 15 Dec '15

15 Dec '15

#9996: Support symbols in GHCi tab completion -------------------------------------+------------------------------------- Reporter: shachaf | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.8.4 Component: GHCi | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Right now, when typing e.g. `>` followed by two tabs, GHCi shows every name in scope rather than just names beginning with `>`. It even lists operators as possible completions, but ignores it when you type the beginning of an operator's name. It would be better if it could actually complete every option it shows as a possible completion. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9996> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8294: T7478 fails on Mac OS X with "unexpected bindingNone" from ld
by GHC 15 Dec '15

15 Dec '15

#8294: T7478 fails on Mac OS X with "unexpected bindingNone" from ld -----------------------------------+--------------------------------------- Reporter: ezyang | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHC API | Version: 7.7 Keywords: | Operating System: MacOS X Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: T7478 Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- (Tangentially, the test script was swallowing up relevant output; you need to get rid of the output hook to see any debugging output from GHC proper). Linker step fails: {{{ *** Linker: /usr/bin/gcc -m64 -fno-stack-protector -DTABLES_NEXT_TO_CODE -m64 -v -o A -Wl,-no_compact_unwind C.o -L/Users/ezyang/Dev/ghc-init/libraries/base /dist-install/build -L/Users/ezyang/Dev/ghc-init/libraries/integer-gmp /dist-install/build -L/Users/ezyang/Dev/ghc-init/libraries/ghc-prim/dist- install/build -L/Users/ezyang/Dev/ghc-init/rts/dist/build /var/folders/l8/1lth36c11yg8dv_3kz779_th0000gn/T/ghc26290_0/ghc26290_10.o -lHSbase-4.7.0.0-ghc7.7.20130913 -lHSinteger-gmp-0.5.1.0-ghc7.7.20130913 -lHSghc-prim-0.3.1.0-ghc7.7.20130913 -lHSrts-ghc7.7.20130913 -lffi -liconv -lm -ldl -Wl,-u,_ghczmprim_GHCziTypes_Izh_static_info -Wl,-u,_ghczmprim_GHCziTypes_Czh_static_info -Wl,-u,_ghczmprim_GHCziTypes_Fzh_static_info -Wl,-u,_ghczmprim_GHCziTypes_Dzh_static_info -Wl,-u,_base_GHCziPtr_Ptr_static_info -Wl,-u,_ghczmprim_GHCziTypes_Wzh_static_info -Wl,-u,_base_GHCziInt_I8zh_static_info -Wl,-u,_base_GHCziInt_I16zh_static_info -Wl,-u,_base_GHCziInt_I32zh_static_info -Wl,-u,_base_GHCziInt_I64zh_static_info -Wl,-u,_base_GHCziWord_W8zh_static_info -Wl,-u,_base_GHCziWord_W16zh_static_info -Wl,-u,_base_GHCziWord_W32zh_static_info -Wl,-u,_base_GHCziWord_W64zh_static_info -Wl,-u,_base_GHCziStable_StablePtr_static_info -Wl,-u,_ghczmprim_GHCziTypes_Izh_con_info -Wl,-u,_ghczmprim_GHCziTypes_Czh_con_info -Wl,-u,_ghczmprim_GHCziTypes_Fzh_con_info -Wl,-u,_ghczmprim_GHCziTypes_Dzh_con_info -Wl,-u,_base_GHCziPtr_Ptr_con_info -Wl,-u,_base_GHCziPtr_FunPtr_con_info -Wl,-u,_base_GHCziStable_StablePtr_con_info -Wl,-u,_ghczmprim_GHCziTypes_False_closure -Wl,-u,_ghczmprim_GHCziTypes_True_closure -Wl,-u,_base_GHCziPack_unpackCString_closure -Wl,-u,_base_GHCziIOziException_stackOverflow_closure -Wl,-u,_base_GHCziIOziException_heapOverflow_closure -Wl,-u,_base_ControlziExceptionziBase_nonTermination_closure -Wl,-u,_base_GHCziIOziException_blockedIndefinitelyOnMVar_closure -Wl,-u,_base_GHCziIOziException_blockedIndefinitelyOnSTM_closure -Wl,-u,_base_ControlziExceptionziBase_nestedAtomically_closure -Wl,-u,_base_GHCziWeak_runFinalizzerBatch_closure -Wl,-u,_base_GHCziTopHandler_flushStdHandles_closure -Wl,-u,_base_GHCziTopHandler_runIO_closure -Wl,-u,_base_GHCziTopHandler_runNonIO_closure -Wl,-u,_base_GHCziConcziIO_ensureIOManagerIsRunning_closure -Wl,-u,_base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure -Wl,-u,_base_GHCziConcziSync_runSparks_closure -Wl,-u,_base_GHCziConcziSignal_runHandlers_closure -Wl,-search_paths_first Using built-in specs. Target: i686-apple-darwin11 Configured with: /private/var/tmp/llvmgcc42/llvmgcc42-2336.11~182/src/configure --disable- checking --enable-werror --prefix=/Applications/Xcode.app/Contents/Developer/usr/llvm-gcc-4.2 --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program- prefix=llvm- --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with- slibdir=/usr/lib --build=i686-apple-darwin11 --enable- llvm=/private/var/tmp/llvmgcc42/llvmgcc42-2336.11~182/dst- llvmCore/Developer/usr/local --program-prefix=i686-apple-darwin11- --host=x86_64-apple-darwin11 --target=i686-apple-darwin11 --with-gxx- include-dir=/usr/include/c++/4.2.1 Thread model: posix gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00) /usr/llvm-gcc-4.2/bin/../libexec/gcc/i686-apple-darwin11/4.2.1/collect2 -dynamic -arch x86_64 -macosx_version_min 10.8.3 -weak_reference_mismatches non-weak -o A -lcrt1.10.6.o -L/Users/ezyang/Dev /ghc-init/libraries/base/dist-install/build -L/Users/ezyang/Dev/ghc- init/libraries/integer-gmp/dist-install/build -L/Users/ezyang/Dev/ghc- init/libraries/ghc-prim/dist-install/build -L/Users/ezyang/Dev/ghc- init/rts/dist/build -L/usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple- darwin11/4.2.1/x86_64 -L/Applications/Xcode.app/Contents/Developer/usr /llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1/x86_64 -L/usr/llvm- gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1 -L/usr/llvm- gcc-4.2/bin/../lib/gcc -L/Applications/Xcode.app/Contents/Developer/usr /llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1 -L/usr/llvm- gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/../../.. -L/Applications/Xcode.app/Contents/Developer/usr/llvm-gcc-4.2/lib/gcc/i686 -apple-darwin11/4.2.1/../../.. -no_compact_unwind C.o /var/folders/l8/1lth36c11yg8dv_3kz779_th0000gn/T/ghc26290_0/ghc26290_10.o -lHSbase-4.7.0.0-ghc7.7.20130913 -lHSinteger-gmp-0.5.1.0-ghc7.7.20130913 -lHSghc-prim-0.3.1.0-ghc7.7.20130913 -lHSrts-ghc7.7.20130913 -lffi -liconv -lm -ldl -u _ghczmprim_GHCziTypes_Izh_static_info -u _ghczmprim_GHCziTypes_Czh_static_info -u _ghczmprim_GHCziTypes_Fzh_static_info -u _ghczmprim_GHCziTypes_Dzh_static_info -u _base_GHCziPtr_Ptr_static_info -u _ghczmprim_GHCziTypes_Wzh_static_info -u _base_GHCziInt_I8zh_static_info -u _base_GHCziInt_I16zh_static_info -u _base_GHCziInt_I32zh_static_info -u _base_GHCziInt_I64zh_static_info -u _base_GHCziWord_W8zh_static_info -u _base_GHCziWord_W16zh_static_info -u _base_GHCziWord_W32zh_static_info -u _base_GHCziWord_W64zh_static_info -u _base_GHCziStable_StablePtr_static_info -u _ghczmprim_GHCziTypes_Izh_con_info -u _ghczmprim_GHCziTypes_Czh_con_info -u _ghczmprim_GHCziTypes_Fzh_con_info -u _ghczmprim_GHCziTypes_Dzh_con_info -u _base_GHCziPtr_Ptr_con_info -u _base_GHCziPtr_FunPtr_con_info -u _base_GHCziStable_StablePtr_con_info -u _ghczmprim_GHCziTypes_False_closure -u _ghczmprim_GHCziTypes_True_closure -u _base_GHCziPack_unpackCString_closure -u _base_GHCziIOziException_stackOverflow_closure -u _base_GHCziIOziException_heapOverflow_closure -u _base_ControlziExceptionziBase_nonTermination_closure -u _base_GHCziIOziException_blockedIndefinitelyOnMVar_closure -u _base_GHCziIOziException_blockedIndefinitelyOnSTM_closure -u _base_ControlziExceptionziBase_nestedAtomically_closure -u _base_GHCziWeak_runFinalizzerBatch_closure -u _base_GHCziTopHandler_flushStdHandles_closure -u _base_GHCziTopHandler_runIO_closure -u _base_GHCziTopHandler_runNonIO_closure -u _base_GHCziConcziIO_ensureIOManagerIsRunning_closure -u _base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure -u _base_GHCziConcziSync_runSparks_closure -u _base_GHCziConcziSignal_runHandlers_closure -search_paths_first -lSystem -lgcc -lSystem ld: warning: PIE disabled. Absolute addressing (perhaps -mdynamic-no-pic) not allowed in code signed PIE, but used in _Main_main_info from C.o. To fix this warning, don't compile with -mdynamic-no-pic or link with -Wl,-no_pie final section layout: __TEXT/__text addr=0x100000D30, size=0x00000218, fileOffset=0x00000D30, type=1 __TEXT/__stubs addr=0x100000F48, size=0x0000001E, fileOffset=0x00000F48, type=27 __TEXT/__stub_helper addr=0x100000F68, size=0x00000042, fileOffset=0x00000F68, type=31 __TEXT/__eh_frame addr=0x100000FB0, size=0x00000048, fileOffset=0x00000FB0, type=18 __DATA/__program_vars addr=0x100001000, size=0x00000028, fileOffset=0x00001000, type=29 __DATA/__got addr=0x100001028, size=0x00000020, fileOffset=0x00001028, type=28 __DATA/__nl_symbol_ptr addr=0x100001048, size=0x00000010, fileOffset=0x00001048, type=28 __DATA/__la_symbol_ptr addr=0x100001058, size=0x00000028, fileOffset=0x00001058, type=26 __DATA/__data addr=0x100001080, size=0x00000040, fileOffset=0x00001080, type=0 __DATA/__const addr=0x1000010C0, size=0x00000018, fileOffset=0x000010C0, type=0 __DATA/__common addr=0x1000010D8, size=0x00000020, fileOffset=0x00000000, type=24 ld: unexpected bindingNone in '_Main_main_info' from C.o for architecture x86_64 collect2: ld returned 1 exit status T7478: T7478: phase `Linker' failed (exitcode = 1) }}} Unfortunately, I don't know what a bindingNone is... -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8294> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9632: Promotable type synonyms (or: synonyms to promoted types)
by GHC 14 Dec '15

14 Dec '15

#9632: Promotable type synonyms (or: synonyms to promoted types) -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: checker) | Operating System: Keywords: | Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Difficulty: Unknown | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I want to use '''synonyms to promoted types''' in the same places where I can use the '''promoted types''': {{{#!hs {-# LANGUAGE DataKinds, KindSignatures #-} module PromotableTypeSynonyms where data B = T | F data P :: B -> * type B' = B data P' :: B' -> * -- using B' synonym here is currently not allowed }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9632> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10250: API Annotations : add Locations in hsSyn were layout occurs
by GHC 14 Dec '15

14 Dec '15

#10250: API Annotations : add Locations in hsSyn were layout occurs -------------------------------------+------------------------------------- Reporter: alanz | Owner: alanz Type: task | Status: new Priority: normal | Milestone: 7.10.2 Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple ApiAnnotations | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- At the moment ghc-exactprint, which uses the GHC API Annotations to provide a framework for roundtripping Haskell source code with optional AST edits, has to implement a horrible workaround to manage the points where layout needs to be captured. These are MatchGroup HsDo HsCmdDo HsLet LetStmt HsCmdLet GRHSs To provide a more natural representation, the contents subject to layout rules need to be wrapped in a SrcSpan. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10250> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10238: Update libffi shortly before first GHC 7.12.1 RC
by GHC 14 Dec '15

14 Dec '15

#10238: Update libffi shortly before first GHC 7.12.1 RC -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: highest | Milestone: 7.12.1 Component: Runtime | Version: System | Operating System: Unknown/Multiple Keywords: libffi | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Making this ticket so I don't forget to check for the latest libffi release shortly before the first RC (like I missed that "libffi-3.2.1 was released on November 12, 2014" which would have been in time for 7.10.1RC1) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10238> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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