June 2014 - ghc-tickets

[GHC] #9169: Add mkWeakTMVar to Control.Concurrent.STM.TMVar
by GHC 15 Dec '14

15 Dec '14

#9169: Add mkWeakTMVar to Control.Concurrent.STM.TMVar -------------------------------------+------------------------------------- Reporter: basvandijk | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: libraries (other) | Version: 7.8.2 Keywords: stm | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- I just needed a Weak pointer to a TMVar: {{{ -- | Make a 'Weak' pointer to a 'TMVar', using the second argument as -- a finalizer to run when 'TMVar' is garbage-collected. mkWeakTMVar :: TMVar a -> IO () -> IO (Weak (TMVar a)) mkWeakTMVar tmv@(TMVar (TVar t#)) f = IO $ \s -> case mkWeak# t# tmv f s of (# s1, w #) -> (# s1, Weak w #) }}} It might make sense to add a similar function for TSem as well. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9169> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8778: Typeable TypeNats
by GHC 15 Dec '14

15 Dec '14

#8778: Typeable TypeNats -------------------------------------------+------------------------------- Reporter: dmcclean | Owner: Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler (Type checker) | Version: 7.8.1-rc1 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: 4385 | Test Case: | Blocking: -------------------------------------------+------------------------------- It would be useful (the case I have at hand is for some scenarios involving checking of physical dimensions) to be able to combine the Data.Dynamic story with the GHC.TypeLits story. A Typeable instance for every Nat is the sticking point. (I do not know if this is even theoretically possible.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8778> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8988: Documentation build fails if GHCi is unavailable
by GHC 15 Dec '14

15 Dec '14

#8988: Documentation build fails if GHCi is unavailable -------------------------------------+------------------------------------- Reporter: cjwatson | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.8.1 checker) | Operating System: Linux Keywords: | Type of failure: Building GHC Architecture: arm | failed Difficulty: Easy (less than 1 | Test Case: hour) | Blocking: Blocked By: | Related Tickets: | -------------------------------------+------------------------------------- Joachim Breitner [http://www.haskell.org/pipermail/glasgow-haskell- users/2014-March/024730.html reported] that the documentation fails to build on Debian armhf: {{{ 0% ( 0 / 5) in 'WwLib' 0% ( 0 / 2) in 'DmdAnal' 0% ( 0 / 2) in 'WorkWrap' compiler/typecheck/TcSplice.lhs-boot:29:1: TcSplice.tcTopSpliceExpr is exported by the hs-boot file, but not exported by the module compiler/typecheck/TcSplice.lhs-boot:37:1: TcSplice.runMetaE is exported by the hs-boot file, but not exported by the module compiler/typecheck/TcSplice.lhs-boot:38:1: TcSplice.runMetaP is exported by the hs-boot file, but not exported by the module compiler/typecheck/TcSplice.lhs-boot:39:1: TcSplice.runMetaT is exported by the hs-boot file, but not exported by the module compiler/typecheck/TcSplice.lhs-boot:40:1: TcSplice.runMetaD is exported by the hs-boot file, but not exported by the module 67% ( 2 / 3) in 'CmmPipeline' 0% ( 0 / 3) in 'StgCmmHpc' 0% ( 0 / 13) in 'PrelInfo' 0% ( 0 / 4) in 'StgCmmCon' 0% ( 0 / 2) in 'StgCmmExpr' 0% ( 0 / 6) in 'StgCmmBind' 0% ( 0 / 2) in 'CmmParse' 0% ( 0 / 2) in 'StgCmm' 5% ( 9 /175) in 'TcRnMonad' make[2]: *** [compiler/stage2/doc/html/ghc/ghc.haddock] Error 1 }}} The attached patch fixes this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8988> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8951: genSym uses atomic_inc but doesn't link arm_atomic_spin_lock
by GHC 15 Dec '14

15 Dec '14

#8951: genSym uses atomic_inc but doesn't link arm_atomic_spin_lock --------------------------------+---------------------------------------- Reporter: cjwatson | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.8.1-rc1 Keywords: | Operating System: Linux Architecture: arm | Type of failure: Building GHC failed Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | --------------------------------+---------------------------------------- On Debian armel, a snapshot of GHC 7.8 from 20140228 fails to build as follows: https://buildd.debian.org/status/fetch.php?pkg=ghc&arch=armel&ver=7.8.20140… {{{ "inplace/bin/ghc-stage2" -o utils/haddock/dist/build/tmp/haddock -hisuf hi -osuf o -hcsuf hc -static -H32m -O -lffi -optl-pthread -optc-mlong-calls -hide-all-packages -i -iutils/haddock/driver -iutils/haddock/src -iutils/haddock/vendor/attoparsec-0.10.4.0 -iutils/haddock/dist/build -iutils/haddock/dist/build/autogen -Iutils/haddock/dist/build -Iutils/haddock/dist/build/autogen -optP-DIN_GHC_TREE -optP-include -optPutils/haddock/dist/build/autogen/cabal_macros.h -package Cabal-1.18.1.3 -package array-0.5.0.0 -package base-4.7.0.0 -package bytestring-0.10.4.0 -package containers-0.5.4.0 -package deepseq-1.3.0.2 -package directory-1.2.0.2 -package filepath-1.3.0.2 -package ghc-7.8.0.20140228 -package xhtml-3000.2.1 -funbox-strict-fields -Wall -fwarn-tabs -O2 -XHaskell2010 -no-user-package-db -rtsopts -odir utils/haddock/dist/build -hidir utils/haddock/dist/build -stubdir utils/haddock/dist/build utils/haddock/dist/build/Main.o utils/haddock/dist/build/Documentation/Haddock.o utils/haddock/dist/build/Data/Attoparsec.o utils/haddock/dist/build/Data/Attoparsec/ByteString.o utils/haddock/dist/build/Data/Attoparsec/ByteString/Char8.o utils/haddock/dist/build/Data/Attoparsec/Combinator.o utils/haddock/dist/build/Data/Attoparsec/Number.o utils/haddock/dist/build/Data/Attoparsec/ByteString/FastSet.o utils/haddock/dist/build/Data/Attoparsec/ByteString/Internal.o utils/haddock/dist/build/Data/Attoparsec/Internal.o utils/haddock/dist/build/Data/Attoparsec/Internal/Types.o utils/haddock/dist/build/Haddock.o utils/haddock/dist/build/Haddock/Interface.o utils/haddock/dist/build/Haddock/Interface/Rename.o utils/haddock/dist/build/Haddock/Interface/Create.o utils/haddock/dist/build/Haddock/Interface/AttachInstances.o utils/haddock/dist/build/Haddock/Interface/LexParseRn.o utils/haddock/dist/build/Haddock/Interface/ParseModuleHeader.o utils/haddock/dist/build/Haddock/Parser.o utils/haddock/dist/build/Haddock/Parser/Util.o utils/haddock/dist/build/Haddock/Utf8.o utils/haddock/dist/build/Haddock/Utils.o utils/haddock/dist/build/Haddock/Backends/Xhtml.o utils/haddock/dist/build/Haddock/Backends/Xhtml/Decl.o utils/haddock/dist/build/Haddock/Backends/Xhtml/DocMarkup.o utils/haddock/dist/build/Haddock/Backends/Xhtml/Layout.o utils/haddock/dist/build/Haddock/Backends/Xhtml/Names.o utils/haddock/dist/build/Haddock/Backends/Xhtml/Themes.o utils/haddock/dist/build/Haddock/Backends/Xhtml/Types.o utils/haddock/dist/build/Haddock/Backends/Xhtml/Utils.o utils/haddock/dist/build/Haddock/Backends/LaTeX.o utils/haddock/dist/build/Haddock/Backends/HaddockDB.o utils/haddock/dist/build/Haddock/Backends/Hoogle.o utils/haddock/dist/build/Haddock/ModuleTree.o utils/haddock/dist/build/Haddock/Types.o utils/haddock/dist/build/Haddock/Doc.o utils/haddock/dist/build/Haddock/Version.o utils/haddock/dist/build/Haddock/InterfaceFile.o utils/haddock/dist/build/Haddock/Options.o utils/haddock/dist/build/Haddock/GhcUtils.o utils/haddock/dist/build/Haddock/Convert.o utils/haddock/dist/build/Paths_haddock.o /«PKGBUILDDIR»/compiler/stage2/build/libHSghc-7.8.0.20140228.a(genSym.o): In function `genSym': genSym.c:(.text+0x84): undefined reference to `arm_atomic_spin_lock' genSym.c:(.text+0x88): undefined reference to `arm_atomic_spin_unlock' collect2: error: ld returned 1 exit status make[2]: *** [utils/haddock/dist/build/tmp/haddock] Error 1 }}} Our armel architecture satisfies "arm_HOST_ARCH && defined(arm_HOST_ARCH_PRE_ARMv6)", so cas() in includes/stg/SMP.h will (uniquely among architectures) not be entirely inline: it calls arm_atomic_spin_lock and arm_atomic_spin_unlock, which are in libHSrts. 7.8 introduces compiler/cbits/genSym.c which uses atomic_inc. How should the linkage requirements be satisfied here? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8951> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8240: Better error messages for type family constraints
by GHC 11 Dec '14

11 Dec '14

#8240: Better error messages for type family constraints ------------------------------------+------------------------------------- Reporter: simonpj | 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: | ------------------------------------+------------------------------------- Consider this constraint {{{ F Int ~ Bool -- Arising (say) on line 5 F Int ~ Char -- Arising (say) on line 10 }}} At the moment we'll combine the two to {{{ F Int ~ Bool -- Arising on line 5 Bool ~ Char -- Arising on line 10 }}} The second of these errors is "insoluble" and is reported first. But it's totally misleading: nowhere in the program did we directly need `Int~Char`. Another variant of this came up in Trac #8227. There we get the constraint {{{ Scalar (V a) ~ t0 Scalar (V a) ~ t0 -> t0 }}} which leads to {{{ Scalar (V a) ~ t0 -> t0 t0 ~ t0 -> t0 -- Occurs check }}} which gives the confusing error {{{ T8227.hs:16:44: Occurs check: cannot construct the infinite type: t0 ~ t0 -> t0 Expected type: Scalar (V (t0 -> t0)) Actual type: Scalar (V a) }}} I think the solution is * Do not combine two Wanteds {{{ [W] F tys ~ t1 [W] F tys ~ t2 }}} unless t1 and t2 are both touchable unification variables. * Instead (perhaps) generate a Derived constraint {{{ [D] t1 ~ t2 }}} to express the fact that t1 and t2 had better end up equal. * To do this the inert set would need to contain many `CTyFunEq` constraints with the same LHS. I'm not very sure about this, and no time now, so I'm just making this ticket to record the issue. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8240> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9090: Untouchable higher-kinded type variable in connection with RankNTypes, ConstraintKinds and TypeFamilies
by GHC 11 Dec '14

11 Dec '14

#9090: Untouchable higher-kinded type variable in connection with RankNTypes, ConstraintKinds and TypeFamilies -------------------------------------+------------------------------------- Reporter: kosmikus | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.8.2 checker) | Operating System: Unknown/Multiple Keywords: | Type of failure: GHC rejects Architecture: Unknown/Multiple | valid program Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- I have the following module {{{ {-# LANGUAGE RankNTypes, ConstraintKinds, TypeFamilies #-} import GHC.Exts (Constraint) type family D (c :: Constraint) :: Constraint type instance D (Eq a) = Eq a -- checks f :: Eq b => (forall a. D (Eq a) => f a -> Bool) -> f b -> Bool f g x = g x -- checks f' :: Eq b => (forall a. Eq a => f a -> Bool) -> f b -> Bool f' = f -- checks, so GHC seems to think that both types are interchangeable f'' :: Eq b => (forall a. D (Eq a) => f a -> Bool) -> f b -> Bool f'' = f' -- checks test' y = f' (\ (Just x) -> x /= x) y -- fails test y = f (\ (Just x) -> x /= x) y -- fails too, unsurprisingly test'' y = f'' (\ (Just x) -> x /= x) y }}} The module checks with GHC-7.6.3, but fails in GHC-7.8.2 and GHC-7.9.20140430 with {{{ src/Test.hs:24:16: Couldn't match type ‘f’ with ‘Maybe’ ‘f’ is untouchable inside the constraints (D (Eq a)) bound by a type expected by the context: (D (Eq a)) => f a -> Bool at src/Test.hs:24:10-35 ‘f’ is a rigid type variable bound by the inferred type of test :: Eq b => f b -> Bool at src/Test.hs:24:1 Possible fix: add a type signature for ‘test’ Expected type: f a Actual type: Maybe a Relevant bindings include y :: f b (bound at src/Test.hs:24:6) test :: f b -> Bool (bound at src/Test.hs:24:1) In the pattern: Just x In the first argument of ‘f’, namely ‘(\ (Just x) -> x /= x)’ In the expression: f (\ (Just x) -> x /= x) y src/Test.hs:27:20: Couldn't match type ‘f’ with ‘Maybe’ ‘f’ is untouchable inside the constraints (D (Eq a)) bound by a type expected by the context: (D (Eq a)) => f a -> Bool at src/Test.hs:27:12-39 ‘f’ is a rigid type variable bound by the inferred type of test'' :: Eq b => f b -> Bool at src/Test.hs:27:1 Possible fix: add a type signature for ‘test''’ Expected type: f a Actual type: Maybe a Relevant bindings include y :: f b (bound at src/Test.hs:27:8) test'' :: f b -> Bool (bound at src/Test.hs:27:1) In the pattern: Just x In the first argument of ‘f''’, namely ‘(\ (Just x) -> x /= x)’ In the expression: f'' (\ (Just x) -> x /= x) y }}} I'd expect it to typecheck. At first, I thought this might be related in some way to #8985. That's why I tested with HEAD, but while #8985 seems indeed to be fixed, this is still a problem there. Also, while my simplified test case compiles with GHC-7.6.3, my original more complicated program does not, so there might be another report forthcoming if I manage to isolate the difference. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9090> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8894: Clean up `Coercible` plumbing
by GHC 03 Dec '14

03 Dec '14

#8894: Clean up `Coercible` plumbing ------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Currently, the way `Coercible` is exported (with an data type in `GHC.Types` and a built-in !TyCon exported in `GHC.Prim`) works, but is confusing and should be cleaned up. Probably by exporting it directly from `GHC.Types`. Care needs to be taken that ghci and haddock display the data from modified built-in !TyCon; when I tried that a while ago it was displayed as a regular data type by one of them. If that is still the case and I didn't just do a mistake back then, this probably needs to be understood and fixed. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8894> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9142: LLVM HEAD rejects aliases used by LLVM codegen
by GHC 03 Dec '14

03 Dec '14

#9142: LLVM HEAD rejects aliases used by LLVM codegen ------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- LLVM HEAD has [https://github.com/llvm- mirror/llvm/commit/38048cdb1c016e1429004ddf4adfa40a8d853cbf changed] the behavior of aliases to reject references to things other than definitions. This unfortunately means that the handling of externs breaks, {{{ "inplace/bin/ghc-stage1" -static -H64m -O0 -fllvm -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist- ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -package-name rts -dcmm-lint -i -irts -irts/dist/build -irts/dist/build/autogen -Irts/dist/build -Irts/dist/build/autogen -O2 -c rts/Apply.cmm -o rts/dist/build/Apply.o You are using a new version of LLVM that hasn't been tested yet! We will try though... Alias must point to a definition i8* @"barf$alias" Alias must point to a definition i8* @"stg_gc_unpt_r1$alias" Alias must point to a definition i8* @"stg_apply_interp_info$alias" Alias must point to a definition i8* @"stg_yield_to_interpreter$alias" Alias must point to a definition i8* @"stg_ap_stack_entries$alias" Alias must point to a definition i8* @"__stg_gc_enter_1$alias" Alias must point to a definition i8* @"stg_upd_frame_info$alias" LLVM ERROR: Broken module found, compilation aborted! }}} In reference to the following aliases,. {{{ @barf = external global i8 @barf$alias = alias private i8* @barf @stg_gc_unpt_r1 = external global i8 @stg_gc_unpt_r1$alias = alias private i8* @stg_gc_unpt_r1 @stg_apply_interp_info = external global i8 @stg_apply_interp_info$alias = alias private i8* @stg_apply_interp_info @stg_yield_to_interpreter = external global i8 @stg_yield_to_interpreter$alias = alias private i8* @stg_yield_to_interpreter @stg_ap_stack_entries = external global i8 @stg_ap_stack_entries$alias = alias private i8* @stg_ap_stack_entries @__stg_gc_enter_1 = external global i8 @__stg_gc_enter_1$alias = alias private i8* @__stg_gc_enter_1 @stg_upd_frame_info = external global i8 @stg_upd_frame_info$alias = alias private i8* @stg_upd_frame_info }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9142> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8548: Coercible does not resolve type family application
by GHC 02 Dec '14

02 Dec '14

#8548: Coercible does not resolve type family application -------------------------------------------+------------------------------- Reporter: nomeata | Owner: nomeata Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.6.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: #8503 | Test Case: | Blocking: -------------------------------------------+------------------------------- With GND implemented using `Coercible` (See #8503) the test for #4185 fails. A minimal example is: {{{ {-# LANGUAGE TypeFamilies #-} module CoerceNewtypeFamily where import GHC.Exts data family Foo k newtype instance Foo Int = FooInt Int x :: Foo Int -> Int x = coerce }}} yielding {{{ [1 of 1] Compiling CoerceNewtypeFamily ( CoerceNewtypeFamily.hs, CoerceNewtypeFamily.o ) CoerceNewtypeFamily.hs:11:5: No instance for (Coercible (Foo Int) Int) because ‛Foo Int’ and ‛Int’ are different types. arising from a use of ‛coerce’ In the expression: coerce In an equation for ‛x’: x = coerce }}} I guess the `Coercible` finding code needs to simply type family equations if possible. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8548> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9240: "read . show ≡ id" not satisfied by Data.Fixed
by GHC 02 Dec '14

02 Dec '14

#9240: "read . show ≡ id" not satisfied by Data.Fixed ------------------------------------+------------------------------------- Reporter: hvr | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: libraries/base | Version: 7.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #9213 | ------------------------------------+------------------------------------- As pointed out in #9213, the desired property "read . show ≡ id" is not satisfied for all resolutions. For instance, consider the following example: {{{ > data B7 > instance HasResolution B7 where resolution _ = 128 > 1.070 :: Fixed B7 1.062 > 1.062 :: Fixed B7 1.054 > read "1.070" :: Fixed B7 1.062 > read "1.062" :: Fixed B7 1.054 }}} This behaviour can be reproduced all the way back to GHC 7.2.1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9240> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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