October 2014 - ghc-tickets

[GHC] #9652: Bootstrapping GHC HEAD against itself doesn't work
by GHC 27 Dec '14

27 Dec '14

#9652: Bootstrapping GHC HEAD against itself doesn't work -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I've got a partial patch: {{{ diff --git a/ghc.mk b/ghc.mk index eedb023..37ef2f2 100644 --- a/ghc.mk +++ b/ghc.mk @@ -719,7 +719,7 @@ ifneq "$(BINDIST)" "YES" ifneq "$(BOOTSTRAPPING_CONF)" "" ifeq "$(wildcard $(BOOTSTRAPPING_CONF))" "" -$(shell echo "[]" >$(BOOTSTRAPPING_CONF)) +$(shell $(GHC_PKG) init $(BOOTSTRAPPING_CONF)) endif endif }}} But I'm dying here: {{{ ===--- building phase 1 make -r --no-print-directory -f ghc.mk phase=1 phase_1_builds libraries/hpc/ghc.mk:3: libraries/hpc/dist-boot/build/.depend-v.haskell: No such file or directory compiler/ghc.mk:646: compiler/stage1/build/.depend-v.haskell: No such file or directory ghc/ghc.mk:114: ghc/stage1/build/.depend.haskell: No such file or directory "rm" -f ghc/stage1/build/.depend.haskell.tmp "/home/hs01/ezyang/ghc-head/inplace/bin/ghc-stage2" -M -static -H32m -O -package-db libraries/bootstrapping.conf -hide-all-packages -i -ighc/. -ighc/stage1/build -ighc/stage1/build/autogen -Ighc/stage1/build -Ighc/stage1/build/autogen -optP-include -optPghc/stage1/build/autogen/cabal_macros.h -package-key array_GX4NwjS8xZkC2ZPtjgwhnz -package-key base_ESD4aQEEWwsHtYJVc1BwtJ -package-key bytes_Kc0PyaputnzDnBdZW0y2Gv -package-key direc_1OR7Bu5EIqqJUPTpfzOCIt -package-key filep_34DFDFT9FVD9pRLLgh8IdQ -package-key ghc_GE0xPzNsQzT2p10hpwDwSW -package-key proce_JJ2k66FcGHSLNmYZUkX8Td -package-key unix_4dEexQFispVG782agZacZC -Wall -XHaskell2010 -no-user-package-db -rtsopts -odir ghc/stage1/build -hidir ghc/stage1/build -stubdir ghc/stage1/build -dep- makefile ghc/stage1/build/.depend.haskell.tmp -dep-suffix "" -include-pkg- deps ghc/./Main.hs <command line>: cannot satisfy -package-key ghc_GE0xPzNsQzT2p10hpwDwSW (use -v for more information) ghc/ghc.mk:114: recipe for target 'ghc/stage1/build/.depend.haskell' failed make[1]: *** [ghc/stage1/build/.depend.haskell] Error 1 Makefile:71: recipe for target 'all' failed make: *** [all] Error 2 }}} A bit hard to diagnose due to #9651. Recording this so I don't forget. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9652> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9032: Panic with self-import
by GHC 27 Dec '14

27 Dec '14

#9032: Panic with self-import -----------------------------------+--------------------------------------- Reporter: jstolarek | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- I've run into GHC panic with this code: {{{ {-# OPTIONS_GHC -fno-warn-unused-imports #-} module Singletons.Star where import Data.Singletons.Prelude import Data.Singletons.Decide import Data.Singletons.CustomStar import Singletons.Nat import Singletons.Star -- <------- HERE data Vec :: * -> Nat -> * where VNil :: Vec a Zero VCons :: a -> Vec a n -> Vec a (Succ n) $(singletonStar [''Nat, ''Int, ''String, ''Maybe, ''Vec]) }}} This is a test in `singletons` package that leads to a panic when run: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.8.2 for x86_64-unknown-linux): tcIfaceGlobal (local): not found: singletons-1.0:Singletons.Star.TFCo:R:DemoteRep*KProxy{tc r0} [] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I was unable to minimize the test case. Reproducing requires following steps: 1. Installing latest th-desugar library from github: {{{ git clone https://github.com/goldfirere/th-desugar.git cd th-desugar cabal install }}} 2. Getting latest development version of singletons: {{{ git clone https://github.com/goldfirere/singletons cd singletons git checkout 56734c2bda721cb9a6a3021b901e3b29d6564f0c make tests }}} All should go well. Now you need to edit file `tests/compile-and- dump/Singletons/Star.hs` and uncomment `import Singletons.Star` line. It should be possible to reproduce the bug with: {{{ cd tests/compile-and-dump/ghc -package-name singletons-1.0 Singletons/Star.hs -i../../dist/build -c -XTemplateHaskell }}} It's important to run `make tests` first so that all interface files required by `Star.hs` are in place. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9032> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8696: linking fails with 'relocation R_X86_64_PC32 against undefined symbol'
by GHC 23 Dec '14

23 Dec '14

#8696: linking fails with 'relocation R_X86_64_PC32 against undefined symbol' ----------------------------------+------------------------------ Reporter: Kata | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc1 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: Other Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------ Building ekmett's lens package from HEAD (revision 80c1fddf) with the following error fragment: {{{ Last 10 lines of the build log ( /home/kata/.cabal/logs/lens-4.0.log ): [77 of 85] Compiling Data.Vector.Lens ( src/Data/Vector/Lens.hs, dist/build/Data/Vector/Lens.o ) [78 of 85] Compiling Data.Vector.Generic.Lens ( src/Data/Vector/Generic/Lens.hs, dist/build/Data/Vector/Generic/Lens.o ) [79 of 85] Compiling Generics.Deriving.Lens ( src/Generics/Deriving/Lens.hs, dist/build/Generics/Deriving/Lens.o ) [80 of 85] Compiling GHC.Generics.Lens ( src/GHC/Generics/Lens.hs, dist/build/GHC/Generics/Lens.o ) [81 of 85] Compiling System.Exit.Lens ( src/System/Exit/Lens.hs, dist/build/System/Exit/Lens.o ) [82 of 85] Compiling System.FilePath.Lens ( src/System/FilePath/Lens.hs, dist/build/System/FilePath/Lens.o ) [83 of 85] Compiling System.IO.Error.Lens ( src/System/IO/Error/Lens.hs, dist/build/System/IO/Error/Lens.o ) /usr/bin/ld: dist/build/Control/Lens/TH.dyn_o: relocation R_X86_64_PC32 against undefined symbol `lenszm4zi0_ControlziLensziInternalziTH_appsE1zulgo_info' can not be used when making a shared object; recompile with -fPIC /usr/bin/ld: final link failed: Bad value collect2: error: ld returned 1 exit status cabal: Error: some packages failed to install: lens-4.0 failed during the building phase. The exception was: ExitFailure 1 }}} Full log is attached. I'm not trying to build with shared libraries, or profiling, or anything like that. I can reproduce this failure starting from a fresh Debian testing install as follows: 1. Bootstrap GHC HEAD. {{{ sudo aptitude install ghc=7.6.3-6 happy=1.19.0-1 alex=3.1.0-1 sudo apt-get build-dep ghc cd /var/tmp git clone git://git.haskell.org/ghc.git cd ghc git checkout e01367ff ./sync-all get ./boot ./configure # Adjust the -j option to taste. make -j4 sudo make install }}} 2. Bootstrap cabal-install. {{{ cd /var/tmp wget http://www.haskell.org/cabal/release/cabal-install-1.18.0.2/cabal- install-1.18.0.2.tar.gz -O - | tar xzf - cd cabal-install-1.18.0.2 patch -p3 < cabal-install-ghc-HEAD.patch # see attached sudo aptitude install zlib1g-dev ./bootstrap.sh export PATH=$HOME/.cabal/bin:$PATH cabal update }}} 3. Build lens. {{{ cd /var/tmp git clone https://github.com/ekmett/lens cd lens git checkout 80c1fddf cabal install cpphs cabal install # this fails }}} Using gcc Debian 4.8.2-14, ld 2.24. The GHC fingerprint and output of `ghc --info` is attached. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8696> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9744: Make program name and project version configurable
by GHC 23 Dec '14

23 Dec '14

#9744: Make program name and project version configurable -------------------------------------+------------------------------------- Reporter: luite | Owner: luite Type: feature request | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- GHC uses `cProjectVersion` in a few places and `ghc` is hardcoded as the program name. This is used for example for determining the location of the user package database (`getAppUserDataDirectory "ghc"`) and the names of dynamic libraries. I've been working around this for GHCJS, but it requires copying quite a bit of code. I have a patch that adds the program name and version to `Settings` that I'll submit once I've tested GHCJS with HEAD. My patch just allows these settings to be changed by GHC API clients. However, we could also make GHC itself read its own values from the `settings` file. This way we could add a version tag to a GHC installation without recompiling, keeping its packages and package databases separate from existing ones. Let me know if there's any interest in this and I'll add it to the patch. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9744> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9751: add runMeta Hook or TcM variant of hscCompileCoreExprHook
by GHC 23 Dec '14

23 Dec '14

#9751: add runMeta Hook or TcM variant of hscCompileCoreExprHook -------------------------------------+------------------------------------- Reporter: luite | Owner: luite Type: task | Status: new Priority: normal | Milestone: 7.10.1 Component: GHC API | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- GHCJS has to jump through hoops to make annotations work and to get the necessary information for linking a TH splice. The main reason is that `hscCompileCoreExprHook` does not expose the `TcM` environment. Easiest fix would be to add {{{#!hs hscCompileCoreExprTcMHook :: HscEnv -> SrcSpan -> CoreExpr -> TcM HValue }}} to `Hooks`, but it'd be better to hook `runMeta` instead. Unfortunately `runMeta` is polymorphic, so it could be more tricky. I'm going to see if I can hook `runMeta` in a reasonable way, and if I run out of time for 7.10.1, send a patch with `hscCompileCoreExprTcMHook` instead. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9751> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9732: Pattern synonyms and unboxed values
by GHC 23 Dec '14

23 Dec '14

#9732: Pattern synonyms and unboxed values -------------------------------------+------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Compile- Blocked By: | time crash Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- It's possible to declare a toplevel unboxed value with a pattern synonym, which causes a panic: {{{ {-# LANGUAGE PatternSynonyms, MagicHash #-} pattern P = 0# }}} (compare with error on `x = 0#`). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9732> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8650: Unexpected behaviour of import ccall "header.h function"
by GHC 21 Dec '14

21 Dec '14

#8650: Unexpected behaviour of import ccall "header.h function" ------------------------------------+-------------------------------------- Reporter: nh2 | 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: Documentation bug Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+-------------------------------------- When I write {{{ foreign import ccall "myheader.h myfunction" function :: IO ... }}} Is GHC supposed to check the existence of the header file, or do anything with it? Because I can still write {{{"myheaderBLA.h myfunction"}}} and it doesn't care about the first word (no error, ever, not even in linking, executable builds all fine). ---- Relatedly, I can write {{{ foreign import ccall "some.rubbish" f :: IO ... }}} and as long as {{{"some.rubbish"}}} contains a dot, nothin in the system will ever complain. carter suggested that maybe names with a dot inside are ignored by a linker. This leads me to the question: In my example above, is {{{myheaderBLA.h}}} actually understood as some kind of file and ignored by e.g. GHC, or is it a garbled symbol name? In that case, why does http://www.haskell.org/onlinereport/haskell2010/haskellch8.html suggest {{{ccall "string.h strlen"}}}? In the other case, why would it suggest this if the {{{"string.h"}}} part is ignored? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8650> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9316: GHC 7.8.3 no longer infers correct type in presence of type families and constraints
by GHC 19 Dec '14

19 Dec '14

#9316: GHC 7.8.3 no longer infers correct type in presence of type families and constraints -------------------------------------+------------------------------------- Reporter: ocharles | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Differential Revisions: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: -------------------------------------+------------------------------------- The following code fails to compile under GHC 7.8.3: {{{ {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE QuasiQuotes #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TemplateHaskell #-} {-# LANGUAGE TypeFamilies #-} module SingletonsBug where import Control.Applicative import Data.Constraint (Dict(..)) import Data.Singletons import Data.Singletons.TH (singletons) import Data.Traversable (for) $(singletons [d| data SubscriptionChannel = BookingsChannel |]) type family T (c :: SubscriptionChannel) :: * type instance T 'BookingsChannel = Bool witnessC :: SSubscriptionChannel channel -> Dict (Show (T channel), SingI channel) witnessC SBookingsChannel = Dict forAllSubscriptionChannels :: forall m r. (Applicative m) => (forall channel. (SingI channel, Show (T channel)) => SSubscriptionChannel channel -> m r) -> m r forAllSubscriptionChannels f = withSomeSing BookingsChannel $ \(sChannel) -> case witnessC sChannel of Dict -> f sChannel }}} {{{ SingletonsBug.hs:38:15: Could not deduce (SingI channel0) arising from a use of ‘f’ from the context (Applicative m) bound by the type signature for forAllSubscriptionChannels :: Applicative m => (forall (channel :: SubscriptionChannel). (SingI channel, Show (T channel)) => SSubscriptionChannel channel -> m r) -> m r at SingletonsBug.hs:(32,6)-(34,8) or from ((Show (T a), SingI a)) bound by a pattern with constructor Dict :: forall (a :: Constraint). (a) => Dict a, in a case alternative at SingletonsBug.hs:38:7-10 The type variable ‘channel0’ is ambiguous Note: there is a potential instance available: instance SingI 'BookingsChannel -- Defined at SingletonsBug.hs:19:3 In the expression: f sChannel In a case alternative: Dict -> f sChannel In the expression: case witnessC sChannel of { Dict -> f sChannel } SingletonsBug.hs:38:17: Couldn't match type ‘channel0’ with ‘a’ because type variable ‘a’ would escape its scope This (rigid, skolem) type variable is bound by a type expected by the context: Sing a -> m r at SingletonsBug.hs:(36,3)-(38,24) Expected type: SSubscriptionChannel channel0 Actual type: Sing a Relevant bindings include sChannel :: Sing a (bound at SingletonsBug.hs:36:36) In the first argument of ‘f’, namely ‘sChannel’ In the expression: f sChannel }}} However, this works fine in GHC 7.8.2. If I change one line to this: {{{ withSomeSing BookingsChannel $ \(sChannel :: SSubscriptionChannel c) -> }}} The code compiles in GHC 7.8.3. Another change that doesn't require a type signature (but changes the program) is to change that constraint from: {{{ Show (T channel), SingI channel }}} to just {{{ SingI channel }}} It seems that the use of the type family breaks the inference, but this might be a bit of a red herring! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9316> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9575: -XAutoDeriveTypeable fails to generate instances
by GHC 19 Dec '14

19 Dec '14

#9575: -XAutoDeriveTypeable fails to generate instances -------------------------------------+------------------------------------- Reporter: hvr | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.4 Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- The following doesn't compile with GHC 7.8.3, but works with GHC HEAD. I couldn't find a matching ticket, so I don't know if this was fixed knowingly or not... {{{#!hs {-# LANGUAGE AutoDeriveTypeable #-} import Data.Typeable (Typeable) data T1 = C1 Int deriving (Eq,Ord) tvoid :: Typeable a => a -> IO () tvoid _ = return () main :: IO () main = tvoid (C1 0) }}} ...fails for GHC 7.8.3 with {{{ No instance for (Typeable T1) arising from a use of ‘tvoid’ In the expression: tvoid (C1 0) In an equation for ‘main’: main = tvoid (C1 0) }}} I'm marking this with high priority, as it makes `-XAutoDeriveTypeable` unusable on GHC 7.8.3 as it stands. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9575> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8984: Improve output of failed GeneralizedNewtypeDeriving coercion due to type roles
by GHC 19 Dec '14

19 Dec '14

#8984: Improve output of failed GeneralizedNewtypeDeriving coercion due to type roles -------------------------------------------+------------------------------- Reporter: haasn | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.8.1 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------+------------------------------- When trying to build acme-schoenfinkel (as an example), I came across an error like this: {{{ Control/Category/Schoenfinkel.hs:66:48: Could not coerce from ‘cat (cat b c, b) c’ to ‘cat (WrappedSchoenfinkel cat b c, b) c’ because ‘cat (cat b c, b) c’ and ‘cat (WrappedSchoenfinkel cat b c, b) c’ are different types. arising from the coercion of the method ‘app’ from type ‘forall b c. cat (cat b c, b) c’ to type ‘forall b c. WrappedSchoenfinkel cat (WrappedSchoenfinkel cat b c, b) c’ Possible fix: use a standalone 'deriving instance' declaration, so you can specify the instance context yourself When deriving the instance for (ArrowApply (WrappedSchoenfinkel cat)) }}} It was not immediately clear to me as a user that this was caused due to it wanting GNT which was now being blocked by type roles (rightfully so, as this instance allows UnsafeCoerce!), and beyond that, what the specific rule that triggered this was. In this case the failure is due to ‘WrappedSchoenfinkel cat b c’ not being nominally equal to ‘cat b c’, in the type ‘(WrappedSchoenfinkel cat b c, b)’, which is required to be nominally equal to ‘(cat b c, b)’ because it's used as a parameter to the variable ‘cat’. Printing a location breakdown and context information similar to this to the user would help understanding and debugging roles a lot. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8984> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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