December 2016 - ghc-tickets

[GHC] #12979: -fspecialise-aggressively is not documented
by GHC 24 Jan '17

24 Jan '17

#12979: -fspecialise-aggressively is not documented -------------------------------------+------------------------------------- Reporter: mpickering | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: newcomer | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I couldn't find any documentation for `-fspecialise-aggressively`. The flag is explained in `compiler/specialise/Specialise` in the note `[Specialise imported INLINABLE things]` but doesn't appear in the user manual! The flag was introduced in b9e49d3e9580e13d89efd1f779cb76f610e0d6e0. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12979> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12663: amazonka-ec2 fails to build with --split-objs
by GHC 24 Jan '17

24 Jan '17

#12663: amazonka-ec2 fails to build with --split-objs -------------------------------------+------------------------------------- Reporter: joehillen | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Linux Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I've created a repo for reproducing this bug: https://github.com/joehillen/ec2-split-objs-bug The bug can appear as either: {{{ [189 of 207] Compiling Network.AWS.EC2.Waiters ( gen/Network/AWS/EC2/Waiters.hs, .stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/Network/AWS/EC2/Waiters.o ) [190 of 207] Compiling Network.AWS.EC2.DeleteVPNConnection ( gen/Network/AWS/EC2/DeleteVPNConnection.hs, .stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/Network/AWS/EC2/DeleteVPNConnection.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-unknown-linux): tyThingTyCon Identifier ‘$fFoldableFirst_$cfold’ Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} or {{{ [189 of 207] Compiling Network.AWS.EC2.Waiters ( gen/Network/AWS/EC2/Waiters.hs, .stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/Network/AWS/EC2/Waiters.o ) [190 of 207] Compiling Network.AWS.EC2.DeleteVPNConnection ( gen/Network/AWS/EC2/DeleteVPNConnection.hs, .stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/Network/AWS/EC2/DeleteVPNConnection.o ) /tmp/stack11/amazonka- ec2-1.4.3/gen/Network/AWS/EC2/DeleteVPNConnection.hs:51:25: error: • Couldn't match expected type ‘Either a0 a10’ with actual type ‘a1 -> ShowS’ • Probable cause: ‘showsPrec’ is applied to too few arguments In the first argument of ‘GHC.Show.showList__’, namely ‘(showsPrec 0)’ In the expression: GHC.Show.showList__ (showsPrec 0) In an equation for ‘showList’: showList = GHC.Show.showList__ (showsPrec 0) When typechecking the code for ‘showList’ in a derived instance for ‘Show DeleteVPNConnection’: To see the code I am typechecking, use -ddump-deriv /tmp/stack11/amazonka- ec2-1.4.3/gen/Network/AWS/EC2/DeleteVPNConnection.hs:104:23: error: • Couldn't match expected type ‘Either a2 a3’ with actual type ‘a4 -> ShowS’ • Probable cause: ‘showsPrec’ is applied to too few arguments In the first argument of ‘GHC.Show.showList__’, namely ‘(showsPrec 0)’ In the expression: GHC.Show.showList__ (showsPrec 0) In an equation for ‘showList’: showList = GHC.Show.showList__ (showsPrec 0) When typechecking the code for ‘showList’ in a derived instance for ‘Show DeleteVPNConnectionResponse’: To see the code I am typechecking, use -ddump-deriv }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12663> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13018: TH-spliced pattern synonym declaration fails to typecheck
by GHC 23 Jan '17

23 Jan '17

#13018: TH-spliced pattern synonym declaration fails to typecheck -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 8.1 Haskell | 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 pattern synonyms typechecks without issue: {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE PatternSynonyms #-} module Works where data T a where MkT :: Eq b => b -> T a pattern P :: b -> T a pattern P x <- MkT x }}} But if you try to create `P` from a Template Haskell splice, it will fail to typecheck: {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE TemplateHaskell #-} module Bug where data T a where MkT :: Eq b => b -> T a $([d| pattern P :: b -> T a; pattern P x <- MkT x |]) }}} {{{ $ /opt/ghc/head/bin/ghc Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:9:3: error: • Couldn't match expected type ‘b0’ with actual type ‘b’ ‘b’ is a rigid type variable bound by a pattern with constructor: MkT :: forall a b. Eq b => b -> T a, in a pattern synonym declaration at Bug.hs:9:3-52 ‘b0’ is a rigid type variable bound by the signature for pattern synonym ‘P’ at Bug.hs:9:3-52 • In the declaration for pattern synonym ‘P’ • Relevant bindings include x_a4tP :: b (bound at Bug.hs:9:3) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13018> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8156: amd64 + in-tree gmp build broken
by GHC 23 Jan '17

23 Jan '17

#8156: amd64 + in-tree gmp build broken -------------------------------------+------------------------------------- Reporter: errge | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.8.1 Component: Build System | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 (amd64) | Type of failure: Building GHC Difficulty: Easy (less than 1 | failed hour) | Test Case: Blocked By: | Blocking: Related Tickets: #4022 #4366 #4374 | -------------------------------------+------------------------------------- Currently, the GHC build system has an in-tree GMP. This GMP seems to be used only if there is no usable GMP found on the system and the user didn't provide one using configure flags. When we build GHC using an external shared version of GMP, the resulting GHC is dynamically linked against GMP and also the generated programs are linked dynamically against GMP. When the in-tree GMP is used, it is built statically, even if the GHC we are building is shared GHC on GNU/Linux. This feature is currently broken on amd64 (#4366, #4022), but is working currently very well on Linux i686. Apart from the breakage this setting is very flexible and I'd be very happy if it were possible to keep it, in spite of removeal requests like #4374. When there is a system GMP, nothing would change, this is the most typical usage, e.g. distributions are all building this way. On the other hand, if the user removes his GMP (maybe we should provide an option to explicity trigger this in ./configure, instead of having to remove GMP); she can build a GHC that is not linked dynamically against GMP and the resulting programs are not linked either. This makes it possible to generate binaries that link dynamically against libc (no -static) which is quite compatible amongst versions, but doesn't require a libgmp.so to run. For binary deployments this seems to be the best kind of setup nowadays. Now, if we were only able to fix this for amd64. See this: https://www.gentoo.org/proj/en/base/amd64/howtos/index.xml?part=1&chap=3 On amd64 we can continue to compile GMP statically and link into the binary library, we just have to compile GMP with the fPIC. I attached the patch to fix this. Previously a similar patch has been rejected in #4022 because "this shouldn't be platform specific", but this is clearly not the case, this is specific to amd64. Tadaaaam: {{{ errge@sid64:~/ghc/inplace/bin$ cat test.hs main = print (2^100) errge@sid64:~/ghc/inplace/bin$ ./ghc-stage2 test.hs [1 of 1] Compiling Main ( test.hs, test.o ) Linking test ... errge@sid64:~/ghc/inplace/bin$ ./test 1267650600228229401496703205376 errge@sid64:~/ghc/inplace/bin$ ldd ./test linux-vdso.so.1 (0x00007fff79962000) libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fe4b9a83000) librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fe4b987a000) libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fe4b9676000) libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fe4b92c6000) libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fe4b90a6000) /lib64/ld-linux-x86-64.so.2 (0x00007fe4b9d83000) }}} No GMP! I attach the build file patch to the bugreport. So, can we please apply this patch and just keep the in-tree GMP? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8156> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12785: GHC panic, TypeFamily in equality constraint
by GHC 23 Jan '17

23 Jan '17

#12785: GHC panic, TypeFamily in equality constraint -------------------------------------+------------------------------------- Reporter: heisenbug | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 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: -------------------------------------+------------------------------------- Compiling the attached module I get {{{ $ ghc --interactive Tree.hs GHCi, version 8.1.20161030: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Tree ( Tree.hs, interpreted ) Tree.hs:28:63: error:ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20161030 for x86_64-apple-darwin): tcTyVarDetails cobox0_a1eK :: (m_a1ej[sk:2] :: Peano) ~# ('S n_a1eJ[ssk:3] :: Peano) Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1076:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1080:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Var.hs:457:22 in ghc:Var Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} When switching the call to `SBranchX` in line 29 to a call to `SBranch` the program compiles. So I suspect that the problem is rooted in the extra constraint attached to constructor `SBranchX`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12785> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9223: Type equality makes type variable untouchable
by GHC 21 Jan '17

21 Jan '17

#9223: Type equality makes type variable untouchable -------------------------------------------+------------------------------- Reporter: Feuerbach | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.8.2 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------+------------------------------- This doesn't look right: {{{ {-# LANGUAGE RankNTypes, TypeFamilies #-} type family TF (m :: * -> *) run1 :: (forall m . Monad m => m a) -> a run1 = undefined run2 :: (forall m . (Monad m, TF m ~ ()) => m a) -> a run2 = undefined -- this works x1 = run1 (return ()) -- this fails x2 = run2 (return ()) {- Couldn't match expected type ‘a’ with actual type ‘()’ ‘a’ is untouchable inside the constraints (Monad m, TF m ~ ()) bound by a type expected by the context: (Monad m, TF m ~ ()) => m a at untouchable.hs:15:6-21 ‘a’ is a rigid type variable bound by the inferred type of x2 :: a at untouchable.hs:15:1 Relevant bindings include x2 :: a (bound at untouchable.hs:15:1) In the first argument of ‘return’, namely ‘()’ In the first argument of ‘run2’, namely ‘(return ())’ -} }}} I would expect x2 to type check just like x1 does. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9223> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12750: hGetContents leads to late/silent failures
by GHC 21 Jan '17

21 Jan '17

#12750: hGetContents leads to late/silent failures -------------------------------------+------------------------------------- Reporter: | Owner: massimo.zaniboni | Type: bug | Status: new Priority: normal | Milestone: Component: Core | Version: 8.0.1 Libraries | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: https://github.com/massimo- | zaniboni/ghc_lazy_file_content_error| Blocking: | Related Tickets: #9236 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I have the same problem described in the closed ticket #9236 This is a test-case https://github.com/massimo- zaniboni/ghc_lazy_file_content_error I tried with ghc 7.10.3 and 8.0.1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12750> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10515: ghc: panic: tyThingTyCon Identifier ‘$fStencil:.a(,,,,)7’
by GHC 21 Jan '17

21 Jan '17

#10515: ghc: panic: tyThingTyCon Identifier ‘$fStencil:.a(,,,,)7’ -------------------------------------+------------------------------------- Reporter: yongqli | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Has anyone seen something like this? {{{ <no location info>: ghc: panic! (the 'impossible' happened) (GHC version 7.10.1.20150519 for x86_64-unknown-linux): tyThingTyCon Identifier ‘$fStencil:.a(,,,,)7’ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10515> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12727: ghc: panic! (the 'impossible' happened) - piResultTy
by GHC 21 Jan '17

21 Jan '17

#12727: ghc: panic! (the 'impossible' happened) - piResultTy -------------------------------------+------------------------------------- Reporter: ocharles | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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: -------------------------------------+------------------------------------- Oddly this only happens on our build server, not on my local machine. On compilation, I get: {{{ [187 of 273] Compiling Query.Order ( Query/Order.hs, dist/build/Query/Order.o ) Query/Order.hs:340:1: warning: [-Wredundant-constraints] • Redundant constraint: MonadBaseControl IO m • In the type signature for: updateOrdersSuccess :: (MonadBaseControl IO m, MonadTransaction m) => m () ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-unknown-linux): piResultTy Maybe Int64 a1_a4WiL Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} The configuration parameters are: {{{ configureFlags: --verbose --prefix=/nix/store /qxfjd5jxr593dn43i3659s86d0rdllyv-circuithub-api-0.0.4 --libdir=$prefix/lib/$compiler --libsubdir=$pkgid --with-gcc=gcc --package-db=/tmp/nix-build-circuithub-api-0.0.4.drv-0/package.conf.d --ghc-option=-j1 --disable-split-objs --disable-library-profiling --disable-profiling --disable-shared --enable-library-vanilla --disable- executable-dynamic --disable-tests }}} I've attached Query/Order.hs, but you won't be able to compile it stand- alone. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12727> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12162: Concatenation of type level symbols missing
by GHC 21 Jan '17

21 Jan '17

#12162: Concatenation of type level symbols missing -------------------------------------+------------------------------------- Reporter: augustss | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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: -------------------------------------+------------------------------------- Type level string literals (of kind Symbol), should have a concatenation operation. It's very useful, e.g., in the library for strongly typed relations that we have. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12162> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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