December 2018 - ghc-tickets

[GHC] #14030: Implement the "Derive Lift instances for data types in template-haskell" proposal
by GHC 06 Mar '19

06 Mar '19

#14030: Implement the "Derive Lift instances for data types in template-haskell" proposal -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: Template | Version: 8.3 Haskell | 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: -------------------------------------+------------------------------------- Back in September 2015, I [https://mail.haskell.org/pipermail/libraries/2015-September/026117.html proposed] using the `DeriveLift` extension to, well, derive `Lift` instance for data types in the `template-haskell` library. The proposal was well received, but I was unable to implement it at the time due to `DeriveLift`'s newness (having only been introduced in GHC 8.0). Now that GHC 8.0 is the oldest version of GHC that we support bootstrapping with, this is no longer an obstacle. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14030> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12596: can't find interface-file declaration
by GHC 06 Mar '19

06 Mar '19

#12596: can't find interface-file declaration -------------------------------------+------------------------------------- Reporter: mwotton | 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: -------------------------------------+------------------------------------- full repro at https://github.com/mwotton/liftwoes/issues/1 ``` /home/mark/projects/liftwoes/src/Lib.hs:14:11: error: • Can't find interface-file declaration for variable Data.Text.Internal.pack Probable cause: bug in .hi-boot file, or inconsistent .hi file Use -ddump-if-trace to get an idea of which file caused the error • In the first argument of ‘(:)’, namely ‘Data.Text.Internal.pack ((:) 'A' [])’ In the first argument of ‘HS.fromList’, namely ``` {{{#!hs {-# LANGUAGE OverloadedStrings #-} {-# LANGUAGE TemplateHaskell #-} module Lib where import Data.Data import qualified Data.Set as HS import qualified Data.Text as T import qualified Data.Text.IO as T import Data.Time -- import Instances.TH.Lift import Instances import Language.Haskell.TH.Syntax table = $(do r <- runIO (HS.fromList . T.lines <$> T.readFile "/usr/share/dict/words") [|r|] ) someFunc = do print $ HS.member "foo" table }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12596> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10892: ApplicativeDo should use *> and <*
by GHC 05 Mar '19

05 Mar '19

#10892: ApplicativeDo should use *> and <* -------------------------------------+------------------------------------- Reporter: simonmar | Owner: Type: task | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- From @ekmett: Would it be possible to tweak the generation to use `(<*)` or `(*>)` where appropriate when the result isn't being used? For many Applicatives this can be a massive asymptotic win in terms of sharing and/or computational cost. When desugaring using (<*) you'd just omit any handling of the unused result instead. {{{ (\x y -> ...) <$> foo <* bar <*> baz }}} corresponds to {{{ do x <- foo bar y <- baz return ... }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10892> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13633: testwsdeque failure on POWER8
by GHC 05 Mar '19

05 Mar '19

#13633: testwsdeque failure on POWER8 ---------------------------------------+---------------------------------- Reporter: trommler | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 8.1 Keywords: SMP | Operating System: Linux Architecture: powerpc64 | Type of failure: Runtime crash Test Case: rts/testwsdeque | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ---------------------------------------+---------------------------------- On a POWER8 `testwsdeque` fails occasionally under load: {{{ Wrong exit code for testwsdeque(threaded1)(expected 0 , actual 134 ) Stderr ( testwsdeque ): internal error: FAIL: 277808608 3 13 (GHC version 8.3.20170430 for powerpc64le_unknown_linux) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13633> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15658: strange inferred kind with TypeInType
by GHC 05 Mar '19

05 Mar '19

#15658: strange inferred kind with TypeInType -------------------------------------+------------------------------------- Reporter: dmwit | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.2 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: -------------------------------------+------------------------------------- This type family has a strange kind to begin with: {{{ {-# Language TypeFamilies , TypeInType #-} type family F f a :: a }}} But it gets even stranger when you ask ghci what it thinks about F: {{{ > :k F F :: * -> forall a -> a }}} There is a forall which doesn't seem to bind any variables and hasn't got the customary delimiting dot. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15658> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14037: Fix fusion for GHC's utility functions
by GHC 05 Mar '19

05 Mar '19

#14037: Fix fusion for GHC's utility functions -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In a patchset I'm working on, I encountered a smallish "bytes allocated" regression in `perf/compiler/T5631`. After some sleuthing, I discovered that the regression is caused by using a `zipWith3M` where previously there was a `zipWithM`. Interestingly, it was not the zipped function that caused the problem, but the `zipWith3M` itself. Further sleuthing found that `zipWithM` is inlined into a combination of `sequenceA` and `zipWith`, both of which have been taught to work nicely with fusion. I thought of doing the same to GHC's `zipWith3M`, but I discovered that `base`'s `zipWith3` has no rules or inlining pragmas, suggesting that it does not fuse. I was quite surprised to find this, thinking that all functions as basic as `zipWith3` in `base` would play nicely with fusion. (Perhaps it does fuse -- I didn't actually check.) I then checked out GHC's `MonadUtils`, which defines a bunch of functions, some of which must be hammered on, and only one of which has any kind of performance- enhancing pragma. (The one is `zipWithAndUnzipM`, whose `INLINABLE` pragma was added only after much pain suffered by your dear author.) So: this ticket is a request to sweep through `MonadUtils` and `Util` and perhaps `ListSetOps`, looking for performance enhancements via fusion, tighter definitions, and such. Also, get `zipWith3` (and the other `zipWith`s) to fuse in `base`. I figure this is all some fairly low-hanging fruit for performance improvements in GHC. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14037> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15072: Teach the testsuite driver about response files
by GHC 05 Mar '19

05 Mar '19

#15072: Teach the testsuite driver about response files -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.2 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: -------------------------------------+------------------------------------- Currently `T14697` is disabled on Windows as that test produces a long enough command-line (mostly `-D` flags) that it runs amok of the Windows command-line length limit. It seems like the solution here will be to teach the testsuite driver to invoke GHC with a response file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15072> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16112: T11334b fails in the devel2 way
by GHC 05 Mar '19

05 Mar '19

#16112: T11334b fails in the devel2 way -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.8.1 Component: Compiler | Version: 8.6.3 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: -------------------------------------+------------------------------------- {{{patch --- dependent/should_fail/T11334b.run/T11334b.stderr.normalised 2018-12-30 16:00:25.377677569 +0000 +++ dependent/should_fail/T11334b.run/T11334b.comp.stderr.normalised 2018-12-30 16:00:25.377677569 +0000 @@ -1,24 +1,13 @@ +ghc: panic! (the 'impossible' happened) + (GHC version 8.7.20181230 for x86_64-unknown-linux): + ASSERT failed! + f_aBF[tau:2] + 2 + 1 + Call stack: + CallStack (from HasCallStack): + callStackDoc, called at compiler/utils/Outputable.hs:<line>:<column> in <package-id>:Outputable + pprPanic, called at compiler/utils/Outputable.hs:<line>:<column> in <package-id>:Outputable + assertPprPanic, called at compiler/typecheck/TcType.hs:<line>:<column> in <package-id>:TcType -T11334b.hs:8:14: - Cannot default kind variable ‘f0’ - of kind: k0 -> * - Perhaps enable PolyKinds or add a kind signature - In an expression type signature: Proxy 'Compose - In the expression: Proxy :: Proxy 'Compose - In an equation for ‘p’: p = Proxy :: Proxy 'Compose - -T11334b.hs:8:14: - Cannot default kind variable ‘g0’ - of kind: k10 -> k0 - Perhaps enable PolyKinds or add a kind signature - In an expression type signature: Proxy 'Compose - In the expression: Proxy :: Proxy 'Compose - In an equation for ‘p’: p = Proxy :: Proxy 'Compose - -T11334b.hs:8:14: - Cannot default kind variable ‘a0’ - of kind: k10 - Perhaps enable PolyKinds or add a kind signature - In an expression type signature: Proxy 'Compose - In the expression: Proxy :: Proxy 'Compose - In an equation for ‘p’: p = Proxy :: Proxy 'Compose +Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16112> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15508: concprog001 fails with various errors when compiled with -prof
by GHC 05 Mar '19

05 Mar '19

#15508: concprog001 fails with various errors when compiled with -prof -------------------------------------+------------------------------------- Reporter: osa1 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Profiling | Version: 8.5 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): Phab:D5051 | Wiki Page: -------------------------------------+------------------------------------- I'm observing a few different runtime errors. I'm not sure if they're because of different bugs so I'm filing one ticket for now. Reproduce with GHC HEAD: {{{ prog001 git:(master) $ ghc-stage2 Mult.hs -prof -fprof-auto -fforce-recomp -debug [1 of 7] Compiling Stream ( Stream.hs, Stream.o ) [2 of 7] Compiling Converter ( Converter.hs, Converter.o ) [3 of 7] Compiling Thread ( Thread.hs, Thread.o ) [4 of 7] Compiling Utilities ( Utilities.hs, Utilities.o ) [5 of 7] Compiling Trit ( Trit.hs, Trit.o ) [6 of 7] Compiling Arithmetic ( Arithmetic.hs, Arithmetic.o ) [7 of 7] Compiling Main ( Mult.hs, Mult.o ) Linking Mult ... prog001 git:(master) $ ./Mult +RTS -DS Mult: internal error: ASSERTION FAILED: file rts/sm/Sanity.c, line 210 (GHC version 8.7.20180809 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug zsh: abort (core dumped) ./Mult +RTS -DS }}} I tried to fix this in Phab:D5051 but it's causing a segfault in test `T11108` when run with profiling. Not sure what the problem is yet. It's very easy to trigger other kind of panics in `concprog001`, just try different compile and runtime flag combinations: {{{ prog001 git:(master) $ ghc-stage2 Mult.hs -prof -fprof-auto -fforce-recomp -threaded [1 of 7] Compiling Stream ( Stream.hs, Stream.o ) [2 of 7] Compiling Converter ( Converter.hs, Converter.o ) [3 of 7] Compiling Thread ( Thread.hs, Thread.o ) [4 of 7] Compiling Utilities ( Utilities.hs, Utilities.o ) [5 of 7] Compiling Trit ( Trit.hs, Trit.o ) [6 of 7] Compiling Arithmetic ( Arithmetic.hs, Arithmetic.o ) [7 of 7] Compiling Main ( Mult.hs, Mult.o ) Linking Mult ... prog001 git:(master) $ ./Mult +RTS -N2 zsh: segmentation fault (core dumped) ./Mult +RTS -N2 }}} Yet another way: {{{ prog001 git:(master) $ ghc-stage2 Mult.hs -prof -fprof-auto -fforce-recomp -threaded -debug [1 of 7] Compiling Stream ( Stream.hs, Stream.o ) [2 of 7] Compiling Converter ( Converter.hs, Converter.o ) [3 of 7] Compiling Thread ( Thread.hs, Thread.o ) [4 of 7] Compiling Utilities ( Utilities.hs, Utilities.o ) [5 of 7] Compiling Trit ( Trit.hs, Trit.o ) [6 of 7] Compiling Arithmetic ( Arithmetic.hs, Arithmetic.o ) [7 of 7] Compiling Main ( Mult.hs, Mult.o ) Linking Mult ... prog001 git:(master) $ ./Mult +RTS -N2 Mult: internal error: invalid closure, info=0x947edc (GHC version 8.7.20180809 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug zsh: abort (core dumped) ./Mult +RTS -N2 }}} It seems to work fine when not compiled for profiling so marking this bug as a profiler bug. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15508> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14671: Make the Template Haskell class Lift work over typed expressions
by GHC 05 Mar '19

05 Mar '19

#14671: Make the Template Haskell class Lift work over typed expressions -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Template | Version: 8.2.2 Haskell | Keywords: | Operating System: Unknown/Multiple TemplateHaskell | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- At the moment we have the `Lift` class in TH: {{{ class Lift t where lift :: t -> Q Exp }}} But that loses type information. What we want is this: {{{ Lift t where typedLift :: t -> Q (TExp t) lift :: Lift t => t -> Q Exp lift = fmap unType . typedLift }}} Otherwise, when you want the typed version, people resort to unsafe-coerce operations, which are entirely unnecessary. See [https://mail.haskell.org/pipermail/libraries/2018-January/028409.html this thread on the libraries list]. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14671> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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