March 2018 - ghc-tickets

[GHC] #14944: Compile speed regression
by GHC 19 Apr '18

19 Apr '18

#14944: Compile speed regression -------------------------------------+------------------------------------- Reporter: br1 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.1 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: -------------------------------------+------------------------------------- Compile time went from 5 seconds in 7.6.1 to 12 seconds in 8.2.2 and then down to 10 seconds in 8.4.1. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14944> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14710: GHC 8.4.1-alpha allows the use of kind polymorphism without PolyKinds
by GHC 19 Apr '18

19 Apr '18

#14710: GHC 8.4.1-alpha allows the use of kind polymorphism without PolyKinds -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.4.1 Component: Compiler | Version: 8.4.1-alpha1 (Type checker) | Keywords: PolyKinds | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC accepts Unknown/Multiple | invalid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This program: {{{#!hs {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE ImpredicativeTypes #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE MultiParamTypeClasses #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} {-# OPTIONS_GHC -ddump-deriv #-} module Bug where import Data.Coerce import Data.Proxy class C a b where c :: Proxy (x :: a) -> b newtype I a = MkI a instance C x a => C x (Bug.I a) where c = coerce @(forall (z :: x). Proxy z -> a) @(forall (z :: x). Proxy z -> I a) c }}} is rightfully rejected by GHC 8.2.2: {{{ $ /opt/ghc/8.2.2/bin/ghc Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:20:16: error: Unexpected kind variables Perhaps you intended to use PolyKinds In a type argument | 20 | c = coerce @(forall (z :: x). Proxy z -> a) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Bug.hs:21:16: error: Unexpected kind variables Perhaps you intended to use PolyKinds In a type argument | 21 | @(forall (z :: x). Proxy z -> I a) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }}} But GHC 8.4.1-alpha2 actually //accepts// this program! {{{ $ /opt/ghc/8.4.1/bin/ghci Bug.hs GHCi, version 8.4.0.20180118: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Ok, one module loaded. }}} This is almost certainly bogus. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14710> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14689: Load order of .ghci config files is counterintuitive
by GHC 19 Apr '18

19 Apr '18

#14689: Load order of .ghci config files is counterintuitive -------------------------------------+------------------------------------- Reporter: hal9zillion | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #14250, #6017 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Basically ghci seems to give precedence to global .ghci conguration settings by applying them after any local/project specific .ghci files: https://github.com/ghc/ghc/blob/314bc31489f1f4cd69e913c3b1e33236b2bdf553/gh… OTOH there are a couple of open issues where people dont like the idea of local ghci evaluation for security reasons: #6017 #14250 I suggest the following resolution: - Change the order or evaluation from global first to local - include a new ghci setting that prevents/enables the evaluation of local/project specific .ghci files for people who wish to avoid the security concerns some people have - This flag can then be set in the global .ghci file I believe this would both address the counterintuitive loading strategy implied currently (i was convinced local .ghci files didnt work because when i changed the prompt it was always overwritten by my global config) and the security question. The only question then would be if evaluation of project/local .ghci files would be on or off by default. I would favour the former but that is just personal preference. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14689> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12860: GeneralizedNewtypeDeriving + MultiParamTypeClasses sends typechecker into an infinite loop
by GHC 17 Apr '18

17 Apr '18

#12860: GeneralizedNewtypeDeriving + MultiParamTypeClasses sends typechecker into an infinite loop -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | 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: -------------------------------------+------------------------------------- This worked in GHC 7.6.3, but ever since GHC 7.8, this code will cause the typechecker to loop infinitely: {{{#!hs {-# LANGUAGE FunctionalDependencies #-} {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# LANGUAGE MultiParamTypeClasses #-} module Bug where class C a b | a -> b where c :: a -> Int newtype Foo a = Foo a deriving (C b) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12860> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9074: GHC 7.8.2's ghci does not track missing symbols when loading non-Haskell object files
by GHC 17 Apr '18

17 Apr '18

#9074: GHC 7.8.2's ghci does not track missing symbols when loading non-Haskell object files ------------------------------------+------------------------------------- Reporter: massysett | Owner: Type: bug | Status: new Priority: normal | 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: | ------------------------------------+------------------------------------- I have a package that bundles in C library sources. I never had a problem with this when using GHC 7.6. In GHC 7.8, the order of the c-sources in the cabal file now matters. Sources must be listed earlier if they have symbols that subsequently loaded object files will need. If the c-sources are in the wrong order, when running "cabal repl" I get Loading object (static) dist/build/decnumber/src/decQuad.o ... ghc: panic! (the 'impossible' happened) (GHC version 7.8.2 for x86_64-unknown-linux): Loading temp shared object failed: /tmp/ghc14294_0/ghc14294_1.so: undefined symbol: DECSTICKYTAB Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug When using the same code and cabal file with GHC 7.6, "cabal repl" works fine: GHCi loads each static object (regardless of ordering in the cabal file), links up the necessary symbols, and launches successfully. Haskell Cafe discussion here: http://www.haskell.org/pipermail/haskell-cafe/2014-May/114041.html -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9074> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11045: Loading temp shared object failed - undefined symbol
by GHC 17 Apr '18

17 Apr '18

#11045: Loading temp shared object failed - undefined symbol -------------------------------------+------------------------------------- Reporter: sjakobi | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While re-compiling [https://github.com/commercialhaskell/stack stack]: {{{ $ stack install --ghc-options -O2 stack-0.1.7.0: configure Configuring stack-0.1.7.0... stack-0.1.7.0: build Preprocessing library stack-0.1.7.0... [30 of 74] Compiling Stack.Types.Docker ( src/Stack/Types/Docker.hs, .stack-work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/Types/Docker.o ) [31 of 74] Compiling Options.Applicative.Complicated ( src/Options/Applicative/Complicated.hs, .stack- work/dist/x86_64-linux/Cabal-1.22.4.0/build/Options/Applicative/Complicated.o ) [32 of 74] Compiling Stack.Types.Config ( src/Stack/Types/Config.hs, .stack-work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/Types/Config.o ) [33 of 74] Compiling Stack.Constants ( src/Stack/Constants.hs, .stack- work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/Constants.o ) [Stack.Types.Config changed] [34 of 74] Compiling Stack.Types.Internal ( src/Stack/Types/Internal.hs, .stack-work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/Types/Internal.o ) [Stack.Types.Config changed] [35 of 74] Compiling Stack.Types.StackT ( src/Stack/Types/StackT.hs, .stack-work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/Types/StackT.o ) [36 of 74] Compiling Stack.Docker.GlobalDB ( src/Stack/Docker/GlobalDB.hs, .stack-work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/Docker/GlobalDB.o ) [Stack.Types.Config changed] [37 of 74] Compiling Stack.Types.Package ( src/Stack/Types/Package.hs, .stack-work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/Types/Package.o ) [Stack.Types.Config changed] [38 of 74] Compiling Stack.Types.Build ( src/Stack/Types/Build.hs, .stack- work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/Types/Build.o ) [39 of 74] Compiling Stack.Types ( src/Stack/Types.hs, .stack- work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/Types.o ) [Stack.Types.Build changed] [40 of 74] Compiling Stack.GhcPkg ( src/Stack/GhcPkg.hs, .stack- work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/GhcPkg.o ) [Stack.Constants changed] [41 of 74] Compiling Stack.PackageIndex ( src/Stack/PackageIndex.hs, .stack-work/dist/x86_64-linux/Cabal-1.22.4.0/build/Stack/PackageIndex.o ) [Data.Binary.VersionTagged changed] ghc: panic! (the 'impossible' happened) (GHC version 7.10.2 for x86_64-unknown-linux): Loading temp shared object failed: /tmp/ghc22553_0/libghc_96.so: undefined symbol: stackzuFHzzONQT9HI3ATX2xQH198L_StackziTypesziCompiler_zdfBinaryCompilerVersionzuzdszdfGSumM2_closure Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug -- While building package stack-0.1.7.0 using: /home/simon/.stack/setup-exe-cache/setup-Simple- Cabal-1.22.4.0-x86_64-linux-ghc-7.10.2 --builddir=.stack- work/dist/x86_64-linux/Cabal-1.22.4.0/ build lib:stack exe:stack --ghc- options " -ddump-hi -ddump-to-file" Process exited with code: ExitFailure 1 $ git show commit 2fb2d11fffddde3c44920f7ea93e34b9d3195dad Author: Emanuel Borsboom <manny(a)fpcomplete.com> Date: Sun Nov 1 05:21:16 2015 -0800 <snip> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11045> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11499: Loading temp shared object failed in GHCi
by GHC 17 Apr '18

17 Apr '18

#11499: Loading temp shared object failed in GHCi --------------------------------------+------------------------------- Reporter: alfa07 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.10.3 Keywords: | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+------------------------------- While trying to launch ghci got the following error: ❯ stack ghci The following GHC options are incompatible with GHCi and have not been passed to it: -threaded -Odph Using main module: 1. Package `line-segment-intersection' component exe:demo with main-is file: /Users/maxim/Dev/ComputationGeometry/LineSegmentIntersection/app/Main.hs Configuring GHCi with the following packages: line-segment-intersection, GLUT, GLUtil, boundingboxes, freetype-simple, freetype2 GHCi, version 7.10.3: http://www.haskell.org/ghc/ :? for help ghc: panic! (the 'impossible' happened) (GHC version 7.10.3 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/dz/lm9jncs90nq0vn_5j7xhpg2xqyfj66/T/ghc23900_0/libghc_25.dylib, 5): Symbol not found: _bdf_driver_class Referenced from: /var/folders/dz/lm9jncs90nq0vn_5j7xhpg2xqyfj66/T/ghc23900_0/libghc_25.dylib Expected in: flat namespace in /var/folders/dz/lm9jncs90nq0vn_5j7xhpg2xqyfj66/T/ghc23900_0/libghc_25.dylib Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11499> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14972: MacOS panic on TH
by GHC 17 Apr '18

17 Apr '18

#14972: MacOS panic on TH -------------------------------------+------------------------------------- Reporter: harpocrates | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I recently did a clean build of master (affdea82bb70e5a912b679a169c6e9a230e4c93e) and, while everything successfully finished, I'm getting panics every time I try to use this GHC for something that involves TH. For example: {{{#!hs {-# language TemplateHaskell #-} pure [] main = pure [] }}} Crashes with {{{ $ ./inplace/bin/ghc-stage2 th.hs [1 of 1] Compiling Main ( th.hs, th.o ) ghc-stage2: loadArchive: Failed reading header from `/Users/atheriault/Documents/code/ghc/libraries/integer-gmp/dist- install/build/gmp' ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.5.20180325 for x86_64-apple-darwin): loadArchive "/Users/atheriault/Documents/code/ghc/libraries /integer-gmp/dist-install/build/gmp": failed Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Normally I'd assume I haven't correctly configured something, yet I had no problem building and running GHC on this machine a month or so ago... -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14972> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14988: Memory strain while compiling HLint
by GHC 17 Apr '18

17 Apr '18

#14988: Memory strain while compiling HLint -------------------------------------+------------------------------------- Reporter: mcandre | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: FreeBSD Architecture: x86_64 | Type of failure: Compile-time (amd64) | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I want to setup a build bot for generating Haskell binaries in an automated fashion, however even with 4 GB of RAM, cabal is unable to build HLint in HardenedBSD. Specifically, GHC is choking on mmap errors while compiling HLint's huge dependency tree. Can we somehow shrink the massive memory usage of GHC, so that common packages HLint can be built on medium-low build bots? Imagine GHC running on a RaspberryPi: You're gonna have a bad time. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14988> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12982: Missed constant folding oportunities
by GHC 17 Apr '18

17 Apr '18

#12982: Missed constant folding oportunities -------------------------------------+------------------------------------- Reporter: erikd | Owner: Type: feature | Status: new request | Priority: normal | Milestone: 8.4.1 Component: | Version: 8.0.1 libraries/hoopl | 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: -------------------------------------+------------------------------------- A work colleague of mine found that some expressions were not being constant folded as expected. For example: {{#!hs module Test where import Data.Int number :: Int64 number = 2 ^ 10 - 3 }}} compiled using: {{{ ghc -O2 -keep-s-file -c test.hs }}} should result in an assembler file containing the constant `1021` but doesn't. However, if I change the above expression to: {{{ number = 1024 -3 }}} then the output assembler files does contain the value `1021`. I did a bit of a search and found some constant folding code in the `hoopl` library, but that doesn't seem to be what GHC actually uses. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12982> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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