April 2017 - ghc-tickets

[GHC] #11298: Implicit call stack empty in instance declarations
by GHC 01 Nov '17

01 Nov '17

#11298: Implicit call stack empty in instance declarations -------------------------------------+------------------------------------- Reporter: pikajude | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Given the following code: {{{#!hs {-# LANGUAGE ImplicitParams #-} import GHC.Stack class Foo a where foo :: a -> String main = putStrLn $ foo () }}} In GHC 7.11.20151216, the following instances result in no output: {{{#!hs instance Foo () where foo () = prettyCallStack ?loc }}} {{{#!hs fooHelper = prettyCallStack ?loc instance Foo () where foo () = fooHelper }}} Though this one does: {{{#!hs fooHelper () = prettyCallStack ?loc instance Foo () where foo = fooHelper }}} The aforementioned instances all yield output with GHC 7.10.3 (after replacing `prettyCallStack` with `showCallStack`). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11298> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13372: Attach CallStack to IOError, add CallStack constraints to relevant functions in base
by GHC 31 Oct '17

31 Oct '17

#13372: Attach CallStack to IOError, add CallStack constraints to relevant functions in base -------------------------------------+------------------------------------- Reporter: ezyang | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 8.1 libraries/base | 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: -------------------------------------+------------------------------------- In #12096 it is requested that we add CallStack to SomeException. This is a more conservative request for adding CallStack to IOError only. IOError is already an abstract data type, so it is a simple matter to augment it with space for a CallStack. The main design flex point is whether or not a `CallStack` should be associated with an IOError when it is constructed, or when it is thrown. There are pros and cons to both: 1. If it is associated at construction time, the call stack will reflect when the IOError was constructed, not when it was thrown. This could be arbitrarily far away from the actual throw site. I've been mostly using CallStack for monadic code, and so my primary concern is with where in the monadic code the exception was thrown, so this info isn't really what I want. 2. If it is associated at throw time, there are a few other problems. First, if someone uses throwIO rather than ioError, we won't actually associate a CallStack with the value. Second, if a user is rethrowing an exception, they may accidentally overwrite the old stack trace; but it was the original one that I wanted. For now, I suggest going with (1). Here is the proposal: * Add `ioeGetCallStack` and `ioeSetCallStack`, for setting and getting the `CallStack` recorded in `IOError` * `userError` and `mkIOError` gain a `HasCallStack` constraint. We have a choice for `annotateIOError`, but my suggestion is to NOT annotate it. * Let's annotate all functions that (transitively) may raise an IOError in base with `HasCallStack`. The primary benefit is now if I have a "file not found" exception or similar, I automatically get a stack trace saying exactly what code was run where the file was not found. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13372> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12143: ApplicativeDo Fails to Desugar 'return True'
by GHC 31 Oct '17

31 Oct '17

#12143: ApplicativeDo Fails to Desugar 'return True' -------------------------------------+------------------------------------- Reporter: MichaelBurge | 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: -------------------------------------+------------------------------------- If I bring in a spurious parameter, ApplicativeDo correctly infers Functor. {{{ Prelude> :t \m -> do { x <- m; return True; } \m -> do { x <- m; return True; } :: Functor f => f t -> f Bool Prelude> :t \m -> do { m; return True; } \m -> do { m; return True; } :: Monad m => m a -> m Bool }}} However, without the spurious parameter, ApplicativeDo assumes monad. {{{ Prelude> :t do { return True; } do { return True; } :: Monad m => m Bool }}} The first block in particular shows two examples that seem inconsistent when placed next to each other. It seems like if 'x' is unused, then 'x <- m' and 'm' should be equivalent. I would expect all of these to desugar to Functor or Applicative. And maybe 'return True' should be Monad, but 'do { return True; }' should be Applicative? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12143> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13222: Update formalism for join points
by GHC 30 Oct '17

30 Oct '17

#13222: Update formalism for join points -------------------------------------+------------------------------------- Reporter: lukemaurer | Owner: lukemaurer Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Keywords: JoinPoints | 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 rather flagrantly violated the entreaties in `CoreLint` about updating the formalism (namely by adding join points). Need to fix that. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13222> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13038: implementation of Modus ponens and Modus tollens
by GHC 28 Oct '17

28 Oct '17

#13038: implementation of Modus ponens and Modus tollens -------------------------------------+------------------------------------- Reporter: vanto | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 8.0.1 libraries/base | 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: -------------------------------------+------------------------------------- Can we have in Prelude - Booleans, Modus ponens and Modus tollens implemented? Or in another module? reminder:[[BR]] P is a proposition and v(p) is the logic value of P.[[BR]] P is true, v(P) = 1[[BR]] P is false, v(P) = 0[[BR]] P -> Q is always true in propositional logic. Modus ponens:[[BR]] v(P) = 1[[BR]] v(P -> Q) = 1[[BR]] v(Q) = 1[[BR]] v(P) and v(P -> q) are premiss, v(q) is the conclusion.[[BR]] or in a more general form[[BR]] P : X is A[[BR]] P -> Q : A -> B[[BR]] Q : X is B[[BR]] Modus tollens:[[BR]] v(Q) = 0[[BR]] v(P -> Q) = 1[[BR]] v(P) = 0[[BR]] v(Q) and v(P -> Q) are premiss, v(P) is the conclusion.[[BR]] or in a more general form[[BR]] not Q : X is not B[[BR]] P -> Q : A -> B[[BR]] not P : X is not A[[BR]][[BR]] As well as using the numbers 0 and 1 for the respective values false and true, we'll use the letters F for False and T for True.[[BR]] We are always:[[BR]] v(F) = 0[[BR]] v(T) = 1[[BR]] v(P -> Q) = 1[[BR]] -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13038> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13394: PatternSynonyms/OverloadedStrings regression in GHC HEAD
by GHC 27 Oct '17

27 Oct '17

#13394: PatternSynonyms/OverloadedStrings regression in GHC HEAD -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple PatternSynonyms | Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- `purescript-0.10.7` fails to build with GHC HEAD at the moment due to an apparent regression in the way pattern synonyms and overloaded strings interact. Here is a simplified example: {{{#!hs {-# LANGUAGE OverloadedStrings #-} {-# LANGUAGE PatternSynonyms #-} module Bug where import Data.ByteString newtype ProperName = ProperName { runProperName :: ByteString -- purescript actually uses the Text type, but this works -- just as well for the purposes of illustrating the bug } newtype ModuleName = ModuleName [ProperName] pattern TypeDataSymbol :: ModuleName pattern TypeDataSymbol = ModuleName [ProperName "Type",ProperName "Data", ProperName "Symbol"] }}} Compiling this with GHC 7.10.3 or 8.0.2 works without issue. In GHC HEAD, if you compile this with optimization enabled, it'll trigger a GHC panic: {{{ $ ~/Software/ghc5/inplace/bin/ghc-stage2 -O1 -fforce-recomp Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20170303 for x86_64-unknown-linux): isUnliftedType r_a28T :: TYPE rep_a28S Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1191:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1195:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1961:10 in ghc:Type }}} The presence of optimization is crucial for reproducing this bug, as compiling it with `-O0` does not trigger the panic. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13394> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13356: gmp/ghc.mk's use of TARGETPLATFORM and BUILDPLATFORM is wrong
by GHC 23 Oct '17

23 Oct '17

#13356: gmp/ghc.mk's use of TARGETPLATFORM and BUILDPLATFORM is wrong -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- `libraries/integer-gmp/gmp/ghc.mk` invokes `libgmp`'s configure script with the options {{{ --host=$(TARGETPLATFORM) --build=$(BUILDPLATFORM) }}} Using `TARGETPLATFORM` is wrong, as it is the GHC-munged target triple. For example if the triple passed to the top-level configure script was `--target=aarch64-apple-darwin14` (for iPhone), `TARGETPLATFORM` will be `aarch64-apple-ios`, which `configure` does not understand. Instead of `TARGETPLATFORM` we should use `TargetPlatformFull`. I don't think we have a corresponding variable for `BUILDPLATFORM`, so we should add one if it's important. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13356> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12479: build fail of commercialhaskell.com with stack build on mac os x sierra beta 4
by GHC 20 Oct '17

20 Oct '17

#12479: build fail of commercialhaskell.com with stack build on mac os x sierra beta 4 -------------------------------------+------------------------------------- Reporter: stephenb | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Hi, git clone (commit dfe55e97ed86567aafca2e5f3c19096e2a4cb50f - Sep 20th 2016) of commercialhaskell.com from github: {{{ https://github.com/commercialhaskell/commercialhaskell.com.git }}} follow instructions from that repo exactly for os x (stacksetup installed ghc-7.10.2, but i have seen similar issue with 8): {{{ $ brew install icu4c Add the following to your ~/.stack/stack.yaml: extra-include-dirs: - /usr/local/opt/icu4c/include extra-lib-dirs: - /usr/local/opt/icu4c/lib Now: $ stack build }}} Hit one minor issue in build process with icu4c, resolving with following stack build: {{{ stack build --extra-lib-dirs=/usr/local/opt/icu4c/lib --extra-include- dirs=/usr/local/opt/icu4c/include }}} reach build of yesod-auth, with a failure: {{{ yesod-auth-1.4.6: configure yesod-auth-1.4.6: build texmath-0.8.2.2: copy/register Progress: 35/38 -- While building package yesod-auth-1.4.6 using: /Users/stephen/.stack/setup-exe-cache/x86_64-osx/setup-Simple- Cabal-1.22.4.0-ghc-7.10.2 --builddir=.stack- work/dist/x86_64-osx/Cabal-1.22.4.0 build --ghc-options " -ddump-hi -ddump-to-file" Process exited with code: ExitFailure 1 Logs have been written to: /Users/stephen/Documents/github/commercialhaskell.com/.stack-work/logs /yesod-auth-1.4.6.log Configuring yesod-auth-1.4.6... Building yesod-auth-1.4.6... Preprocessing library yesod-auth-1.4.6... [ 1 of 11] Compiling Yesod.PasswordStore ( Yesod/PasswordStore.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/Yesod/PasswordStore.o ) /private/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/stack49268 /yesod-auth-1.4.6/Yesod/PasswordStore.hs:166:31: Warning: Defaulting the following constraint(s) to type ‘Integer’ (Integral b0) arising from a use of ‘^’ at Yesod/PasswordStore.hs:166:31 (Num b0) arising from the literal ‘32’ at Yesod/PasswordStore.hs:166:32-33 In the first argument of ‘(-)’, namely ‘2 ^ 32’ In the first argument of ‘(*)’, namely ‘(2 ^ 32 - 1)’ In the second argument of ‘(>)’, namely ‘(2 ^ 32 - 1) * hLen’ /private/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/stack49268 /yesod-auth-1.4.6/Yesod/PasswordStore.hs:419:1: Warning: Defined but not used: ‘toStrict’ /private/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/stack49268 /yesod-auth-1.4.6/Yesod/PasswordStore.hs:422:1: Warning: Defined but not used: ‘fromStrict’ [ 2 of 11] Compiling Yesod.Auth.Message ( Yesod/Auth/Message.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/Yesod/Auth/Message.o ) /private/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/stack49268 /yesod-auth-1.4.6/Yesod/Auth/Message.hs:22:1: Warning: The import of ‘Data.Monoid’ is redundant except perhaps to import instances from ‘Data.Monoid’ To import instances alone, use: import Data.Monoid() [ 3 of 11] Compiling Yesod.Auth.Routes ( Yesod/Auth/Routes.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.4.0/build/Yesod/Auth/Routes.o ) [ 4 of 11] Compiling Yesod.Auth ( Yesod/Auth.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.4.0/build/Yesod/Auth.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.10.2 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ghc64990_0/libghc_21.dylib, 5): no suitable image found. Did find: /var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ghc64990_0/libghc_21.dylib: malformed mach-o: load commands size (34176) > 32768 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} So reporting.... I've seen the same error attempting to brew install haskell-stack on sierra betas 3 and 4, but on those occasions, an issue with libghc_44.dylib causing the problem. {{{ [ 4 of 87] Compiling System.Process.Read ( src/System/Process/Read.hs, dist/dist-sandbox-558713ad/build/System/Process/Read.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ghc67839_0/libghc_44.dylib, 5): no suitable image found. Did find: /var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ghc67839_0/libghc_44.dylib: malformed mach-o: load commands size (40560) > 32768 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} stack version: {{{ Version 1.1.2, Git revision cebe10e845fed4420b6224d97dcabf20477bbd4b (3646 commits) x86_64 hpack-0.14.0 }}} stack exec env returns: {{{ stack exec env Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.tEAdTiAWFI/Render GHC_PACKAGE_PATH=/Users/stephen/Documents/github/commercialhaskell.com /.stack- work/install/x86_64-osx/lts-3.0/7.10.2/pkgdb:/Users/stephen/.stack/snapshots/x86_64-osx/lts-3.0/7.10.2/pkgdb:/Users/stephen/.stack/programs/x86_64-osx/ghc-7.10.2/lib/ghc-7.10.2/package.conf.d HASKELL_DIST_DIR=.stack-work/dist/x86_64-osx/Cabal-1.22.4.0 HASKELL_PACKAGE_SANDBOX=/Users/stephen/.stack/snapshots/x86_64-osx/lts-3.0/7.10.2/pkgdb HASKELL_PACKAGE_SANDBOXES=/Users/stephen/Documents/github/commercialhaskell… /.stack- work/install/x86_64-osx/lts-3.0/7.10.2/pkgdb:/Users/stephen/.stack/snapshots/x86_64-osx/lts-3.0/7.10.2/pkgdb: HOME=/Users/stephen LANG=en_IE.UTF-8 LOGNAME=stephen NAME=Stephen Barrett OLDPWD=/Users/stephen/Documents/github PATH=/Users/stephen/Documents/github/commercialhaskell.com/.stack- work/install/x86_64-osx/lts-3.0/7.10.2/bin:/Users/stephen/.stack/snapshots/x86_64-osx/lts-3.0/7.10.2/bin:/Users/stephen/.stack/programs/x86_64-osx/ghc-7.10.2/bin:/Users/stephen/Library/Haskell/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin PWD=/Users/stephen/Documents/github/commercialhaskell.com SECURITYSESSIONID=186a6 SHELL=/bin/bash SHLVL=1 SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.RTM6V8Lo2y/Listeners STACK_EXE=/Library/Haskell/ghc-8.0.1-x86_64/bin/stack TERM=xterm-256color TERM_PROGRAM=Apple_Terminal TERM_PROGRAM_VERSION=377 TERM_SESSION_ID=020844C9-1E8A-410E-8892-43DC0C5A8C0B TMPDIR=/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ USER=stephen XPC_FLAGS=0x0 XPC_SERVICE_NAME=0 _=/usr/local/bin/stack __CF_USER_TEXT_ENCODING=0x1F5:0x0:0x6C }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12479> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13613: Simplify fixIO
by GHC 19 Oct '17

19 Oct '17

#13613: Simplify fixIO -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: Core | Version: 8.0.1 Libraries | 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: -------------------------------------+------------------------------------- Now that we have `noDuplicate#`, I think we can make `fixIO` much simpler, and perhaps also faster, using something like what we do for `ST`. {{{#!hs data Res a = Res (# State# RealWorld, a #) fixIO f = IO $ \s -> let Res r@(# _s', a #) = unIO (noDuplicate >> f a) s in r }}} If `f` forks an `IO` thread demanding `a`, the `noDuplicate` should ensure that the computation is not re-entered, and the thread should wait for the main computation to complete. So I believe, anyway. The comment about eager blackholing here is a bit vague and doesn't give an example. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13613> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13385: ghci fails to start when -XRebindableSyntax is passed
by GHC 19 Oct '17

19 Oct '17

#13385: ghci fails to start when -XRebindableSyntax is passed -------------------------------------+------------------------------------- Reporter: mgsloan | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.2 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: -------------------------------------+------------------------------------- Running "ghci -XRebindableSyntax" yields the following output: {{{ GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help <interactive>:1:6: error: Not in scope: ‘>>’ <interactive>:1:70: error: Not in scope: ‘>>’ <interactive>:1:135: error: Not in scope: ‘return’ }}} This appears to be a regression, as it does not occur with ghc-7.10.3. Originally reported as a stack issue by Michal Konecny - https://github.com/commercialhaskell/stack/issues/3043 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13385> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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