September 2013 - ghc-tickets

[GHC] #8129: Constraint solver panic when -ddump-tc-trace is used
by GHC 01 Oct '13

01 Oct '13

#8129: Constraint solver panic when -ddump-tc-trace is used -------------------------------------+------------------------------------- Reporter: adamgundry | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.7 checker) | Operating System: Unknown/Multiple Keywords: | Type of failure: Compile-time Architecture: Unknown/Multiple | crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- {{{ {-# LANGUAGE MultiParamTypeClasses, TypeFamilies #-} {-# OPTIONS_GHC -ddump-tc-trace #-} type family F (x :: *) :: * class (y ~ F x) => C x y z = () :: C x y => () }}} causes a panic while tracing the typechecker: {{{ solveNestedImplications starting { original inerts = Equalities: Type-function equalities: [D] _ :: F x_aeH ~ y_aeI (CFunEqCan) Dictionaries: [W] $dC_aeK :: C x_aeH y_aeI (CDictCan) Irreds: Insolubles = {} Solved dicts 0 Solved funeqs 0 thinner_inerts = Equalities:ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.7.20130812 for i386-unknown-linux): No match in record selector ctev_evar }}} If `-ddump-tc-trace` is not used, the correct constraint solving error is generated: {{{ Could not deduce (C x0 y0) arising from the ambiguity check for an expression type signature from the context (C x y) bound by an expression type signature: C x y => () }}} It seems that `prepareInertsForImplications` in `TcSMonad` assumes that all the `inert_funeqs` are givens or wanteds; if there are some deriveds, then the above panic results. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8129> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8389: Building GHC 7.7 fails at haddock step
by GHC 30 Sep '13

30 Sep '13

#8389: Building GHC 7.7 fails at haddock step ----------------------------------+---------------------------------------- Reporter: dsamperi | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.6.3 Keywords: | Operating System: Linux Architecture: | Type of failure: Building GHC failed Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | ----------------------------------+---------------------------------------- Building GHC (following instructions at GitHub) leads to a panic while running git/ghc/inplace/bin/haddock. OS is Fedora Linux 18. Installed latest version of cabal-install, Alex, Happy, and Haddock. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8389> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4061: Implement mutually recursive view patterns
by GHC 30 Sep '13

30 Sep '13

#4061: Implement mutually recursive view patterns -------------------------------------+------------------------------------ Reporter: batterseapower | Owner: Type: feature request | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 6.13 Resolution: wontfix | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by rwbarton): * difficulty: => Unknown Comment: BTW, since the view patterns in your example are not mutually recursive, you can use this hack to break up the top level scope: {{{ {-# LANGUAGE ViewPatterns, TemplateHaskell #-} module RecursiveViewPatterns where (foo, unzip -> (bars, bazs)) = undefined [d||] -- or return [] (spqr, ($ foo) -> metavariable) = undefined }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4061#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8257: System.Mem: Expose performMinorGC
by GHC 30 Sep '13

30 Sep '13

#8257: System.Mem: Expose performMinorGC ------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: libraries/base | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- We already have {{{ performGC }}} which triggers a major garbage collection. In many cases, it is useful to trigger a minor one; exposing it is as simple as Simon Marlow suggested in https://groups.google.com/d/msg/fa.haskell/-q6sINValu8/_Z7odE6O5PsJ. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8257> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8386: AMP warning on "hiding (join)"
by GHC 30 Sep '13

30 Sep '13

#8386: AMP warning on "hiding (join)" -------------------------+------------------------------------------------- Reporter: | Owner: monoidal | Status: new Type: bug | Milestone: Priority: | Version: 7.7 normal | Operating System: Unknown/Multiple Component: | Type of failure: Incorrect warning at Compiler | compile-time Keywords: | Test Case: Architecture: | Blocking: Unknown/Multiple | Difficulty: | Unknown | Blocked By: | Related Tickets: | -------------------------+------------------------------------------------- This file gives an AMP warning, but it shouldn't. It's a slightly modified version of http://ghc.haskell.org/trac/ghc/ticket/8004#comment:15. {{{ module Foo (join) where import Prelude hiding (join) -- import Prelude () gives no warning join :: () join = () }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8386> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8385: Various testsuite fixes
by GHC 30 Sep '13

30 Sep '13

#8385: Various testsuite fixes ------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- See https://github.com/rwbarton/testsuite/compare/rwbarton. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8385> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7633: Checkable "minimal complete definitions"
by GHC 30 Sep '13

30 Sep '13

#7633: Checkable "minimal complete definitions" -------------------------------------------------+------------------------- Reporter: shachaf | Owner: Type: feature request | Status: patch Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Test Case: warnings/minimal/WarnMinimal | Difficulty: Blocking: | Unknown | Blocked By: | Related Tickets: #6028 -------------------------------------------------+------------------------- Comment (by Krzysztof Gogolewski <krz.gogolewski@…>): In [changeset:6fa8a5906c3f0e425b3505ae7c6717ec29e3e47b/testsuite]: {{{ #!CommitTicketReference repository="testsuite" revision="6fa8a5906c3f0e425b3505ae7c6717ec29e3e47b" Update prog001 output (see #7633) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7633#comment:44> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5889: -fno-prof-count-entries leads to linking errors
by GHC 30 Sep '13

30 Sep '13

#5889: -fno-prof-count-entries leads to linking errors ----------------------------------------------+---------------------------- Reporter: akio | Owner: Type: bug | Status: closed Priority: normal | Milestone: 7.6.2 Component: Compiler | Version: 7.4.1 Resolution: fixed | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: GHC rejects valid program | (amd64) Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Changes (by akio): * status: new => closed * resolution: => fixed Comment: I cannot reproduce this error with GHC 7.6.2. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5889#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8370: Ranked Instances
by GHC 29 Sep '13

29 Sep '13

#8370: Ranked Instances ------------------------------------+------------------------------------- Reporter: wvv | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- This is a first part of 3 depended extensions: Ranked Instances => Inherit Instances => Newclasses This is very easy to implement. And it gives big advantages. And further developing. I suggest to add "rank" to instance. Now the system of instances is flat, and compiler takes all of instances and check if only 1 match. If it is not(less or more than 1) - compiler trow an error. With rankings compiler * set N=0 * took all N-ranked instances and * => try to find only one match instance. * -> If it found only 1 - this is RESULT: needed instance, * -> If it found many instances - throw an error * -> If compiler found NO instances, compiler set N=N+1 and repeat * If N=MaxRank and still no matches compiler throw an error We use `RankedInstances` '''before''' `OverlappingInstances` (which must include `RankedInstances`), and in many cases instead of. == Proposed grammar == We add "rank N" between "instance" word and ".", where N is a number {{{ {-# LANGUAGE RankedInstances #-} instance rank 1. C a => D a where ... }}} == Default Rank == If instance has no rank, this means it has 0 rank {{{ instance C a => D a where ... ~ instance rank 0. C a => D a where ... }}} This is a backward compatibility. '''Examples''' 1) {{{ instance rank 1. C Int a where ... -- (A) instance C a Bool where ... -- (B) rank 0 }}} 1+) {{{ instance rank 1. C Int a where ... -- (A) instance rank 1. C a Bool where ... -- (B) instance C Int Bool where ... -- (C) rank 0 }}} 2) {{{ instance rank 1. C Int [a] where ... -- (C) instance C Int [Int] where ... -- (D) }}} As we see, all instances are unambiguous! == Backward Compatibility == Without -XRankedInstances all instances with hight rank n, where n >0 - are not exported More information (about all 3 extensions) is here http://haskell.1045720.n5.nabble.com/Proposal-RankedInstances- tt5737152.html -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8370> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #8004: Applicative/Monad proposal related warnings (AMP phase 1)
by GHC 29 Sep '13

29 Sep '13

#8004: Applicative/Monad proposal related warnings (AMP phase 1) -------------------------------------+------------------------------------ Reporter: quchen | Owner: quchen Type: feature request | Status: closed Priority: high | Milestone: 7.8.1 Component: Compiler | Version: 7.6.3 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by thoughtpolice): * status: patch => closed * resolution: => fixed Comment: Thanks for the patch, David. This should be fixed and roughly complete the work as of b9127f4472594e8d0c2f28f72b6042172efcaec0. If there are any more bugs, please file new tickets. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8004#comment:21> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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