December 2018 - ghc-tickets

[GHC] #10841: Run handler on STM retry
by GHC 03 Mar '19

03 Mar '19

#10841: Run handler on STM retry -------------------------------------+------------------------------------- Reporter: shlevy | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: libraries | Version: 7.10.2 (other) | Keywords: stm | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- It would be nice to have a function like: {{{#!hs -- | Perform a series of STM actions atomically. -- -- Whenever the transaction retries, run the handler. If it doesn't return 'Nothing', -- stop the retrying and return the value given by the handler. atomicallyWithRetryHandler :: STM a -> IO (Maybe a) -> IO a }}} This would allow tracking retry statistics, printing debug messages on each retry, etc. without resorting to unsafeIOToSTM which can't safely do things like printing. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10841> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13002: :set -O does not work in .ghci file
by GHC 03 Mar '19

03 Mar '19

#13002: :set -O does not work in .ghci file --------------------------------------+---------------------------- Reporter: George | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.1 Keywords: | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: Other Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+---------------------------- {{{#!hs {-# OPTIONS_GHC -Wall #-} module Foo where testFromTo :: Int -> Int testFromTo n = length ([0..(10^n)] :: [Int]) }}} {{{ cat ~/.ghci :set +s :set -fobject-code :set -O bash-3.2$ touch Foo.hs bash-3.2$ ghci GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /Users/gcolpitts/.ghci Prelude> :load Foo :load Foo [1 of 1] Compiling Foo ( Foo.hs, Foo.o ) Ok, modules loaded: Foo (Foo.o). (0.15 secs,) Prelude Foo> testFromTo 5 testFromTo 5 100001 (0.02 secs, 8,885,888 bytes) Prelude Foo> :quit :quit Leaving GHCi. bash-3.2$ touch Foo.hs bash-3.2$ ghci -fobject-code -O GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /Users/gcolpitts/.ghci Prelude> :load Foo :load Foo [1 of 1] Compiling Foo ( Foo.hs, Foo.o ) Ok, modules loaded: Foo (Foo.o). (0.15 secs,) Prelude Foo> testFromTo 5 testFromTo 5 100001 (0.02 secs, 98,400 bytes) }}} While supplying -fobject-code -O as an argument to ghci seems like an easy workaround that isn't feasible as far as I know when using emacs thus setting priority to normal rather than low. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13002> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12847: ghci -fobject-code -O2 doesn't do the same optimisations as ghc --make -O2
by GHC 03 Mar '19

03 Mar '19

#12847: ghci -fobject-code -O2 doesn't do the same optimisations as ghc --make -O2 -------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Other Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- From IRC: I have a module that takes around 10 seconds to compile on ghc --make -O2, but only around 3 seconds on ghci -fobject-code -O2. > bgamari: that is surprising I've put the -v timing output of the two cases into https://gist.github.com/nh2/e9bc4732111bfe422d8e606c10f8f0ac I'm comparing the 2 files with `meld` for spotting differences easily. Check e.g. `Result size of Tidy Core` which seems to have 3x as many terms for ghc, and `Simplifier [Mymodule]` doesn't seem to run in ghci The first time terms are different is at `Desugar, the first time a factor 3 comes in is after `Specialize`. > bgamari: wow, it sounds like the simplifier isn't getting run as aggressively in GHCi I'm running this on Ubuntu 16.04 inside nix (but happens the same way outside nix). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12847> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15857: Need for better warnings arising from StarIsType extension
by GHC 02 Mar '19

02 Mar '19

#15857: Need for better warnings arising from StarIsType extension -------------------------------------+------------------------------------- Reporter: jrp | Owner: (none) Type: feature | Status: new request | Priority: low | Milestone: Component: Compiler | Version: 8.6.1 Keywords: StarIsType | Operating System: Unknown/Multiple NoStarIsType | Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- If I redefine `type (*) = (,)` I am given not given a warning that it doesn't do what I expect, when building with cabal new-repl or cabal new- build, because the `StarIsType` extension is now enabled by default. Instead or a warning, I get (correct but confusing) error messages. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15857> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14069: RTS linker maps code as writable
by GHC 01 Mar '19

01 Mar '19

#14069: RTS linker maps code as writable -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.4.1 Component: Runtime | Version: 8.0.1 System (Linker) | 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: -------------------------------------+------------------------------------- GHC's RTS linker maps executable code in writable pages, representing a significant potential exploit point for arbitrary code execution. OpenBSD disallows running program that do this by default. Fix this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14069> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11503: TypeError woes (incl. pattern match checker)
by GHC 01 Mar '19

01 Mar '19

#11503: TypeError woes (incl. pattern match checker) -------------------------------------+------------------------------------- Reporter: goldfire | 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: -------------------------------------+------------------------------------- When I say {{{ {-# LANGUAGE DataKinds, GADTs, KindSignatures, TypeFamilies, UndecidableInstances #-} {-# OPTIONS_GHC -fwarn-incomplete-patterns #-} module Bug where import GHC.TypeLits import GHC.Exts ( Constraint ) type family NotInt a where NotInt Int = TypeError (Text "That's Int, silly.") NotInt _ = (() :: Constraint) data T a where MkT1 :: a -> T a MkT2 :: NotInt a => T a foo :: T Int -> Int foo (MkT1 x) = x }}} I get {{{ Bug.hs:19:1: warning: Pattern match(es) are non-exhaustive In an equation for ‘foo’: Patterns not matched: MkT2 }}} But I shouldn't. Even worse, perhaps, GHC accepts my pattern-match against `MkT2` if I add it. If I change the `TypeError` to `False ~ True`, I get the correct behavior. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11503> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15641: Git repositories have several problems
by GHC 01 Mar '19

01 Mar '19

#15641: Git repositories have several problems -------------------------------------+------------------------------------- Reporter: flip101 | Owner: hvr Type: bug | Status: new Priority: high | Milestone: Component: Trac & Git | Version: 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: -------------------------------------+------------------------------------- I have some problems with the repositories. When i try to clone from the official repo: {{{ » git clone --single-branch --branch master --depth=1 --recursive git://git.haskell.org/ghc.git ghc-head Cloning into 'ghc-head'... fatal: The remote end hung up unexpectedly fatal: early EOF fatal: index-pack failed }}} Maybe it's because the git server version is old (1.9.1). Without `--depth=1` it works, but anyway it's an issue. With the github mirror i have another problem: {{{ Cloning into 'libraries/Cabal'... fatal: remote error: ghc/packages/Cabal is not a valid repository name Email support(a)github.com for help fatal: clone of 'git://github.com/ghc/packages/Cabal.git' into submodule path 'libraries/Cabal' failed }}} With the phabricator repo the following issue: command: {{{ git clone --depth=1 --single-branch --branch ghc-8.6 --recursive https://phabricator.haskell.org/diffusion/GHC/glasgow-haskell-compiler.git ghc-8.6-head }}} error: {{{ Cloning into '.arc-linters/arcanist-external-json-linter'... error: RPC failed; HTTP 503 curl 22 The requested URL returned error: 503 first byte timeout fatal: The remote end hung up unexpectedly fatal: clone of 'https://phabricator.haskell.org/diffusion/GHC/arcanist- external-json-linter.git' into submodule path '.arc-linters/arcanist- external-json-linter' failed }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15641> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16015: git notes logic breaks CircleCI validation of pull requests
by GHC 01 Mar '19

01 Mar '19

#16015: git notes logic breaks CircleCI validation of pull requests -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.6.3 Component: Compiler | Version: 8.6.2 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: -------------------------------------+------------------------------------- Due to missing credentials. David, can you have a look? https://circleci.com/gh/ghc/ghc/12493 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16015> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15800: Overlapping instances error with single instance
by GHC 01 Mar '19

01 Mar '19

#15800: Overlapping instances error with single instance -------------------------------------+------------------------------------- Reporter: roland | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 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: -------------------------------------+------------------------------------- {{{ {-# LANGUAGE MultiParamTypeClasses, FlexibleContexts, FlexibleInstances #-} module Bug where class C a b instance C a Int x :: () x = undefined :: C a Int => () }}} {{{ ghc -c Bug.hs Bug.hs:10:18: error: • Overlapping instances for C a0 Int Matching givens (or their superclasses): C a Int bound by an expression type signature: forall a. C a Int => () at Bug.hs:10:18-30 Matching instances: instance C a Int -- Defined at Bug.hs:7:10 (The choice depends on the instantiation of ‘a0’) • In the ambiguity check for an expression type signature To defer the ambiguity check to use sites, enable AllowAmbiguousTypes In an expression type signature: C a Int => () In the expression: undefined :: C a Int => () | 10 | x = undefined :: C a Int => () | ^^^^^^^^^^^^^ }}} The "matching instances" bit of the error messages only lists a single instance. Doesn't it take at least two instances for something to overlap? Also, following the algorithm laid out in the user guide (section "Overlapping Instances"), it appears this program should be accepted. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15800> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16020: Hadrian: correctly Install libffi shared object files
by GHC 01 Mar '19

01 Mar '19

#16020: Hadrian: correctly Install libffi shared object files -------------------------------------+------------------------------------- Reporter: davide | Owner: (none) Type: task | Status: new Priority: high | Milestone: 8.6.3 Component: Build System | Version: 8.6.2 (Hadrian) | 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 Phab:D5423 a hack to correctly install the libffi .so files is implemented. This is a quick and dirty solution to fix the hadrian build. Note [Hadrian: install libffi hack] from that patch and also issue #15837 have more details, but ultimately hadrian should not have a special case for libffi. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16020> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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