July 2018 - ghc-tickets

[GHC] #15324: -ddump-splices does not parenthesize rank-n contexts correctly
by GHC 12 Jul '18

12 Jul '18

#15324: -ddump-splices does not parenthesize rank-n contexts correctly -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Template | Version: 8.4.3 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: -------------------------------------+------------------------------------- Ryan discovers another `-ddump-splices` bug—news at 11: {{{#!hs {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TemplateHaskell #-} {-# OPTIONS_GHC -ddump-splices #-} module Bug where $([d| f :: forall a. (Show a => a) -> a f _ = undefined |]) }}} {{{ $ /opt/ghc/8.4.3/bin/ghci Bug.hs -dsuppress-uniques GHCi, version 8.4.3: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:(6,3)-(8,6): Splicing declarations [d| f :: forall a. (Show a => a) -> a f _ = undefined |] ======> f :: forall a. Show a => a -> a f _ = undefined }}} Notice that `f`'s type signature is pretty-printed as `forall a. Show a => a -> a`, which is just wrong. Patch incoming. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15324> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15331: -ddump-splices does not parenthesize visible type applications correctly
by GHC 12 Jul '18

12 Jul '18

#15331: -ddump-splices does not parenthesize visible type applications correctly -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 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: -------------------------------------+------------------------------------- So many `-ddump-splices` bugs... {{{#!hs {-# LANGUAGE TemplateHaskell #-} {-# LANGUAGE TypeApplications #-} {-# OPTIONS_GHC -ddump-splices #-} module Bug where import Data.Proxy $([d| f :: Proxy (Int -> Int) f = Proxy @(Int -> Int) |]) }}} {{{ $ /opt/ghc/8.6.1/bin/ghci Bug.hs GHCi, version 8.6.0.20180627: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:(8,3)-(10,6): Splicing declarations [d| f_a1Dg :: Proxy (Int -> Int) f_a1Dg = Proxy @(Int -> Int) |] ======> f_a4tx :: Proxy (Int -> Int) f_a4tx = Proxy @Int -> Int }}} Ack—`Proxy @Int -> Int` should actually be `Proxy @(Int -> Int)`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15331> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15301: Regression in Natural desugaring
by GHC 12 Jul '18

12 Jul '18

#15301: Regression in Natural desugaring -------------------------------------+------------------------------------- Reporter: hsyl20 | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 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: -------------------------------------+------------------------------------- My recent merged patch "Built-in Natural literals in Core" https://phabricator.haskell.org/rGHCfe770c211631e7b4c9b0b1e88ef9b6046c6585ef introduced a regression when desugaring large numbers. Patch coming. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15301> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15289: isUnliftedType GHC panic on pattern with True :: Maybe
by GHC 12 Jul '18

12 Jul '18

#15289: isUnliftedType GHC panic on pattern with True :: Maybe -------------------------------------+------------------------------------- Reporter: Remi | Owner: (none) Type: bug | Status: new Priority: low | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: aarch64 | Type of failure: Compile-time | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE ScopedTypeVariables #-} module Oops where pattern What = True :: Maybe }}} Fails on 8.4.3 with: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): isUnliftedType (Maybe |> {co_a1Dg3}) :: TYPE t_a1Dg9[tau:1] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1939:10 in ghc:Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I'm currently cloning from git, and will try to get around to check it with HEAD over the next days. BTW, it's not a show-stopper for me. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15289> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15303: API Annotations lost when parsing tyapp
by GHC 12 Jul '18

12 Jul '18

#15303: API Annotations lost when parsing tyapp -------------------------------------+------------------------------------- Reporter: alanz | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect API Unknown/Multiple | annotation Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In `Parser.y`, the `typapp` production has {{{#!hs | SIMPLEQUOTE qconop {% ams (sLL $1 $> $ TyElOpr (unLoc $2)) [mj AnnSimpleQuote $1] } | SIMPLEQUOTE varop {% ams (sLL $1 $> $ TyElOpr (unLoc $2)) [mj AnnSimpleQuote $1] } }}} By using `unLoc $2` we are discarding any annotations attached to the `qconop` or `qvarop`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15303> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15341: :info prints kinds in closed type family equations without enabling -fprint-explicit-kinds
by GHC 12 Jul '18

12 Jul '18

#15341: :info prints kinds in closed type family equations without enabling -fprint-explicit-kinds -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Keywords: TypeFamilies | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Load this file into GHCi: {{{#!hs {-# LANGUAGE PolyKinds #-} {-# LANGUAGE TypeFamilies #-} module Bug where type family Foo (a :: k) :: k where Foo a = a }}} And run `:info` on `Foo`: {{{ $ /opt/ghc/8.4.3/bin/ghci Bug.hs GHCi, version 8.4.3: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/ryanglscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Ok, one module loaded. λ> :i Foo type family Foo (a :: k) :: k where Foo k a = a -- Defined at Bug.hs:5:1 }}} Note that when printing the equation for `Foo`, the kind `k` is treated as though it were the first visible argument to `Foo`, even though `-fprint- explicit-kinds` is not enabled. This is because `ppr_tc_args` in `IfaceType` does not take `-fprint-explicit-kinds` into account. Patch incoming (pending a `./validate`). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15341> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15342: Mark -XAutoDeriveTypeable as deprecated
by GHC 12 Jul '18

12 Jul '18

#15342: Mark -XAutoDeriveTypeable as deprecated -------------------------------------+------------------------------------- Reporter: monoidal | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 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: -------------------------------------+------------------------------------- The language extension `-XAutoDeriveTypeable` is not needed since #9858. It was earlier marked as redundant in GHC documentation. I propose that GHC gives a clear deprecation message. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15342> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14808: GHC HEAD regression: GADT constructors no longer quantify tyvars in topological order
by GHC 12 Jul '18

12 Jul '18

#14808: GHC HEAD regression: GADT constructors no longer quantify tyvars in topological order -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.6.1 Component: Compiler | Version: 8.5 (Type checker) | Keywords: GADTs | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #14529, #14796 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Originally noticed in #14796. This program: {{{#!hs {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE TypeApplications #-} module Bug where import Data.Kind data ECC ctx f a where ECC :: ctx => f a -> ECC ctx f a f :: [()] -> ECC () [] () f = ECC @() @[] @() }}} Typechecks in GHC 8.2.2 and 8.4.1, but not in GHC HEAD: {{{ $ ~/Software/ghc2/inplace/bin/ghc-stage2 Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:12:5: error: • Couldn't match type ‘()’ with ‘[]’ Expected type: [()] -> ECC (() :: Constraint) [] () Actual type: () [] -> ECC (() :: Constraint) () [] • In the expression: ECC @() @[] @() In an equation for ‘f’: f = ECC @() @[] @() | 12 | f = ECC @() @[] @() | ^^^^^^^^^^^^^^^ Bug.hs:12:10: error: • Expected kind ‘* -> *’, but ‘()’ has kind ‘*’ • In the type ‘()’ In the expression: ECC @() @[] @() In an equation for ‘f’: f = ECC @() @[] @() | 12 | f = ECC @() @[] @() | ^^ Bug.hs:12:14: error: • Expecting one more argument to ‘[]’ Expected a type, but ‘[]’ has kind ‘* -> *’ • In the type ‘[]’ In the expression: ECC @() @[] @() In an equation for ‘f’: f = ECC @() @[] @() | 12 | f = ECC @() @[] @() | ^^ }}} This is because the order of type variables for `ECC` has changed between GHC 8.4.1 and HEAD. In 8.4.1, it's {{{ $ /opt/ghc/8.4.1/bin/ghci Bug.hs -XTypeApplications -fprint-explicit- foralls GHCi, version 8.4.0.20180209: 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. λ> :type +v ECC ECC :: forall (ctx :: Constraint) (f :: * -> *) a. ctx => f a -> ECC ctx f a }}} In GHC HEAD, however, it's: {{{ $ ~/Software/ghc2/inplace/bin/ghc-stage2 --interactive Bug.hs -XTypeApplications -fprint-explicit-foralls GHCi, version 8.5.20180213: 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. λ> :type +v ECC ECC :: forall (f :: * -> *) a (ctx :: Constraint). ctx => f a -> ECC ctx f a }}} This regression was introduced in fa29df02a1b0b926afb2525a258172dcbf0ea460 (Refactor ConDecl: Trac #14529). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14808> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8581: Add support for explicitly-bidirectional pattern synonyms
by GHC 12 Jul '18

12 Jul '18

#8581: Add support for explicitly-bidirectional pattern synonyms ------------------------------------+------------------------------------- Reporter: cactus | Owner: cactus Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: 5144 | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Some patterns cannot, by themselves, be turned over into an expression, so they have to be defined as unidirectional. Maybe the most trivial example would be {{{ pattern P -> _ }}} Sometimes, however, it would be desirable to give an explicit way of turning these pattern synonyms into expressions. The PatternSynonyms wiki page has this example: {{{ import qualified Data.Sequence as Seq pattern Empty -> (Seq.viewl -> Seq.EmptyL) pattern x :< xs -> (Seq.viewl -> x Seq.:< xs) pattern xs :> x -> (Seq.viewr -> xs Seq.:> x) }}} It would make a ton of sense to be able to use this cons/snoc notation as "constructors" for `Seq`s. The proposed syntax for this {{{ pattern x :< xs -> (Seq.viewl -> x Seq.:< xs) where x :< xs = x Seq.<| xs }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8581> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #314: #line pragmas not respected inside nested comments
by GHC 12 Jul '18

12 Jul '18

#314: #line pragmas not respected inside nested comments -------------------------------------+------------------------------------- Reporter: nobody | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: 6.4 (Parser) | Resolution: None | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: read032 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4934 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: new => patch * differential: => Phab:D4934 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/314#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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