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[GHC] #9121: Presence of dyn_o files not checked? upon recompilation
by GHC 28 Feb '19

28 Feb '19

#9121: Presence of dyn_o files not checked? upon recompilation ------------------------------------+------------------------------------- Reporter: andreas.abel | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | 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: | ------------------------------------+------------------------------------- When I interrupt a compilation (initiated with cabal), and then recompile (with cabal), it can happen that gcc fails with missing .dyn_o file. I have "shared:True" in my .cabal/config file. [I can of course do cabal clean to work around, but since a full recompilation is about 10 min, I try to avoid this.] time cabal install --disable-library-profiling --disable-documentation Resolving dependencies... In order, the following will be installed: Agda-2.3.3 (latest: 2.3.2.2) (reinstall) Warning: Note that reinstalls are always dangerous. Continuing anyway... Configuring Agda-2.3.3... Building Agda-2.3.3... Preprocessing library Agda-2.3.3... [116 of 273] Compiling Agda.TypeChecking.Monad.Base[boot] ( src/full/Agda/TypeChecking/Monad/Base.hs-boot, dist/build/Agda/TypeChecking/Monad/Base.o-boot ) ... [239 of 273] Compiling Agda.TypeChecking.Conversion ( src/full/Agda/TypeChecking/Conversion.hs, dist/build/Agda/TypeChecking/Conversion.o ) [Agda.Syntax.Translation.InternalToAbstract changed] ^Cmake: *** [install-bin] Interrupt time cabal install --disable-library-profiling --disable-documentation Resolving dependencies... In order, the following will be installed: Agda-2.3.3 (latest: 2.3.2.2) (reinstall) Warning: Note that reinstalls are always dangerous. Continuing anyway... Configuring Agda-2.3.3... Building Agda-2.3.3... Preprocessing library Agda-2.3.3... [116 of 273] Compiling Agda.TypeChecking.Monad.Base[boot] ( src/full/Agda/TypeChecking/Monad/Base.hs-boot, dist/build/Agda/TypeChecking/Monad/Base.o-boot ) ... [273 of 273] Compiling Agda.Main ( src/full/Agda/Main.hs, dist/build/Agda/Main.o ) [Agda.Compiler.Epic.Compiler changed] gcc: error: dist/build/Agda/TypeChecking/Conversion.dyn_o: No such file or directory Failed to install Agda-2.3.3 cabal: Error: some packages failed to install: Agda-2.3.3 failed during the building phase. The exception was: ExitFailure 1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9121> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16371: GHC should be more forgiving with visible dependent quantification in visible type applications
by GHC 27 Feb '19

27 Feb '19

#16371: GHC should be more forgiving with visible dependent quantification in visible type applications -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.9 (Type checker) | Keywords: | Operating System: Unknown/Multiple VisibleDependentQuantification | Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- GHC HEAD currently rejects the following code: {{{#!hs {-# LANGUAGE ImpredicativeTypes #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} module Bug where import Data.Kind import Data.Proxy f :: forall k a. Proxy a f = Proxy g :: forall (a :: forall x -> x -> Type). Proxy a g = f @(forall x -> x -> Type) @a }}} {{{ GHCi, version 8.9.20190227: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:14:6: error: • Illegal visible, dependent quantification in the type of a term: forall x -> x -> * (GHC does not yet support this) • In the type signature: g :: forall (a :: forall x -> x -> Type). Proxy a | 14 | g :: forall (a :: forall x -> x -> Type). Proxy a | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }}} But GHC is being too conservative here. `forall x -> x -> *` //isn't// the type of a term here, but rather the kind of a type variable, and it's perfectly admissible to use visible dependent quantification in such a scenario. The immediate reason that this happens is because of this code: {{{#!hs vdqAllowed (TypeAppCtxt {}) = False }}} Unfortunately, fixing this bug isn't as simply as changing `False` to `True`. If you do that, then GHC becomes //too// forgiving and allows things like this: {{{#!hs {-# LANGUAGE ImpredicativeTypes #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeApplications #-} lol :: forall a. a lol = undefined t2 = lol @(forall a -> a -> a) }}} Here, visible dependent quantification is leaking into the type of a term, which we definitely don't want to happen. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16371> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15869: Discrepancy between seemingly equivalent type synonym and type family
by GHC 27 Feb '19

27 Feb '19

#15869: Discrepancy between seemingly equivalent type synonym and type family -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.2 (Type checker) | Keywords: TypeFamilies | 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: -------------------------------------+------------------------------------- Consider the following code: {{{#!hs {-# LANGUAGE DataKinds #-} {-# LANGUAGE ImpredicativeTypes #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} module Bug where import Data.Kind type KindOf1 (a :: k) = k type family KindOf2 (a :: k) :: Type where KindOf2 (a :: k) = k data A (a :: Type) :: a -> Type type family Apply1 (f :: KindOf1 A) (a :: Type) (x :: a) :: Type where Apply1 f a x = f a x }}} `Apply1` kind-checks, which is just peachy. Note that `Apply1` uses `KindOf1`, which is a type synonym. Suppose I wanted to swap out `KindOf1` for `KindOf2`, which is (seemingly) an equivalent type family. I can define this: {{{#!hs type family Apply2 (f :: KindOf2 A) -- (f :: forall a -> a -> Type) (a :: Type) (x :: a) :: Type where Apply2 f a x = f a x }}} However, GHC rejects this! {{{ $ /opt/ghc/8.6.2/bin/ghc Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:25:10: error: • Expecting two more arguments to ‘f’ Expected kind ‘KindOf2 A’, but ‘f’ has kind ‘* -> a -> *’ • In the first argument of ‘Apply2’, namely ‘f’ In the type family declaration for ‘Apply2’ | 25 | Apply2 f a x = f a x | ^ }}} I find this quite surprising, since I would have expected `KindOf1` and `KindOf2` to be functionally equivalent. Even providing explicit `forall`s does not make it kind-check: {{{#!hs type family Apply2 (f :: KindOf2 A) -- (f :: forall a -> a -> Type) (a :: Type) (x :: a) :: Type where forall (f :: KindOf2 A) (a :: Type) (x :: a). Apply2 f a x = f a x }}} Although the error message does change a bit: {{{ $ ~/Software/ghc3/inplace/bin/ghc-stage2 Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:26:20: error: • Expected kind ‘* -> a -> *’, but ‘f’ has kind ‘KindOf2 A’ • In the type ‘f a x’ In the type family declaration for ‘Apply2’ | 26 | Apply2 f a x = f a x | ^^^^^ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15869> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14419: Check kinds for ambiguity
by GHC 27 Feb '19

27 Feb '19

#14419: Check kinds for ambiguity -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 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: -------------------------------------+------------------------------------- GHC does an ambiguity check on types. It should also do the same for kinds. Here is a program that should be rejected: {{{#!hs type family F a data T :: F a -> Type }}} `T`'s kind is ambiguous, and any occurrence of `T` will be rejected. Instead of rejecting usage sites, let's just reject the definition site. This check would be disabled by `AllowAmbiguousTypes`. Happily, I think the implementation should be easy, and that the current algorithm to check for ambiguous types should work for kinds, too. After all, types and kinds are the same these days. This was inspired by #14203, but no need to read that ticket to understand this one. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14419> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13408: Consider inferring a higher-rank kind for type synonyms
by GHC 27 Feb '19

27 Feb '19

#13408: Consider inferring a higher-rank kind for type synonyms -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: TypeInType | 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 terms, a definition comprising one non-recursive equation may have a higher-rank type inferred. For example: {{{#!hs f :: (forall a. a -> a -> a) -> Int f z = z 0 1 g = f }}} `g` gets an inferred type equal to `f`'s. However, this fails at the type level: {{{#!hs type F (z :: forall a. a -> a -> a) = z 0 1 type G = F }}} If anything is strange here, it's that the term-level definition is accepted. GHC should not be in the business of inferring higher-rank types. But there is an exception for definitions comprising one non- recursive equation. This ticket proposes expanding this behavior to the type level, allowing `G` to be accepted. This is spun off from #13399, but is not tightly coupled to that ticket. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13408> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15755: randomRIO panic on (GHC version 8.4.3 for x86_64-apple-darwin)
by GHC 27 Feb '19

27 Feb '19

#15755: randomRIO panic on (GHC version 8.4.3 for x86_64-apple-darwin) -------------------------------------+------------------------------------- Reporter: cmal | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Keywords: randomRIO | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- randomRIO (1,100) ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-apple-darwin): nameModule system $dShow_a78p Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15755> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16080: runTestTT from ghci caused a panic.
by GHC 27 Feb '19

27 Feb '19

#16080: runTestTT from ghci caused a panic. -------------------------------------+------------------------------------- Reporter: | Owner: (none) emacstheviking | Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.4 Keywords: | Operating System: Unknown/Multiple Architecture: x86 | Type of failure: Compile-time | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Inside a REPL within Emacs+Intero-mode, running a stack project. I am writing a simple lexer for fun and I decided to try to see why I wasn't getting expected behaviour from an HUnit function. {{{ runTestTT classificationTests ghc: panic! (the 'impossible' happened) (GHC version 8.4.4 for x86_64-unknown-linux): nameModule system $dShow_a5Xw Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16080> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16088: The 'impossible' happened when I was trying to use getCurrentDirectory in repl in spacemacs.
by GHC 27 Feb '19

27 Feb '19

#16088: The 'impossible' happened when I was trying to use getCurrentDirectory in repl in spacemacs. -------------------------------------+------------------------------------- Reporter: hanrai | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.4 Keywords: | Operating System: Windows Architecture: x86_64 | Type of failure: None/Unknown (amd64) | Test Case: | Blocked By: getCurrentDirectory | Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I got this message when I type 'getCurrentDirectory' in repl in spacemacs. ghc.exe: panic! (the 'impossible' happened) (GHC version 8.4.4 for x86_64-unknown-mingw32): nameModule system $dShow_adyn Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler\utils\Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler\basicTypes\Name.hs:241:3 in ghc:Name Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16088> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16367: Panic when trying to openFile
by GHC 27 Feb '19

27 Feb '19

#16367: Panic when trying to openFile --------------------------------------+---------------------------------- Reporter: vilem | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.4.3 Keywords: | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: Runtime crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+---------------------------------- {{{ $ stack repl Note: No local targets specified, so a plain ghci will be started with no package hiding or package options. If you want to use package hiding and options, then you can try one of the following: * If you want to start a different project configuration than /Users/vl200/.stack/global-project/stack.yaml, then you can use stack init to create a new stack.yaml for the packages in the current directory. * If you want to use the project configuration at /Users/vl200/.stack/global-project/stack.yaml, then you can add to its 'packages' field. Configuring GHCi with the following packages: GHCi, version 8.4.3: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /Users/vl200/.ghci Loaded GHCi configuration from /private/var/folders/km/1g5b7h891674vhv9z1g4d9cw0000gn/T/haskell-stack- ghci/2a3bbd58/ghci-script Prelude> import System.IO Prelude System.IO> openFile ".g .granule .gitignore .ghc .ghci .gitconfig Prelude System.IO> openFile ".granule" Re Read ReadMode ReadS ReadWriteMode Real RealFloat RealFrac RelativeSeek Prelude System.IO> openFile ".granule" ReadMode ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-apple-darwin): nameModule system $dShow_a1QJ Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug}}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16367> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16356: Unexpected type application in default declaration
by GHC 27 Feb '19

27 Feb '19

#16356: Unexpected type application in default declaration -------------------------------------+------------------------------------- Reporter: int-index | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 (Type checker) | 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: -------------------------------------+------------------------------------- All of these work: {{{#!hs {-# LANGUAGE PolyKinds, TypeApplications, TypeFamilies, FlexibleInstances #-} import Data.Kind (Type) data B (a :: k) type family FClosed :: k -> Type where FClosed @k = B @k type family FOpen :: k -> Type type instance FOpen @k = B @k class FAssocClass k where type FAssoc :: k -> Type instance FAssocClass k where type FAssoc @k = B @k }}} This one doesn't: {{{#!hs class FAssocDefaultClass k where type FAssocDefault :: k -> Type type FAssocDefault @k = B @k }}} {{{ A.hs:21:23: error: Unexpected type application @k In the default declaration for ‘FAssocDefault’ | 21 | type FAssocDefault @k = B @k | }}} So, what are the rules of the game? Let's fix this and document in the User's Guide. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16356> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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