March 2016 - ghc-tickets

[GHC] #11334: GHC panic when calling typeOf on a promoted data constructor
by GHC 22 Mar '16

22 Mar '16

#11334: GHC panic when calling typeOf on a promoted data constructor -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.1 (Type checker) | 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: -------------------------------------+------------------------------------- Here's what I did in GHCi to trigger the panic: {{{ $ inplace/bin/ghc-stage2 --interactive GHCi, version 8.1.20160101: http://www.haskell.org/ghc/ :? for help λ> :set -XDataKinds λ> :m Data.Typeable Data.Functor.Compose λ> typeOf (Proxy :: Proxy 'Compose) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20160101 for x86_64-unknown-linux): piResultTy * TYPE 'Lifted * Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Enabling `-XPolyKinds` doesn't trigger the error, though; #10343 will be triggered instead: {{{ λ> :set -XPolyKinds λ> typeOf (Proxy :: Proxy 'Compose) <interactive>:5:1: error: • No instance for (Typeable a0) arising from a use of ‘typeOf’ • In the expression: typeOf (Proxy :: Proxy Compose) In an equation for ‘it’: it = typeOf (Proxy :: Proxy Compose) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11334> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2530: deriving Show adds extra parens for constructor with record syntax
by GHC 22 Mar '16

22 Mar '16

#2530: deriving Show adds extra parens for constructor with record syntax -------------------------------------+------------------------------------- Reporter: spl | Owner: bgamari Type: bug | Status: patch Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 6.8.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D669, Wiki Page: | Phab:D2027 -------------------------------------+------------------------------------- Changes (by bgamari): * status: new => patch * differential: Phab:D669 => Phab:D669, Phab:D2027 @@ -6,1 +6,1 @@ - {{{ + {{{#!hs New description: Since record construction binds more tightly than function application, no parentheses are needed when passing a constructor with record syntax to a function constructor. As a result, we can pass {{{Just A {x = 5}}}} as shown below. {{{#!hs module Main where data A = A {x :: Int} deriving (Show) main :: IO () main = print $ Just A {x = 5} }}} But we get the result in the GHCi session below: {{{ *Main> main Just (A {x = 5}) }}} I tried looking through {{{TcGenDeriv}}}, but didn't figure out quite where the parenifying was done. {{{nested_compose_Expr}}}? {{{show_thingies}}}? I just wanted to make a ticket for general knowledge. Of course, this is not a real bug. Perhaps you could reclassify it as a feature. Either way, it would be nice to have. -- Comment: Phab:D2027 reverts to the previous behavior including redundant parens as described in comment:36. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2530#comment:38> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11734: coercionKind and coercionKindRole do potentially inefficient repeated substitutions
by GHC 22 Mar '16

22 Mar '16

#11734: coercionKind and coercionKindRole do potentially inefficient repeated substitutions -------------------------------------+------------------------------------- Reporter: niteria | Owner: Type: task | 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: -------------------------------------+------------------------------------- As pointed out by @simonpj in phab:D2024: > I hate the idea of substituting for a single type variable at a time. Its a recipe for non-linear behaviour. Maybe we should gather the foralls and the type args and try to do it all at once? > > Anyway, that's not the fault of this patch, although this patch may make it worse. Because when substituting into a monotype, the inscope set is not used; but if we do it one at a time we substitute into a`ForallCo` so we do inspect the inscope set. > > See Type.piResultTys. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11734> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5939: Standalone deriving Generic on type with instantiated arguments
by GHC 21 Mar '16

21 Mar '16

#5939: Standalone deriving Generic on type with instantiated arguments -------------------------------------+------------------------------------- Reporter: dreixel | Owner: dreixel Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.5 Resolution: fixed | Keywords: Generics Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | GenCannotDoRep0 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * keywords: => Generics -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5939#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7255: Wrong suggestion when deriving Generic on an instantiated type
by GHC 21 Mar '16

21 Mar '16

#7255: Wrong suggestion when deriving Generic on an instantiated type -------------------------------------+------------------------------------- Reporter: dreixel | Owner: dreixel Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Resolution: fixed | Keywords: Generics Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | GenCannotDoRep0 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * keywords: => Generics -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7255#comment:4> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 21 Mar '16

21 Mar '16

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: niteria Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: 11362 | Blocking: Related Tickets: #10424 | Differential Rev(s): Phab:D910, | Phab:D1073, Phab:D1133, Phab:D1192, | Phab:D1268, Phab:D1360, Phab:D1373, Wiki Page: | Phab:D1396, Phab:D1457, Phab:D1468, DeterministicBuilds | Phab:D1487, Phab:D1504, Phab:D1508 -------------------------------------+------------------------------------- Comment (by Bartosz Nitka <niteria@…>): In [changeset:"2cb55772c5359e5d71d34e5d42a4a7deb6a5d3db/ghc" 2cb5577/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="2cb55772c5359e5d71d34e5d42a4a7deb6a5d3db" Remove unnecessary Ord instance for ConLike The Ord instance for ConLike uses Unique order which is bad for determinism. Fortunately it's not used, so we can just delete it. The is part of the effort to make Unique comparisons explicit. Test Plan: ./validate Reviewers: austin, simonmar, bgamari, simonpj Reviewed By: simonpj Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2018 GHC Trac Issues: #4012 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:144> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11329: Visible type applications: failing tests with WAY=hpc
by GHC 21 Mar '16

21 Mar '16

#11329: Visible type applications: failing tests with WAY=hpc -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.11 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-head --info | grep Project [("Project name","The Glorious Glasgow Haskell Compilation System") ,("Project version","8.1.20151231") ,("Project Git commit id","8afeaad919dc67643b4eff14efafb48b59039b2b") }}} {{{ $ make slowtest TEST='VtaParse Vta1 Vta2' VERBOSE=2 TEST_HC=ghc-head ... =====> VtaParse(normal) 1 of 3 [0, 0, 0] =====> VtaParse(hpc) 1 of 3 [0, 0, 0] Compile failed (status 256) errors were: ghc: panic! (the 'impossible' happened) (GHC version 8.1.20151231 for x86_64-unknown-linux): dsExpr:HsTypeOut Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug *** unexpected failure for VtaParse(hpc) =====> VtaParse(optasm) 1 of 3 [0, 1, 0] =====> Vta1(normal) 2 of 3 [0, 1, 0] =====> Vta1(hpc) 2 of 3 [0, 1, 0] Compile failed (status 256) errors were: ghc: panic! (the 'impossible' happened) (GHC version 8.1.20151231 for x86_64-unknown-linux): dsExpr:HsTypeOut Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug *** unexpected failure for Vta1(hpc) =====> Vta1(optasm) 2 of 3 [0, 2, 0] =====> Vta2(normal) 3 of 3 [0, 2, 0] =====> Vta2(hpc) 3 of 3 [0, 2, 0] Compile failed (status 256) errors were: ghc: panic! (the 'impossible' happened) (GHC version 8.1.20151231 for x86_64-unknown-linux): dsExpr:HsTypeOut Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug *** unexpected failure for Vta2(hpc) =====> Vta2(optasm) 3 of 3 [0, 3, 0] Unexpected results from: TEST="Vta1 Vta2 VtaParse" }}} Tests added in commit 2db18b8135335da2da9918b722699df684097be9. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11329> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11711: Typechecker assertion failure
by GHC 21 Mar '16

21 Mar '16

#11711: Typechecker assertion failure -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 8.0.1-rc2 (Type checker) | 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: -------------------------------------+------------------------------------- I've seen this program both fail with a typechecker assertion and Core lint violations with various GHC versions, {{{#!hs {-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE ViewPatterns #-} {-# LANGUAGE TypeInType #-} module Hi where import Data.Kind (Type) data (:~~:) a b where HRefl :: a :~~: a data TypeRep (a :: k) where TrTyCon :: String -> TypeRep k -> TypeRep (a :: k) TrApp :: forall k1 k2 (a :: k1 -> k2) (b :: k1). TypeRep (a :: k1 -> k2) -> TypeRep (b :: k1) -> TypeRep (a b) class Typeable (a :: k) where typeRep :: TypeRep a data TypeRepX where TypeRepX :: forall k (a :: k). TypeRep a -> TypeRepX eqTypeRep :: TypeRep a -> TypeRep b -> Maybe (a :~~: b) eqTypeRep = undefined typeRepKind :: forall k (a :: k). TypeRep a -> TypeRep k typeRepKind = undefined funResultTy :: TypeRepX -> TypeRepX -> Maybe TypeRepX funResultTy (TypeRepX f) (TypeRepX x) | Just HRefl <- (typeRep :: TypeRep Type) `eqTypeRep` typeRepKind f , TRFun arg res <- f , Just HRefl <- arg `eqTypeRep` x = Just (TypeRepX res) | otherwise = Nothing trArrow :: TypeRep (->) trArrow = undefined pattern TRFun :: forall fun. () => forall arg res. (fun ~ (arg -> res)) => TypeRep arg -> TypeRep res -> TypeRep fun pattern TRFun arg res <- TrApp (TrApp (eqTypeRep trArrow -> Just HRefl) arg) res }}} The most recent type checker error is, {{{ $ ~/ghc/ghc-testing/inplace/bin/ghc-stage2 -dcore-lint ~/Hi.hs [1 of 1] Compiling Hi ( /home/ben/Hi.hs, /home/ben/Hi.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20160315 for x86_64-unknown-linux): tcTyVarDetails cobox_a1Nm :: k_a1N4[ssk] ~# Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11711> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11708: Typechecker hangs when checking type families with -ddump-tc-trace turned on
by GHC 21 Mar '16

21 Mar '16

#11708: Typechecker hangs when checking type families with -ddump-tc-trace turned on -------------------------------------+------------------------------------- Reporter: kcsongor | Owner: kcsongor Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 (Type checker) | Keywords: typefamilies | Operating System: Unknown/Multiple trace hangs | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I have the following code, which is supposed to fail with a type error. However, when compiled with HEAD using the -ddump-tc-trace flag, the type checker hangs. {{{#!hs {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE DataKinds #-} module Test where import Data.Proxy test :: (IsElem a as ~ 'True) => Proxy a -> Proxy as -> Bool test _ _ = True x = test (Proxy :: Proxy Int) (Proxy :: Proxy '[]) type family IsElem (x :: k) (xs :: [k]) where IsElem x '[] = 'False IsElem x (x ': xs) = 'True IsElem x (y ': xs) = IsElem x xs }}} The reason is that in typecheck/TcHsType.hs, the type family tycons are type-checked with knot-tying, however, they are being traced, forcing their evaluation which causes the typechecker to hang. My proposed fix is to only print the safe values that we know are constructed by the time of tracing. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11708> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4114: Add a flag to remove/delete intermediate files generated by GHC
by GHC 20 Mar '16

20 Mar '16

#4114: Add a flag to remove/delete intermediate files generated by GHC -------------------------------------+------------------------------------- Reporter: guest | Owner: kaiha Type: feature request | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 6.10.4 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #2258 | Differential Rev(s): Phab:D2021 Wiki Page: | -------------------------------------+------------------------------------- Changes (by kaiha): * status: new => patch * differential: => Phab:D2021 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4114#comment:24> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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