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Re: [GHC] #1087: bang patterns with infix ops
by GHC 03 Oct '18

03 Oct '18

#1087: bang patterns with infix ops -------------------------------------+------------------------------------- Reporter: dons | Owner: int-index Type: bug | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.6 (Parser) | Resolution: | Keywords: bang patterns Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by int-index): * owner: (none) => int-index -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1087#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] Batch modify: #15499, #15667, #8763, #12005, #13704, #14907, ...
by GHC 03 Oct '18

03 Oct '18

Batch modification to #15499, #15667, #8763, #12005, #13704, #14907, #15053, #15196, #15481, #15552, #15578, #13477 by RyanGlScott: milestone to 8.6.2 Comment: Moving to the 8.6.2 milestone, since these tickets were all recently marked as merge. -- Tickets URL: <http://ghc.haskell.org/trac/ghc/query?id=15499%2C15667%2C8763%2C12005%2C137…> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12556: `stimes` adds extra power to Semigroup
by GHC 03 Oct '18

03 Oct '18

#12556: `stimes` adds extra power to Semigroup -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: task | Status: new Priority: normal | Milestone: Component: | Version: 8.0.1 libraries/base | 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: -------------------------------------+------------------------------------- {{{ ghci> stimes 0 (undefined :: [_]) [] }}} ghci> stimes 0 undefined () }}} makes it seem like `stimes 0` has some knowledge about `mempty` from `Monoid` but it has the following type {{{#!hs stimes 0 :: Semigroup a => a -> a }}} Desired behaviour? Given that type (assuming it only has the power of `<>`) I would have assumed this behaviour {{{ ghci> data L a = N | C a (L a) deriving Show ghci> instance Semigroup (L a) where (<>) = undefined ghci| ghci> stimes 0 (undefined :: L _) *** Exception: stimes: positive multiplier expected }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12556> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15693: Abstracting out pattern into a pattern synonym fails with scary error
by GHC 03 Oct '18

03 Oct '18

#15693: Abstracting out pattern into a pattern synonym fails with scary error -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple PatternSynonyms | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This '''works''' {{{#!hs {-# Language DataKinds, TypeOperators, PolyKinds, PatternSynonyms, GADTs #-} import Data.Kind data Ctx :: Type -> Type where E :: Ctx(Type) (:&:) :: a -> Ctx(as) -> Ctx(a -> as) data ApplyT(kind::Type) :: kind -> Ctx(kind) -> Type where AO :: a -> ApplyT(Type) a E AS :: ApplyT(ks) (f a) ctx -> ApplyT(k -> ks) f (a:&:ctx) foo :: ApplyT(Type -> Type -> Type) Either a -> () foo (ASSO (Left a)) = () pattern ASSO a = AS (AS (AO a)) }}} but then you might think, let's give a name (pattern synonym) to `ASSO (Left a)` This '''fails''' {{{#!hs {-# Language DataKinds, TypeOperators, PolyKinds, PatternSynonyms, GADTs #-} import Data.Kind data Ctx :: Type -> Type where E :: Ctx(Type) (:&:) :: a -> Ctx(as) -> Ctx(a -> as) data ApplyT(kind::Type) :: kind -> Ctx(kind) -> Type where AO :: a -> ApplyT(Type) a E AS :: ApplyT(ks) (f a) ctx -> ApplyT(k -> ks) f (a:&:ctx) pattern ASSO a = AS (AS (AO a)) pattern ASSOLeft a = ASSO (Left a) }}} {{{ $ ghci -ignore-dot-ghci 464.hs GHCi, version 8.7.20180828: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( hs/464.hs, interpreted ) hs/464.hs:16:22: error: • Couldn't match type ‘k1’ with ‘*’ ‘k1’ is a rigid type variable bound by the signature for pattern synonym ‘ASSOLeft’ at hs/464.hs:16:1-34 Expected type: ApplyT kind a b Actual type: ApplyT (* -> * -> *) Either (a1 ':&: (a20 ':&: 'E)) • In the expression: ASSO (Left a) In an equation for ‘ASSOLeft’: ASSOLeft a = ASSO (Left a) | 16 | pattern ASSOLeft a = ASSO (Left a) | ^^^^^^^^^^^^^ hs/464.hs:16:28: error: • Could not deduce: k1 ~ * from the context: (kind ~ (k -> ks), a ~~ f, b ~~ (a2 ':&: ctx), ks ~ (k1 -> ks1), f a2 ~~ f1, ctx ~~ (a3 ':&: ctx1), ks1 ~ *, f1 a3 ~~ a4, ctx1 ~~ 'E) bound by a pattern with pattern synonym: ASSO :: forall kind (a :: kind) (b :: Ctx kind). () => forall ks k (f :: k -> ks) (a1 :: k) (ctx :: Ctx ks) ks1 k1 (f1 :: k1 -> ks1) (a2 :: k1) (ctx1 :: Ctx ks1) a3. (kind ~ (k -> ks), a ~~ f, b ~~ (a1 ':&: ctx), ks ~ (k1 -> ks1), f a1 ~~ f1, ctx ~~ (a2 ':&: ctx1), ks1 ~ *, f1 a2 ~~ a3, ctx1 ~~ 'E) => a3 -> ApplyT kind a b, in a pattern synonym declaration at hs/464.hs:16:22-34 ‘k1’ is a rigid type variable bound by a pattern with pattern synonym: ASSO :: forall kind (a :: kind) (b :: Ctx kind). () => forall ks k (f :: k -> ks) (a1 :: k) (ctx :: Ctx ks) ks1 k1 (f1 :: k1 -> ks1) (a2 :: k1) (ctx1 :: Ctx ks1) a3. (kind ~ (k -> ks), a ~~ f, b ~~ (a1 ':&: ctx), ks ~ (k1 -> ks1), f a1 ~~ f1, ctx ~~ (a2 ':&: ctx1), ks1 ~ *, f1 a2 ~~ a3, ctx1 ~~ 'E) => a3 -> ApplyT kind a b, in a pattern synonym declaration at hs/464.hs:16:22-34 When matching types a3 :: k1 b0 :: * Expected type: a4 Actual type: Either a1 b0 • In the pattern: Left a In the pattern: ASSO (Left a) In the declaration for pattern synonym ‘ASSOLeft’ | 16 | pattern ASSOLeft a = ASSO (Left a) | ^^^^^^ Failed, no modules loaded. Prelude> }}} ---- Can I, as a user, assume that any valid pattern `foo (ASSO (Left a)) = ...` can be abstracted into a pattern synonym? There error message is too scary for me to sensibly know what to expect -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15693> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15698: SingleEntry update flag for Stg bindings is not used
by GHC 03 Oct '18

03 Oct '18

#15698: SingleEntry update flag for Stg bindings is not used -------------------------------------+------------------------------------- Reporter: osa1 | Owner: (none) Type: task | Status: new Priority: lowest | Milestone: 8.6.1 Component: Compiler | Version: 8.6.1 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: -------------------------------------+------------------------------------- I was looking at code generation for bindings with different update flags. Update flag type is defined as: {{{ data UpdateFlag = ReEntrant | Updatable | SingleEntry }}} I realized that we don't care about the difference between `ReEntrant` and `SingleEntry`, we only care about whether a binding is updatable or not, which is defined as {{{ isUpdatable :: UpdateFlag -> Bool isUpdatable ReEntrant = False isUpdatable SingleEntry = False isUpdatable Updatable = True }}} So we could remove `SingleEntry` and replace all uses of it with `ReEntrant` and everything would work the same. This raises the question of whether we're missing an optimisation in the code generator. Looking at code generation differences of updatable and non-updatable bindings, it seems like for a thunk (a binding with no arguments) we generate a thunk header and push an update frame regardless of the update flag. As far as I can see, update flag is only used when generating AP and selector thunks (we don't generate AP or selector thunks if the binding is not updatable). My question is: it seems to me that if a thunk is single entry then we should be able to give it a non-thunk type (maybe FUN?) and avoid pushing an update frame in `closureCodeBody`. Am I missing anything or is this possible? Is this worth trying? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15698> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15701: HEAD: Build failure in ghc-prim
by GHC 03 Oct '18

03 Oct '18

#15701: HEAD: Build failure in ghc-prim -------------------------------------+------------------------------------- Reporter: trommler | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Building GHC at changeset:21efbc7599e39ec93b8b I see the following message: {{{ checking whether GCC supports __atomic_ builtins... no configure: creating ./config.status config.status: error: cannot find input file: `ghc-prim.buildinfo.in' libraries/ghc-prim/ghc.mk:4: recipe for target 'libraries/ghc-prim/dist- install/package-data.mk' failed }}} And indeed there is no file `ghc-prim.buildinfo.in` in libraries/ghc-prim. There is no 8.7 for version so I am leaving it empty. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15701> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7897: MakeTypeRep fingerprints be proper, robust fingerprints
by GHC 03 Oct '18

03 Oct '18

#7897: MakeTypeRep fingerprints be proper, robust fingerprints -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by adamgundry): * cc: adamgundry (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7897#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7897: MakeTypeRep fingerprints be proper, robust fingerprints
by GHC 03 Oct '18

03 Oct '18

#7897: MakeTypeRep fingerprints be proper, robust fingerprints -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by adamgundry): Another use case for this is in the `safecopy` package (see https://github.com/acid-state/acid- state/issues/102#issuecomment-426327014), where it would be useful to be able to notice that the developer has changed a type used for binary serialization purposes. That said, perhaps a TH/Generics solution would be possible, so it may not be worth changing the current semantics of fingerprints. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7897#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2783: RTS -K/-M options not honored
by GHC 03 Oct '18

03 Oct '18

#2783: RTS -K/-M options not honored -----------------------------------+------------------------------ Reporter: j.waldmann | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 6.10.2 Component: Runtime System | Version: 6.10.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86 Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -----------------------------------+------------------------------ Changes (by bgamari): * owner: igloo => (none) * type: merge => bug * status: closed => new * resolution: fixed => Comment: It looks like this should be re-opened. The associated test has been fragile in the CircleCI slow-validate way. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2783#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9136: Constant folding in Core could be better
by GHC 03 Oct '18

03 Oct '18

#9136: Constant folding in Core could be better ------------------------------+-------------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Runtime performance bug Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | ------------------------------+-------------------------------------------- Constant folding in Core is still a bit feeble. For example, when staring at the code for `nofib/shootout/k-nucleotide` I saw this expression: {{{ (x +# 8) -# 1 }}} which would be relatively easy to optimise. The difficulty is knowing where to stop. What about `(8 +# x) -# 1`? Anyway, this ticket is to record the issue. Currently constant folding is done by the built-in RULES in `compiler/prelude/PrelRules`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9136> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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