July 2018 - ghc-tickets

[GHC] #8708: Kind annotation in tuple not parsed
by GHC 04 Oct '18

04 Oct '18

#8708: Kind annotation in tuple not parsed -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Parser) | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- Consider this: {{{ {-# LANGUAGE KindSignatures #-} foo :: (Int, Int :: *) foo = undefined }}} HEAD reports {{{ /Users/rae/temp/Bug.hs:5:18: parse error on input ‛::’ }}} Changing the line to {{{ foo :: (Int, (Int :: *)) }}} fixes the problem. Note the extra parentheses. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8708> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11622: Annotating types in type familiy equations without parentheses
by GHC 04 Oct '18

04 Oct '18

#11622: Annotating types in type familiy equations without parentheses -------------------------------------+------------------------------------- Reporter: Iceland_jack | 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 annotating types in right-hand side of type family equations parentheses are required: {{{#!hs type family F a where F _ = (Int :: Type) }}} instead of {{{#!hs type family F a where F _ = Int :: Type }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11622> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15233: You can always set fixity of (:), with no effect
by GHC 04 Oct '18

04 Oct '18

#15233: You can always set fixity of (:), with no effect -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.5 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: -------------------------------------+------------------------------------- This works in a normal file {{{#!hs infixl 5 : }}} or in ghci {{{ $ ghci GHCi, version 8.5.20180314: http://www.haskell.org/ghc/ :? for help Prelude> infixr 5 : Prelude> }}} and has no effect -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15233> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15167: DerivClause list is not populated for (TyConI (DataD ...))
by GHC 04 Oct '18

04 Oct '18

#15167: DerivClause list is not populated for (TyConI (DataD ...)) -------------------------------------+------------------------------------- Reporter: 0xd34df00d | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Template | Version: 8.4.2 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: -------------------------------------+------------------------------------- {{{#!haskell % cat Test.hs {-# LANGUAGE LambdaCase #-} module Test where import Language.Haskell.TH test :: Name -> Q [Dec] test name = reify name >>= \case TyConI dec -> do runIO $ print dec pure [] _ -> pure [] % cat Run.hs {-# LANGUAGE TemplateHaskell #-} import Test data Foo = Foo deriving (Eq, Ord, Show) test ''Foo % ghc Run.hs [2 of 2] Compiling Main ( Run.hs, Run.o ) DataD [] Main.Foo [] Nothing [NormalC Main.Foo []] [] }}} One might expect the `DataD` to mention `Eq, Ord, Show` in the `DerivClause` list, but it doesn't. This behavior manifests with every ghc version I tried: 8.0.2, 8.2.2, 8.4.2. I also asked a question whether it's intended behaviour on #haskell, and I've been advised to open a bug report, so here it is. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15167> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11251: isInstance does not work on Typeable with base-4.8 anymore
by GHC 04 Oct '18

04 Oct '18

#11251: isInstance does not work on Typeable with base-4.8 anymore -------------------------------------+------------------------------------- Reporter: songzh | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.10.1 libraries/base | Keywords: Typeable, | Operating System: Unknown/Multiple isInstance | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs > :set -XTemplateHaskell > :m +Data.Tyepable > :m +Language.Haskell.TH --- With GHC 7.8 or earlier versions of GHC (I only tried with GHC 7.6, but my friends tried on 7.8 and earlier versoin) > $(isInstance ''Typeable [ConT ''Char] >>= stringE.show) "True" --- With GHC 7.10.1 > $(isInstance ''Typeable [ConT ''Char] >>= stringE.show) "False" }}} I have noticed that standalone derivings of Typeable instances in Data.Typeable are disappared magically in base-4.8 of GHC 7.10,also one cannot query the instances of it by using `:i Typeable` in GHCi, however, obviously, I can use `typeOf` function in base-4.8 to get the TypeRep of Char. The problem is that `isInstance` in template-haskell library doesn't know Char and many other types are instances of Typeable anymore. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11251> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13365: Kind-inference for poly-kinded GADTs
by GHC 04 Oct '18

04 Oct '18

#13365: Kind-inference for poly-kinded GADTs -------------------------------------+------------------------------------- Reporter: crockeea | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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: -------------------------------------+------------------------------------- With `-XPolyKinds`, GADTs require kind signatures where they should be inferred. Moreover, the error when these kind sigs are omitted is baffling. {{{ {-# LANGUAGE PolyKinds, GADTs #-} import GHC.TypeLits data C (x :: k) a where C1 :: (KnownNat x) => a -> Foo x a C2 :: a -> Foo Int a }}} {{{ error: • Expected kind ‘k’, but ‘x1’ has kind ‘Nat’ • In the first argument of ‘Foo’, namely ‘x’ In the type ‘Foo x a’ In the definition of data constructor ‘C1’ }}} From this error, I would never expect that putting a kind signature on `a` would help here. But a signature shouldn't be required at all: it's clear from the GADT constructors that `a :: *`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13365> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15457: (~) and (!) are parsed inconsistently in types (plus documentation warts)
by GHC 04 Oct '18

04 Oct '18

#15457: (~) and (!) are parsed inconsistently in types (plus documentation warts) -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: 8.4.3 (Parser) | 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: -------------------------------------+------------------------------------- (Spawned from https://ghc.haskell.org/trac/ghc/ticket/10056?replyto=41#comment:41) `~` and `!` are slightly special in the parser to allow strict annotations and lazy annotations (with `-XStrict`) in data types. As a result, we initially parse all uses of `~`/`!` as bangs, and we use a post-parsing pass (`mergeOps`/`splitTilde`) to figure out which uses of `~` are actually meant to refer to the equality type constructor. There's a couple of unsatisfying things here: 1. `splitTilde` handles `~`, but not `!`. This means that any use of `!` as a type operator will not work, as evidenced by this GHCi session: {{{ λ> type a ! b = Either a b <interactive>:1:6: error: Malformed head of type or class declaration: a !b }}} We should update `splitTilde` to handle `!` as well. (And perhaps give that function a new name to reflect its more ambitious goals.) 2. `Note [Parsing ~]` is supposed to explain all of this hullabaloo, but it does a rather poor job of it. Let's add some more prose to it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15457> 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] #9136: Constant folding in Core could be better
by GHC 02 Oct '18

02 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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[GHC] #10791: Add a --disable-large-memory-space configure option
by GHC 02 Oct '18

02 Oct '18

#10791: Add a --disable-large-memory-space configure option -------------------------------------+------------------------------------- Reporter: erikd | Owner: erikd Type: feature | Status: new request | Priority: normal | Milestone: 7.12.1 Component: Build | Version: 7.11 System | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- GHC recently started using large (1TB) address space on 64 bit systems. This feature is enabled by default but does not work on arm64-linux or amd64-solaris. Even just for testing, it would be nice to be able to disable this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10791> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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