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[GHC] #14391: Make the simplifier independent of the typechecker
by GHC 05 Oct '18

05 Oct '18

#14391: Make the simplifier independent of the typechecker -------------------------------------+------------------------------------- Reporter: nomeata | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.3 Keywords: newcomer | 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 noticed that the simplifier module depends on all of the type checker, and HsSyn stuff, and renamer stuff, which I found strange. After a little investigation, it seems that the simplifier depends on CoreMonad, and that pulls some very few type-checker related things: 1. {{{ import TcRnMonad ( initTcForLookup ) import {-# SOURCE #-} TcSplice ( lookupThName_maybe ) }}} for {{{ thNameToGhcName :: TH.Name -> CoreM (Maybe Name) thNameToGhcName th_name = do hsc_env <- getHscEnv liftIO $ initTcForLookup hsc_env (lookupThName_maybe th_name) }}} which is not even used in GHC, but only in GHC Plugins, so this could probably be moved to a separate module pulled in by GhcPlugins.hs 2. {{{ import TcEnv ( lookupGlobal ) }}} for {{{ instance MonadThings CoreM where lookupThing name = do { hsc_env <- getHscEnv ; liftIO $ lookupGlobal hsc_env name } }}} This might be a bit harder to disentangle. But if successful, it would probably make building GHC in parallel quite a bit faster. And it just seems strange to me that the Core-to-Core code should depend on the type checker… Simon says: > Both of these code paths go through initTcForLookup which is massive overkill, as the comment with `TcEnv.lookupGlobal` says. There's clearly a ToDo here to strip off the redundant stuff and do a minimal lookup. I am optimistically marking this as `newcomer` because it is a refactoring task, and a good way of learning a bit about various pieces, with a reasonably clear notion of “success”. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14391> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15383: T3171 doesn't terminate with Interrupted message on Darwin
by GHC 05 Oct '18

05 Oct '18

#15383: T3171 doesn't terminate with Interrupted message on Darwin -------------------------------------+------------------------------------- Reporter: bgamari | 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: -------------------------------------+------------------------------------- I am seeing `T3171` fail with incorrect stderr output on Darwin (e.g. https://circleci.com/gh/ghc/ghc/7106) {{{ Actual stdout output differs from expected: --- ./ghci/should_run/T3171.run/T3171.stdout.normalised 2018-07-14 21:24:25.000000000 -0700 +++ ./ghci/should_run/T3171.run/T3171.run.stdout.normalised 2018-07-14 21:24:25.000000000 -0700 @@ -1 +0,0 @@ -Interrupted. *** unexpected failure for T3171(normal) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15383> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15235: GHCi's claim of infixr 0 (->) is a lie
by GHC 04 Oct '18

04 Oct '18

#15235: GHCi's claim of infixr 0 (->) is a lie -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- Currently, if you query the `:info` for `(->)` in GHCi, it will give you: {{{ $ ghci GHCi, version 8.4.3: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/ryanglscott/.ghci λ> :i (->) data (->) (a :: TYPE q) (b :: TYPE r) -- Defined in ‘GHC.Prim’ infixr 0 `(->)` <instances elided> }}} This fixity information appears to be plain wrong, as the following program demonstrates: {{{#!hs {-# LANGUAGE TypeOperators #-} module Bug where import Data.Type.Equality type (~>) = (->) infixr 0 ~> f :: (a ~> b -> c) :~: (a ~> (b -> c)) f = Refl }}} Since `(~>)` and `(->)` are both `infixr 0`, I would expect `a ~> b -> c` to associate as `a ~> (b -> c)`, like the type signature for `f` wants to prove. However, GHC believes otherwise: {{{ $ ghc Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:10:5: error: • Occurs check: cannot construct the infinite type: a ~ a ~> b Expected type: ((a ~> b) -> c) :~: (a ~> (b -> c)) Actual type: ((a ~> b) -> c) :~: ((a ~> b) -> c) • In the expression: Refl In an equation for ‘f’: f = Refl • Relevant bindings include f :: ((a ~> b) -> c) :~: (a ~> (b -> c)) (bound at Bug.hs:10:1) | 10 | f = Refl | ^^^^ }}} Reading the error message above, it appears that GHC gives `(->)` an even //lower// precedence than 0, since it associates `a ~> b -> c` as `(a ~> b) -> c`. I'm not sure how to reconcile these two facts. There are at least a couple of options I can think of: 1. Claim `(->)` has a negative fixity. 2. Try to change GHC so that `(->)` really is `infixr 0`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15235> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[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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Re: [GHC] #4861: Documentation for base does not include special items
by GHC 04 Oct '18

04 Oct '18

#4861: Documentation for base does not include special items -------------------------------------+------------------------------------- Reporter: NeilMitchell | Owner: (none) Type: bug | Status: closed Priority: low | Milestone: 8.8.1 Component: Core Libraries | Version: 7.0.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Documentation | Unknown/Multiple bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5167 Wiki Page: | -------------------------------------+------------------------------------- Comment (by harpocrates): As far as GHC is concerned, this is fixed. Progress on the Haddock-side changes is tracked in https://github.com/haskell/haddock/issues/368. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4861#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15705: Confusing parser error in 8.6
by GHC 04 Oct '18

04 Oct '18

#15705: Confusing parser error in 8.6 -------------------------------------+------------------------------------- Reporter: diatchki | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.6.1 (Parser) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | error/warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider the following example: {{{ f x = case x of A -> 'a' B -> 'b' }}} The problem here is that `B` is misaligned, which is quite a common mistake, especially in a bigger case block. GHC reports the following error: {{{ Unexpected case expression in function application: case x of { A -> 'a' } You could write it with parentheses Or perhaps you meant to enable BlockArguments? }}} This is quite confusing, especially since the program won't parse, `BlockArguments` or not. My guess is that we are being a bit too eager with reporting the `BlockArguments` issue. One way to work around this would be to just remember if we used `BlockArguments` while parsing, but only do the check that the extension is enabled after a successful parse. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15705> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4861: Documentation for base does not include special items
by GHC 04 Oct '18

04 Oct '18

#4861: Documentation for base does not include special items -------------------------------------+------------------------------------- Reporter: NeilMitchell | Owner: (none) Type: bug | Status: closed Priority: low | Milestone: 8.8.1 Component: Core Libraries | Version: 7.0.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Documentation | Unknown/Multiple bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5167 Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * milestone: 8.6.1 => 8.8.1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4861#comment:14> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4861: Documentation for base does not include special items
by GHC 04 Oct '18

04 Oct '18

#4861: Documentation for base does not include special items -------------------------------------+------------------------------------- Reporter: NeilMitchell | Owner: (none) Type: bug | Status: closed Priority: low | Milestone: 8.6.1 Component: Core Libraries | Version: 7.0.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Documentation | Unknown/Multiple bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5167 Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * status: patch => closed * resolution: => fixed * milestone: ⊥ => 8.6.1 Comment: This eight-year old ticket has finally been fixed with the two commits above. Hooray! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4861#comment:13> 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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