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[GHC] #16280: Update Latest page of User's Guide to GHC 8.6.3
by GHC 03 Feb '19

03 Feb '19

#16280: Update Latest page of User's Guide to GHC 8.6.3 -------------------------------------+------------------------------------- Reporter: wataru86 | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 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: -------------------------------------+------------------------------------- Latest version of GHC is 8.6.3. However, latest page of User's Guide is 8.6.2(https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/index…. Please Update to GHC 8.6.3. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16280> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12001: RFC: Add pattern synonyms to base
by GHC 02 Feb '19

02 Feb '19

#12001: RFC: Add pattern synonyms to base -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 7.10.3 libraries/base | 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: -------------------------------------+------------------------------------- Since we have pattern synonyms it's worth considering if some belong in base: [https://hackage.haskell.org/package/lens-4.14/docs/Data-Complex-Lens.html Data.Complex.Lens] contains patterns that could be defined in base, here are some more suggestions: === Data.Array === {{{#!hs pattern ArrayIx :: Ix i => (i, i) -> [(i, e)] -> Array i e pattern ArrayIx low'high xs <- ((\arr -> (bounds arr, assocs arr)) -> (low'high, xs)) where ArrayIx low'high xs = array low'high xs }}} === Data.Bits === {{{#!hs pattern ZeroBits :: (Eq a, Bits a) => a pattern ZeroBits <- ((== zeroBits) -> True) where ZeroBits = zeroBits pattern BitSize :: Bits a => Int -> a pattern BitSize n <- (bitSizeMaybe -> Just n) pattern Signed :: Bits a => a pattern Signed <- (isSigned -> True) pattern Unsigned :: Bits a => a pattern Unsigned <- (isSigned -> False) pattern PopCount :: Bits a => Int -> a pattern PopCount n <- (popCount -> n) }}} === Data.Char === {{{#!hs pattern ControlChar :: Char pattern ControlChar <- (isControl -> True) pattern SpaceChar :: Char pattern SpaceChar <- (isSpace -> True) }}} === Data.Complex === {{{#!hs pattern Conjugate :: Num a => Complex a -> Complex a pattern Conjugate a <- (conjugate -> a) where Conjugate a = conjugate a pattern Polar :: RealFloat a => a -> a -> Complex a pattern Polar m theta <- (polar -> (m, theta)) where Polar m theta = mkPolar m theta -- See https://github.com/ekmett/lens/issues/653 pattern Real :: Num a => a -> Complex a pattern Real r <- r :+ _ where Real r = r :+ 0 pattern Imaginary :: Num a => a -> Complex a pattern Imaginary i <- _ :+ i where Imaginary i = 0 :+ i }}} === GHC.Float === {{{#!hs pattern NegativeZero :: RealFloat a => a pattern NegativeZero <- (isNegativeZero -> True) where NegativeZero = -0 pattern Denormalized :: RealFloat a => a pattern Denormalized <- (isDenormalized -> True) pattern NaN :: RealFloat a => a pattern NaN <- (isNaN -> True) where NaN = 0 / 0 -- How ever negative infinity is handled pattern Infinity :: RealFloat a => a pattern Infinity <- ((== 1 / 0) -> True) where Infinity = 1 / 0 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12001> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16277: Make JUnit report stdout/stderr in more cases
by GHC 02 Feb '19

02 Feb '19

#16277: Make JUnit report stdout/stderr in more cases -------------------------------------+------------------------------------- Reporter: mpickering | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 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: -------------------------------------+------------------------------------- In https://gitlab.haskell.org/ghc/ghc/merge_requests/210 we made a start to improve the junit output to also include stderr/stdout when appropriate. However, the patch only handles a few cases, it is reasonably straightforward to handle more cases but the refactoring was a bit more involved than I was prepared to do at the time. To find more places, look in `testlib.py` and grep for `failBecause`. There are examples such as `bad stderr` and `bad stdout` which would also benefit from reporting the stderr. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16277> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16240: Core visible conditional compilation/static definition/code selection based upon static key values
by GHC 02 Feb '19

02 Feb '19

#16240: Core visible conditional compilation/static definition/code selection based upon static key values -------------------------------------+------------------------------------- Reporter: carter | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.7 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 the way we write haskell code to handle multiple platforms or configurations use the C preprocessor (CPP) in traditional mode. there are several challenges with this 1) tooling dependency 2) not actually designed for haskell code 3) no compiler support for checking the syntax / name / type well- formedness of each alternative code fragment under the associated environment assumptions. Abstractly, CPP uses a mapping from Names to Maybe (Either String Integer) or something to that effect. theres two ways we could then treat a "HPP" design: 1) just like CPP traditional mode, its just splicing tokens together. a) One implication of this design choice would be that to be able to check/ parse the different combinations of compilation, you'd need to be able to enumerate the set of maps of key value pairs of interest, and then you'd roughly want to have each Module be actually a {{{ Map (Map String (Maybe (Either String Integer))) Module) }}} this would have some pretty obvious code blowup issues, at least if you wanted to full on type check each combination in full. 2) only allow "HPP" to work on valid syntactic units, eg expressions, right hand sides, patterns, top level definition, etc, and provide a magic primop or several that would look roughly like NOTE: it could also just be at the Haskell post type inference phase, not necessarily at core level {{{ DefinitionDispatchTermLevel :: [(Map String (Maybe (Either String Integer)) , CoreTerm)] -> --- set of all #if/else/ifdef etc conditionals? Map (String) (Maybe (Either String Integer)) -> -- actual CPP flag combination used CoreTerm -> --- actual term ghc / optimizer works with and manipulates CoreTerm }}} this sketched out constructor representation overlooks a few things, eg the ability to do interval predicates and various boolean algebra operations, which WOULD be expressible in a fully fleshed out approch to this, but i'm elliding to keep simple. i think approach (1) or something like it would have the benefit of mostly working "today" wrt how we use CPP, and checking/coverage could be done via some package level or module level enumeration of cpp value mappings that you wnat to be checked or even generated approach (2) adds a funny looking operation to core/haskell terms/types representation where you could carry around "alternative expressions" plus the "selected expression". and thus you could do some amount of syntax/type checking for those altnerative platforms? either way, this is just me jotting down some thoughts on this because its been discussed on and off for a while now as an eventual nice to have for ghc. Also quite a complicated design space! :) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16240> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16255: Visible kind application defeats type family with higher-rank result kind
by GHC 02 Feb '19

02 Feb '19

#16255: Visible kind application defeats type family with higher-rank result kind -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.7 (Type checker) | Keywords: | Operating System: Unknown/Multiple TypeApplications, TypeFamilies | Architecture: | Type of failure: GHC accepts Unknown/Multiple | invalid program Test Case: | Blocked By: Blocking: | Related Tickets: #15740 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- After #15740, GHC now (correctly) rejects this program: {{{#!hs {-# LANGUAGE DataKinds #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE TypeFamilies #-} module Bug where import Data.Kind data SBool :: Bool -> Type type family F :: forall k. k -> Type where F = SBool }}} {{{ $ ~/Software/ghc5/inplace/bin/ghc-stage2 --interactive Bug.hs GHCi, version 8.7.20190115: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:12:7: error: • Expected kind ‘forall k. k -> *’, but ‘SBool’ has kind ‘Bool -> *’ • In the type ‘SBool’ In the type family declaration for ‘F’ | 12 | F = SBool | ^^^^^ }}} However, there's a very simple way to circumvent this: add a visible kind application to `F`'s equation. {{{#!hs type family F :: forall k. k -> Type where F @Bool = SBool }}} If I understand things correctly, GHC shouldn't allow this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16255> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11004: hsc2hs does not handle single quotes properly
by GHC 01 Feb '19

01 Feb '19

#11004: hsc2hs does not handle single quotes properly -------------------------------------+------------------------------------- Reporter: sergv | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: hsc2hs | Version: 7.10.2 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: -------------------------------------+------------------------------------- The tool gets confused by quotes for promoted constructors (https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/promotion.h… #promotion-syntax). Here's an example: {{{#!hs {-# LANGUAGE DataKinds #-} {-# LANGUAGE GADTs #-} data Foo = Foo | Bar data Indexed ix where Indexed :: Indexed 'Foo main :: IO () main = print $ #size int }}} gets translated into {{{#!hs {-# LINE 1 "Test.hsc" #-} {-# LANGUAGE DataKinds #-} {-# LINE 2 "Test.hsc" #-} {-# LANGUAGE GADTs #-} data Foo = Foo | Bar data Indexed ix where Indexed :: Indexed 'Foo main :: IO () main = print $ #size int }}} Then GHC complains about `#size`: {{{ Test.hsc:10:16: parse error on input ‘#’ }}} Judging from the source of utils/hsc2hs/HSCParser.hs, the tool treats single quotes the same way as double quotes. I.e. it looks for balanced, possibly multiline, strings delimited by '. At least, it seems unnecessary to expect newlines in that string-like structure, because character literals cannot contain newlines, AFAIK. It's interesting to note that this problem looks like a bit of an edge case, since highlighting in the ticket seems to be confused as well. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11004> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15514: Older Trac ticket links redirect to this site, but not to the specific ticket
by GHC 01 Feb '19

01 Feb '19

#15514: Older Trac ticket links redirect to this site, but not to the specific ticket -------------------------------------+------------------------------------- Reporter: ChaiTRex | Owner: hvr Type: bug | Status: new Priority: normal | Milestone: Component: Trac & Git | Version: 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: -------------------------------------+------------------------------------- == Current behavior == An old ticket link is redirected to this new site, just not to the actual ticket, so some form of redirection is configured: || ||= old link =||= redirects to =|| ||= HTTP =|| http://hackage.haskell.org/trac/ghc/ticket/698 || https://ghc.haskell.org/trac/ghc || ||= HTTPS =|| https://hackage.haskell.org/trac/ghc/ticket/698 || https://ghc.haskell.org/trac/ghc || == Desired outcome == An old ticket link should redirect to the actual ticket: || ||= old link =||= redirects to =|| ||= HTTP =|| http://hackage.haskell.org/trac/ghc/ticket/698 || https://ghc.haskell.org/trac/ghc/ticket/698 || ||= HTTPS =|| https://hackage.haskell.org/trac/ghc/ticket/698 || https://ghc.haskell.org/trac/ghc/ticket/698 || -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15514> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16276: Feature request: Polymorphic kinds in Data.Functor.Classes
by GHC 01 Feb '19

01 Feb '19

#16276: Feature request: Polymorphic kinds in Data.Functor.Classes -------------------------------------+------------------------------------- Reporter: siddharthist | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Keywords: polykinds | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The classes in Data.Functor.Classes have a somewhat restrictive kind signature: {{{ *Data.Functor.Classes> :k Eq1 Eq1 :: (* -> *) -> Constraint }}} As a result, we redefine [1] many of them in the [https://hackage.haskell.org/package/parameterized-utils-1.0.1/docs/Data- Parameterized-Classes.html parameterized-utils] library. It would be quite easy to make more polymorphic (have kind "(k -> *) -> Constraint"). If everyone thinks this is a good idea, I'm happy to submit a pull request. [1]: To be precise, there are actually a few axes along which the classes in parameterized-utils vary from those in base. Some, like OrdF, require more type-level evidence. Others, like EqF, don't require their type parameter to have the corresponding instance. There are a lot of points in the design space here. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16276> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16275: type hole in hs-boot file triggers GHC internal error
by GHC 01 Feb '19

01 Feb '19

#16275: type hole in hs-boot file triggers GHC internal error -------------------------------------+------------------------------------- Reporter: j.waldmann | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 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: -------------------------------------+------------------------------------- Put each line in a separate file, the last one is B.hs-boot {{{ module A where { import {-# SOURCE #-} B } module B where { } module B where { data T a ; foo :: T _ } }}} then {{{ $ ghci A.hs GHCi, version 8.6.3: http://www.haskell.org/ghc/ :? for help [1 of 3] Compiling B[boot] ( B.hs-boot, interpreted ) B.hs-boot:1:38: error: • GHC internal error: ‘_’ is not in scope during type checking, but it passed the renamer tcl_env of environment: [] • In the first argument of ‘T’, namely ‘_’ In the type signature: foo :: T _ | 1 | module B where { data T a ; foo :: T _ } | ^ }}} I know the program is invalid (the hole has no valid instance) but still it should not produce an internal error? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16275> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16273: Hadrian turns on `-Wno-unused-imports` for text when using integer-simple
by GHC 01 Feb '19

01 Feb '19

#16273: Hadrian turns on `-Wno-unused-imports` for text when using integer-simple -------------------------------------+------------------------------------- Reporter: mpickering | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.6.3 (Hadrian) | 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: -------------------------------------+------------------------------------- In `Settings.Warnings`, hadrian turns on `-Wno-unused-imports` for the `text` package when building with `integer-simple`. It would be good to fix `text` so we can remove this special case. 1. Build GHC with `integer-simple` and `-Werror` 2. Remove the special case for `text` in `Settings.Warnings`. 3. Fix the warnings in `text` appropriately so the build finishes. 4. Push the fix upstream and then update the submodule. This could also be debugged without having to build ghc by downloading an [https://gitlab.haskell.org/ghc/ghc/-/jobs/artifacts/master/download?job =validate-x86_64-linux-deb9-integer-simple integer-simple bindist]. Also see: https://github.com/haskell/text/issues/250 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16273> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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