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[GHC] #16224: CPUTime001 is fragile
by GHC 25 Jan '19

25 Jan '19

#16224: CPUTime001 is fragile -------------------------------------+------------------------------------- Reporter: bgamari | 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: -------------------------------------+------------------------------------- I have seen CPUTime001 fail spuriously on several occasions. In [[https://gitlab.haskell.org/ghc/ghc/-/jobs/15989|one such occasion]]: {{{#!diff --- libraries/base/tests/CPUTime001.run/CPUTime001.stdout.normalised 2019-01-23 18:53:32.601027719 +0000 +++ libraries/base/tests/CPUTime001.run/CPUTime001.run.stdout.normalised 2019-01-23 18:53:32.601027719 +0000 @@ -1,4 +1,4 @@ 1028457 1664079 2692537 -(True,True) +(False,True) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16224> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12599: Add Hadrian build artifacts to gitignore
by GHC 25 Jan '19

25 Jan '19

#12599: Add Hadrian build artifacts to gitignore -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: task | 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: -------------------------------------+------------------------------------- Andrey wrote requesting the following, > For top-level `.gitignore`: > {{{ > # ------------------------------------------------------------------------------------- > # Hadrian's stuff. Note, **/stageN/ folders will be relocated to _build/ after > # resolving https://github.com/snowleopard/hadrian/issues/113 > # ------------------------------------------------------------------------------------- > _build/ > hadrian/ > **/stage?/ > }}} > > For `.gitignore` in affected submodules (array, deepseq, directory, filepath, > hoopl, hpc, process, utils/hsc2hs): > > {{{ > # ------------------------------------------------------------------------------------- > # Hadrian's stuff. Note, stageN/ folders will be relocated to top-level _build/ > # after resolving https://github.com/snowleopard/hadrian/issues/113 > # ------------------------------------------------------------------------------------- > stage?/ > }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12599> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16235: Hadrian devel2 builds Haddock
by GHC 25 Jan '19

25 Jan '19

#16235: Hadrian devel2 builds Haddock -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.6.3 (Hadrian) | 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: -------------------------------------+------------------------------------- ... but `make` did not, with devel2. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16235> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16103: docs-haddock Hadrian target doesn't work reliably
by GHC 25 Jan '19

25 Jan '19

#16103: docs-haddock Hadrian target doesn't work reliably -------------------------------------+------------------------------------- Reporter: harpocrates | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.6.3 (Hadrian) | 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: -------------------------------------+------------------------------------- Starting with a clean build, the following doesn't work: {{{ $ ./hadrian/build.sh -c docs-haddock }}} However, it does work if you've already run `./hadrian/build.sh -c`. Here's a sample `--verbose` log (this was produced with `./hadrian/build.sh -c --build-root=_qkst-integer-simple --flavour=quickest docs-haddock --integer-simple --verbose`, but the problem exhibits even without all the extra options): {{{ Up to date Up to date | ContextData oracle: resolving data for 'haddock' (Stage2, v)... | Configure package 'haddock' Configuring haddock-2.22.0... creating /Users/atheriault/Code/ghc/_qkst-integer-simple/stage2/utils/haddock/build /Users/atheriault/Code/ghc/_qkst-integer-simple/stage1/bin/ghc --numeric- version /Users/atheriault/Code/ghc/_qkst-integer-simple/stage1/bin/ghc is version 8.7.20181227 /Users/atheriault/Code/ghc/_qkst-integer-simple/stage0/bin/ghc-pkg --version /Users/atheriault/Code/ghc/_qkst-integer-simple/stage0/bin/ghc-pkg is version 8.7.20181227 /Users/atheriault/Code/ghc/_qkst-integer-simple/stage1/bin/ghc --supported-languages /Users/atheriault/Code/ghc/_qkst-integer-simple/stage1/bin/ghc --info Reading installed packages... /Users/atheriault/Code/ghc/_qkst-integer-simple/stage0/bin/ghc-pkg dump --global -v0 '--global-package-db=/Users/atheriault/Code/ghc/_qkst- integer-simple/stage1/lib/package.conf.d' /Users/atheriault/Code/ghc/_qkst-integer-simple/stage1/bin/ghc --print- libdir '-ghcversion-file=/Users/atheriault/Code/ghc/_qkst-integer- simple/generated/ghcversion.h' CallStack (from HasCallStack): die', called at ./Distribution/Simple/Configure.hs:969:20 in Cabal-2.5.0.0-inplace:Distribution.Simple.Configure configureFinalizedPackage, called at ./Distribution/Simple/Configure.hs:467:12 in Cabal-2.5.0.0-inplace:Distribution.Simple.Configure configure, called at ./Distribution/Simple.hs:596:20 in Cabal-2.5.0.0-inplace:Distribution.Simple confHook, called at ./Distribution/Simple/UserHooks.hs:67:5 in Cabal-2.5.0.0-inplace:Distribution.Simple.UserHooks configureAction, called at ./Distribution/Simple.hs:178:19 in Cabal-2.5.0.0-inplace:Distribution.Simple defaultMainHelper, called at ./Distribution/Simple.hs:148:3 in Cabal-2.5.0.0-inplace:Distribution.Simple defaultMainWithHooksNoReadArgs, called at src/Hadrian/Haskell/Cabal/Parse.hs:145:14 in main:Hadrian.Haskell.Cabal.Parse hadrian: Encountered missing dependencies: xhtml ==3000.2.* shakeArgsWith 0.000s 0% Function shake 0.010s 0% Database read 0.317s 12% === With database 0.018s 0% Running rules 2.166s 86% ========================= Total 2.511s 99% Error when running Shake build system: at src/Main.hs:58:30-42: * Depends on: docs-haddock at src/Rules/Documentation.hs:79:9-48: * Depends on: _qkst-integer-simple/docs/html/libraries/index.html at src/Rules/Documentation.hs:136:9-24: * Depends on: _qkst-integer-simple/docs/html/libraries/ghc-prim/ghc- prim.haddock at src/Hadrian/Builder.hs:70:5-23: * Depends on: _qkst-integer-simple/stage2/bin/haddock at src/Development/Shake/Internal/Rules/Oracle.hs:157:43-68: * Depends on: OracleQ (ContextDataKey (Context {stage = Stage2, package = Package {pkgType = Program, pkgName = "haddock", pkgPath = "utils/haddock"}, way = v})) at src/Hadrian/Haskell/Cabal/Parse.hs:202:5-36: * Depends on: _qkst-integer-simple/stage2/utils/haddock/setup-config * Raised the exception: ExitFailure 1 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16103> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9476: Implement late lambda-lifting
by GHC 25 Jan '19

25 Jan '19

#9476: Implement late lambda-lifting -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- This ticket exists to coordinate work on Nick Frisby's '''late lambda- lifting''' optimisation. * Wiki page: [wiki:LateLamLift]. All the details are here. * Branch in GHC repo: `wip/llf` * Related tickets * #9279: local closure remains in final program * #9374: static argument transformation -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9476> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16213: Unnecessary error
by GHC 25 Jan '19

25 Jan '19

#16213: Unnecessary error -------------------------------------+------------------------------------- Reporter: pjljvdlaar | 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: -------------------------------------+------------------------------------- I don't know whether this is a bug or a feature request.... When compiling {{{ {-# LANGUAGE DataKinds #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE FlexibleInstances #-} module Main where data Term (b::Bool) where Const :: Int -> Term 'True Sum :: --Show (TermList v) => TermList v -> Term 'False instance Show (Term b) where show (Const a) = "(Const " ++ show a ++ ")" show (Sum a) = "(Sum " ++ show a ++ ")" data TermList (xs :: [ Bool ]) where TNil :: TermList '[] TCons :: Term x -> TermList xs -> TermList (x ': xs) instance Show (TermList '[]) where show TNil = "Nil" instance Show (TermList xs) => Show (TermList (x ': xs)) where show (TCons a b) = "(Cons " ++ show a ++ " " ++ show b ++ ")" main :: IO () main = do putStrLn "Hello world!" }}} one gets the error {{{ src\Main.hs:37:31: error: * Could not deduce (Show (TermList v)) arising from a use of `show' from the context: b ~ 'False bound by a pattern with constructor: Sum :: forall (v :: [Bool]). TermList v -> Term 'False, in an equation for `show' at src\Main.hs:37:11-15 * In the first argument of `(++)', namely `show a' In the second argument of `(++)', namely `show a ++ ")"' In the expression: "(Sum " ++ show a ++ ")" | 37 | show (Sum a) = "(Sum " ++ show a ++ ")" | ^^^^^^ }}} Yet, both patterns are matched, i.e. '[] and (x ': xs), so I was surprised the compiler could not figure this out! By out commenting 'Show (TermList v) => ' the code complies fine. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16213> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16237: Run check-api-annotations and check-ppr on all parseable test code
by GHC 25 Jan '19

25 Jan '19

#16237: Run check-api-annotations and check-ppr on all parseable test code -------------------------------------+------------------------------------- Reporter: alanz | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Test Suite | 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: -------------------------------------+------------------------------------- The `check-ppr` utility checks that `parse (ppr (parse s)) === parse s` holds, when given a file to test. Likewise, the `check-api-annotations` utility checks that all API annotations are actually attached to the `ParsedSource` output, and that they do not precede their attachment span. At the moment these checks are only run on a subset of code, as explicitly called for in the `/testsuite/tests/printer` and `/testsuite/tests/ghc- api/annotations` tests. These properties are supposed to hold for all GHC parseable haskell. So rather than requiring individual developers to add specific tests to confirm their new features work properly, extend the test framework to make a pass over all the files that are expected to be parseable, and run these checks on them. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16237> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16234: Unable to resolve type families
by GHC 25 Jan '19

25 Jan '19

#16234: Unable to resolve type families -------------------------------------+------------------------------------- Reporter: crockeea | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: #16211 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following code {{{ {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE TypeFamilies #-} import Control.Monad.Classes (MonadReader) --import Control.Monad.Primitive () import Control.Monad.Trans.State.Lazy (StateT) main :: (n ~ StateT () IO, MonadReader () n) => IO () main = undefined }}} produces the error (cleaned up for readability) {{{ Main.hs:9:1: error: * No instance for (monad-classes.MonadReaderN (monad-classes.FindTrue '[monad-classes.CanDo (StateT () IO) (monad-classes.EffReader ()), monad-classes.CanDo IO (monad-classes.EffReader ())]) () (StateT () IO)) arising from a use of `main' * In the expression: main When checking the type of the IO action `main' | 9 | main = undefined | ^ }}} This is the same error as #16211, but that ticket uses a slightly different example to trigger the error upon recompile. The relevant instances are all available in `monad-classes`. {{{ class Monad m => MonadReaderN (n :: Peano) r m instance Monad m => MonadReaderN Zero r (StateT r m) type family CanDo (m :: (* -> *)) (eff :: k) :: Bool type instance CanDo (StateT s m) eff = StateCanDo s eff type family StateCanDo s eff where StateCanDo s (EffState s) = True StateCanDo s (EffReader s) = True type family FindTrue (bs :: [Bool]) :: Peano where FindTrue (True ': t) = Zero FindTrue (False ': t) = Succ (FindTrue t) data EffReader (e :: *) }}} I can reproduce with the attached package using GHC-8.6.3 and cabal: {{{ $ cabal sandbox init $ cabal install --only-dependencies $ cabal build }}} I was unable to minimize the attached example any further. Here's two ways to make the error go away: 1. `import Control.Monad.Primitive ()`. It's unclear why this would help because according to the maintainer of monad-classes, it has no transitive dependencies on `primitive`. 2. Change the signature of `main` to `main :: (MonadReader () (StateT () IO) => IO ()` -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16234> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16220: -Wmissing-signatures should warn when top-level signature is partial
by GHC 24 Jan '19

24 Jan '19

#16220: -Wmissing-signatures should warn when top-level signature is partial -------------------------------------+------------------------------------- Reporter: aspiwack | Owner: (none) Type: feature | Status: new request | 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: -------------------------------------+------------------------------------- I'd like GHC to emit a warning for the following definition: {{{#!hs g :: _ g = True }}} But not for that one: {{{#!hs f :: Int f = x where x :: _ x = 1 }}} The context is that I'm using partial signatures to help the type checker give the right type to a binding, with no intention of filling the holes later. (what Richard calls elision [https://github.com/ghc-proposals/ghc- proposals/pull/194 here]) The warning accompanying partial signatures (`-Wpartial-type-signatures`) effectively treats `_`-s in type signatures as holes which are meant to be filled (the type-level equivalent of typed holes). Which is not useful to my usage. I can deactivate `-Wpartial-type-signatures`, however, it seems to me that, in that case, a partial top-level signature is just as bad as a missing top-level signature. So it seems to me that whenever I have `-Wmissing-signatures` enabled I also want to warn for partial top-level signatures. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16220> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16203: Unhelpful names for wildcard type variables
by GHC 24 Jan '19

24 Jan '19

#16203: Unhelpful names for wildcard type variables -------------------------------------+------------------------------------- Reporter: simonpj | 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: -------------------------------------+------------------------------------- Consider {{{ {-# LANGUAGE PartialTypeSignatures #-} f :: _ -> _ f x = x }}} With GHC 8.6 we got {{{ T16152.hs:10:6: warning: [-Wpartial-type-signatures] • Found type wildcard ‘_’ standing for ‘w’ Where: ‘w’ is a rigid type variable bound by the inferred type of f :: w -> w at T16152.hs:11:1-7 • In the type signature: f :: _ -> _ | 10 | f :: _ -> _ | ^ T16152.hs:10:11: warning: [-Wpartial-type-signatures] • Found type wildcard ‘_’ standing for ‘w’ Where: ‘w’ is a rigid type variable bound by the inferred type of f :: w -> w at T16152.hs:11:1-7 • In the type signature: f :: _ -> _ | 10 | f :: _ -> _ | ^ }}} But with HEAD we get {{{ T16152.hs:10:6: warning: [-Wpartial-type-signatures] • Found type wildcard ‘_’ standing for ‘_’ Where: ‘_’ is a rigid type variable bound by the inferred type of f :: _ -> _ at T16152.hs:11:1-7 • In the type ‘_ -> _’ In the type signature: f :: _ -> _ | 10 | f :: _ -> _ | ^ T16152.hs:10:11: warning: [-Wpartial-type-signatures] • Found type wildcard ‘_’ standing for ‘_’ Where: ‘_’ is a rigid type variable bound by the inferred type of f :: _ -> _ at T16152.hs:11:1-7 • In the type ‘_ -> _’ In the type signature: f :: _ -> _ | 10 | f :: _ -> _ | ^ }}} Saying "Found type wildcard ‘_’ standing for ‘_’" is unhelpful. The "w" form is much better. The change is caused by {{{ commit 17bd163566153babbf51adaff8397f948ae363ca Author: mynguyen <mnguyen1(a)brynmawr.edu> Date: Tue Dec 18 11:52:26 2018 -0500 Visible kind application }}} which has this patch {{{ -newWildTyVar _name +newWildTyVar = do { kind <- newMetaKindVar ; uniq <- newUnique ; details <- newMetaDetails TauTv - ; let name = mkSysTvName uniq (fsLit "w") + ; let name = mkSysTvName uniq (fsLit "_") tyvar = (mkTcTyVar name kind details) ; traceTc "newWildTyVar" (ppr tyvar) ; return tyvar } }}} What was the reason for this change? Can we change "_" back to "w" please? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16203> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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