March 2019 - ghc-tickets

[GHC] #16407: Non-versioned haddock.exe is not part of the Windows bindist tarball
by GHC 08 Mar '19

08 Mar '19

#16407: Non-versioned haddock.exe is not part of the Windows bindist tarball ----------------------------------------+--------------------------------- Reporter: cocreature | Owner: (none) Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.6.4 Keywords: | Operating System: Windows Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- The GHC 8.6.3 Windows bindist tarball contained both `ghc-8.6.3/bin/haddock-8.6.3.exe` as well as `ghc-8.6.4/bin/haddock.exe`. However, the 8.6.4 tarball only contains the executable with a version suffix `ghc-8.6.4/bin/haddock-8.6.4.exe`. This broke some users, e.g., the Shake CI https://ci.appveyor.com/project/ndmitchell/shake/builds/22909548#L971 but also `rules_haskell` which assume the existence of that executable. Assuming this change was not intentional, it would be great if we could get a bindist that contains the unversioned haddock.exe. Not sure if this is related to #16398. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16407> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16378: bkpcabal01 fails with recent Cabal
by GHC 08 Mar '19

08 Mar '19

#16378: bkpcabal01 fails with recent Cabal -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.8.1 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: -------------------------------------+------------------------------------- After bumping `Cabal` on the `ghc-8.8` branch `bkpcabal01` fails: {{{ =====> bkpcabal01(normal) 85 of 6807 [0, 0, 0] cd "backpack/cabal/bkpcabal01/bkpcabal01.run" && $MAKE -s --no-print- directory bkpcabal01 CLEANUP=1 Wrong exit code for bkpcabal01()(expected 0 , actual 2 ) Stdout ( bkpcabal01 ): Makefile:9: recipe for target 'bkpcabal01' failed Stderr ( bkpcabal01 ): Error: The following packages are broken because other packages they depend on are missing. These broken packages must be rebuilt before they can be used. planned package bkpcabal01-0.1.0.0 is broken due to missing package p-0.1+FBOSaiWyMx9DR2UZVI6wQJ }}} Anyone know what is going on here? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16378> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16342: Kind inference crash
by GHC 08 Mar '19

08 Mar '19

#16342: Kind inference crash -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- Here's a gnarly test case {{{ {-# LANGUAGE MultiParamTypeClasses, TypeInType, ConstrainedClassMethods, ScopedTypeVariables #-} module Foo where import Data.Proxy class C (a::ka) x where cop :: D a x => x -> Proxy a -> Proxy a cop _ x = x :: Proxy (a::ka) class D (b::kb) y where dop :: C b y => y -> Proxy b -> Proxy b dop _ x = x :: Proxy (b::kb) }}} This crashes every recent GHC with {{{ • GHC internal error: ‘kb’ is not in scope during type checking, but it passed the renamer tcl_env of environment: [avu :-> Type variable ‘b’ = b :: ka, avv :-> Type variable ‘y’ = y :: *, avw :-> Identifier[x::Proxy b, NotLetBound], avx :-> Type variable ‘ka’ = ka :: *] • In the kind ‘kb’ In the first argument of ‘Proxy’, namely ‘(b :: kb)’ In an expression type signature: Proxy (b :: kb) | 13 | dop _ x = x :: Proxy (b::kb) | ^^ }}} Yikes. Reason: * `C` and `D` are mutually recursive * `ka` and `kb` get bound to unification variables, and then get unified in the kind-inference phase * As a result the utterly-final class for `C` and `D` end up with the same `TyVar` for `ka`/`kb`. * And then, for one of them, the tyvar is not in scope when (much, much later) we check the default declaration. Gah! In `generaliseTcTyCon` I think we may need to do a reverse-map to ensure that each of the final `tyConTyVars` has the `Name` from this declaration, rather than accidentally getting a `Name` from another decl in the mutually recursive group. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16342> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16221: Core Lint error with a data type
by GHC 08 Mar '19

08 Mar '19

#16221: Core Lint error with a data type -------------------------------------+------------------------------------- Reporter: monoidal | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.7 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following data declaration fails `-dcore-lint` {{{ #!haskell {-# LANGUAGE PolyKinds, ExplicitForAll, ExistentialQuantification #-} module T16221 where data T0 a = forall k (b :: k). MkT0 (T0 b) !Int }}} The test case was extracted from T14066a, the bang is to force the data type to have a wrapper. This has been present at least since GHC 8.0. {{{ <no location info>: warning: In the type ‘T0 a_a1wY’ Kind application error in type ‘T0 a_a1wY’ Function kind = forall k. k -> * Arg kinds = [(k_X1x2, *), (a_a1wY, k_a1wZ)] Fun: k_X1x2 (a_a1wY, k_a1wZ) <no location info>: warning: In the expression: MkT0 @ k_X1x2 @ a_a1wY @ k_X1x2 @ b_a1x0 dt_a1xC dt_X1xK Kinds don't match in type application: Type variable: a_X1xw :: k_X1x2 Arg type: a_a1wY :: k_a1wZ Linted Arg kind: k_a1wZ <no location info>: warning: In the type ‘T0 a_a1wY’ Kind application error in type ‘T0 a_a1wY’ Function kind = forall k. k -> * Arg kinds = [(k_X1x2, *), (a_a1wY, k_a1wZ)] Fun: k_X1x2 (a_a1wY, k_a1wZ) <no location info>: warning: In the expression: MkT0 @ k_X1x2 @ a_a1wY @ k_X1x2 @ b_a1x0 dt_a1xC dt_X1xK Kinds don't match in type application: Type variable: a_X1xw :: k_X1x2 Arg type: a_a1wY :: k_a1wZ Linted Arg kind: k_a1wZ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16221> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16263: GHC accepts illegal constraint in kind
by GHC 08 Mar '19

08 Mar '19

#16263: GHC accepts illegal constraint in kind -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Keywords: TypeInType | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- GHC 8.6 accepts {{{#!hs data Q :: Eq a => Type }}} It shouldn't, as we can't have `Eq a` as a constraint in kinds. Note that writing a constructor for `Q` is rejected. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16263> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16392: In ghci, revertCAFs should be executed in the external interpreter when necessary
by GHC 08 Mar '19

08 Mar '19

#16392: In ghci, revertCAFs should be executed in the external interpreter when necessary -------------------------------------+------------------------------------- Reporter: lolotp | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | 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 believe this bug was discovered and reported earlier here, https://mail.haskell.org/pipermail/ghc-devs/2018-June/015842.html. I stumbled upon this while tracking down a problem with ghci. To describe the problem, we call revertCAFs whenever we load modules in ghci so that they can be re-evaluated. This however, doesn't work as intended when use with `-fexternal-interpreter` because the CAFs of loaded modules actually live in the external interpreter process instead while `revertCAFs` only work for CAFs in the ghci process. To fix this, we should call revertCAFs in the external interpreter when it's used. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16392> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16391: "Quantified type's kind mentions quantified type variable" error with fancy-kinded GADT
by GHC 08 Mar '19

08 Mar '19

#16391: "Quantified type's kind mentions quantified type variable" error with fancy-kinded GADT -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 (Type checker) | Keywords: TypeInType | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Given the following: {{{#!hs {-# LANGUAGE DataKinds #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE TypeFamilies #-} import Data.Kind type Const (a :: Type) (b :: Type) = a }}} GHC happily accepts these definitions: {{{#!hs type family F :: Const Type a where F = Int type TS = (Int :: Const Type a) }}} However, the situation becomes murkier with data types. For some reason, GHC //rejects// this definition: {{{#!hs data T :: Const Type a where MkT :: T }}} {{{ $ /opt/ghc/8.6.3/bin/ghc Bug.hs [1 of 1] Compiling Main ( Bug.hs, Bug.o ) Bug.hs:14:3: error: • Quantified type's kind mentions quantified type variable (skolem escape) type: forall a1. T of kind: Const * a • In the definition of data constructor ‘MkT’ In the data type declaration for ‘T’ | 14 | MkT :: T | ^^^^^^^^ }}} I'm not quite sure how to interpret that error message, but it seems fishy to me. Even fishier is the fact that GHC //accepts// this slight modification of `T`: {{{#!hs data T2 :: Const Type a -> Type where MkT2 :: T2 b }}} Quite mysterious. ----- I briefly looked into where this error message is being thrown from. It turns out if you make this one-line change to GHC: {{{#!diff diff --git a/compiler/typecheck/TcValidity.hs b/compiler/typecheck/TcValidity.hs index 218f539c68..c7925767f9 100644 --- a/compiler/typecheck/TcValidity.hs +++ b/compiler/typecheck/TcValidity.hs @@ -635,7 +635,7 @@ check_type ve@(ValidityEnv{ ve_tidy_env = env, ve_ctxt = ctxt ; check_type (ve{ve_tidy_env = env'}) tau -- Allow foralls to right of arrow - ; checkTcM (not (any (`elemVarSet` tyCoVarsOfType phi_kind) tvs)) + ; checkTcM (not (any (`elemVarSet` exactTyCoVarsOfType phi_kind) tvs)) (forAllEscapeErr env' ty tau_kind) } where }}} Then GHC will accept `T`. Whether this change is the right choice to make, I don't think I'm qualified to say. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16391> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16400: Hadrian: support shake's --lint-fsatrace feature
by GHC 07 Mar '19

07 Mar '19

#16400: Hadrian: support shake's --lint-fsatrace feature -------------------------------------+------------------------------------- Reporter: davide | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.6.3 (Hadrian) | Keywords: lint shake | Operating System: Unknown/Multiple hadrian fsatrace | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Shake's `--lint-fsatrace` feature uses [https://github.com/jacereda/fsatrace fsatrace] to track file accesses of external commands. This allows for more accurate dependency linting which is important e.g. for caching. Hadrian already accepts the `--lint-fsatrace` command line option (it is passed on to shake automatically), but it currently has no effect. The shake options are not set correctly (In particular [https://github.com/jacereda/fsatrace shakeLintInside] must be set). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16400> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16405: Plugin tests are remarkably fragile on Windows
by GHC 07 Mar '19

07 Mar '19

#16405: Plugin tests are remarkably fragile on Windows -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- There is something odd afoot in the tests in `testsuite/tests/plugins` on Windows. In any given testsuite run at least half a dozen of these tests fail for one reason or another (often a timeout sometimes another). I'm collecting these failures here to try to make sense of them: {{{ =====> T16260(normal) 6833 of 6839 [2, 14, 0] cd "plugins/T16260.run" && $MAKE -s --no-print-directory -C simple-plugin package.T16260 TOP=/c/GitLabRunner/builds/78d7d3f9/0/ghc/ghc/testsuite cd "plugins/T16260.run" && $MAKE -s --no-print-directory T16260 --- plugins/T16260.run/T16260.stdout.normalised 2019-03-06 03:20:38.902713500 +0000 +++ plugins/T16260.run/T16260.run.stdout.normalised 2019-03-06 03:20:38.903686400 +0000 @@ -1,4 +0,0 @@ -False -None -True -Safe Actual stdout output differs from expected: diff -uw "plugins/T16260.run/T16260.stdout.normalised" "plugins/T16260.run/T16260.run.stdout.normalised" }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16405> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16404: Type error recovery crash
by GHC 07 Mar '19

07 Mar '19

#16404: Type error recovery crash -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- This program is derived from #16376: {{{ {-# LANGUAGE TypeApplications #-} module Bug where h x = let f = id @Maybe in Just f }}} If you compile with `-fdefer-type-errors -dcore-lint` you'll get {{{ *** Core Lint errors : in result of Desugar (before optimization) *** <no location info>: warning: In the expression: f_arZ @ a_at1 Out of scope: f_arZ :: forall a. a [LclId] *** Offending Program *** Rec { $trModule :: Module [LclIdX] $trModule = Module (TrNameS "main"#) (TrNameS "T16376"#) h :: forall p a. p -> Maybe a [LclIdX] h = \ (@ p_asV) (@ a_at1) -> case typeError @ ('TupleRep '[]) @ ((* -> *) ~# *) "T16376.hs:4:19: error:\n\ \ \\226\\128\\162 Expecting one more argument to \\226\\128\\152Maybe\\226\\128\\153\n\ \ Expected a type, but \\226\\128\\152Maybe\\226\\128\\153 has kind \\226\\128\\152* -> *\\226\\128\\153\n\ \ \\226\\128\\162 In the type \\226\\128\\152Maybe\\226\\128\\153\n\ \ In the expression: id @Maybe\n\ \ In an equation for \\226\\128\\152f\\226\\128\\153: f = id @Maybe\n\ \(deferred type error)"# of co_asZ { __DEFAULT -> letrec { h_at5 :: p_asV -> Maybe a_at1 [LclId] h_at5 = \ (x_arY :: p_asV) -> Just @ a_at1 (f_arZ @ a_at1); } in h_at5 } end Rec } }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16404> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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