July 2016 - ghc-tickets

[GHC] #12147: GHC's Linker Should Support Relocation Type 42
by GHC 25 Aug '16

25 Aug '16

#12147: GHC's Linker Should Support Relocation Type 42 ----------------------------------------+--------------------------------- Reporter: gershomb | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- As per: https://github.com/DanielG/ghc- mod/issues/762#issuecomment-213743585 "gas >= 2.26 uses some new relocation types (in particular type 42, aka R_X86_64_REX_GOTPCRELX), which are not supported by ghc's linker." This causes problems when linking in libs with certain sorts of c bits via the GHC API (at the very least). Support should be added. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12147> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12115: CoreLint error in safe program
by GHC 25 Aug '16

25 Aug '16

#12115: CoreLint error in safe program -------------------------------------+------------------------------------- Reporter: osa1 | Owner: 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: -------------------------------------+------------------------------------- This correct program is failing with a CoreLint error: {{{ {-# LANGUAGE MagicHash, UnboxedTuples #-} module Main where import GHC.Prim import GHC.Types showAlt0 :: (# Void#, (# #) #) -> String showAlt0 (# _, (# #) #) = "()" main :: IO () main = return () }}} Error: {{{ *** Core Lint errors : in result of Desugar (after optimization) *** <no location info>: warning: In the type ‘(# Void#, (# #) #) -> String’ Kind application error in type ‘(# Void#, (# #) #)’ Function kind = * -> * -> TYPE 'UnboxedTupleRep Arg kinds = [('VoidRep, RuntimeRep), ('UnboxedTupleRep, RuntimeRep), (Void#, TYPE 'VoidRep), ((# #), TYPE 'VoidRep)] core_err.hs:13:1: warning: [RHS of showAlt0 :: (# Void#, (# #) #) -> String] The type of this binder doesn't match the type of its RHS: showAlt0 Binder's type: (# Void#, (# #) #) -> String Rhs type: (# Void#, (# #) #) -> String }}} Tried with: GHC HEAD, 8.0.1. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12115> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12118: Testsuite driver does not normalise platform-dependent .stdout/stderr files
by GHC 25 Aug '16

25 Aug '16

#12118: Testsuite driver does not normalise platform-dependent .stdout/stderr files -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Test Suite | 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: -------------------------------------+------------------------------------- This change was made without explanation in commit 429f0099ab9adfadc779ca76f3aae1c9c160fb8c: {{{ Author: Esa Ilari Vuokko <ei(a)vuokko.info> Date: Sun Aug 13 12:46:49 2006 +0000 Fix driver not to normalise output when using platform specific output files }}} I don't understand why that change was made. It makes `T11223_link_order_a_b_2_fail` and `T11223_simple_duplicate_lib` fail on Windows, when running with `BINDIST=YES` (or, after accepting the `BINDIST=YES` output, when running with `BINDIST=NO`). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12118> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11960: GHC parallel build failure during "make"
by GHC 25 Aug '16

25 Aug '16

#11960: GHC parallel build failure during "make" -------------------------------------+------------------------------------- Reporter: ilovezfs | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.0.1-rc3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This keeps happening (in the same place every time): {{{ config.status: executing libtool commands config.status: executing include commands config.status: executing src commands # wc on OS X has spaces in its output, which libffi's Makefile # doesn't expect, so we tweak it to sed them out mv libffi/build/Makefile libffi/build/Makefile.orig sed "s#wc -w#wc -w | sed 's/ //g'#" < libffi/build/Makefile.orig > libffi/build/Makefile "touch" libffi/stamp.ffi.static-shared.configure make: *** [all] Error 2 }}} Adding some sleep in various places seems to work around it, so it appears to be a race of some kind during parallel builds. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11960> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11825: Pretty printer doesn't display functional dependency with ‘→’
by GHC 25 Aug '16

25 Aug '16

#11825: Pretty printer doesn't display functional dependency with ‘→’ -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: GHCi | Version: 7.10.3 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: -------------------------------------+------------------------------------- {{{ % ghci -ignore-dot-ghci GHCi, version 8.1.20160117: http://www.haskell.org/ghc/ :? for help Prelude> :set -XUnicodeSyntax Prelude> import Control.Monad.Free Prelude Control.Monad.Free> :set -XUnicodeSyntax Prelude Control.Monad.Free> :i MonadFree class Monad m => MonadFree (f :: * -> *) (m :: * -> *) | m -> f where wrap :: f (m a) -> m a default wrap :: (m ~ t n, Control.Monad.Trans.Class.MonadTrans t, MonadFree f n, Functor f) => f (m a) -> m a -- Defined in ‘Control.Monad.Free.Class’ instance [safe] Functor f => MonadFree f (Free f) -- Defined in ‘Control.Monad.Free’ Prelude Control.Monad.Free> }}} should be {{{ class Monad m => MonadFree (f :: * -> *) (m :: * -> *) | m → f where }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11825> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12041: GHC panics on "print_equality ~"
by GHC 25 Aug '16

25 Aug '16

#12041: GHC panics on "print_equality ~" -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- {{{#!hs {-# Language PolyKinds, TypeFamilies #-} import Data.Kind class Category (p :: i -> i -> Type) where type Ob p :: i -> Constraint data I a b instance Category I where type Ob I = (~) Int }}} fails with {{{ $ ghci -ignore-dot-ghci /tmp/Error.hs GHCi, version 8.1.20160503: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( /tmp/Error.hs, interpreted ) /tmp/Error.hs:10:15: error:ghc: panic! (the 'impossible' happened) (GHC version 8.1.20160503 for x86_64-unknown-linux): print_equality ~ Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug > }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12041> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11833: GHC can't derive polykinded instance of polykinded typeclass for newtype that requires a class constraint
by GHC 25 Aug '16

25 Aug '16

#11833: GHC can't derive polykinded instance of polykinded typeclass for newtype that requires a class constraint -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: RyanGlScott Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: #8865 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- GHC chokes when trying to derive the following: {{{#!hs {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# LANGUAGE PolyKinds #-} module Example where class Category (cat :: k -> k -> *) where catId :: cat a a catComp :: cat b c -> cat a b -> cat a c newtype T (c :: * -> * -> *) a b = MkT (c a b) deriving Category }}} with the following error: {{{ $ /opt/ghc/8.0.1/bin/ghc Example.hs -fprint-explicit-kinds [1 of 1] Compiling Example ( Example.hs, Example.o ) Example.hs:9:57: error: • No instance for (Category * c) arising from the 'deriving' clause of a data type declaration Possible fix: use a standalone 'deriving instance' declaration, so you can specify the instance context yourself • When deriving the instance for (Category * (T c)) }}} I know what is happening. Unlike in #8865, where we were deriving `Category` for a concrete type like `Either`, in the above example we are attempting to derive an instance of the form: {{{#!hs instance Category * c => Category (T * c) where ... }}} (using `-fprint-explicit-kinds` syntax). But `validDerivPred` is checking if `sizePred (Category * c)` equals the number of free type variables in `Category * c`. But note that `sizePred` counts both type variables //and// type constructors, and `*` is a type constructor! So `validDerivPred` erroneously rejects the above instance. To fix this behavior, I think we just need to change `validDerivPred` to only consider the //visible// arguments of `Category` (i.e., only `c`). This should be a pretty easy fix - patch incoming. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11833> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11484: Type synonym using -XTypeInType can't be spliced with TH
by GHC 25 Aug '16

25 Aug '16

#11484: Type synonym using -XTypeInType can't be spliced with TH -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 8.0.1-rc1 Haskell | 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: -------------------------------------+------------------------------------- The following code compiles: {{{#!hs {-# LANGUAGE TemplateHaskell #-} {-# LANGUAGE TypeInType #-} {-# OPTIONS_GHC -ddump-splices #-} module Foo where import Data.Kind type TySyn (k :: *) (a :: k) = () -- $([d| type TySyn2 (k :: *) (a :: k) = () |]) }}} But uncomment the last line, and it doesn't compile: {{{ $ /opt/ghc/head/bin/ghc Foo.hs [1 of 1] Compiling Foo ( Foo.hs, Foo.o ) Foo.hs:10:3-43: Splicing declarations [d| type TySyn2_aBH (k_aBI :: *) (a_aBJ :: k_aBI) = () |] ======> type TySyn2_a4BF (k_a4BG :: Type) (a_a4BH :: k_a4BG) = () Foo.hs:10:3: error: • Couldn't match expected kind ‘GHC.Prim.Any’ with actual kind ‘k1’ • In the type declaration for ‘TySyn2’ Foo.hs:10:3: error: • Kind variable ‘k_a4BG’ is implicitly bound in datatype ‘TySyn2’, but does not appear as the kind of any of its type variables. Perhaps you meant to bind it (with TypeInType) explicitly somewhere? Type variables with inferred kinds: k_a4BG (a_a4BH :: GHC.Prim.Any) • In the type declaration for ‘TySyn2’ }}} There are two issues here: 1. The error message claims that `TySyn2` is a datatype when it is actually a type synonym. This should be easy enough to fix; just change [http://git.haskell.org/ghc.git/blob/89bdac7635e6ed08927d760aa885d3e7ef3edb8… the code] that throws the error message to invoke [http://git.haskell.org/ghc.git/blob/89bdac7635e6ed08927d760aa885d3e7ef3edb8… tyConFlavour]. 2. For some reason, the type variable `a` in `TySyn2` fails to kind-check. Somehow, an `Any` got in there, but I'm not sure where it snuck in. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11484> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11976: Error message mentions impredicative polymorphism
by GHC 25 Aug '16

25 Aug '16

#11976: Error message mentions impredicative polymorphism -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 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: -------------------------------------+------------------------------------- When we apply `Lens` to too many arguments in the `:kind` command we get a sensible error message {{{ ghci> type Lens s a = forall f. Functor f => (a -> f a) -> (s -> f s) ghci> :kind Lens _ _ Lens _ _ :: * ghci> :kind Lens _ _ _ <interactive>:1:1: error: • Expecting one fewer argument to ‘Lens t0 t1’ Expected kind ‘k0 -> k1’, but ‘Lens t0 t1’ has kind ‘*’ • In the type ‘Lens _ _ _’ }}} but use the same in a type signature or annotation and it complains about impredicative polymorphism {{{ ghci> :t undefined :: Lens _ _ _ <interactive>:1:1: error: • Illegal polymorphic type: Lens _ _1 GHC doesn't yet support impredicative polymorphism • In the expression: undefined :: Lens _ _ _ ghci> a :: Lens _ _ _; a = undefined <interactive>:6:1: error: Illegal polymorphic type: Lens _ _1 GHC doesn't yet support impredicative polymorphism }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11976> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11941: stage restriction mentioned when an identifier is out of scope
by GHC 25 Aug '16

25 Aug '16

#11941: stage restriction mentioned when an identifier is out of scope -------------------------------------+------------------------------------- Reporter: aavogt | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc2 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: -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE TemplateHaskell #-} import Data.Monoid const (return []) $ mempty { getFrst = Just () } }}} {{{ typeErrBug.hs:5:21: error: • GHC stage restriction: ‘getFrst’ is used in a top-level splice, quasi-quote, or annotation, and must be imported, not defined locally • In the second argument of ‘($)’, namely ‘mempty {getFrst = Just ()}’ In the expression: const (return []) $ mempty {getFrst = Just ()} typeErrBug.hs:5:30: error: Not in scope: ‘getFrst’ Perhaps you meant one of these: ‘getFirst’ (imported from Data.Monoid), ‘getLast’ (imported from Data.Monoid) }}} The stage restriction error shouldn't be mentioned: `getFrst` isn't defined at all while the "not defined locally" phrase says it's defined (in the wrong spot). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11941> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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