March 2014 - ghc-tickets

[GHC] #8745: GeneralizedNewtypeDeriving is still not Safe
by GHC 24 Mar '14

24 Mar '14

#8745: GeneralizedNewtypeDeriving is still not Safe ------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc1 Keywords: Safe | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- In GHC 7.8, !GeneralizedNewtypeDeriving (GND) is type-safe, due to the advent of roles. Although GND allows looking through unimported constructors, the notion of abstraction has changed -- for a type to be fully abstract in 7.8, it must not export its constructors, and the roles of all its parameters must be nominal. Thus, it would seem that GND should be Safe; that is, in the Safe Haskell subset. See also #5498. Currently, GND is not considered Safe. Along similar lines, the `Coercible` and `coerce` mechanism could be considered Safe, but there is no way to import these into a Safe module (they are in `GHC.Exts`). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8745> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8378: Cross-compiling from x86_64-unknown-linux-gnu to x86_64-sun-solaris2 with mkGmpConstants workaround fails to build objects for integer-gmp
by GHC 24 Mar '14

24 Mar '14

#8378: Cross-compiling from x86_64-unknown-linux-gnu to x86_64-sun-solaris2 with mkGmpConstants workaround fails to build objects for integer-gmp -------------------------------------+------------------------------------- Reporter: AlainODea | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: Keywords: solaris,integer- | Operating System: Unknown/Multiple gmp | Type of failure: Building GHC Architecture: Unknown/Multiple | failed Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: 8373,8366,8361 | -------------------------------------+------------------------------------- Here is the script I used to get build dependencies: {{{ sudo apt-get update sudo apt-get install --assume-yes ghc libncurses5-dev \ mesa-common-dev freeglut3-dev libedit-dev cabal install happy alex haddock }}} Here is the build bootstrap script I am using on a clean Ubuntu 13.04 install: {{{ #!/bin/bash export TARGET=x86_64-sun-solaris2.11 export PREFIX=$HOME/Documents/gcc/cross/$TARGET export SYSROOT=$PREFIX/sysroot export PATH=$PATH:$PREFIX/bin export GCC=$PREFIX/bin/$TARGET-gcc export LD=$PREFIX/bin/$TARGET-ld export NM=$PREFIX/bin/$TARGET-nm export OBJDUMP=$PREFIX/bin/$TARGET-objdump git clone git://github.com/ghc/ghc pushd ghc echo "Stage1Only = YES" >> mk/build.mk cp mk/build.mk{.sample,} ./sync-all --no-dph get perl boot patch -d libraries/haskeline/ -p1 < \ ../ghc-patches/0001-Include-termios.h-for- solaris2-host.-Fixes-8366.patch cp $SYSROOT/opt/local/include/gmp.h libraries/integer-gmp/gmp/ ./configure \ --host=x86_64-unknown-linux-gnu \ --build=x86_64-unknown-linux-gnu \ --target=x86_64-sun-solaris2 \ --with-gcc=$GCC \ --with-ld=$LD \ --with-nm=$NM \ --with-objdump=$OBJDUMP make # will fail with failure to run mkGmpDerivedConstants scp inplace/lib/bin/mkGmpDerivedConstants root@ns2:. ssh root@ns2 "./mkGmpDerivedConstants" > \ libraries/integer-gmp/mkGmpDerivedConstants/dist/GmpDerivedConstants.h make cat << __EOF__ >> libraries/base/include/HsBaseConfig.h #define HTYPE_DOUBLE Double #define HTYPE_FLOAT Float __EOF__ make #make -j $(nproc) popd }}} The log of the run is attached. It is too large for the ticket body and apparently too large for Gist as well. Somewhere along the way the build forgets integer-gmp and no objects are built for it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8378> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7684: cgrun071 segfaults
by GHC 24 Mar '14

24 Mar '14

#7684: cgrun071 segfaults ----------------------------------+---------------------------------- Reporter: tibbe | Owner: Type: bug | Status: closed Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.7 Resolution: fixed | Keywords: Operating System: MacOS X | Architecture: x86_64 (amd64) Type of failure: Runtime crash | Difficulty: Unknown Test Case: cgrun071 | Blocked By: Blocking: | Related Tickets: ----------------------------------+---------------------------------- Changes (by thoughtpolice): * status: merge => closed Comment: Merged in 7.8, thanks! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7684#comment:60> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8831: Cannot use Template Haskell splice in ghci
by GHC 23 Mar '14

23 Mar '14

#8831: Cannot use Template Haskell splice in ghci ------------------------------------+--------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Template Haskell | Version: 7.8.1-rc1 Keywords: | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+--------------------------------- I have this module: {{{ {-# LANGUAGE TemplateHaskell #-} module A where foo = [| 3 |] }}} Now, I do this in ghci: {{{ > :seti -XTemplateHaskell > :load A.hs [1 of 1] Compiling A ( A.hs, interpreted ) Ok, modules loaded: A. > $foo Loading package array-0.5.0.0 ... linking ... done. Loading package deepseq-1.3.0.2 ... linking ... done. Loading package containers-0.5.4.0 ... linking ... done. Loading package pretty-1.1.1.1 ... linking ... done. Loading package template-haskell ... linking ... done. unknown package: main }}} The problem is the last line, failing to find the `main` package. I can reproduce this issue in 7.8rc1 and in HEAD. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8831> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8856: ScopedTypeVariables & PolyKinds lead to weird error message
by GHC 23 Mar '14

23 Mar '14

#8856: ScopedTypeVariables & PolyKinds lead to weird error message ------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- When I try to compile {{{ {-# LANGUAGE ScopedTypeVariables, RankNTypes, PolyKinds #-} module Bug where import Data.Proxy foo = (undefined :: Proxy a) :: forall a. Proxy a }}} I get {{{ Bug.hs:7:27: Kind variable ‘k’ used as a type In an expression type signature: Proxy a In the expression: (undefined :: Proxy a) :: forall a. Proxy a In an equation for ‘foo’: foo = (undefined :: Proxy a) :: forall a. Proxy a }}} This is all the more odd given that `k` does not appear in my code! This bug happens both in HEAD and in 7.8.1 RC 2. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8856> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8889: GHCI reports nasty type signatures
by GHC 23 Mar '14

23 Mar '14

#8889: GHCI reports nasty type signatures ----------------------------------+------------------------------ Reporter: MikeIzbicki | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.8.1-rc1 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: Other Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------ Load a file that contains: {{{ {-# LANGUAGE TypeFamilies , ConstraintKinds , MultiParamTypeClasses , UndecidableInstances , FlexibleInstances #-} import GHC.Prim import Prelude hiding (Functor(..)) class Functor f where type C_fmap_a f a :: Constraint type C_fmap_a f a = () type C_fmap_b f b :: Constraint type C_fmap_b f b = () fmap :: (C_fmap_a f a, C_fmap_b f b) => (a -> b) -> f a -> f b fmap1 :: (ValidFunctor f a, ValidFunctor f b) => (a -> b) -> f a -> f b fmap2 :: (ValidFunctor' f a, ValidFunctor' f b) => (a -> b) -> f a -> f b type ValidFunctor f a = ( Functor f , C_fmap_a f a , C_fmap_b f a ) class ValidFunctor f a => ValidFunctor' f a instance ValidFunctor f a => ValidFunctor' f a }}} Then check the following types in ghci {{{ ghci> :t fmap fmap :: (t, t1, Functor f, C_fmap_b f b ~ t1, C_fmap_a f a ~ t) => (a -> b) -> f a -> f b ghci> :t fmap1 fmap1 :: (t, t1, t2, t3, Functor f, C_fmap_b f b ~ t3, C_fmap_b f a ~ t1, C_fmap_a f b ~ t2, C_fmap_a f a ~ t) => (a -> b) -> f a -> f b ghci> :t fmap2 fmap2 :: (t, t1, t2, t3, Functor f, C_fmap_b f b ~ t3, C_fmap_b f a ~ t1, C_fmap_a f b ~ t2, C_fmap_a f a ~ t) => (a -> b) -> f a -> f b }}} These types are much nastier looking than they need to be. There are two problems: 1) Bogus types t,t1,t2,t3 are introduced when they don't need to be. This is confuses the type signatures quite a bit. 2) The type alias ValidFunctor is being desugared in the type signature for fmap1. This makes type aliases for constraints rather pointless. Also, I tried to solve problem two by adding an extra class, and hoping the class would be displayed instead, but this still doesn't work. I assume this is actually intended behavior though. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8889> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8892: Ghc panics (variable not found)
by GHC 23 Mar '14

23 Mar '14

#8892: Ghc panics (variable not found) -----------------------------------+--------------------------------------- Reporter: jwlato | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- When attempting to compile a module with ghc-7.8-RC2, using the flags `--ghc-options=-j8 -O2 -Werror`, I encountered this error: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.8.0.20140228 for x86_64-unknown-linux): StgCmmEnv: variable not found foldlM'_loop{v i1iSV} [lid] local binds for: }}} followed by about 1100 bindings (none of are the binding in question). Omitting the `-j` flag makes no difference. Building `-O0` succeeds. I don't have a standalone test case, and it's not clear to me how to make one as I have no idea what's causing this. I'll try to narrow it down, but if anyone could suggest some flags to twiddle or some other factor to adjust I'd appreciate it. I'm suspecting that it's a function referenced from inlining something vector-related. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8892> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8893: -XPolyKinds causes "*** Exception: Prelude.(!!): index too large"
by GHC 23 Mar '14

23 Mar '14

#8893: -XPolyKinds causes "*** Exception: Prelude.(!!): index too large" -----------------------------------+--------------------------------------- Reporter: ghorn | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc2 Keywords: PolyKinds | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- The following program will compile fine: {{{ {-# OPTIONS_GHC -Wall #-} {-# Language DeriveFunctor #-} --{-# Language PolyKinds #-} module Bug where data V a = V [a] deriving Functor data C x a = C (V (P x a)) deriving Functor data P x a = P (x a) deriving Functor }}} But when PolyKinds is enabled, GHC crashes with {{{ $ ghc Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:9:37:ghc: panic! (the 'impossible' happened) (GHC version 7.8.0.20140228 for x86_64-unknown-linux): Prelude.(!!): index too large }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8893> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8776: Displaying pattern synonym for a GADT
by GHC 23 Mar '14

23 Mar '14

#8776: Displaying pattern synonym for a GADT ------------------------------------+------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | 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: | ------------------------------------+------------------------------------- Define {{{ {-# LANGUAGE PatternSynonyms, GADTs #-} data A x y where B :: A x x pattern P = B }}} and in GHCi we see {{{ λ> :i P pattern (t ~ t) => P :: A t t1 -- Defined at X.hs:5:9 }}} It should be `(t ~ t1)`. Just a problem with displaying, the pattern works correctly. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8776> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8917: :kind! does not work under type constructors
by GHC 23 Mar '14

23 Mar '14

#8917: :kind! does not work under type constructors ------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.8.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Say I have the following: {{{ {-# LANGUAGE DataKinds, PolyKinds, TypeFamilies #-} module Scratch where data Nat = Zero | Succ Nat type family a + b where Zero + a = a (Succ n) + m = Succ (n + m) }}} I load this into ghci. See what happens next: {{{ GHCi, version 7.8.0.20140228: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. [1 of 1] Compiling Scratch ( Scratch.hs, interpreted ) Ok, modules loaded: Scratch. *Scratch> :kind! Zero + Succ Zero Zero + Succ Zero :: Nat = 'Succ 'Zero *Scratch> :kind! Succ (Zero + Zero) Succ (Zero + Zero) :: Nat = 'Succ ('Zero + 'Zero) }}} Note the last line. It doesn't reduce under the `Succ`! I will fix shortly. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8917> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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