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[GHC] #11159: '-interactive-print myPrint' forgotten after :load or :reload
by GHC 24 Dec '15

24 Dec '15

#11159: '-interactive-print myPrint' forgotten after :load or :reload -------------------------------------+------------------------------------- Reporter: hukarere | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | 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: -------------------------------------+------------------------------------- Hi, I would like to use a custom print function. I tried all possible ways for setting it: (1) running ghci -interactive-print myPrint; (2) adding ':set -interactive-print myPrint' to ~/.ghci; (3) typing ':set -interactive- print myPrint' interactively. It works, but only before :load or :reload. After that,it's forgotten (standard print used again) and I have to type ':set -interactive-print myPrint' again. Is there a way to make this setting persistent, i. e. survive after :load or :reload? Thanks. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11159> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10404: GHC panic when creating a monomorphised pattern synonym for GADT
by GHC 23 Dec '15

23 Dec '15

#10404: GHC panic when creating a monomorphised pattern synonym for GADT -------------------------------------+------------------------------------- Reporter: | Owner: Iceland_jack | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1-rc1 Component: Compiler | Operating System: Linux Keywords: | Type of failure: GHC rejects Architecture: x86 | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- I have an expression {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE PatternSynonyms #-} data Exp a where Fun :: (a -> b) - (Exp a -> Exp b) }}} and I want to create a pattern synonym for Int-expressions: {{{#!hs -- This works: -- pattern :: (a -> b) -> (Exp a -> Exp b) -- pattern IntFun f x = Fun f x pattern :: (Int -> Int) -> (Exp Int -> Exp Int) pattern IntFun f x = Fun f x }}} which results in {{{#!hs % ghci -ignore-dot-ghci Panic.hs GHCi, version 7.10.0.20150316: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( Panic.hs, interpreted ) Panic.hs:8:28: Couldn't match type ‘a’ with ‘Int’ ‘a’ is a rigid type variable bound by a pattern with constructor Fun :: forall b a. (a -> b) -> Exp a -> Exp b, in a pattern synonym declaration at Panic.hs:8:22 Expected type: Int -> Int Actual type: a -> Int Relevant bindings include b :: Exp a (bound at Panic.hs:8:28) a :: a -> Int (bound at Panic.hs:8:26) Failed, modules loaded: none. }}} So I try to be sneaky: {{{#!hs pattern :: (a ~ Int) => (a -> b) -> (Exp a -> Exp b) pattern IntFun f x = Fun f x -- % ghci -ignore-dot-ghci Panic.hs -- … -- Couldn't match type ‘a’ with ‘Int’ -- ‘a’ is a rigid type variable bound by -- the type signature for IntFun :: (a1 -> b) -> Exp a1 -> Exp b -- at Panic.hs:8:22 }}} and if I constrain both type variables it panics {{{#!hs pattern :: (a ~ Int, b ~ Int) => (a -> b) -> (Exp a -> Exp b) pattern IntFun f x = Fun f x -- Couldn't match type ‘b’ with ‘Int’ -- ‘b’ is untouchable -- inside the constraints () -- bound by the type signature for -- IntFun :: (a1 -> b) -> Exp a1 -> Exp b -- at Panic.hs:8:9-14ghc: panic! (the 'impossible' happened) -- (GHC version 7.10.0.20150316 for i386-unknown-linux): -- No skolem info: b_alF[sk] -- -- Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} The final version should look like: {{{#!hs type Name = String data Exp a where Fun :: Name -> (a -> b) -> (Exp a -> Exp b) ... pattern Suc :: Exp Int -> Exp Int pattern Suc n <- Fun _ _ n where Suc n = Fun "suc" (+ 1) n }}} Shouldn't this work? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10404> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10432: panic with kind polymorphism
by GHC 23 Dec '15

23 Dec '15

#10432: panic with kind polymorphism -------------------------------------+------------------------------------- Reporter: Ashley | Owner: Yakeley | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1 Component: Compiler | Operating System: Unknown/Multiple (Type checker) | Type of failure: None/Unknown Keywords: | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE ExistentialQuantification, PolyKinds, DataKinds, RankNTypes, GADTs, TypeOperators #-} module Bug where import Data.Type.Equality data WrappedType = forall a. WrapType a; matchReflK :: forall (a :: ka) (b :: kb) (r :: *). ('WrapType a :~: 'WrapType b) -> (('WrapType a ~ 'WrapType b) => r) -> r; matchReflK Refl r = r; }}} give this: {{{ Bug.hs:8:15: Couldn't match kind ‘ka’ with ‘kb’ ‘ka’ is untouchable inside the constraints ('WrapType a ~ 'WrapType b) bound by the type signature for matchReflK :: ('WrapType a ~ 'WrapType b) => r at Bug.hs:(8,15)-(9,74)ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): No skolem info: ka_aqv[sk] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I actually think GHC should accept this (and furthermore infer `ka ~ kb`). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10432> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11039: Panic with incorrect pattern synonym signature
by GHC 23 Dec '15

23 Dec '15

#11039: Panic with incorrect pattern synonym signature -------------------------------------+------------------------------------- Reporter: mpickering | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 7.11 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: -------------------------------------+------------------------------------- {{{ {-# LANGUAGE PatternSynonyms #-} module Foo () where data A a = A a pattern Q :: () => (A ~ f) => a -> f a pattern Q a = A a }}} error with HEAD {{{ poly-export2.hs:7:9: error:ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20151030 for x86_64-apple-darwin): No skolem info: f_amp[sk] }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11039> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11278: Spurious potential superclass cycle with constraint synonyms
by GHC 23 Dec '15

23 Dec '15

#11278: Spurious potential superclass cycle with constraint synonyms -------------------------------------+------------------------------------- Reporter: ezyang | Owner: simonpj Type: bug | Status: new Priority: high | Milestone: 8.0.1 Component: Compiler | Version: 7.11 (Type checker) | Keywords: | 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 superclass cycle detector isn't smart enough to deal with constraint synonyms: {{{ {-# LANGUAGE ConstraintKinds #-} module A where type K a = (Show a, Read a) class K a => C a where }}} On HEAD I get: {{{ A.hs:4:1: error: • Potential superclass cycle for ‘C’ one of whose superclasses is ‘GHC.Classes.(%,%)’ one of whose superclass constraints is headed by a type variable: ‘c1’ Use UndecidableSuperClasses to accept this • In the class declaration for ‘C’ }}} The error goes away if the constraint synonym only has one constraint in it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11278> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10897: Incorrect ASSERT for buildPatSyn
by GHC 23 Dec '15

23 Dec '15

#10897: Incorrect ASSERT for buildPatSyn -------------------------------------+------------------------------------- Reporter: ezyang | Owner: cactus Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Consider the following two files: {{{ -- A.hs {-# LANGUAGE PatternSynonyms #-} module A where pattern Single :: a -> a pattern Single x = x -- B.hs module B where import A Single y = True }}} When I build these using one-shot compilation using a debugged GHC (i.e. with ASSERTs) I get the following error: {{{ [ezyang@hs01 ghc-quick3]$ inplace/bin/ghc-stage2 -c A.hs -fforce-recomp [ezyang@hs01 ghc-quick3]$ inplace/bin/ghc-stage2 -c B.hs -fforce-recomp ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150918 for x86_64-unknown-linux): ASSERT failed! file compiler/iface/BuildTyCl.hs, line 210 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I expanded the assert and discovered it was claiming the universal type variables of the matcher should be equal to the type variables of the pattern declaration. This assert cannot possibly be right: the matcher and the pattern declaration are typechecked separately and there's no reason that the local binders should actually be the same. The equality test here should be done up to alpha-renaming. The other thing I found a bit puzzling was whether or not it mattered whether or not we used the local type variables from the matcher or the freshly bound ones. I suppose if we are consistent it shouldn't matter, so I don't think the code is buggy, just a bad ASSERT. BTW: this assert problem doesn't show up with `--make` because the assert occurs during typechecking of interface files, and with `--make` we don't need to typecheck an interface file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10897> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11137: configure is broken for the unix package
by GHC 23 Dec '15

23 Dec '15

#11137: configure is broken for the unix package -------------------------------------+------------------------------------- Reporter: pgj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.11 libraries/unix | 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: -------------------------------------+------------------------------------- A few weeks ago (around November 1, 2015), the FreeBSD builders started to fail building GHC-HEAD with an error message something like that: {{{ [...] /usr/home/ghc-builder/work/builder/tempbuild/build/libraries/unix/dist- install/build/libHSunix-2.7.1.0-ghc7.11.20151126.so: undefined reference to `fdatasync' collect2: error: ld returned 1 exit status `gcc48' failed in phase `Linker'. (Exit code: 1) ghc/ghc.mk:121: recipe for target 'ghc/stage2/build/tmp/ghc-stage2' failed gmake[1]: *** [ghc/stage2/build/tmp/ghc-stage2] Error 1 Makefile:121: recipe for target 'all' failed gmake: *** [all] Error 2 }}} That is because {{{fdatasync(2)}}} is not implemented on FreeBSD. Apparently, it is handled in the respective file ({{{System/Posix/Unistd.hsc}}}), though it relies on the variable ({{{HAVE_FDATASYNC}}}) generated at the {{{configure}}} phase. But for some reason, the {{{configure}}} script of the {{{unix}}} package fails to detect this as it says the following: {{{ "inplace/bin/ghc-cabal" configure libraries/unix dist-install "" --with- ghc="/usr/home/ghc-builder/work/builder/tempbuild/build/inplace/bin/ghc- stage1" --with-ghc-pkg="/usr/home/ghc- builder/work/builder/tempbuild/build/inplace/bin/ghc-pkg" --disable- library-for-ghci --enable-library-vanilla --enable-library-profiling --enable-shared --with-hscolour="/usr/local/bin/HsColour" --configure- option=CFLAGS="-Wall -fno-stack-protector -Werror=unused-but-set- variable -Wno-error=inline" --configure-option=LDFLAGS=" " --configure- option=CPPFLAGS=" " --gcc-options="-Wall -fno-stack-protector -Werror =unused-but-set-variable -Wno-error=inline " --configure-option=--with- iconv-includes="/usr/local/include" --configure-option=--with-iconv- libraries="/usr/local/lib" --configure-option=--with-gmp- includes="/usr/local/include" --configure-option=--with-gmp- libraries="/usr/local/lib" --with-gcc="/usr/local/bin/gcc48" --with- ld="/usr/local/bin/ld" --configure-option=--with-cc="/usr/local/bin/gcc48" --with-ar="/usr/local/bin/ar" --with-alex="/usr/local/bin/alex" --with- happy="/usr/local/bin/happy" Configuring unix-2.7.1.0... [...] checking for fdatasync... yes }}} That is the corresponding part of the {{{config.log}}}: {{{ configure:4242: checking for fdatasync configure:4263: /usr/local/bin/gcc48 -c -Wall -fno-stack-protector -Werror=unused-but-set-variable -Wno-error=inline conftest.c >&5 conftest.c: In function 'main': conftest.c:71:1: warning: implicit declaration of function 'fdatasync' [-Wimplicit-function-declaration] fdatasync(4); ^ configure:4263: $? = 0 configure:4271: result: yes }}} Looks like GCC is willing to compile the test code, although it notes that it cannot find the declaration of the {{{fdatasync()}}} function. Unfortunately, the {{{configure}}} script does not instruct GCC to do any linking or be serious on such warnings, so it happily proceeds. For the reference, previously the {{{config.log}}} said something like that instead: {{{ configure:4230: checking for fdatasync configure:4230: /usr/local/bin/gcc48 -o conftest -Wall -fno-stack- protector -Werror=unused-but-set-variable -Wno-error=inline conftest.c >&5 /tmp//ccDCjZtO.o: In function `main': conftest.c:(.text+0xa): undefined reference to `fdatasync' collect2: error: ld returned 1 exit status configure:4230: $? = 1 [...] }}} I am inclined to think that this is caused by the commit [https://github.com/haskell/unix/commit/b06446edd4753f964a46d27ddae864fad97a… b06446edd4753f964a46d27ddae864fad97adc13] for the {{{unix}}} package. Perhaps the following change can fix that, at least it fixed for me: {{{ --- a/mk/warnings.mk +++ b/mk/warnings.mk @@ -16,6 +16,7 @@ SRC_CC_WARNING_OPTS += -Werror=unused-but-set-variable endif # gcc 4.6 gives 3 warning for giveCapabilityToTask not being inlined SRC_CC_WARNING_OPTS += -Wno-error=inline +SRC_CC_WARNING_OPTS += -Werror=implicit-function-declaration endif else }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11137> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11265: Internal error, using pattern synonym as instance head
by GHC 23 Dec '15

23 Dec '15

#11265: Internal error, using pattern synonym as instance head -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- {{{!#hs {-# LANGUAGE PatternSynonyms, DataKinds #-} pattern A = True class F a instance F A }}} when loaded in ghci it results in an internal error {{{!#hs % g internal.hs GHCi, version 7.11.20151216: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( internal.hs, interpreted ) internal.hs:5:12: error: • GHC internal error: ‘A’ is not in scope during type checking, but it passed the renamer tcl_env of environment: [] • In the first argument of ‘F’, namely ‘A’ In the instance declaration for ‘F A’ Failed, modules loaded: none. Prelude> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11265> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11274: Confused type checker with typed holes and a missing instance (also panic)
by GHC 23 Dec '15

23 Dec '15

#11274: Confused type checker with typed holes and a missing instance (also panic) -------------------------------------+------------------------------------- Reporter: Xandaros | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- If your file contains a typed hole and a case where an instance is missing, the type checker will not find the missing instance and only report the hole. If -fdefer-typed-holes is set, this results in a panic. (Using ghci, the panic occurs when any definition of the module is being evaluated) Minimal working example: {{{#!hs {-# OPTIONS_GHC -fdefer-typed-holes #-} data Asd = Asd someHole = _asd missingInstance :: Asd -> Asd -> Bool missingInstance x y = x == y }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11274> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9739: GHC 7.8 chokes on recursive classes
by GHC 23 Dec '15

23 Dec '15

#9739: GHC 7.8 chokes on recursive classes -------------------------------------+------------------------------------- Reporter: bitonic | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.8.3 checker) | Operating System: Keywords: | Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Difficulty: Unknown | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Type checking this makes GHC 7.8.3 loop: {{{#!hs {-# LANGUAGE MultiParamTypeClasses #-} module Foo where class Class3 a => Class1 a where class Class2 t a where class2 :: (Class3 t) => a -> m class (Class1 t, Class2 t t) => Class3 t where }}} Does not happen in 7.6.3. I think it's something to do with the `Class3` constraint appearing in `class2`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9739> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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