February 2016 - ghc-tickets

Re: [GHC] #1574: Broken link testing
by GHC 19 Feb '16

19 Feb '16

#1574: Broken link testing -------------------------------------+------------------------------------- Reporter: iampure@… | Owner: Type: task | Status: new Priority: lowest | Milestone: Component: Documentation | Version: 6.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Documentation | Unknown/Multiple bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by thomie): * keywords: newcomer => * type: feature request => task Comment: Removing newcomers keyword, since it doesn't seem a popular task. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1574#comment:25> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8981: ghc-pkg complains about missing haddock interface files
by GHC 19 Feb '16

19 Feb '16

#8981: ghc-pkg complains about missing haddock interface files --------------------------+------------------------------------------------ Reporter: | Owner: thoughtpolice | Status: new Type: bug | Milestone: 7.8.2 Priority: normal | Version: 7.8.1 Component: | Operating System: MacOS X Compiler | Type of failure: Incorrect result at runtime Keywords: ghc- | Test Case: pkg | Blocking: Architecture: x86_64 | (amd64) | Difficulty: | Unknown | Blocked By: | Related Tickets: | --------------------------+------------------------------------------------ As Conal reported on the mailing list[1], `ghc-pkg check` on Mavericks allegedly returns: {{{ bash-3.2$ ghc-pkg check Warning: haddock-interfaces: /Users/conal/.cabal/share/doc/x86_64-osx- ghc-7.8.1/uniplate-1.6.12/html/uniplate.haddock doesn't exist or isn't a file Warning: haddock-interfaces: /Users/conal/.cabal/share/doc/x86_64-osx- ghc-7.8.1/polyparse-1.9/html/polyparse.haddock doesn't exist or isn't a file Warning: haddock-interfaces: /Users/conal/.cabal/share/doc/x86_64-osx- ghc-7.8.1/ghc-syb-utils-0.2.1.2/html/ghc-syb-utils.haddock doesn't exist or isn't a file Warning: haddock-interfaces: /Users/conal/.cabal/share/doc/x86_64-osx- ghc-7.8.1/constraints-0.3.5/html/constraints.haddock doesn't exist or isn't a file Warning: haddock-html: /Users/conal/.cabal/share/doc/x86_64-osx- ghc-7.8.1/constraints-0.3.5/html doesn't exist or isn't a directory Warning: haddock-interfaces: /Users/conal/.cabal/share/doc/x86_64-osx- ghc-7.8.1/newtype-0.2/html/newtype.haddock doesn't exist or isn't a file Warning: haddock-html: /Users/conal/.cabal/share/doc/x86_64-osx- ghc-7.8.1/newtype-0.2/html doesn't exist or isn't a directory }}} It's not fatal, but makes the output much more annoying. I figured this would have been caught by validate or somesuch, but apparently not. Marking for 7.8.2. I'm looking into this soon. [1]http://www.haskell.org/pipermail/glasgow-haskell- users/2014-April/024846.html -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8981> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #393: functions without implementations
by GHC 19 Feb '16

19 Feb '16

#393: functions without implementations -------------------------------------+------------------------------------- Reporter: c_maeder | Owner: Type: feature request | Status: closed Priority: normal | Milestone: ⊥ Component: Compiler (Type | Version: None checker) | Resolution: wontfix | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by thomie): * status: new => closed * resolution: None => wontfix Comment: As mentioned in comment:24, the preferred way to do define a function without definition is to use `-fdefer-typed-holes`: {{{ f = _ }}} Let's use our spare development cycles somewhere else, and close this ticket wontfix. Don't hesitate to reopen if you disagree. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/393#comment:28> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #229: Integer overflow in array allocation
by GHC 18 Feb '16

18 Feb '16

#229: Integer overflow in array allocation -------------------------------------+------------------------------------- Reporter: josefs | Owner: rwbarton Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Core Libraries | Version: 7.9 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * milestone: 8.0.1 => 8.2.1 Comment: This will not happen for GHC 8.0. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/229#comment:26> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11588: haddock documents misleading type signature for TypeError in GHC.TypeLits
by GHC 18 Feb '16

18 Feb '16

#11588: haddock documents misleading type signature for TypeError in GHC.TypeLits -------------------------------------+------------------------------------- Reporter: carter | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Documentation | 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: -------------------------------------+------------------------------------- {{{ type family TypeError a :: b }}} is what is shown in the haddocks, which is misleading, at least to those accustomed to reading vanilla type families. 1) its impossible from the haddock info to know that the actual type signature is `type family TypeError (a :: ErrorMessage) :: b` , that requires reading the source of the module (a generally useful thing always, but still, disappointing that its needed to understand this) 2) i also need read the source to notice that the definition of the type family is a closed with no cases! It seems odd (at least to me) that haddock doesn't disclose the closedness. (this might be an artifact of it being an empty closed type family, which wasn't possible prior to ghc 8.0 anyways) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11588> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11572: BangPatterns-related behavior regressions on GHC 8.0
by GHC 18 Feb '16

18 Feb '16

#11572: BangPatterns-related behavior regressions on GHC 8.0 -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: highest | Milestone: 8.0.1 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: -------------------------------------+------------------------------------- When you compile this code: {{{#!hs {-# LANGUAGE BangPatterns #-} main :: IO () main = let !_ = (undefined :: ()) in print 2 }}} with GHC 8.0.1-rc2 with any level of optimizations, it will print `2` instead of throwing `undefined` like GHC 7.10.3 does. Note that changing `undefined :: ()` to something like `undefined :: Int#` is enough to invoke `undefined` when compiled, but if you run this code in GHCi: {{{ λ> :set -XMagicHash -XBangPatterns λ> import GHC.Prim λ> let !_ = (undefined :: Int#) in print 2 }}} You get something even stranger: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.0.20160204 for x86_64-unknown-linux): dsLet: unlifted !_ = (undefined :: Int#) print @ Integer $dShow_a2ky 2 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11572> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11604: Build system fails after submodule update
by GHC 18 Feb '16

18 Feb '16

#11604: Build system fails after submodule update -------------------------------------+------------------------------------- Reporter: niteria | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | 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: -------------------------------------+------------------------------------- I got [https://phabricator.haskell.org/P100 this] error after updating the transformers submodule with `git submodule update --remote libraries/transformers`. Steps to repro: {{{ git checkout 426a25c719f74054758eaaf15daf5760f8d068fb make clean && make distclean && ./boot && ./configure && make git submodule update --remote libraries/transformers make }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11604> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11605: GHC accepts overlapping instances without pragma
by GHC 18 Feb '16

18 Feb '16

#11605: GHC accepts overlapping instances without pragma -------------------------------------+------------------------------------- Reporter: bennofs | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc2 (Type checker) | Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: GHC accepts (amd64) | invalid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following code is accepted by GHC (I've tested versions 7.6.3, 7.8.4, 7.10.2, ghc 8.0.0.20160204 (rc2) and ghc 7.11.2015121 (git commit 28638dfe79e915f33d75a1b22c5adce9e2b62b97)), even though it obviously uses OverlappingInstances (yet the extension is not enabled, nor are any of the new overlappable/ing pragmas used). {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE MultiParamTypeClasses #-} import Data.Type.Equality import Data.Proxy import Debug.Trace class TypeEq a b where eqProofClass :: Maybe (a :~: b) instance TypeEq a b where eqProofClass = Nothing instance TypeEq a a where eqProofClass = Just Refl data Foo a = Foo a instance Eq a => Eq (Foo a) where Foo a1 == Foo a2 = case eqProofClass :: Maybe (a :~: Int) of Just Refl -> traceShow (a1 :: Int,a2) (a1 == a2) Nothing -> a1 == (undefined :: a) main :: IO () main = do print (Foo (1 :: Int) == Foo 2) putStrLn "--" print (Foo 'a' == Foo 'b') {- $output (1,2) False -- False -} }}} The example does no longer compiles if I add `TypeEq a Int` to the instance context, it then rightfully requests `OverlappingInstances` to be enabled. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11605> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11602: Exponential behaviour in typeKind, unifyTys etc
by GHC 18 Feb '16

18 Feb '16

#11602: Exponential behaviour in typeKind, unifyTys etc -------------------------------------+------------------------------------- Reporter: simonpj | 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: -------------------------------------+------------------------------------- In Trac #11371 Bartosz found some very suspicious performance behaviour. Specifically: * See comment 42 of #11371, which says that `liftCoMatch` and `promoteCoercion` is responsible for a significant fraction of all compiler allocation. Why so expensive? Especially since only used from `OptCoercion`. * There are two comments in `Unify` saying {{{ ty_co_match_app menv subst ty1a ty1b co2a co2b = do { -- TODO (RAE): Remove this exponential behavior. subst1 <- ty_co_match menv subst ki1a ki2a ki_ki_co ki_ki_co }}} and {{{ unify_ty_app ty1a ty1b ty2a ty2b = do { -- TODO (RAE): Remove this exponential behavior. let ki1a = typeKind ty1a ki2a = typeKind ty2a ; unify_ty ki1a ki2a (mkNomReflCo liftedTypeKind) }}} NB: `ty_co_match_app` is also called from `liftCoMatch`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11602> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11563: fvProv falls into a hole (instead of detecting missing type argument) (regression from -rc1 to -rc2)
by GHC 18 Feb '16

18 Feb '16

#11563: fvProv falls into a hole (instead of detecting missing type argument) (regression from -rc1 to -rc2) -------------------------------------+------------------------------------- Reporter: j.waldmann | 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: -------------------------------------+------------------------------------- This program has an error (T is missing an argument) {{{ data T a ; class C t ; instance C s => C T }}} which makes 8-rc2 fall into a hole: {{{ /opt/ghc/ghc-8.0.0.20160204/bin/ghc -c Bug.hs ghc: panic! (the 'impossible' happened) (GHC version 8.0.0.20160204 for x86_64-unknown-linux): fvProv falls into a hole {ap6} }}} It is detected by 8-rc1: {{{ /opt/ghc/ghc-8.0.0.20160111/bin/ghc -c Bug.hs Bug.hs:1:40: error: • Illegal instance declaration for ‘C T’ (All instance types must be of the form (T a1 ... an) where a1 ... an are *distinct type variables*, and each type variable appears at most once in the instance head. Use FlexibleInstances if you want to disable this.) • In the instance declaration for ‘C T’ Bug.hs:1:42: error: • Expecting one more argument to ‘T’ Expected a type, but ‘T’ has kind ‘* -> *’ • In the first argument of ‘C’, namely ‘T’ In the instance declaration for ‘C T’ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11563> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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