February 2016 - ghc-tickets

[GHC] #10671: inplace/bin/ghc-stage1 doesn't respect --with-ld override
by GHC 19 May '16

19 May '16

#10671: inplace/bin/ghc-stage1 doesn't respect --with-ld override -------------------------------------+------------------------------------- Reporter: mfox | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build | Version: 7.10.1 System | Keywords: | Operating System: Linux Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Building ghc 7.10.1 on RHEL 5.8. I need to override the old system linker which lacks features and performance. I get stage1 built but then it forgets the override. Configure: ./configure --prefix=/home/cavtools/opt/ghc-7.10.1 --with- ld=/home/cavtools/64/pkg/bin/gld --with-ar=/home/cavtools/64/pkg/bin/gar --with-ranlib=/home/cavtools/64/pkg/bin/granlib settings: [("GCC extra via C opts", " -fwrapv"), ("C compiler command", "/usr/bin/gcc"), ("C compiler flags", " -fno-stack-protector"), ("C compiler link flags", ""), ("Haskell CPP command","/usr/bin/gcc"), ("Haskell CPP flags","-E -undef -traditional "), ("ld command", "/home/cavtools/64/pkg/bin/gld"), ("ld flags", ""), ("ld supports compact unwind", "YES"), ("ld supports build-id", "YES"), ("ld supports filelist", "NO"), ("ld is GNU ld", "YES"), ("ar command", "/home/cavtools/64/pkg/bin/gar"), ("ar flags", "q"), ("ar supports at file", "YES"), ("touch command", "touch"), ("dllwrap command", "/bin/false"), ("windres command", "/bin/false"), ("libtool command", "libtool"), ("perl command", "/usr/bin/perl"), ("target os", "OSLinux"), ("target arch", "ArchX86_64"), ("target word size", "8"), ("target has GNU nonexec stack", "True"), ("target has .ident directive", "True"), ("target has subsections via symbols", "False"), ("Unregisterised", "NO"), ("LLVM llc command", "llc"), ("LLVM opt command", "opt") ] inplace/lib/settings: [("GCC extra via C opts", " -fwrapv"), ("C compiler command", "/usr/bin/gcc"), ("C compiler flags", " -fno-stack-protector"), ("C compiler link flags", ""), ("Haskell CPP command","/usr/bin/gcc"), ("Haskell CPP flags","-E -undef -traditional "), ("ld command", "/home/cavtools/64/pkg/bin/gld"), ("ld flags", ""), ("ld supports compact unwind", "YES"), ("ld supports build-id", "YES"), ("ld supports filelist", "NO"), ("ld is GNU ld", "YES"), ("ar command", "/home/cavtools/64/pkg/bin/gar"), ("ar flags", "q"), ("ar supports at file", "YES"), ("touch command", "touch"), ("dllwrap command", "/bin/false"), ("windres command", "/bin/false"), ("libtool command", "libtool"), ("perl command", "/usr/bin/perl"), ("target os", "OSLinux"), ("target arch", "ArchX86_64"), ("target word size", "8"), ("target has GNU nonexec stack", "True"), ("target has .ident directive", "True"), ("target has subsections via symbols", "False"), ("Unregisterised", "NO"), ("LLVM llc command", "llc"), ("LLVM opt command", "opt") ] Failure looks like: "inplace/bin/ghc-stage1" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -H32m -O -this-package-key ghcpr_8TmvWUcS1U1IKHT0levwg3 -hide-all- packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist-install/build -ilibraries/ghc-prim/dist-install/build/autogen -Ilibraries/ghc-prim/dist- install/build -Ilibraries/ghc-prim/dist-install/build/autogen -Ilibraries /ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist- install/build/autogen/cabal_macros.h -package-key rts -this-package-key ghc-prim -XHaskell2010 -O2 -no-user-package-db -rtsopts -odir libraries/ghc-prim/dist-install/build -hidir libraries/ghc-prim/dist- install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc-prim/./GHC/IntWord64.hs -o libraries/ghc-prim/dist- install/build/GHC/IntWord64.p_o -dyno libraries/ghc-prim/dist- install/build/GHC/IntWord64.dyn_o /usr/bin/ld: unrecognized option '--build-id=none' /usr/bin/ld: use the --help option for usage information collect2: ld returned 1 exit status But why are you using /usr/bin/ld? I told you not to use /usr/bin/ld! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10671> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8207: Show instance for Language in DynFlags
by GHC 17 May '16

17 May '16

#8207: Show instance for Language in DynFlags ------------------------------------+------------------------------------- Reporter: Fuuzetsu | Owner: Type: feature request | Status: new Priority: low | Milestone: Component: GHC API | 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: | ------------------------------------+------------------------------------- I feel that the GHC API could benefit from a Show instance for Language in DynFlags.hs. Currently, if we want to display the language being used we have to do something like {{{ foo inf = case hmi_language inf of Nothing -> Nothing Just Haskell98 -> Just "Haskell98" Just Haskell2010 -> Just "Haskell2010" }}} This is pretty much just the Show instance (over Maybe) and Haskell can derive it for us automatically: we just need to change `deriving Enum` to `deriving (Enum, Show)`. The above solution is not the most robust ever as if this data type is ever changed, this starts to form an incomplete pattern. If we have a catch all `_`, GHC complains about overlapping patterns. Easily solved with `show <$> hmi_language inf`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8207> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10333: hs-boot modification doesn't induce recompilation
by GHC 16 May '16

16 May '16

#10333: hs-boot modification doesn't induce recompilation -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC accepts Unknown/Multiple | invalid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Consider these modules: X.hs-boot {{{ module X where }}} Y.hs {{{ module Y where import {-# SOURCE #-} X data T = T data S = S T }}} X.hs {{{ module X where import Y }}} `ghc --make Y.hs` will compile fine. Now, modify `X.hs-boot` to add a `data T` (which will cause an ambiguous identifier error in Y.hx`. Run `ghc --make Y.hs` and nothing happens! (You might also notice something else a bit funny, which is that `X.hs` gets compiled, even though it's not directly in the import chain of Y. I think this might be intentional but I'm not sure.) Discovered this while poking around #10182. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10333> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11099: Incorrect warning about redundant constraints
by GHC 12 May '16

12 May '16

#11099: Incorrect warning about redundant constraints -------------------------------------+------------------------------------- Reporter: diatchki | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 (Type checker) | 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: -------------------------------------+------------------------------------- The following program results in an incorrect warning about a redundant constraint: {{{ {-# LANGUAGE TypeFamilies #-} type family SomeFun a f :: (SomeFun i ~ [a], Read a) => proxy i -> a f _ = read "HELLO" }}} This is the warning: {{{ Redundant constraint: SomeFun i ~ [a] In the type signature for: f :: (SomeFun i ~ [a], Read a) => proxy i -> a }}} I tried it on GHC version 7.11.20151029 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11099> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10181: Lint check: arity invariant
by GHC 11 May '16

11 May '16

#10181: Lint check: arity invariant -------------------------------------+------------------------------------- Reporter: nomeata | Owner: nomeata Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The Arity of an ID should not exceed the arity of its type, nor the arity of its strictness signature, if it is a bottoming signatures. This should be checked by a lint check (suggested by SPJ in https://phabricator.haskell.org/D747?id=2498#inline-6058) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10181> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9478: Partial type signatures
by GHC 10 May '16

10 May '16

#9478: Partial type signatures -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: Phab:D168 -------------------------------------+------------------------------------- This ticket tracks progress on '''partial type signatures'''. * Wiki page [wiki:PartialTypeSignatures] * Phabricator link: Phab:D168 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9478> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11432: Cannot export operator newtype
by GHC 10 May '16

10 May '16

#11432: Cannot export operator newtype -------------------------------------+------------------------------------- Reporter: phadej | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc1 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 TypeOperators #-} module Main (main, (-.->)(..)) where main :: IO () main = return () newtype (f -.-> g) a = Fn { apFn :: f a -> g a } }}} Fails to compile with {{{ [1 of 1] Compiling Main ( fn.hs, interpreted ) fn.hs:2:20: error: Not in scope: ‘-.->’ fn.hs:2:20: error: The export item ‘(-.->)(..)’ attempts to export constructors or class methods that are not visible here }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11432> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11655: Ambiguous types in pattern synonym not determined by functional dependencies
by GHC 08 May '16

08 May '16

#11655: Ambiguous types in pattern synonym not determined by functional dependencies -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- The Glorious Glasgow Haskell Compilation System, version 8.1.20160117 {{{#!hs {-# LANGUAGE UndecidableInstances, KindSignatures, DataKinds, GADTs, MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances #-} data Ty ty where I :: Ty Int A :: Ty a -> Ty [a] data NUM = MKINT data SCALAR = MKNUM NUM data TYPE = MKSCALAR SCALAR | MKARR TYPE -- Each type determines a TYPE -- Int -> MKSCALAR (MKNUM MKINT) -- [Int] -> MKARR (MKSCALAR (MKNUM MKINT)) class GetTy ty (rep :: TYPE) | ty -> rep where getTy :: Ty ty instance GetTy Int (MKSCALAR (MKNUM MKINT)) where getTy = I instance GetTy a rep => GetTy [a] (MKARR rep) where getTy = A getTy data Unary a b where Un :: (GetTy a a_rep, GetTy b b_rep) => UnOp a b -> (a -> b) -> Unary a b data UnOp a b where OpLen :: UnOp [a] Int data E a where UnOp :: Unary a b -> (E a -> E b) }}} Now I'd like to create an explicitly-bidirectional pattern synonym, defining a unidirectional pattern synonym works fine: {{{#!hs pattern Len xs <- UnOp (Un OpLen _) xs }}} but the inferred type is rejected: {{{#!hs -- >>> :i Len -- pattern Len :: () => (GetTy a a_rep, GetTy t b_rep, -- a GHC.Prim.~# [a1], t GHC.Prim.~# Int) => E a -> E t pattern Len :: () => (GetTy a a_rep, GetTy t b_rep, a ~ [a1], t ~ Int) => E a -> E t pattern Len xs <- UnOp (Un OpLen _) xs -- tgxg.hs:31:37-38: error: … -- • Could not deduce (GetTy a1 rep) arising from a pattern -- from the context: (GetTy a a_rep, GetTy t b_rep) -- bound by a pattern with constructor: -- Un :: forall a b (a_rep :: TYPE) (b_rep :: TYPE). -- (GetTy a a_rep, GetTy b b_rep) => -- UnOp a b -> (a -> b) -> Unary a b, -- in a pattern synonym declaration -- at /tmp/tgxg.hs:31:25-34 -- or from: (a ~ [a1], t ~ Int) -- bound by a pattern with constructor: -- OpLen :: forall a. UnOp [a] Int, -- in a pattern synonym declaration -- at /tmp/tgxg.hs:31:28-32 -- The type variable ‘rep’ is ambiguous -- • In the declaration for pattern synonym ‘Len’ -- Compilation failed. }}} Constructing it works fine: {{{#!hs len :: GetTy a rep => E [a] -> E Int len = UnOp (Un OpLen length) }}} but adding it to the pattern makes it fail: {{{#!hs pattern Len xs <- UnOp (Un OpLen _) xs where Len xs = len xs -- tgxg.hs:32:18-23: error: … -- • Could not deduce (GetTy a1 rep) arising from a use of ‘len’ -- from the context: (GetTy a a_rep, GetTy t b_rep, a ~ [a1], t ~ Int) -- bound by the type signature for: -- Main.$bLen :: (GetTy a a_rep, GetTy t b_rep, a ~ [a1], t ~ Int) => -- E a -> E t -- at /tmp/tgxg.hs:(31,1)-(32,23) -- The type variable ‘rep’ is ambiguous -- These potential instances exist: -- instance GetTy Int ('MKSCALAR ('MKNUM 'MKINT)) -- -- Defined at /tmp/tgxg.hs:14:10 -- instance GetTy a rep => GetTy [a] ('MKARR rep) -- -- Defined at /tmp/tgxg.hs:17:10 -- • In the expression: len xs -- In an equation for ‘$bLen’: $bLen xs = len xs -- Compilation failed. }}} Mixing functional dependencies, GADTs and pattern synonyms is confusing to me but is GHC correct that this type is ambiguous and if so what is missing? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11655> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11641: Allow wildcards for parameters functionally determined (also type synonyms)
by GHC 08 May '16

08 May '16

#11641: Allow wildcards for parameters functionally determined (also type synonyms) -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: lowest | Milestone: Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple PartialTypeSignatures | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs class F a b | a -> b where foo :: a -- ... myFoo :: F a b => a myFoo = foo }}} Since ''b'' is not used and fully determined by ''a'' could the restriction on wildcards in constraints be lifted? {{{#!hs myFoo :: F a _ => a myFoo = foo }}} and eventually hiding it behind a type synonym: {{{#!hs type F' a = F a _ myFoo' :: F' a => a myFoo' = foo }}} I raised this issue at ICFP 2014, I haven't looked into whether dominique's response to [https://haskell- phabricator.global.ssl.fastly.net/D168#4818 my comment] applies. ---- I could achieve similar things with a type family but that work as I'd intended. ---- Or CPP :) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11641> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10775: Enable PolyKinds in GHC.Generics
by GHC 06 May '16

06 May '16

#10775: Enable PolyKinds in GHC.Generics -------------------------------------+------------------------------------- Reporter: | Owner: RyanGlScott | Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 7.10.2 libraries/base | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- As suggested in [https://mail.haskell.org/pipermail/libraries/2015-July/025981.html this] Haskell libraries mailing list thread. Among other benefits, this would allow use of generic functions with `Proxy t` when `t` is of a kind other than `*`. There seem to be more changes required than just putting `{-# LANGUAGE PolyKinds #-}` in `GHC.Generics`, however, since I tried doing that myself and found myself unable to properly derive `Generic(1)` instances in `GHC.Generics`. Here is a snippet of the resulting error message: {{{ libraries/base/GHC/Generics.hs:826:1: error: Couldn't match type ‘M1 i0 c0 (M1 i1 c1 U1) p0’ with ‘M1 D x’ Expected type: Rep (Proxy t) x Actual type: M1 i0 c0 (M1 i1 c1 U1) p0 Relevant bindings include from :: Proxy t -> Rep (Proxy t) x (bound at libraries/base/GHC/Generics.hs:826:1) In the expression: M1 (M1 U1) In an equation for ‘from’: from Proxy = M1 (M1 U1) When typechecking the code for ‘from’ in a derived instance for ‘Generic (Proxy t)’: To see the code I am typechecking, use -ddump-deriv libraries/base/GHC/Generics.hs:826:1: error: Couldn't match type ‘M1 t0 t1 (M1 t3 t4 U1) t2’ with ‘M1 D x’ Expected type: Rep (Proxy t) x Actual type: M1 t0 t1 (M1 t3 t4 U1) t2 Relevant bindings include to :: Rep (Proxy t) x -> Proxy t (bound at libraries/base/GHC/Generics.hs:826:1) In the pattern: M1 (M1 U1) In an equation for ‘to’: to (M1 (M1 U1)) = Proxy When typechecking the code for ‘to’ in a derived instance for ‘Generic (Proxy t)’: To see the code I am typechecking, use -ddump-deriv In the instance declaration for ‘Generic (Proxy t)’ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10775> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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