February 2018 - ghc-tickets

[GHC] #10855: GHC rejects code that Haskell 2010 report accepts
by GHC 01 Feb '18

01 Feb '18

#10855: GHC rejects code that Haskell 2010 report accepts -------------------------------------+------------------------------------- Reporter: goldfire | 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 Revisions: | -------------------------------------+------------------------------------- According to [https://www.haskell.org/onlinereport/haskell2010/haskellch3.html#x8-220003 The Haskell 2010 Report], the following two modules should compile. But they don't, failing with parse errors: {{{ {-# LANGUAGE Haskell2010 #-} module Bug where bool = - case b of False -> 0; True -> (-1) }}} {{{ {-# LANGUAGE Haskell2010 #-} instance Num (IO a) where negate = id main = - do putStrLn "hi!" }}} Note the unary `-` signs. I'm not sure whether we should complicate the parser to fix these, but we should document the compliance-failure in the manual. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10855> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10074: Implement the 'Improved LLVM Backend' proposal
by GHC 01 Feb '18

01 Feb '18

#10074: Implement the 'Improved LLVM Backend' proposal -------------------------------------+------------------------------------- Reporter: | Owner: thoughtpolice thoughtpolice | Status: new Type: task | Milestone: 7.12.1 Priority: high | Version: Component: Compiler | Operating System: Unknown/Multiple (LLVM) | Type of failure: None/Unknown Keywords: llvm, | Blocked By: codegen | Related Tickets: Architecture: | Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: Phab:D530 | -------------------------------------+------------------------------------- This is a meta ticket designed to reflect the current implementation status of the 'Improved LLVM Backend' proposal, documented here: https://ghc.haskell.org/trac/ghc/wiki/ImprovedLLVMBackend -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10074> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14695: ghc --interactive error: "gcc: error: libgmp.so: No such file or directory"
by GHC 01 Feb '18

01 Feb '18

#14695: ghc --interactive error: "gcc: error: libgmp.so: No such file or directory" -------------------------------------+------------------------------------- Reporter: osa1 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 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 get this error when I run hello world with `ghci` or `runghc`: {{{ $ ghc-stage2 --interactive Hello.hs GHCi, version 8.5.20180117: http://www.haskell.org/ghc/ :? for help gcc: error: libgmp.so: No such file or directory gcc: fatal error: no input files compilation terminated. `gcc' failed in phase `gcc'. (Exit code: 1) }}} It works with 8.2.2's `runghc` and `ghci` so it seems like a regression to me. This also causes validate failure on my laptop, because at one point validate script runs `runghc`. OS: Xubuntu 16.04.2 `libgmp.so` location: {{{ ➜ ~ locate libgmp.so /usr/lib/x86_64-linux-gnu/libgmp.so /usr/lib/x86_64-linux-gnu/libgmp.so.10 /usr/lib/x86_64-linux-gnu/libgmp.so.10.3.0 /usr/lib/x86_64-linux-gnu/openssl-1.0.0/engines/libgmp.so }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14695> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12245: Deriving Data at higher kinds
by GHC 01 Feb '18

01 Feb '18

#12245: Deriving Data at higher kinds -------------------------------------+------------------------------------- Reporter: simonpj | 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: -------------------------------------+------------------------------------- Here's what [https://mail.haskell.org/pipermail/generics/2016-June/000564.html Lennart Spitzner wanted to do]: {{{ > {-# LANGUAGE StandaloneDeriving #-} > {-# LANGUAGE DeriveDataTypeable #-} > {-# LANGUAGE FlexibleInstances #-} > > import Data.Data ( Data ) > > data Foo f = Foo (f Bool) (f Int) > > deriving instance Data (Foo []) > deriving instance Data (Foo Maybe) }}} Of course you can't derive `Data` for `Foo` because we don't know what `f` is, so Lennart is making multiple instances, one for each instance of `f`. It's a bit clumsy. What we would really like is {{{ deriving instance (forall a. Data => Data (f a)) => Data (Foo f) }}} but we don't have higher order instances yet! So Lennart is manually making two instances. This should work, but he gets {{{ > Main.hs: line 45, column 1: > Multiple declarations of ‘$cr2C’ > Declared at: Main.hs:44:1 > Main.hs:45:1 > Main.hs: line 45, column 1: > Multiple declarations of ‘$tr2D’ > Declared at: Main.hs:44:1 > Main.hs:45:1 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12245> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2256: Incompleteness of type inference: must quantify over implication constraints
by GHC 01 Feb '18

01 Feb '18

#2256: Incompleteness of type inference: must quantify over implication constraints -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: lowest | Milestone: Component: Compiler (Type | Version: 6.8.2 checker) | Keywords: Resolution: | QuantifiedConstraints 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: | -------------------------------------+------------------------------------- Changes (by simonpj): * keywords: QuantifedConstraints => QuantifiedConstraints -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2256#comment:29> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2256: Incompleteness of type inference: must quantify over implication constraints
by GHC 01 Feb '18

01 Feb '18

#2256: Incompleteness of type inference: must quantify over implication constraints -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: lowest | Milestone: Component: Compiler (Type | Version: 6.8.2 checker) | Keywords: Resolution: | QuantifedConstraints 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: | -------------------------------------+------------------------------------- Changes (by simonpj): * keywords: => QuantifedConstraints -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2256#comment:28> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2893: Implement "Quantified constraints" proposal
by GHC 01 Feb '18

01 Feb '18

#2893: Implement "Quantified constraints" proposal -------------------------------------+------------------------------------- Reporter: porges | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.1 Resolution: | Keywords: | QuantifiedConstraints Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4353 Wiki Page: | -------------------------------------+------------------------------------- Description changed by simonpj: Old description: > See: [wiki:QuantifiedContexts Quantified constraints wiki page] New description: See: [wiki:QuantifiedConstraints Quantified constraints wiki page] -- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2893#comment:32> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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