April 2016 - ghc-tickets

[GHC] #11213: Incorrect reported pattern synonym signature
by GHC 12 Apr '16

12 Apr '16

#11213: Incorrect reported pattern synonym signature -------------------------------------+------------------------------------- Reporter: mpickering | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple PatternSynonyms | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ data T where MkT :: (Show b) => b -> T --pattern ExNumPat :: () => Show b => b -> T pattern ExNumPat x = MkT x }}} GHC reports that `ExNumPat` is missing a signature (correctly) but it reports the wrong type. The correct type is the one commented out. {{{ pstest.hs:12:1: warning: Top-level binding with no type signature: ExNumPat :: forall b. Show b => b -> T }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11213> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11790: (More) missing instances for Identity and Const
by GHC 11 Apr '16

11 Apr '16

#11790: (More) missing instances for Identity and Const -------------------------------------+------------------------------------- Reporter: duairc | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.10.3 libraries/base | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): D2079 | Wiki Page: -------------------------------------+------------------------------------- I made a similar ([https://ghc.haskell.org/trac/ghc/ticket/11210 #11210]) issue a few months ago and submitted a [https://phabricator.haskell.org/D1626 patch] which was accepted. There are some more instances I want to add: {{{ instance Num a => Num (Identity a) instance Real a => Real (Identity a) instance Integral a => Integral (Identity a) instance Fractional a => Fractional (Identity a) instance Floating a => Floating (Identity a) instance RealFrac a => RealFrac (Identity a) instance RealFloat a => RealFloat (Identity a) instance Bits a => Bits (Identity a) instance FiniteBits a => FiniteBits (Identity a) instance IsString => IsString (Identity a) instance Num a => Num (Const a b) instance Real a => Real (Const a b) instance Integral a => Integral (Const a b) instance Fractional a => Fractional (Const a b) instance Floating a => Floating (Const a b) instance RealFrac a => RealFrac (Const a b) instance RealFloat a => RealFloat (Const a b) instance Bits a => Bits (Const a b) instance FiniteBits a => FiniteBits (Const a b) instance IsString => IsString (Const a b) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11790> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10001: GHC crash trying to build a project within Nix-shell
by GHC 11 Apr '16

11 Apr '16

#10001: GHC crash trying to build a project within Nix-shell -------------------------------------+------------------------------------- Reporter: wolftune | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash Test Case: | Blocked By: Blocking: | Related Tickets: 9825 Differential Revisions: | -------------------------------------+------------------------------------- {{{ <no location info>: ghc: panic! (the 'impossible' happened) (GHC version 7.8.4 for x86_64-unknown-linux): Loading temp shared object failed: /run/user/1000/ghc19915_0/ghc19915_20.so: failed to map segment from shared object Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug [20 of 99] Compiling Settings.StaticFiles ( Settings/StaticFiles.hs, dist/build/Settings/StaticFiles.o ) <no location info>: ghc: panic! (the 'impossible' happened) (GHC version 7.8.4 for x86_64-unknown-linux): Loading temp shared object failed: /run/user/1000/ghc19915_0/ghc19915_21.so: failed to map segment from shared object }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10001> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11818: Haddock's Sphinx documentation breaks `make install` if doc building is disabled
by GHC 11 Apr '16

11 Apr '16

#11818: Haddock's Sphinx documentation breaks `make install` if doc building is disabled -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: high | Milestone: 8.0.1 Component: Compiler | Version: 8.0.1-rc3 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: -------------------------------------+------------------------------------- slyfox reported that `make install` fails on his setup which lacks `sphinx`, {{{ /usr/bin/install -c -m 644 libraries/prologue.txt "/var/tmp/portage/dev- lang/ghc-9999/image/usr/share/doc/ghc-9999/html/libraries/" /usr/bin/install -c -m 755 libraries/gen_contents_index "/var/tmp/portage /dev-lang/ghc-9999/image/usr/share/doc/ghc-9999/html/libraries/" for i in utils/haddock/doc/haddock; do \ cp -Rp $i "/var/tmp/portage/dev- lang/ghc-9999/image/usr/share/doc/ghc-9999/html"; \ done cp: cannot stat 'utils/haddock/doc/haddock': No such file or directory ghc.mk:936: recipe for target 'install_docs' failed make[1]: *** [install_docs] Error 1 Makefile:129: recipe for target 'install' failed }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11818> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11623: Wrong error message for type family definition that is wrong in multiple ways
by GHC 11 Apr '16

11 Apr '16

#11623: Wrong error message for type family definition that is wrong in multiple ways -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ GHCi, version 8.1.20160212: http://www.haskell.org/ghc/ :? for help Prelude> :set -XTypeFamilies Prelude> type family T where { Maybe T = Int } <interactive>:2:23: error: • Too many parameters to T: T is unexpected; expected only no parameters • In the type family declaration for ‘T’ }}} This error message is wrong ("Too many parameters to `T`"). Seems like GHC checks whether the equation `Maybe T = Int` has the right number of arguments before it checks whether it is actually headed by `T`. Then the error message is worded in a way that assumes the instance head actually was `T`. The 7.10 error message was better in this regard: {{{ <interactive>:3:23: Number of parameters must match family declaration; expected 0 In the type family declaration for ‘T’ }}} but it would be even better to generate the error below (that is generated once the number of arguments is correct) for the original program: {{{ Prelude> type family T a where { Maybe (T ()) = Int } <interactive>:5:25: error: • Mismatched type name in type family instance. Expected: T Actual: Maybe • In the type family declaration for ‘T’ }}} We should generate that error before kind-checking the definition too. I don't really understand the difference between these two cases though, so maybe my guess is wrong. {{{ Prelude> type family T where { T () = Int } <interactive>:10:23: error: • Too many parameters to T: () is unexpected; expected only no parameters • In the type family declaration for ‘T’ Prelude> type family T :: * -> * where { T () = Int } <interactive>:11:33: error: • Number of parameters must match family declaration; expected 0 • In the equations for closed type family ‘T’ In the type family declaration for ‘T’ }}} (As an aside, "expected only no parameters" is awkward, if there is some legitimate way to generate this message. It should just be "expected no parameters".) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11623> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11463: Template Haskell applies too many arguments to kind synonym
by GHC 11 Apr '16

11 Apr '16

#11463: Template Haskell applies too many arguments to kind synonym -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 8.0.1-rc1 Haskell | Keywords: TypeInType, | Operating System: Unknown/Multiple TypeApplications | Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: #11376 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Running the following code: {{{#!hs {-# LANGUAGE TemplateHaskell #-} {-# LANGUAGE TypeInType #-} module IdStarK where import Data.Kind import Language.Haskell.TH type Id a = a data Proxy (a :: Id k) = Proxy $(return []) main :: IO () main = do putStrLn $(reify ''Proxy >>= stringE . pprint) putStrLn $(reify ''Proxy >>= stringE . show) }}} Gives a result I wouldn't have expected: {{{ $ /opt/ghc/head/bin/runghc IdStarK.hs data IdStarK.Proxy (a_0 :: IdStarK.Id * k_1) = IdStarK.Proxy TyConI (DataD [] IdStarK.Proxy [KindedTV a_1627394516 (AppT (AppT (ConT IdStarK.Id) StarT) (VarT k_1627394515))] Nothing [NormalC IdStarK.Proxy []] []) }}} From the output, it appears that `Id` is being applied to ''two'' arguments, both `*` and `k`! Perhaps this indirectly (or directly) a consequence of #11376? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11463> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11809: Template Haskell record splices are not renamer-resolved correctly.
by GHC 11 Apr '16

11 Apr '16

#11809: Template Haskell record splices are not renamer-resolved correctly. -------------------------------------+------------------------------------- Reporter: bollmann | Owner: bollmann Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 8.0.1 Haskell | Keywords: Template | Operating System: Unknown/Multiple Haskell Renamer Records | Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While working on ticket #8761, I noticed that splicing in record selectors with Template Haskell seems to cause renamer issues in GHC HEAD. Consider the following TH splice: {{{#!hs {- Test splicing in a data type with records -} [d| data D a = MkD { unD :: a } someD = MkD "Hello" getD = unD someD -- unD should resolve to the record selector above! |] getD' = unD someD -- dito here outside of the splice! }}} While GHC 7.10.3 accepts this splice and renames it correctly, GHC HEAD fails with the following error message (with `-ddump-splices` enabled): {{{ [1 of 1] Compiling Error ( Error.hs, Error.o ) Error.hs:(6,1)-(11,3): Splicing declarations [d| someD_apF = MkD_apD "Hello" getD_apG = unD someD_apF data D_apC a_apH = MkD_apD {unD :: a_apH} |] ======> data D_a4SA a_a4SD = MkD_a4SB {unD_a4SC :: a_a4SD} someD_a4Sy = MkD_a4SB "Hello" getD_a4Sz = unD_a4SC someD_a4Sy Error.hs:6:1: error: The exact Name ‘unD_a4SC’ is not in scope Probable cause: you used a unique Template Haskell name (NameU), perhaps via newName, but did not bind it If that's it, then -ddump-splices might be useful }}} I'm not sure as to what introduced this bug, but investigating it I found that the notes - `NOTE [Binders in Template Haskell] in Convert.hs`, and - `NOTE [Looking up Exact RdrNames] in RnEnv.hs` are not respected by function `newRecordSelector` in `rename/RnNames.hs`. I've fixed this function accordingly in Phab:D1940 for #8761, but since that patch is not going to be part of 8.0.1, Richard suggested to fix it separately in this ticket. I'm submitting a patch in due course. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11809> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11680: Out-of-scope suggestion given for an out-of-scope variable when using TH
by GHC 11 Apr '16

11 Apr '16

#11680: Out-of-scope suggestion given for an out-of-scope variable when using TH -------------------------------------+------------------------------------- Reporter: jme | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- With GHC 8.x, compiling {{{#!hs {-# LANGUAGE TemplateHaskell #-} module A where import Language.Haskell.TH sep :: Q [Dec] sep = [d| x = () |] }}} and {{{#!hs {-# LANGUAGE TemplateHaskell #-} module B where import A f :: Int f = foo $(sep) foo :: Int foo = 3 }}} produces {{{ $ ghc-HEAD/inplace/bin/ghc-stage2 --version The Glorious Glasgow Haskell Compilation System, version 8.1.20160303 $ ghc-HEAD/inplace/bin/ghc-stage2 B.hs [1 of 2] Compiling A ( A.hs, A.o ) [2 of 2] Compiling B ( B.hs, B.o ) B.hs:8:5: error: • Variable not in scope: foo :: Int • Perhaps you meant ‘foo’ (line 13) }}} The problem is that when the typechecker constructs the suggestion, it uses the currently available `GlobalRdrEnv` rather than the one in existence when the renamer determined that `foo` is unbound. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11680> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11732: Deriving Generic1 interacts poorly with TypeInType
by GHC 11 Apr '16

11 Apr '16

#11732: Deriving Generic1 interacts poorly with TypeInType -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Keywords: TypeInType, | Operating System: Unknown/Multiple Generics | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- From @RyanGlScott, comment:9:ticket:11357: Vanilla datatypes and data family instances are still inconsistent w.r.t. which type variables are considered "instantiated" in a `Generic1` instance. For instance, this is rejected: {{{ λ> data Proxy k (a :: k) = ProxyCon deriving Generic1 }}} {{{ <interactive>:32:43: error: • Can't make a derived instance of ‘Generic1 (Proxy *)’: Proxy must not be instantiated; try deriving `Proxy k a' instead • In the data declaration for ‘Proxy’ }}} And rightfully so, since the visible kind binder `k` is instantiated to `*`. But now it's possible to have an equivalent instance for a data family that squeaks past this check! {{{ λ> data family ProxyFam (a :: y) (b :: z) λ> data instance ProxyFam k (a :: k) = ProxyFamCon deriving Generic1 ==================== Derived instances ==================== Derived instances: instance GHC.Generics.Generic1 (Ghci13.ProxyFam *) where ... }}} [Ryan needs] to investigate further to see why this is the case. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11732> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11804: Export zonkEvBinds from TcHsSyn.
by GHC 11 Apr '16

11 Apr '16

#11804: Export zonkEvBinds from TcHsSyn. -------------------------------------+------------------------------------- Reporter: conal | Owner: Type: feature | Status: new request | 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: -------------------------------------+------------------------------------- Needed for constructing correct constraint-satisfying code (particularly type class instances) in a Core-to-Core transformation. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11804> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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