#14578: Incorrect parenthesization of types in -ddump-deriv -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: Type of failure: Debugging | Unknown/Multiple information is incorrect | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by RyanGlScott: Old description:

Compiling this program on GHC 8.2 or later:

{{{#!hs {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# OPTIONS_GHC -ddump-deriv #-} module Bug where

import Control.Applicative import Data.Functor.Compose import Data.Semigroup

newtype App f a = MkApp (f a) deriving (Functor, Applicative)

instance (Applicative f, Semigroup a) => Semigroup (App f a) where (<>) = liftA2 (<>)

newtype Wat f g a = MkWat (App (Compose f g) a) deriving Semigroup }}}

Will result in some incorrectly pretty-printed types in the `-ddump- deriv` output:

{{{ $ /opt/ghc/8.2.2/bin/ghci Bug.hs -dsuppress-uniques GHCi, version 8.2.2: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted )

==================== Derived instances ==================== Derived class instances:

<elided for brevity>

instance (Data.Semigroup.Semigroup a, GHC.Base.Applicative g, GHC.Base.Applicative f) => Data.Semigroup.Semigroup (Bug.Wat f g a) where (Data.Semigroup.<>) = GHC.Prim.coerce @(Bug.App Data.Functor.Compose.Compose f g a -> Bug.App Data.Functor.Compose.Compose f g a -> Bug.App Data.Functor.Compose.Compose f g a) @(Bug.Wat f g a -> Bug.Wat f g a -> Bug.Wat f g a) (Data.Semigroup.<>) Data.Semigroup.sconcat = GHC.Prim.coerce @(Data.List.NonEmpty.NonEmpty Bug.App Data.Functor.Compose.Compose f g a -> Bug.App Data.Functor.Compose.Compose f g a) @(Data.List.NonEmpty.NonEmpty Bug.Wat f g a -> Bug.Wat f g a) Data.Semigroup.sconcat Data.Semigroup.stimes = GHC.Prim.coerce @(forall (b :: TYPE GHC.Types.LiftedRep). GHC.Real.Integral b => b -> Bug.App Data.Functor.Compose.Compose f g a -> Bug.App Data.Functor.Compose.Compose f g a) @(forall (b :: TYPE GHC.Types.LiftedRep). GHC.Real.Integral b => b -> Bug.Wat f g a -> Bug.Wat f g a) Data.Semigroup.stimes }}}

Notice that is shows `Bug.App Data.Functor.Compose.Compose f g a`, which is wrong. It should be `Bug.App (Data.Functor.Compose.Compose f g) a`.

New description: Compiling this program on GHC 8.2 or later: {{{#!hs {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# OPTIONS_GHC -ddump-deriv #-} module Bug where import Control.Applicative import Data.Functor.Compose import Data.Semigroup newtype App f a = MkApp (f a) deriving (Functor, Applicative) instance (Applicative f, Semigroup a) => Semigroup (App f a) where (<>) = liftA2 (<>) newtype Wat f g a = MkWat (App (Compose f g) a) deriving Semigroup }}} Will result in some incorrectly pretty-printed types in the `-ddump-deriv` output: {{{ $ /opt/ghc/8.2.2/bin/ghci Bug.hs -dsuppress-uniques GHCi, version 8.2.2: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) ==================== Derived instances ==================== Derived class instances: <elided for brevity> instance (Data.Semigroup.Semigroup a, GHC.Base.Applicative g, GHC.Base.Applicative f) => Data.Semigroup.Semigroup (Bug.Wat f g a) where (Data.Semigroup.<>) = GHC.Prim.coerce @(Bug.App Data.Functor.Compose.Compose f g a -> Bug.App Data.Functor.Compose.Compose f g a -> Bug.App Data.Functor.Compose.Compose f g a) @(Bug.Wat f g a -> Bug.Wat f g a -> Bug.Wat f g a) (Data.Semigroup.<>) Data.Semigroup.sconcat = GHC.Prim.coerce @(Data.List.NonEmpty.NonEmpty Bug.App Data.Functor.Compose.Compose f g a -> Bug.App Data.Functor.Compose.Compose f g a) @(Data.List.NonEmpty.NonEmpty Bug.Wat f g a -> Bug.Wat f g a) Data.Semigroup.sconcat Data.Semigroup.stimes = GHC.Prim.coerce @(forall (b :: TYPE GHC.Types.LiftedRep). GHC.Real.Integral b => b -> Bug.App Data.Functor.Compose.Compose f g a -> Bug.App Data.Functor.Compose.Compose f g a) @(forall (b :: TYPE GHC.Types.LiftedRep). GHC.Real.Integral b => b -> Bug.Wat f g a -> Bug.Wat f g a) Data.Semigroup.stimes }}} Notice that it shows `Bug.App Data.Functor.Compose.Compose f g a` within the visible type applications, which is wrong. It should be `Bug.App (Data.Functor.Compose.Compose f g) a`. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14578#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14578: Incorrect parenthesization of types in -ddump-deriv -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: Type of failure: Debugging | Unknown/Multiple information is incorrect | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): And here is why: the type `App (Compose f g) a` is produced by the function [http://git.haskell.org/ghc.git/blob/0a12d92a8f65d374f9317af2759af2b46267ad5c... typeToLHsType]. Here is the line of code that's responsible: {{{#!hs go (TyConApp tc args) = nlHsTyConApp (getRdrName tc) (map go args') where args' = filterOutInvisibleTypes tc args }}} Notice that this does not attempt to put the appropriate `HsParTy`s in place. I think an appropriate way to fix this would be to adopt the same trick that alanz has used elsewhere: apply the [http://git.haskell.org/ghc.git/blob/0a12d92a8f65d374f9317af2759af2b46267ad5c... mk_apps] function to `tc` and `args'`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14578#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14578: Incorrect parenthesization of types in -ddump-deriv -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: Type of failure: Debugging | Unknown/Multiple information is incorrect | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4266 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ryan Scott ): In [changeset:"1bd91a7ac60eba3b0c019e2228f4b2b07f8cd5ad/ghc" 1bd91a7/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="1bd91a7ac60eba3b0c019e2228f4b2b07f8cd5ad" Fix #14578 by checking isCompoundHsType in more places Summary: The `HsType` pretty-printer does not automatically insert parentheses where necessary for type applications, so a function `isCompoundHsType` was created in D4056 towards this purpose. However, it was not used in as many places as it ought to be, resulting in #14578. Test Plan: make test TEST=T14578 Reviewers: alanz, bgamari, simonpj Reviewed By: alanz, simonpj Subscribers: simonpj, rwbarton, thomie, carter GHC Trac Issues: #14578 Differential Revision: https://phabricator.haskell.org/D4266 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14578#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14578: Incorrect parenthesization of types in -ddump-deriv -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: merge Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.2.2 Resolution: fixed | Keywords: deriving Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Debugging | Test Case: information is incorrect | deriving/should_compile/T14578 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4266 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: closed => merge * milestone: => 8.4.1 Comment: Merged in e32f582783. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14578#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler