GHC 8.4.1 pretty-prints data family instances with redundant kind signatures using -ddump-splices
Consider this program:
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeFamilies #-}
{-# OPTIONS_GHC -ddump-splices #-}
module Bug where
$([d| data family Foo :: *
data instance Foo :: * |])
On GHC 8.2.2, this gives the following -ddump-splices
output:
$ /opt/ghc/8.2.2/bin/ghci Bug.hs
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 )
Bug.hs:(6,3)-(7,31): Splicing declarations
[d| data family Foo_a1sB :: *
data instance :: * |]
======>
data family Foo_a494 :: GHC.Types.Type
data instance :: GHC.Types.Type
But on GHC 8.4.1, we have:
$ /opt/ghc/8.4.1/bin/ghci Bug.hs
GHCi, version 8.4.0.20180209: http://www.haskell.org/ghc/ :? for help
Loaded GHCi configuration from /home/rgscott/.ghci
[1 of 1] Compiling Bug ( Bug.hs, interpreted )
Bug.hs:(6,3)-(7,31): Splicing declarations
[d| data family Foo_a1xd :: *
data instance Foo_a1xd :: * :: * |]
======>
data family Foo_a487 :: GHC.Types.Type
data instance Foo_a487 :: GHC.Types.Type :: GHC.Types.Type
Notice how there is a redundant kind signature in data instance Foo_a1xd :: * :: *
.
Trac metadata
Trac field | Value |
---|---|
Version | 8.4.1-alpha3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | alanz |
Operating system | |
Architecture |