Template Haskell needlessly pretty-prints empty instance contexts
This code:
{-# LANGUAGE TemplateHaskell #-}
{-# OPTIONS -ddump-splices #-}
module Bug where
$([d| class Foo a
instance Foo Int
|])
Used to pretty-print like this on GHC 8.0.2:
Bug2.hs:(5,3)-(7,6): Splicing declarations
[d| class Foo_a13B a_a13C
instance Foo_a13B Int |]
======>
class Foo_a3Jo a_a3Jp
instance Foo_a3Jo Int
But on GHC HEAD, it prints a redundant instance context!
Bug2.hs:(5,3)-(7,6): Splicing declarations
[d| class Foo_a1eh a_a1ei
instance Foo_a1eh Int |]
======>
class Foo_a4ly a_a4lz
instance () => Foo_a4ly Int
Trac metadata
Trac field | Value |
---|---|
Version | 8.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Template Haskell |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |