[GHC] #12533: Internal error using redundant forall with default signature
GHC
ghc-devs at haskell.org
Wed Aug 24 19:54:48 UTC 2016
#12533: Internal error using redundant forall with default signature
-------------------------------------+-------------------------------------
Reporter: dfeuer | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 8.0.2
Component: Compiler (Type | Version: 8.0.1
checker) |
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture:
Type of failure: Compile-time | Unknown/Multiple
crash | Test Case:
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
-------------------------------------+-------------------------------------
Changes (by dfeuer):
* component: Compiler => Compiler (Type checker)
Comment:
mniip says this is a renamer problem, with `-ddump-rn` producing
{{{#!hs
class Main.Foo x_apt where
Main.foo :: forall a_apu. x_apt a_apu -> x_apt a_apu
default Main.foo :: forall a_apv. x_apt a_apv -> x_apt a_apv
Main.foo x_apw
= go_apx
where
go_apx :: x_apt a_apu
go_apx = undefined
}}}
That is, GHC is using `a_apu` when it should be using `a_apv`.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12533#comment:1>
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