Panic in tcSimplifyRuleLhs
With this module, both 6.8.3 and the HEAD panic in tcSimplifyRuleLhs
:
{-# LANGUAGE Rank2Types, ScopedTypeVariables #-}
module Foo where
foo :: (forall m. Monad m => Maybe (m a) -> Maybe (m a)) -> Maybe a -> Maybe a
foo _ x = x
{-# RULES
"foo/foo"
forall (f :: forall m. Monad m => Maybe (m a) -> Maybe (m a))
(g :: forall m. Monad m => Maybe (m b) -> Maybe (m b)) x.
foo f (foo g x) = foo (f . g) x
#-}
Note that the rule is incorrectly typed; with the correct types, no panic happens.
Incidentially, I'm not sure if ScopedTypeVariables
should be required here.
Trac metadata
Trac field | Value |
---|---|
Version | 6.8.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | Unknown |
Architecture | Unknown |