"Pattern match has inaccessible right hand side" with TypeRep
When I say
{-# LANGUAGE PatternSynonyms, ViewPatterns #-}
module Bug where
import Type.Reflection
pattern X arg <- (checkFun -> arg)
checkFun :: TypeRep fun -> a
checkFun = undefined
f x = case (x, True) of
(X _, _) -> 5
_ -> 6
g x = case x of
(X _) -> 5
_ -> 6
I get
Bug.hs:13:11: warning: [-Woverlapping-patterns]
Pattern match has inaccessible right hand side
In a case alternative: (X _, _) -> ...
|
13 | (X _, _) -> 5
| ^^^^^^^^^^^^^
I'm troubled by two things:
- There's nothing inaccessible about my right-hand side.
- This happens only for
f
, notg
. If there's no tuple, there's no problem.
Note that this problems requires TypeRep
. Even another polykinded tycon (like Proxy
) didn't trigger the problem.
Trac metadata
Trac field | Value |
---|---|
Version | 8.5 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |