Conflicting typefamily instances not reported with polykinds
GHC fails to report conflicting instances for a open polykinded type family when the two resulting types have different kinds. I would expect conflicts to be detected regardless of the concrete kind of the result.
Minimal Example:
type family Bar a :: k
type instance Bar Int = Int
--type instance Bar Int = Bool -- Conflict detected
type instance Bar Int = [] -- Conflict NOT detected
Trac metadata
Trac field | Value |
---|---|
Version | 7.8.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
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Blocking | |
CC | |
Operating system | |
Architecture |