Function with type error accepted
The following program is accepted by ghc even though it is clearly wrong. The type family T is closed so T Bool cannot ever be reduced, so it must be a type error.
{-# LANGUAGE TypeFamilies #-}
module Err62 where
type family T a where
T Int = ()
x :: T Bool
x = undefined
f :: T Bool -> Bool
f _ = True
y :: Bool
y = f xTrac metadata
| Trac field | Value |
|---|---|
| Version | 7.8.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
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