Confused type checker with typed holes and a missing instance (also panic)
If your file contains a typed hole and a case where an instance is missing, the type checker will not find the missing instance and only report the hole. If -fdefer-typed-holes is set, this results in a panic. (Using ghci, the panic occurs when any definition of the module is being evaluated)
Minimal working example:
{-# OPTIONS_GHC -fdefer-typed-holes #-}
data Asd = Asd
someHole = _asd
missingInstance :: Asd -> Asd -> Bool
missingInstance x y = x == y
Trac metadata
Trac field | Value |
---|---|
Version | 7.10.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
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Blocking | |
CC | |
Operating system | |
Architecture |