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GHC 8 allows ambiguous type without AllowAmbiguousTypes

This module compiles with GHC 8:

{-# LANGUAGE DefaultSignatures #-}
-- {-# LANGUAGE AllowAmbiguousTypes #-} -- Not required with GHC 8.0.1.

module T12151 where

class Put a where
    put :: a

    default put :: t  -- This should be `a` instead of `t`
    put = undefined

GHC 7.10 required AllowAmbiguousTypes, to defer the ambiguity check to use sites.

(Example extracted from the description of #7437 (closed))

Trac metadata
Trac field Value
Version 8.0.1
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler (Type checker)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture
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