content: {-# LINE 1 "GHC.OverloadedLabels.hs" #-}
  {-# LANGUAGE NoImplicitPrelude
             , MultiParamTypeClasses
             , MagicHash
             , KindSignatures
             , DataKinds
    #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  GHC.OverloadedLabels
  -- Copyright   :  (c) Adam Gundry 2015
  -- License     :  see libraries/base/LICENSE
  --
  -- Maintainer  :  cvs-ghc@haskell.org
  -- Stability   :  internal
  -- Portability :  non-portable (GHC extensions)
  --
  -- This module defines the `IsLabel` class is used by the
  -- OverloadedLabels extension.  See the
  -- <https://ghc.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields/OverloadedLabels wiki page>
  -- for more details.
  --
  -- The key idea is that when GHC sees an occurrence of the new
  -- overloaded label syntax @#foo@, it is replaced with
  --
  -- > fromLabel (proxy# :: Proxy# "foo") :: alpha
  --
  -- plus a wanted constraint @IsLabel "foo" alpha@.
  --
  -----------------------------------------------------------------------------
  
  -- Note [Overloaded labels]
  -- ~~~~~~~~~~~~~~~~~~~~~~~~
  -- An overloaded label is represented by the 'HsOverLabel' constructor
  -- of 'HsExpr', which stores a 'FastString'.  It is passed through
  -- unchanged by the renamer, and the type-checker transforms it into a
  -- call to 'fromLabel'.  See Note [Type-checking overloaded labels] in
  -- TcExpr for more details in how type-checking works.
  
  module GHC.OverloadedLabels
         ( IsLabel(..)
         ) where
  
  import GHC.Base ( Symbol )
  import GHC.Exts ( Proxy# )
  
  class IsLabel (x :: Symbol) a where
    fromLabel :: Proxy# x -> a
  