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  • Herbert Valerio Riedel's avatar
    Drop deprecated `OverlappingInstances` from base · cbb20ab2
    Herbert Valerio Riedel authored
    With #9242 the `OverlappingInstances` extension got deprecated, this
    commit adapts the only two remaining places in `base` where it was still
    used.
    
    Starting with this commit, the `Typeable (s t)` instance (which seemingly
    was the motivation for using `OverlappingInstances` in the first place
    when `Typeable` was neither polykinded nor auto-derived-only, see also
    commit ce3fd0e0 which introduced
    overlapping instances) does no longer allow overlapping instances, and
    there doesn't seem to be any good reason to keep allowing overlapping
    instance now.
    
    This also removes redundant `LANGUAGE`/`OPTIONS_GHC` pragmas from
    `Data.Typeable` and refactors the language pragmas into more uniform
    single-line pragmas.
    
    Reviewed By: austin
    
    Differential Revision: https://phabricator.haskell.org/D377
    cbb20ab2