haskell/haskell-ide-engine

Hlint parser error on `pattern`

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#1374 aperta il 28 ago 2019

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Descrizione

Given a module:

module Lib where

foo pattern = pattern

This error message is shown:

/tmp/ghc-mod4106/Lib4105-43.hs:3:5: error:
    parse error on input `pattern'
  module Lib where
  
> foo pattern = pattern

This is documented in https://github.com/ndmitchell/hlint/issues/607. Minimal project to reproduce: https://github.com/fendor/hlint-minimal-pattern

This happens because hlint assumes some default extensions. This makes sense, since hlint is normally not aware of a .cabal or package.yaml file, where extensions may be listed. However, HIE is aware of language extensions and could invoke hlint always with the right extensions.

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