'DynFlag'-free version of 'mkParserFlags'

Authored by harpocrates on Thu, Nov 22, 1:39 PM.

Description

'DynFlag'-free version of 'mkParserFlags'

Obtaining a DynFlags is difficult, making using the lexer/parser
for pure parsing/lexing unreasonably difficult, even with
mkPStatePure.
This is despite the fact that we only really need

  • language extension flags
  • warning flags
  • a handful of boolean options

The new mkParserFlags' function makes is easier to directly construct
a ParserFlags. Furthermore, since pExtsBitmap is just a footgun,
I've gone ahead and made ParserFlags an abstract type.

Reviewers: bgamari, alanz, sjakobi

Reviewed By: bgamari, sjakobi

Subscribers: mpickering, sjakobi, rwbarton, carter

GHC Trac Issues: Trac #11301

Differential Revision: https://phabricator.haskell.org/D5269