[GHC] #14709: Extend the plugin mechanism to access program representation

[GHC]

#14709: Extend the plugin mechanism to access program representation
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        Reporter:  lazac             |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  GHC API           |              Version:  8.2.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |  https://phabricator.haskell.org/D4342
  https://ghc.haskell.org/trac/ghc/wiki/ExtendedPluginsProposal|
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Comment (by ezyang):

 This doesn't really have anything to do with the relative merits/demerits
 of the proposal, but I just wanted to point out:

 > ​Frontend plugins are not applicable, because their usage changes the
 major mode of the compiler. So if the tool developer wants to go on with
 the compilation procedure, he must replicate what GHC would do if the
 frontend plugin was not used. Furthermore, it can't be inserted into a
 normal build environment, since using the --frontend flag clashes with
 other mode flags like --make or --interactive.

 Out of the box these statements are true, but as I mention in
 http://blog.ezyang.com/2017/02/how-to-integrate-ghc-api-programs-with-
 cabal/ there are some relatively simple tricks you can play to solve this
 problem. As another example, https://github.com/ezyang/ghc-shake comes
 with a wrapper program which overrides the meaning of `--make` but
 otherwise keeps all other major modes the same.

 Of course, if the frontend plugin is replacing a mode like `--make`, it
 needs to understand all of the same arguments that `--make` would have
 understood, but that is what you would expect, no?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14709#comment:7>
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