[GHC] #7414: plugins always trigger recompilation

[GHC]

#7414: plugins always trigger recompilation
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Reporter:  jwlato                        |          Owner:                       
    Type:  feature request               |         Status:  new                  
Priority:  normal                        |      Component:  Compiler             
 Version:  7.6.1                         |       Keywords:  plugin, recompilation
      Os:  Unknown/Multiple              |   Architecture:  Unknown/Multiple     
 Failure:  Compile-time performance bug  |      Blockedby:                       
Blocking:                                |        Related:                       
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 When compiling code with a ghc plugin, e.g. '''ghc -O -fplugin SomePlugin
 Main.hs''', recompilation is triggered for every module.  This can make
 plugins difficult to use in environments with many modules shared between
 executables.

 Since a plugin is a GHC library, I would like to propose that plugin
 arguments and interface hashes be included in the dependencies for
 compiled modules, in a similar way to how compiler flags are already
 included.  This would enable ghc to avoid recompilation of modules when
 using plugins, provided that the plugin and plugin options haven't
 changed.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7414>
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