[GHC] #16260: Use of plugins causes -XSafe to fail

[GHC]

#16260: Use of plugins causes -XSafe to fail
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        Reporter:  watashi           |                Owner:  watashi
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.7
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by watashi):

 > Perhaps a better solution is to make all the fields which can modify the
 AST return Maybe so that if any modifications take place then the module
 is marked Unsafe. Plugins can return Nothing if they want to purely
 inspect information.

 I thought about this as well. But `keepRenamedSource` is a useful
 couterexample that modifies the return value but doesn't affect the final
 output.

 I am not familiar with all the use cases of source plugins. Assuming we
 push the responsibility the plugin authors, how bad will it be if they
 forget calling `recordUnsafeInfer` when they should? Is this worse than
 `-fno-safe-haskell`?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16260#comment:5>
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