[GHC] #16075: OPTIONS_GHC Ignored

[GHC]

#16075: OPTIONS_GHC Ignored
-------------------------------------+-------------------------------------
           Reporter:  crockeea       |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.6.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Incorrect
  Unknown/Multiple                   |  error/warning at compile-time
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 When I enable `-Weverything`, some `OPTIONS_GHC` pragmas are respected,
 while others are ignored. For example, with `-Weverything`, this file

 {{{
 main = print "hello"

 foo :: (Num a, Show a) => a -> IO ()
 foo = print . show
 }}}

 generates warnings about:

   1. missing an export list
   2. top-level binding [main] with no type sig
   3. redundant constraint [Num a]

 If I add `{-# OPTIONS_GHC -fno-warn-missing-signatures -fno-warn-missing-
 export-lists -fno-warn-redundant-constraints #-}` to the top of the file
 and recompile, I expect all warnings to go away. But GHC still reports
 that `main` has no signature.


 Note that this problem doesn't occur with `-Wall`. With `-Wall`, the code
 snippet warns about the missing signature on `main`, but when I add the
 `OPTIONS_GHC`, the warning goes away. Thus this problem appears to be
 unique to `Weverything`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16075>
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