[GHC] #14954: Passing -fno-code disables reporting of some warnings

[GHC]

#14954: Passing -fno-code disables reporting of some warnings
-------------------------------------+-------------------------------------
           Reporter:  mrkkrp         |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.2.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 Here is how to reproduce the issue with GHC 8.2.2:

 {{{
 $ cat Main.hs
 module Main (main) where

 main =
   case (1+1) :: Int of
     1 -> return ()


 $ ghc -Wall -Werror -fno-code Main.hs
 [1 of 1] Compiling Main             ( Main.hs, nothing )

 Main.hs:3:1: warning: [-Wmissing-signatures]
     Top-level binding with no type signature: main :: IO ()
   |
 3 | main =
   | ^^^^

 <no location info>: error:
 Failing due to -Werror.


 $ ghc -Wall -Werror Main.hs
 [1 of 1] Compiling Main             ( Main.hs, Main.o )

 Main.hs:3:1: warning: [-Wmissing-signatures]
     Top-level binding with no type signature: main :: IO ()
   |
 3 | main =
   | ^^^^

 Main.hs:4:3: warning: [-Wincomplete-patterns]
     Pattern match(es) are non-exhaustive
     In a case alternative:
         Patterns not matched: p where p is not one of {1}
   |
 4 |   case (1+1) :: Int of
   |   ^^^^^^^^^^^^^^^^^^^^...

 <no location info>: error:
 Failing due to -Werror.
 }}}

 Note that `missing-signature` is reported both times, but the `incomplete-
 patterns` is not reported with `-fno-code`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14954>
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