Passing -fno-code disables reporting of some warnings

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.

Trac metadata

Trac field	Value
Version	8.2.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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