:set +c makes all warnings appear twice, breaking some functionality

[Ptival]

I'm not sure why nobody noticed this, but for me, the :set +c has the bad side-effect of producing this:

<-  [-Wunused-imports]
       The import of ‘Data.Typeable’ is redundant
         except perhaps to import instances from ‘Data.Typeable’
       To import instances alone, use: import Data.Typeable()
   Ok, modules loaded: Variable.
   Collecting type info for 1 module(s) ... 
   
   /home/ptival/chick/lib/Term/Variable.hs:18:1-20: warning: [-Wunused-imports]
       The import of ‘Data.Typeable’ is redundant
         except perhaps to import instances from ‘Data.Typeable’
       To import instances alone, use: import Data.Typeable()

That is, it seems warnings are emitted once when type-checking, then once more when colllecting type information.

This has the bad side effect that features like "removing redundant imports" ask me to remove each import twice!

[ivan-m]

I had wondered why many errors were reported twice, but never bothered to dig into why! Thanks!

[Pitometsu]

Confirm, same behavior.

[vlatkoB]

I see double warnings even with removed "+c".

[ulrikrasmussen]

I can confirm that I also see double warnings. Unsetting "+c" by writing :unset +c in the REPL buffer resolves the problem.

[vlatkoB]

Is there a way to set it automatically? I tried setting

(haskell-interactive-set-+c nil)

but to no avail.