Currently we have only the following generic warning "levels":
-W enable normal warnings -w disable all warnings -Wall enable almost all warnings (details in )
It would be useful to be able to refer collectively to all currently implemented forward-compatibility warnings (e.g. about upcoming changes in
-fwarn-amp) via a symbolic
This way, users have more flexibility in opt-in or out of such warnings. So e.g. the following settings are possible in
ghc-options: -Wall:: enable "almost all warnings" as before. Some compatibility warnings may be part of
-Wall, some won't (yet).
ghc-options: -Wall -Wcompat:: enable "almost all warnings" as well as all currently implemented warnings. E.g. if GHC 8.0 implements
-fwarn-mfp-compatbut doesn't include it in
-Wall, this gives users a way to opt in to get notified early about upcoming changes.
ghc-options: -Wall -Wno-compat:: This enables
-Wall**minus** any future-compat warnings. This is for users who want to be warned at all about any future compat warnings.
ghc-options: -Wcompat:: Of course,
-W(no-)compatcan be used also w/o
-Wall, and then is equivalent to turning on/off the respective individual
ghc-options: -Wall -Wcompat -Wno-mfp-compat:: This would allow to acknowledge the MFP compat warnings, while enabling other future GHC compat warnings.