#11000: Implement `-Wcompat` -------------------------------------+------------------------------------- Reporter: hvr | Owner: Type: feature | Status: new request | Priority: high | Milestone: 8.0.1 Component: Compiler | Version: 7.10.2 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: Design/Warnings -------------------------------------+------------------------------------- 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 `base`, like `-fwarn-amp`) via a symbolic `-Wcompat` flag. This way, users have more flexibility in opt-in or out of such warnings. So e.g. the following settings are possible in `.cabal` files: `ghc-options: -Wall` :: enable "almost all warnings" as before. Some compat warnings maybe part of `-Wall`, some won't (yet). `ghc-options: -Wall -Wcompat` :: enable "almost all warnings" as well as all implemented warnings. E.g. if GHC 8.0 implements `-fwarn-mfp-compat` but doesn't include it in `-Wall`, this allows users to get notified asap about warnings to opt into that `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-)compat` can be used also w/o `-Wall`, and then is equivalent to turning on/off the respective individual `-fwarn-*-compat` flags. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11000 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler