To cite rwbarton from #9757:

...

I think the purpose of compiler warnings should be to warn about code

#3085: warn about language extensions that are not used -------------------------------------+------------------------------------- Reporter: | Owner: PVerswyvelen | Status: new Type: feature | Milestone: 7.10.1 request | Version: 6.10.1 Priority: normal | Keywords: warnings Component: Compiler | extensions language Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: #9757 None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by simonmar): Replying to [comment:33 thomie]: that is probably bad, not code that is probably fine that could be written in a (potentially) better way. (After all, we don't warn about excess parentheses in code either.) That is the domain of hlint, as Richard notes.

Anyone disagree with a `wontfix` here as well?

This is an argument that the warning shouldn't be on by default, or perhaps that it shouldn't be in `-Wall`, but not an argument that we shouldn't implement it at all. We have several warnings that are not part of `-Wall` and fall into the category of "a matter of taste". (FWIW, HLint already does this for a subset of extensions). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/3085#comment:37 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler