#10635: -fwarn-redundant-constraints should not be part of -Wall -------------------------------------+------------------------------------- Reporter: Lemming | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.11 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: #9939, #9973, | Differential Rev(s): #10100, #10183, #11370 | Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): It makes some sense to warn, by default, when a signature is less polymorphic than it could be. After all, it's quite possible that the programmer didn't realise that the function could be more polymorphic. And indeed I found half a dozen cases of redundant constrains in the `base` package when I first implemented it. But * `-fwarn-redundant-constraints` only does part of the job. It does not warn when you use a tighter constraint than necessary, or indeed instantiate what could be a polymorphic variable to a specific type. * People have argued persuasively that they sometimes want a less polymorphic type. So: * It looks as if we should take it out of `-Wall`. Would someone like to do that, it it hasn't happened already? * I'd be open to a design (and a patch) making it possible to say that a specific type signature deliberately has redundant constraint. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10635#comment:26 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler