#14332: Deriving clauses can have forall types -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.2.1 checker) | Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: Type of failure: GHC accepts | Unknown/Multiple invalid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): Replying to [comment:16 simonpj]:
In comment:14 I say that GHC is behaving right.
Except that it's clearly not, as evidenced in comment:7. I don't see a way to fix that short of overhauling how `deriving` clauses are renamed/typechecked, which I don't feel like I'd be able to accomplish without some mentoring.
You seem to think I'm asking for something subtle in the implementationn, but I'm not.
I firmly disagree here—the way GHC typechecks `deriving` clauses is ripe with subtlety! It's caused me endless amounts of headaches trying to fix bugs like #10524 and #10561 in the past, as just two data points. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14332#comment:17 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler