
#15828: Type family equation foralls allow strange re-quantification of class-bound type variables -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.7 Resolution: | Keywords: TypeFamilies Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): Shamefully, the answer is not to pass the `mb_cls` to the call to `bindLHsTyVarBndrs` in `rnFamInstEqn` -- always pass `Nothing`. If an associated class is passed in, then `bindLHsTyVarBndrs` uses the in-scope class variables, which is not what's wanted here. Really, only `bindHsQTyVars` should pass a non-`Nothing` in this parameter. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15828#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler