#14000: Out of scope errors with type families do not mention scope -------------------------------------+------------------------------------- Reporter: EyalLotem | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: TypeFamilies Operating System: Unknown/Multiple | Architecture: Type of failure: Poor/confusing | Unknown/Multiple error message | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"452755de717fad5d8fbfc6330cb42a3335c8912d/ghc" 452755de/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="452755de717fad5d8fbfc6330cb42a3335c8912d" Do not discard insolubles in implications Trac #14000 showed up two errors * In TcRnTypes.dropInsolubles we dropped all implications, which might contain the very insolubles we wanted to keep. This was an outright error, and is why the out-of-scope error was actually lost altogether in Trac #14000 * In TcSimplify.simplifyInfer, if there are definite (insoluble) errors, it's better to suppress the following ambiguity test, because the type may be bogus anyway. See TcSimplify Note [Quantification with errors]. This fix seems a bit clunky, but it'll do for now. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14000#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler