#9359: Deriving clause failure with polymorphic kinds -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | deriving/should_compile/T9359 | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by simonpj): * cc: cheater00@… (added) * testcase: => deriving/should_compile/T9359 Comment: Great bug report, thank you. For good reasons, processing the `deriving` clause is well separated from other processing of the `data instance` declaration. Making kind arguments explicit, the latter gives {{{ data instance CmpInterval * (V (c::*)) Sup = Starting c }}} that is, this only applies at kind `*`, because the RHS says that `c::*`. But when processing the `deriving` clause we were forgetting to kind-check the RHS, so we were trying to derive an instance for `Show (CmpInterval k (V (c::k)) Sup`; and indeed there isn't one. Fix coming. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9359#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler