#10011: The Data instance for Ratio violates internal invariants. -------------------------------------+------------------------------------- Reporter: ekmett | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Core Libraries | Version: 7.10.1-rc1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D625 -------------------------------------+------------------------------------- Comment (by hvr): The following was suggested as regression test by Edward: {{{
:set -XScopedTypeVariables -XTypeOperators -XGADTs :m + Control.Lens Data.Data.Lens Data.Ratio let bad = gmapT (\(x :: b) -> case eqT :: Maybe (b :~: Integer) of Nothing -> x; Just Refl -> x * 2) (1 % 2) :: Rational in bad == numerator bad % denominator bad False }}}
-- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10011#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler