#14832: QuantifiedConstraints: Adding to the context causes failure -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 Resolution: | Keywords: | QuantifiedConstraints wipT2893 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 RyanGlScott): Using the latest commit on the `wip/T2893` branch, this program now gives you a stack overflow! {{{ $ inplace/bin/ghc-stage2 --interactive ../Bug.hs GHCi, version 8.5.20180128: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Main ( ../Bug.hs, interpreted ) ../Bug.hs:15:10: error: • Reduction stack overflow; size = 201 When simplifying the following type: rel xx yy0 Use -freduction-depth=0 to disable this check (any upper bound you could choose might fail unpredictably with minor updates to GHC, so disabling the check is recommended if you're sure that type checking should terminate) • In the instance declaration for ‘Category (With rel)’ | 15 | instance (Refl rel, Trans rel) => Category (With rel) where | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14832#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler