idris-0.9.19.1: test/proofsearch001/proofsearch001.idr
%default total
class C a (f : Bool -> Bool) | a where {}
instance C Int Bool.not where {}
foo : C Int g => {auto pf : g True = False} -> Unit
foo = ()
main : IO ()
main = printLn $ foo -- {pf = Refl}