Goal:
  
  A : Type
  R : ReflectEq A
  x : A
  y : A
  Heq_anonymous : false = (x == y)
  H : x = y
  ============================
   False


DEBUG:Going to execute:
<coq-core.plugins.ltac::unify@0> $1 $2
DEBUG LTAC Evaluated term: (ReflectEq A)
DEBUG LTAC Evaluated term: (false = (x == y))