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


DEBUG:Going to execute:
Tactics.destruct_one_ex
Level 1: Backtrace:

No matching clauses for match.
Level 0: Backtrace:

No matching clauses for match.