Goal:
  
  A : Type
  B : Type
  R : A → B → Type
  l2 : list A
  r : list B
  X : All2 R l2 r
  ============================
   (r = [] ++ r × All2 R [] [] × All2 R l2 r)


DEBUG:Going to execute:
<coq-core.plugins.ltac::eauto@0> $1 $2 $3
DEBUG LTAC Evaluated term: []
DEBUG LTAC Evaluated term: r