Goal:
  
  elt : Type
  eq_elt : elt -> elt -> Prop
  m : t elt
  m' : t elt
  H : forall x y : key, E.eq x y -> find x m = find y m
  H0 : forall x y : key, E.eq x y -> find x m' = find y m'
  H1 : forall (k : key) (e : elt) (p : key × elt),
       E.eq k p.1 /\ e = p.2 ->
       List.In p (elements m) ->
       match find k m with
       | Some x =>
           match find k m' with
           | Some y => eq_elt x y
           | None => False
           end
       | None => match find k m' with
                 | Some _ => False
                 | None => True
                 end
       end
  H3 : forall (k : key) (e : elt) (p : key × elt),
       E.eq k p.1 ->
       e = p.2 ->
       List.In p (elements m') ->
       match find k m with
       | Some x =>
           match find k m' with
           | Some y => eq_elt x y
           | None => False
           end
       | None => match find k m' with
                 | Some _ => False
                 | None => True
                 end
       end
  k : key
  e : elt
  H2 : List.In (k, e) (elements m)
  ============================
   match find k m with
   | Some x =>
       match find k m' with
       | Some y => eq_elt x y
       | None => False
       end
   | None => match find k m' with
             | Some _ => False
             | None => True
             end
   end


DEBUG:Going to execute:
guard_tac H;
            guarded_specialize_gen_hyp_under_binders_by all_ways
             ltac:(guard_noop) H tac
DEBUG LTAC Evaluated term: (H3 ?k ?e ?p ?e0 ?e1 ?i)
DEBUG LTAC Evaluated term: match find ?k m with
                           | Some x =>
                               match find ?k m' with
                               | Some y => eq_elt x y
                               | None => False
                               end
                           | None =>
                               match find ?k m' with
                               | Some _ => False
                               | None => True
                               end
                           end
Level 27: type of H
 has value 
match find ?k m with
| Some x => match find ?k m' with
            | Some y => eq_elt x y
            | None => False
            end
| None => match find ?k m' with
          | Some _ => False
          | None => True
          end
end

Level 27: Backtrace:

No matching clauses for match.
Level 26: Backtrace:

No matching clauses for match.
Level 26: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 26: Backtrace:

No matching clauses for match.
Level 25: Backtrace:

No matching clauses for match.
Level 24: Backtrace:

No matching clauses for match.
Level 23: Backtrace:

No matching clauses for match.
Level 23: Backtrace:

No matching clauses for match.
Level 22: Backtrace:

No matching clauses for match.
Level 22: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 22: Backtrace:

No matching clauses for match.
Level 21: Backtrace:

No matching clauses for match.
Level 20: Backtrace:

No matching clauses for match.
Level 19: Backtrace:

No matching clauses for match.
Level 19: Backtrace:

No matching clauses for match.
Level 18: Backtrace:

No matching clauses for match.
Level 18: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 18: Backtrace:

No matching clauses for match.
Level 17: Backtrace:

No matching clauses for match.
Level 16: Backtrace:

No matching clauses for match.
Level 15: Backtrace:

No matching clauses for match.
Level 15: Backtrace:

No matching clauses for match.
Level 14: Backtrace:

No matching clauses for match.
Level 14: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 14: Backtrace:

No matching clauses for match.
Level 13: Backtrace:

No matching clauses for match.
Level 12: Backtrace:

No matching clauses for match.
Level 11: Backtrace:

No matching clauses for match.
Level 11: Backtrace:

No matching clauses for match.
Level 10: Backtrace:

No matching clauses for match.
Level 10: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 10: Backtrace:

No matching clauses for match.
Level 9: Backtrace:

No matching clauses for match.
Level 8: Backtrace:

No matching clauses for match.
Level 7: Backtrace:

No matching clauses for match.
Level 7: Backtrace:

No matching clauses for match.
Level 6: Backtrace:

No matching clauses for match.
Level 6: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 6: Backtrace:

No matching clauses for match.
Level 5: Backtrace:

No matching clauses for match.
Level 4: Backtrace:

No matching clauses for match.
Level 3: Backtrace:

No matching clauses for match.
Level 3: Backtrace:

No matching clauses for match.
Level 2: Backtrace:

No matching clauses for match.
Level 2: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 2: Backtrace:

No matching clauses for match.
Level 1: Backtrace:

No matching clauses for match.
Level 1: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 0: Backtrace:

No matching clauses for match.
Level 0: Backtrace:

No matching clauses for match.
Level 0: Backtrace:

No matching clauses for match.
Level 1: Backtrace:

No matching clauses for match.
Level 0: Backtrace:

No matching clauses for match.
Level 6: interpretation of term ltac:((let H := fresh in
                                       pose  H  :=
                                        ltac:((let v := tac ltac:(()) in
                                               refine
                                               v)); exact H))
raised the exception
Backtrace:

No matching clauses for match.

Level 6: evaluation of term
raised the exception
Backtrace:

No matching clauses for match.

Level 6: Backtrace:

No matching clauses for match.
Level 5: Backtrace:

No matching clauses for match.
Level 5: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 5: Backtrace:

No matching clauses for match.
Level 5: Backtrace:

No matching clauses for match.
Level 4: Backtrace:

No matching clauses for match.
Level 4: evaluation
raised the exception
Backtrace:

No matching clauses for match.

Level 4: Backtrace:

No matching clauses for match.
Level 3: Backtrace:

No matching clauses for match.
Level 3: Backtrace:

No matching clauses for match.
Level 2: Backtrace:

No matching clauses for match.
Level 2: Backtrace:

No matching clauses for match.
Level 1: Backtrace:

No matching clauses for match.
Level 1: Backtrace:

No matching clauses for match.
Level 2: Backtrace:

No matching clauses for match.
Level 2: Backtrace:

No matching clauses for match.
Level 2: Backtrace:

No matching clauses for match.
Level 1: Backtrace:

No matching clauses for match.
Level 2: Backtrace:

No matching clauses for match.
Level 1: Backtrace:

No matching clauses for match.
Level 1: Backtrace:

No matching clauses for match.