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'
  k : key
  x : elt
  H3 : forall e : elt, find k m' = Some e -> eq_elt x e
  H1 : find k m = Some x
  H4 : exists e : elt, find k m' = Some e
  H5 : forall (k : key) (e : elt),
       find k m' = Some e -> exists e0 : elt, find k m = Some e0
  H2 : forall k : key, find k m' = find k m'
  H6 : forall k : key, find k m = find k m
  ============================
   ?T0


DEBUG:Going to execute:
let H := open_constr:((H _)) in
           guarded_specialize_term_under_binders_by' guard_tac H tac
Level 0: Backtrace:

In environment
elt : Type
eq_elt : elt -> elt -> Prop
m, 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'
k : key
x : elt
H3 : forall e : elt, find k m' = Some e -> eq_elt x e
H1 : find k m = Some x
H4 : exists e : elt, find k m' = Some e
H5 : forall (k : key) (e : elt),
     find k m' = Some e -> exists e0 : elt, find k m = Some e0
H2 : forall k : key, find k m' = find k m'
H6 : forall k : key, find k m = find k m
The term "H1" has type "find k m = Some x" while it is expected to have type
 "find k m' = Some ?e" (cannot unify "m" and "m'").
Level 0: Backtrace:

In environment
elt : Type
eq_elt : elt -> elt -> Prop
m, 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'
k : key
x : elt
H3 : forall e : elt, find k m' = Some e -> eq_elt x e
H1 : find k m = Some x
H4 : exists e : elt, find k m' = Some e
H5 : forall (k : key) (e : elt),
     find k m' = Some e -> exists e0 : elt, find k m = Some e0
H2 : forall k : key, find k m' = find k m'
H6 : forall k : key, find k m = find k m
The term "H1" has type "find k m = Some x" while it is expected to have type
 "find k m' = Some ?e" (cannot unify "m" and "m'").
Level 13: Backtrace:

In environment
elt : Type
eq_elt : elt -> elt -> Prop
m, 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'
k : key
x : elt
H3 : forall e : elt, find k m' = Some e -> eq_elt x e
H1 : find k m = Some x
H4 : exists e : elt, find k m' = Some e
H5 : forall (k : key) (e : elt),
     find k m' = Some e -> exists e0 : elt, find k m = Some e0
H2 : forall k : key, find k m' = find k m'
H6 : forall k : key, find k m = find k m
The term "H1" has type "find k m = Some x" while it is expected to have type
 "find k m' = Some ?e" (cannot unify "m" and "m'").
Level 16: Backtrace:

In environment
elt : Type
eq_elt : elt -> elt -> Prop
m, 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'
k : key
x : elt
H3 : forall e : elt, find k m' = Some e -> eq_elt x e
H1 : find k m = Some x
H4 : exists e : elt, find k m' = Some e
H5 : forall (k : key) (e : elt),
     find k m' = Some e -> exists e0 : elt, find k m = Some e0
H2 : forall k : key, find k m' = find k m'
H6 : forall k : key, find k m = find k m
The term "H1" has type "find k m = Some x" while it is expected to have type
 "find k m' = Some ?e" (cannot unify "m" and "m'").
Level 16: Backtrace:

In environment
elt : Type
eq_elt : elt -> elt -> Prop
m, 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'
k : key
x : elt
H3 : forall e : elt, find k m' = Some e -> eq_elt x e
H1 : find k m = Some x
H4 : exists e : elt, find k m' = Some e
H5 : forall (k : key) (e : elt),
     find k m' = Some e -> exists e0 : elt, find k m = Some e0
H2 : forall k : key, find k m' = find k m'
H6 : forall k : key, find k m = find k m
The term "H1" has type "find k m = Some x" while it is expected to have type
 "find k m' = Some ?e" (cannot unify "m" and "m'").
Level 15: Backtrace:

In environment
elt : Type
eq_elt : elt -> elt -> Prop
m, 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'
k : key
x : elt
H3 : forall e : elt, find k m' = Some e -> eq_elt x e
H1 : find k m = Some x
H4 : exists e : elt, find k m' = Some e
H5 : forall (k : key) (e : elt),
     find k m' = Some e -> exists e0 : elt, find k m = Some e0
H2 : forall k : key, find k m' = find k m'
H6 : forall k : key, find k m = find k m
The term "H1" has type "find k m = Some x" while it is expected to have type
 "find k m' = Some ?e" (cannot unify "m" and "m'").
Level 14: Backtrace:

In environment
elt : Type
eq_elt : elt -> elt -> Prop
m, 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'
k : key
x : elt
H3 : forall e : elt, find k m' = Some e -> eq_elt x e
H1 : find k m = Some x
H4 : exists e : elt, find k m' = Some e
H5 : forall (k : key) (e : elt),
     find k m' = Some e -> exists e0 : elt, find k m = Some e0
H2 : forall k : key, find k m' = find k m'
H6 : forall k : key, find k m = find k m
The term "H1" has type "find k m = Some x" while it is expected to have type
 "find k m' = Some ?e" (cannot unify "m" and "m'").
Level 13: Backtrace:

In environment
elt : Type
eq_elt : elt -> elt -> Prop
m, 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'
k : key
x : elt
H3 : forall e : elt, find k m' = Some e -> eq_elt x e
H1 : find k m = Some x
H4 : exists e : elt, find k m' = Some e
H5 : forall (k : key) (e : elt),
     find k m' = Some e -> exists e0 : elt, find k m = Some e0
H2 : forall k : key, find k m' = find k m'
H6 : forall k : key, find k m = find k m
The term "H1" has type "find k m = Some x" while it is expected to have type
 "find k m' = Some ?e" (cannot unify "m" and "m'").
Level 12: Backtrace:

In environment
elt : Type
eq_elt : elt -> elt -> Prop
m, 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'
k : key
x : elt
H3 : forall e : elt, find k m' = Some e -> eq_elt x e
H1 : find k m = Some x
H4 : exists e : elt, find k m' = Some e
H5 : forall (k : key) (e : elt),
     find k m' = Some e -> exists e0 : elt, find k m = Some e0
H2 : forall k : key, find k m' = find k m'
H6 : forall k : key, find k m = find k m
The term "H1" has type "find k m = Some x" while it is expected to have type
 "find k m' = Some ?e" (cannot unify "m" and "m'").