Goal:
  
  A : Type
  P : A → A → Type
  hd : A
  hd' : A
  tl : list A
  p : P hd hd'
  idx2 : list A
  idx1 : list A
  b : OnOne2 P idx2 idx1
  ============================
   (let H := CoreTactics.block in
    NoConfusion_OnOne2 A P
      {|
        pr1 := {| pr1 := hd :: tl; pr2 := hd' :: tl |};
        pr2 := OnOne2_hd P hd hd' tl p
      |} {| pr1 := {| pr1 := idx2; pr2 := idx1 |}; pr2 := b |}
    → let H0 := CoreTactics.block in
      {|
        pr1 := {| pr1 := hd :: tl; pr2 := hd' :: tl |};
        pr2 := OnOne2_hd P hd hd' tl p
      |} = {| pr1 := {| pr1 := idx2; pr2 := idx1 |}; pr2 := b |})


DEBUG:Going to execute:
destruct p || (case p; clear p)
Level 6: evaluation of term
raised the exception
Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1


Level 5: Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1

Level 4: Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1

Level 4: evaluation
raised the exception
Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1


Level 4: Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1

Level 4: Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1

Level 3: Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1

Level 3: evaluation
raised the exception
Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1


Level 3: Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1

Level 2: Backtrace:


Could not find an instance for "DepElim.DependentEliminationPackage
                                  (OnOne2 P idx2 idx1)"
in
environment:
A : Type
P : A → A → Type
hd, hd' : A
tl : list A
p : P hd hd'
idx2, idx1 : list A
b : OnOne2 P idx2 idx1