finset_induction_bug.lean:30:23: error:invalid 'rewrite' tactic, step produced type incorrect term, details: type mismatch at application @subtype.tag (list A) (@nodup A) x nodup_al' term nodup_al' has type @nodup A (@cons A a l') but is expected to have type @nodup A x rewrite step failed using pattern @cons A_1 a_1 l'_1 proof state: A : Type, h : decidable_eq A, P : finset A → Prop, H1 : P (@empty A), H2 : ∀ ⦃s : finset A⦄ {a : A}, not (@mem A a s) → P s → P (@insert A h a s), s : finset A, u : nodup_list A, l : list A, a : A, l' : list A, IH : ∀ (x : @nodup A l'), P (@quot.mk (nodup_list A) (nodup_list_setoid A) (@subtype.tag (list A) (@nodup A) l' x)), nodup_al' : @nodup A (@cons A a l'), anl' : not (@list.mem A a l'), H3 : @eq (list A) (@list.insert A (λ (a b : A), h a b) a l') (@cons A a l'), nodup_l' : @nodup A l', P_l' : P (@quot.mk (nodup_list A) (nodup_list_setoid A) (@subtype.tag (list A) (@nodup A) l' nodup_l')), H4 : P (@insert A (λ (a b : A), h a b) a (@quot.mk (nodup_list A) (nodup_list_setoid A) (@subtype.tag (list A) (@nodup A) l' nodup_l'))) ⊢ P (@quot.mk (nodup_list A) (nodup_list_setoid A) (@subtype.tag (list A) (@nodup A) (@cons A a l') nodup_al')) finset_induction_bug.lean:30:45: error: don't know how to synthesize placeholder A : Type, h : decidable_eq A, P : finset A → Prop, H1 : P (@empty A), H2 : ∀ ⦃s : finset A⦄ {a : A}, not (@mem A a s) → P s → P (@insert A h a s), s : finset A, u : nodup_list A, l : list A, a : A, l' : list A, IH : ∀ (x : @nodup A l'), P (@quot.mk (nodup_list A) (nodup_list_setoid A) (@subtype.tag (list A) (@nodup A) l' x)), nodup_al' : @nodup A (@cons A a l'), anl' : not (@list.mem A a l'), H3 : @eq (list A) (@list.insert A (λ (a b : A), h a b) a l') (@cons A a l'), nodup_l' : @nodup A l', P_l' : P (@quot.mk (nodup_list A) (nodup_list_setoid A) (@subtype.tag (list A) (@nodup A) l' nodup_l')), H4 : P (@insert A (λ (a b : A), h a b) a (@quot.mk (nodup_list A) (nodup_list_setoid A) (@subtype.tag (list A) (@nodup A) l' nodup_l'))) ⊢ P (@quot.mk (nodup_list A) (nodup_list_setoid A) (@subtype.tag (list A) (@nodup A) (@cons A a l') nodup_al')) finset_induction_bug.lean:16:5: error: failed to add declaration 'finset.induction₂' to environment, value has metavariables remark: set 'formatter.hide_full_terms' to false to see the complete term λ (A : Type) (h : …) (P : …) (H1 : …) (H2 : …) (s : …), @quot.induction_on … … P s (λ (u : …), @subtype.destruct … … … u (λ (l : …), @list.induction_on A … l … (λ (a : A) (l' : …) (IH : …) (nodup_al' : …), assert anl' : …, from …, assert H3 : …, from …, assert nodup_l' : …, from …, assert P_l' : …, from …, ?M_1 …))) finset_induction_bug.lean:30:49: error: invalid end of module, expecting 'end'