big_sep lemmas fail to apply when goal is not eta-expanded
I just ran into a strange problem:
Lemma test {A B} (Φ : nat → A → B → PROP) (l1 : list A) (l2 : list B) :
⊢ big_sepL2 Φ l1 l2.
Proof.
Fail iApply big_sepL2_delete.
(* The command has indeed failed with message:
Tactic failure: iApply: cannot apply
(([∗ list] k↦y1;y2 ∈ ?Goal0;?Goal1, ?Goal k y1 y2)
∗-∗ ?Goal ?Goal2 ?Goal3 ?Goal4
∗ ([∗ list] k↦y1;y2 ∈ ?Goal0;?Goal1, if decide (k = ?Goal2) then emp else ?Goal k y1 y2))%I. *)
iApply (big_sepL2_delete Φ).
(* This works. *)
For some reason Coq needs to be manually given Φ
here. That should not be the case.
The only difference between the lemma statement and the goal is an eta-expansion of Φ
.