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(* Bug report #932 *)
(* Expected time < 1.00s *)
(* Let n be the number of let-in. The complexity comes from the fact
that each implicit arguments of f was in a larger and larger
context. To compute the type of "let _ := f ?Tn 0 in f ?T 0", "f ?Tn
0" is substituted in the type of "f ?T 0" which is ?T. This type is an
evar instantiated on the n variables denoting the "f ?Ti 0". One
obtain "?T[1;...;n-1;f ?Tn[1;...;n-1] 0]". To compute the type of "let
_ := f ?Tn-1 0 in let _ := f ?Tn 0 in f ?T 0", another substitution is
done leading to ?T[1;...;n-2;f ?Tn[1;...;n-2] 0;f ?Tn[1;...;n-2;f
?Tn[1;...;n-2] 0] 0]" and so on. At the end, we get a term of
exponential size *)
(* A way to cut the complexity is to remove the dependency in
anonymous variables in evars; another approach would be to
substitute lazily and/or to simultaneously substitute let binders
and evars *)
Variable P : Set -> Set.
Variable f : forall A : Set, A -> P A.
Check
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
let _ := f _ 0 in
f _ 0.
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