error[E0284]: type annotations needed for `[usize; _]`
  --> $DIR/issue-83606.rs:8:9
   |
LL |     let _ = foo("foo");
   |         ^   ---------- type must be known at this point
   |
note: required by a const generic parameter in `foo`
  --> $DIR/issue-83606.rs:3:8
   |
LL | fn foo<const N: usize>(_: impl std::fmt::Display) -> [usize; N] {
   |        ^^^^^^^^^^^^^^ required by this const generic parameter in `foo`
help: consider giving this pattern a type, where the value of const parameter `N` is specified
   |
LL |     let _: [usize; N] = foo("foo");
   |          ++++++++++++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0284`.