error[E0747]: type provided when a constant was expected
  --> $DIR/inferred_const.rs:6:19
   |
LL |     let a = foo::<_, 2>([0, 1, 2]);
   |                   ^
   |
   = help: const arguments cannot yet be inferred with `_`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0747`.