error[E0107]: missing generics for struct `Vec`
  --> $DIR/generic-type-less-params-with-defaults.rs:9:12
   |
LL |     let _: Vec;
   |            ^^^ expected at least 1 generic argument
   |
note: struct defined here, with at least 1 generic parameter: `T`
  --> $DIR/generic-type-less-params-with-defaults.rs:5:8
   |
LL | struct Vec<T, A = Heap>(
   |        ^^^ -
help: add missing generic argument
   |
LL |     let _: Vec<T>;
   |               +++

error: aborting due to previous error

For more information about this error, try `rustc --explain E0107`.