error[E0658]: use of unstable library feature 'try_reserve': new API (see issue #48043)
  --> $DIR/feature-gate-try_reserve.rs:3:7
   |
LL |     v.try_reserve(10); //~ ERROR: use of unstable library feature 'try_reserve'
   |       ^^^^^^^^^^^
   |
   = help: add #![feature(try_reserve)] to the crate attributes to enable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0658`.