error[E0432]: unresolved import `core`
  --> $DIR/feature-gate-extern_absolute_paths.rs:1:5
   |
LL | use core::default;
   |     ^^^^
   |     |
   |     you might be missing crate `core`
   |     help: try using `std` instead of `core`: `std`

error[E0433]: failed to resolve: you might be missing crate `core`
  --> $DIR/feature-gate-extern_absolute_paths.rs:4:19
   |
LL |     let _: u8 = ::core::default::Default();
   |                   ^^^^ you might be missing crate `core`
   |
help: try using `std` instead of `core`
   |
LL |     let _: u8 = ::std::default::Default();
   |                   ~~~
help: consider importing this module
   |
LL + use std::default;
   |
help: if you import `default`, refer to it directly
   |
LL -     let _: u8 = ::core::default::Default();
LL +     let _: u8 = default::Default();
   |

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0432, E0433.
For more information about an error, try `rustc --explain E0432`.