error[E0658]: unnamed fields are not yet fully implemented
  --> $DIR/unnamed-enum-field-issue-121757.rs:9:5
   |
LL |     _: AstKind<'ast>
   |     ^
   |
   = note: see issue #49804 <https://github.com/rust-lang/rust/issues/49804> for more information
   = help: add `#![feature(unnamed_fields)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error: struct with unnamed fields must have `#[repr(C)]` representation
  --> $DIR/unnamed-enum-field-issue-121757.rs:6:1
   |
LL | struct AstStructure<'ast> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^ struct `AstStructure` defined here
   |
note: unnamed field defined here
  --> $DIR/unnamed-enum-field-issue-121757.rs:9:5
   |
LL |     _: AstKind<'ast>
   |     ^^^^^^^^^^^^^^^^
help: add `#[repr(C)]` to this struct
   |
LL + #[repr(C)]
LL | struct AstStructure<'ast> {
   |

error: unnamed fields can only have struct or union types
  --> $DIR/unnamed-enum-field-issue-121757.rs:9:5
   |
LL |     _: AstKind<'ast>
   |     ^^^^^^^^^^^^^^^^

error[E0609]: no field `kind` on type `&'ast AstStructure<'ast>`
  --> $DIR/unnamed-enum-field-issue-121757.rs:21:15
   |
LL |     match ast.kind {}
   |               ^^^^ unknown field
   |
   = note: available fields are: `id`, `_`

error: aborting due to 4 previous errors

Some errors have detailed explanations: E0609, E0658.
For more information about an error, try `rustc --explain E0609`.