error[E0275]: overflow evaluating the requirement `Runtime: RefUnwindSafe` | = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`cycle_via_builtin_auto_trait_impl`) note: required because it appears within the type `RootDatabase` --> $DIR/cycle-via-builtin-auto-trait-impl.rs:13:8 | LL | struct RootDatabase { | ^^^^^^^^^^^^ note: required for `RootDatabase` to implement `Database` --> $DIR/cycle-via-builtin-auto-trait-impl.rs:17:24 | LL | impl Database for T { | ------------- ^^^^^^^^ ^ | | | unsatisfied trait bound introduced here note: required because it appears within the type `Runtime` --> $DIR/cycle-via-builtin-auto-trait-impl.rs:24:8 | LL | struct Runtime { | ^^^^^^^ error: aborting due to previous error For more information about this error, try `rustc --explain E0275`.