error[E0658]: `?` is not allowed in a `const fn` --> $DIR/const-try-feature-gate.rs:4:5 | LL | Some(())?; | ^^^^^^^^^ | = note: see issue #74935 for more information = help: add `#![feature(const_try)]` to the crate attributes to enable = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date error[E0015]: `?` cannot determine the branch of `Option<()>` in constant functions --> $DIR/const-try-feature-gate.rs:4:5 | LL | Some(())?; | ^^^^^^^^^ | note: impl defined here, but it is not `const` --> $SRC_DIR/core/src/option.rs:LL:COL = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants help: add `#![feature(const_trait_impl)]` to the crate attributes to enable | LL + #![feature(const_trait_impl)] | error[E0015]: `?` cannot convert from residual of `Option<()>` in constant functions --> $DIR/const-try-feature-gate.rs:4:5 | LL | Some(())?; | ^^^^^^^^^ | note: impl defined here, but it is not `const` --> $SRC_DIR/core/src/option.rs:LL:COL = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants help: add `#![feature(const_trait_impl)]` to the crate attributes to enable | LL + #![feature(const_trait_impl)] | error: aborting due to 3 previous errors Some errors have detailed explanations: E0015, E0658. For more information about an error, try `rustc --explain E0015`.