error[E0282]: type annotations needed --> $DIR/cannot-infer-const-args.rs:6:5 | LL | foo(); | ^^^ cannot infer the value of the const parameter `X` declared on the function `foo` | help: consider specifying the generic argument | LL | foo::(); | +++++ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0282`.