error[E0015]: cannot call non-const fn `::plus` in constant functions --> $DIR/call-const-trait-method-fail.rs:25:7 | LL | a.plus(b) | ^^^^^^^ | = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants error: aborting due to previous error For more information about this error, try `rustc --explain E0015`.