error[E0369]: cannot multiply `Thing` by `{integer}` --> $DIR/issue-3820.rs:14:15 | LL | let w = u * 3; | - ^ - {integer} | | | Thing | note: an implementation of `Mul<_>` might be missing for `Thing` --> $DIR/issue-3820.rs:1:1 | LL | struct Thing { | ^^^^^^^^^^^^ must implement `Mul<_>` note: the following trait must be implemented --> $SRC_DIR/core/src/ops/arith.rs:LL:COL | LL | pub trait Mul { | ^^^^^^^^^^^^^^^^^^^^^^^^^ error: aborting due to previous error For more information about this error, try `rustc --explain E0369`.