1error: unused return value of `Interface::f` that must be used
2 --> $DIR/must-use.rs:18:5
3 |
418 | Thing.f();
5 | ^^^^^^^^^^
6 |
7note: the lint level is defined here
8 --> $DIR/must-use.rs:1:9
9 |
101 | #![deny(unused_must_use)]
11 | ^^^^^^^^^^^^^^^
12