warning: unused return value of `add` that must be used
  --> $DIR/issue-103320-must-use-ops.rs:16:5
   |
LL |     x.add(4);
   |     ^^^^^^^^
   |
   = note: this returns the result of the operation, without modifying the original
note: the lint level is defined here
  --> $DIR/issue-103320-must-use-ops.rs:3:9
   |
LL | #![warn(unused_must_use)]
   |         ^^^^^^^^^^^^^^^
help: use `let _ = ...` to ignore the resulting value
   |
LL |     let _ = x.add(4);
   |     +++++++

warning: unused return value of `sub` that must be used
  --> $DIR/issue-103320-must-use-ops.rs:18:5
   |
LL |     x.sub(4);
   |     ^^^^^^^^
   |
   = note: this returns the result of the operation, without modifying the original
help: use `let _ = ...` to ignore the resulting value
   |
LL |     let _ = x.sub(4);
   |     +++++++

warning: unused return value of `mul` that must be used
  --> $DIR/issue-103320-must-use-ops.rs:20:5
   |
LL |     x.mul(4);
   |     ^^^^^^^^
   |
   = note: this returns the result of the operation, without modifying the original
help: use `let _ = ...` to ignore the resulting value
   |
LL |     let _ = x.mul(4);
   |     +++++++

warning: unused return value of `div` that must be used
  --> $DIR/issue-103320-must-use-ops.rs:22:5
   |
LL |     x.div(4);
   |     ^^^^^^^^
   |
   = note: this returns the result of the operation, without modifying the original
help: use `let _ = ...` to ignore the resulting value
   |
LL |     let _ = x.div(4);
   |     +++++++

warning: unused return value of `rem` that must be used
  --> $DIR/issue-103320-must-use-ops.rs:24:5
   |
LL |     x.rem(4);
   |     ^^^^^^^^
   |
   = note: this returns the result of the operation, without modifying the original
help: use `let _ = ...` to ignore the resulting value
   |
LL |     let _ = x.rem(4);
   |     +++++++

warning: 5 warnings emitted