E0240

An expression statement whose Result value is dropped. Discard one deliberately with let _ = f(). Spans the expression.

Machine-applicable fix: none.

Example

This program fails with E0240.

fn main(io: Stdout) -> Result<(), IoError> {
    io.println("hi")
    Ok(())
}

Fixed

The same program, fixed.

fn main(io: Stdout) -> Result<(), IoError> {
    io.println("hi")?
    Ok(())
}

Listed in the checker notes. oskac explain E0240 prints this entry offline.

All error codes