Unnecessary ;

Built from the repository at commit a8614dc.

A ; separates two things on one line that would otherwise need a line break between them: two statements, two fields or methods, two variants, or two match arms, as in let x = 2; print(x * 21). Most other ;s are unnecessary: at the end of a line, at the start of one, right after {, before } or else, at the end of the file, every extra ; in ;;, and after a top-level function, class or enum, which needs no separator before the next item. The program still builds. A ; whose removal would join two lines into one statement stays an error (E0011), as at the start of a line before .f(), and so does a ; where something else must come next, as in let x = ;.

Why

A line break already ends a statement, so a ; there is never needed. Reporting it keeps one way to write a program, and the safe fix removes the ;.

A ; never changes what a block gives. In let y = { x; }, y is still x: the ; does not turn the block's value into unit, as it would in Rust.

Broken

fn main() {
    let x = 1;
    print(x)
}

What sisu says

warning[W0007]: unnecessary `;`
 --> W0007.sisu:2:14
  |
2 |     let x = 1;
  |              ^
  |
help: remove the `;`
  |
2 -     let x = 1;
2 +     let x = 1
  |

sisu: 1 warning
sisu: for more on a code, run `sisu explain <code>`: W0007

Fixed

fn main() {
    let x = 1
    print(x)
}