Block that stands alone as a statement

Built from the repository at commit a8614dc.

A { ... } block is an expression. It belongs where a value does, as in let x = { ... }. A statement cannot start with {.

Why

A block's value is its last expression. As a statement that value would go nowhere, and a scope with no value has no use of its own. Put the block where its value is wanted.

Broken

fn main() {
    {
        let a = 1
        print(a + 2)
    }
}

What sisu says

error[E0081]: a block cannot stand alone as a statement
 --> E0081.sisu:2:5
  |
2 |     {
  |     ^
  |
  = help: bind its value: `let x = { ... }`

sisu: 1 error
sisu: for more on a code, run `sisu explain <code>`: E0081

Fixed

fn main() {
    let total = {
        let a = 1
        a + 2
    }
    print(total)
}

Related

• E0004: { on a line of its own.