Function node_is_statement 

pub fn node_is_statement(node: &AIRNode) -> bool

Returns true if node is a statement-like AIR node — one that performs control flow or mutation and yields no usable value in expression position.

These are exactly the node kinds a target’s expression form (ternary, IIFE, value-match arm) cannot host: break, continue, return, assignment, and an if that yields no value.

An if is statement-like — and so must be emitted in statement position rather than lowered to a ternary / IIFE — exactly when it produces no value:

• it has no else branch (a value-less if cannot be an expression), or
• it has an else branch but both branches are statement bodies (e.g. if (c) { return a } else { return b }), so neither yields a value.

A value if/else (e.g. let x = if (c) { 1 } else { 2 }) always has an else whose branches end in an expression tail, so arm_body_is_statement returns false for them and the if stays an expression. if let … = expr returning a value is likewise unaffected: with an expression-tail else it is not classified here.