fix(vue): preserve array/object destructuring in v-for without extra parentheses

[yacinehmito]

Problem

The formatter was incorrectly adding parentheses around destructuring patterns in v-for directives. For example:

• [key, value] of Object.entries(obj) became ([key, value]) of ...
• { foo, bar } of items became ({ foo, bar }) of ...

This changes the semantics in Vue templates, where (key, value) is interpreted as Vue's v-for index syntax rather than JavaScript array destructuring.

Cause

The issue was in the format_v_for function which added parentheses whenever the left side contained a comma but no parenthesis:

if left.contains(',') && !left.contains('(') {
    format!("({left}) {delimiter} {right}")
}

This logic didn't account for array destructuring [...] or object destructuring {...} which are already valid grouping constructs.

Solution

The fix checks if the left side starts with [, {, or ( before deciding whether to wrap with parentheses:

let left_trimmed = left.trim_start();
let needs_parens = left.contains(',')
    && !left_trimmed.starts_with('(')
    && !left_trimmed.starts_with('[')
    && !left_trimmed.starts_with('{');

This ensures:

• Tuple unpacking still gets parentheses: a, i → (a, i)
• Array destructuring is preserved: [key, value] stays as-is
• Object destructuring is preserved: { foo, bar } stays as-is
• Mixed patterns work correctly: ([key, value], i) stays as-is

Testing

Added test cases covering:

• Simple iteration: a in b, a of b
• Tuple with index: (a, i) in b
• Array destructuring: [key, value] in Object.entries(obj)
• Object destructuring: { foo, bar } in items
• Mixed patterns: ([key, value], i) in Object.entries(obj)

[g-plane]

Thanks!