Single expression closure without parameters

Before formatting:

vm.get_method_or_type_error(
    obj.clone(),
    "__getitem__",
    || format!("'{}' object is not iterable", obj.class().name)
)?;

After formatting:

vm.get_method_or_type_error(obj.clone(), "__getitem__", || {
    format!("'{}' object is not iterable", obj.class().name)
})?;

Maybe lazy string (empty closure params and format! call inside) and other single expression closures should not be split by a new line, and instead being considered as an atomic element?

If I add more arguments, so that a list would be formatted as arg-per-line anyway, it behaves exactly like that and is more readable in my opinion

vm.get_method_or_type_error(
    obj.clone(),
    obj.clone(),
    obj.clone(),
    "__getitem__",
    || format!("hello, world1111111111111112222222222, 2222222221111111111111222"),
)?;

Start by reproducing the before-and-after formatting examples in rustfmt and locate the closure-formatting entry point that splits the zero-parameter single-expression closure. Check existing formatter tests for similar closure cases, then add coverage showing that such closures remain on one line while the longer multi-argument example retains argument-per-line formatting.