structInitOne

pub fn structInitOne(tree: Ast, buffer: *[1]Node.Index, node: Node.Index) full.StructInit {
    assert(tree.nodeTag(node) == .struct_init_one or
        tree.nodeTag(node) == .struct_init_one_comma);
    const type_expr, const first_field = tree.nodeData(node).node_and_opt_node;
    const fields = loadOptionalNodesIntoBuffer(1, buffer, .{first_field});
    return .{
        .ast = .{
            .lbrace = tree.nodeMainToken(node),
            .fields = fields,
            .type_expr = type_expr.toOptional(),
        },
    };
}