You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: permissions_set_readonly_false.rs
    path of file: ./repos/rust-clippy/clippy_lints/src
    
    the code of the file until where you have to start completion: use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::ty::is_type_diagnostic_item;
use rustc_ast::ast::LitKind;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::declare_lint_pass;
use rustc_span::sym;

declare_clippy_lint! {
    /// ### What it does
    /// Checks for calls to `std::fs::Permissions.set_readonly` with argument `false`.
    ///
    /// ### Why is this bad?
    /// On Unix platforms this results in the file being world writable,
    ///
    
    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
        if let ExprKind::MethodCall(path, receiver, [arg], _) = &expr.kind
            && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(receiver), sym::FsPermissions)
            && path.ident.name == sym!(set_readonly)
            && let ExprKind::Lit(lit) = &arg.kind
            && LitKind::Bool(false) == lit.node
        {
            span_lint_and_then(
                cx,
                PERMISSIONS_SET_READONLY_FALSE,
                expr.span,
                "call to `set_readonly` with argument `false`",
                |diag| {
                    diag.note("on Unix platforms this results in the file being world writable");
                    diag.help(
                        "you can set the desired permissions using `PermissionsExt`. For more information, see\n\
                        https://doc.rust-lang.org/std/os/unix/fs/trait.PermissionsExt.html",
                    );
                },
            );
        }
    }