1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::match_def_path;
3 use clippy_utils::source::snippet_with_applicability;
4 use if_chain::if_chain;
5 use rustc_errors::Applicability;
7 use rustc_lint::{LateContext, LateLintPass};
9 use rustc_session::{declare_lint_pass, declare_tool_lint};
11 declare_clippy_lint! {
13 /// Checks for `.to_digit(..).is_some()` on `char`s.
15 /// ### Why is this bad?
16 /// This is a convoluted way of checking if a `char` is a digit. It's
17 /// more straight forward to use the dedicated `is_digit` method.
23 /// let is_digit = c.to_digit(radix).is_some();
25 /// can be written as:
29 /// let is_digit = c.is_digit(radix);
31 #[clippy::version = "1.41.0"]
34 "`char.is_digit()` is clearer"
37 declare_lint_pass!(ToDigitIsSome => [TO_DIGIT_IS_SOME]);
39 impl<'tcx> LateLintPass<'tcx> for ToDigitIsSome {
40 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
42 if let hir::ExprKind::MethodCall(is_some_path, _, is_some_args, _) = &expr.kind;
43 if is_some_path.ident.name.as_str() == "is_some";
44 if let [to_digit_expr] = &**is_some_args;
46 let match_result = match &to_digit_expr.kind {
47 hir::ExprKind::MethodCall(to_digits_path, _, to_digit_args, _) => {
49 if let [char_arg, radix_arg] = &**to_digit_args;
50 if to_digits_path.ident.name.as_str() == "to_digit";
51 let char_arg_ty = cx.typeck_results().expr_ty_adjusted(char_arg);
52 if *char_arg_ty.kind() == ty::Char;
54 Some((true, char_arg, radix_arg))
60 hir::ExprKind::Call(to_digits_call, to_digit_args) => {
62 if let [char_arg, radix_arg] = &**to_digit_args;
63 if let hir::ExprKind::Path(to_digits_path) = &to_digits_call.kind;
64 if let to_digits_call_res = cx.qpath_res(to_digits_path, to_digits_call.hir_id);
65 if let Some(to_digits_def_id) = to_digits_call_res.opt_def_id();
66 if match_def_path(cx, to_digits_def_id, &["core", "char", "methods", "<impl char>", "to_digit"]);
68 Some((false, char_arg, radix_arg))
77 if let Some((is_method_call, char_arg, radix_arg)) = match_result {
78 let mut applicability = Applicability::MachineApplicable;
79 let char_arg_snip = snippet_with_applicability(cx, char_arg.span, "_", &mut applicability);
80 let radix_snip = snippet_with_applicability(cx, radix_arg.span, "_", &mut applicability);
86 "use of `.to_digit(..).is_some()`",
89 format!("{}.is_digit({})", char_arg_snip, radix_snip)
91 format!("char::is_digit({}, {})", char_arg_snip, radix_snip)