95 lines
4.0 KiB
Rust
95 lines
4.0 KiB
Rust
use crate::utils::{match_def_path, snippet_with_applicability, span_lint_and_sugg};
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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declare_clippy_lint! {
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/// **What it does:** Checks for `.to_digit(..).is_some()` on `char`s.
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///
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/// **Why is this bad?** This is a convoluted way of checking if a `char` is a digit. It's
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/// more straight forward to use the dedicated `is_digit` method.
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///
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/// **Example:**
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/// ```rust
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/// # let c = 'c';
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/// # let radix = 10;
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/// let is_digit = c.to_digit(radix).is_some();
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/// ```
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/// can be written as:
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/// ```
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/// # let c = 'c';
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/// # let radix = 10;
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/// let is_digit = c.is_digit(radix);
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/// ```
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pub TO_DIGIT_IS_SOME,
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style,
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"`char.is_digit()` is clearer"
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}
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declare_lint_pass!(ToDigitIsSome => [TO_DIGIT_IS_SOME]);
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impl<'tcx> LateLintPass<'tcx> for ToDigitIsSome {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
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if_chain! {
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if let hir::ExprKind::MethodCall(is_some_path, _, is_some_args, _) = &expr.kind;
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if is_some_path.ident.name.as_str() == "is_some";
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if let [to_digit_expr] = &**is_some_args;
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then {
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let match_result = match &to_digit_expr.kind {
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hir::ExprKind::MethodCall(to_digits_path, _, to_digit_args, _) => {
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if_chain! {
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if let [char_arg, radix_arg] = &**to_digit_args;
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if to_digits_path.ident.name.as_str() == "to_digit";
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let char_arg_ty = cx.typeck_results().expr_ty_adjusted(char_arg);
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if *char_arg_ty.kind() == ty::Char;
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then {
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Some((true, char_arg, radix_arg))
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} else {
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None
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}
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}
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}
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hir::ExprKind::Call(to_digits_call, to_digit_args) => {
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if_chain! {
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if let [char_arg, radix_arg] = &**to_digit_args;
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if let hir::ExprKind::Path(to_digits_path) = &to_digits_call.kind;
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if let to_digits_call_res = cx.qpath_res(to_digits_path, to_digits_call.hir_id);
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if let Some(to_digits_def_id) = to_digits_call_res.opt_def_id();
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if match_def_path(cx, to_digits_def_id, &["core", "char", "methods", "<impl char>", "to_digit"]);
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then {
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Some((false, char_arg, radix_arg))
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} else {
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None
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}
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}
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}
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_ => None
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};
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if let Some((is_method_call, char_arg, radix_arg)) = match_result {
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let mut applicability = Applicability::MachineApplicable;
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let char_arg_snip = snippet_with_applicability(cx, char_arg.span, "_", &mut applicability);
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let radix_snip = snippet_with_applicability(cx, radix_arg.span, "_", &mut applicability);
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span_lint_and_sugg(
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cx,
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TO_DIGIT_IS_SOME,
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expr.span,
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"use of `.to_digit(..).is_some()`",
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"try this",
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if is_method_call {
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format!("{}.is_digit({})", char_arg_snip, radix_snip)
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} else {
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format!("char::is_digit({}, {})", char_arg_snip, radix_snip)
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},
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applicability,
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);
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}
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}
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}
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}
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}
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