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Auto merge of #4801 - mikerite:to_digit_is_some, r=flip1995
To digit is some Add a lint that recommends replacing `to_digit().is_some()` with `is_digit()` on `char`s changelog: Add lint `to_digit_is_some`
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,94 @@ | ||
| use crate::utils::{match_def_path, snippet_with_applicability, span_lint_and_sugg}; | ||
| use if_chain::if_chain; | ||
| use rustc::hir; | ||
| use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass}; | ||
| use rustc::ty; | ||
| use rustc::{declare_lint_pass, declare_tool_lint}; | ||
| use rustc_errors::Applicability; | ||
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| declare_clippy_lint! { | ||
| /// **What it does:** Checks for `.to_digit(..).is_some()` on `char`s. | ||
| /// | ||
| /// **Why is this bad?** This is a convoluted way of checking if a `char` is a digit. It's | ||
| /// more straight forward to use the dedicated `is_digit` method. | ||
| /// | ||
| /// **Example:** | ||
| /// ```rust | ||
| /// # let c = 'c'; | ||
| /// # let radix = 10; | ||
| /// let is_digit = c.to_digit(radix).is_some(); | ||
| /// ``` | ||
| /// can be written as: | ||
| /// ``` | ||
| /// # let c = 'c'; | ||
| /// # let radix = 10; | ||
| /// let is_digit = c.is_digit(radix); | ||
| /// ``` | ||
| pub TO_DIGIT_IS_SOME, | ||
| style, | ||
| "`char.is_digit()` is clearer" | ||
| } | ||
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| declare_lint_pass!(ToDigitIsSome => [TO_DIGIT_IS_SOME]); | ||
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| impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ToDigitIsSome { | ||
| fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) { | ||
| if_chain! { | ||
| if let hir::ExprKind::MethodCall(is_some_path, _, is_some_args) = &expr.kind; | ||
| if is_some_path.ident.name.as_str() == "is_some"; | ||
| if let [to_digit_expr] = &**is_some_args; | ||
| then { | ||
| let match_result = match &to_digit_expr.kind { | ||
| hir::ExprKind::MethodCall(to_digits_path, _, to_digit_args) => { | ||
| if_chain! { | ||
| if let [char_arg, radix_arg] = &**to_digit_args; | ||
| if to_digits_path.ident.name.as_str() == "to_digit"; | ||
| let char_arg_ty = cx.tables.expr_ty_adjusted(char_arg); | ||
| if char_arg_ty.kind == ty::Char; | ||
| then { | ||
| Some((true, char_arg, radix_arg)) | ||
| } else { | ||
| None | ||
| } | ||
| } | ||
| } | ||
| hir::ExprKind::Call(to_digits_call, to_digit_args) => { | ||
| if_chain! { | ||
| if let [char_arg, radix_arg] = &**to_digit_args; | ||
| if let hir::ExprKind::Path(to_digits_path) = &to_digits_call.kind; | ||
| if let to_digits_call_res = cx.tables.qpath_res(to_digits_path, to_digits_call.hir_id); | ||
| if let Some(to_digits_def_id) = to_digits_call_res.opt_def_id(); | ||
| if match_def_path(cx, to_digits_def_id, &["core", "char", "methods", "<impl char>", "to_digit"]); | ||
| then { | ||
| Some((false, char_arg, radix_arg)) | ||
| } else { | ||
| None | ||
| } | ||
| } | ||
| } | ||
| _ => None | ||
| }; | ||
|
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||
| if let Some((is_method_call, char_arg, radix_arg)) = match_result { | ||
| let mut applicability = Applicability::MachineApplicable; | ||
| let char_arg_snip = snippet_with_applicability(cx, char_arg.span, "_", &mut applicability); | ||
| let radix_snip = snippet_with_applicability(cx, radix_arg.span, "_", &mut applicability); | ||
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| span_lint_and_sugg( | ||
| cx, | ||
| TO_DIGIT_IS_SOME, | ||
| expr.span, | ||
| "use of `.to_digit(..).is_some()`", | ||
| "try this", | ||
| if is_method_call { | ||
| format!("{}.is_digit({})", char_arg_snip, radix_snip) | ||
| } else { | ||
| format!("char::is_digit({}, {})", char_arg_snip, radix_snip) | ||
| }, | ||
| applicability, | ||
| ); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,11 @@ | ||
| //run-rustfix | ||
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| #![warn(clippy::to_digit_is_some)] | ||
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| fn main() { | ||
| let c = 'x'; | ||
| let d = &c; | ||
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| let _ = d.is_digit(10); | ||
| let _ = char::is_digit(c, 10); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,11 @@ | ||
| //run-rustfix | ||
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| #![warn(clippy::to_digit_is_some)] | ||
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| fn main() { | ||
| let c = 'x'; | ||
| let d = &c; | ||
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| let _ = d.to_digit(10).is_some(); | ||
| let _ = char::to_digit(c, 10).is_some(); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,16 @@ | ||
| error: use of `.to_digit(..).is_some()` | ||
| --> $DIR/to_digit_is_some.rs:9:13 | ||
| | | ||
| LL | let _ = d.to_digit(10).is_some(); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `d.is_digit(10)` | ||
| | | ||
| = note: `-D clippy::to-digit-is-some` implied by `-D warnings` | ||
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| error: use of `.to_digit(..).is_some()` | ||
| --> $DIR/to_digit_is_some.rs:10:13 | ||
| | | ||
| LL | let _ = char::to_digit(c, 10).is_some(); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `char::is_digit(c, 10)` | ||
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| error: aborting due to 2 previous errors | ||
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