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Add `to_digit_is_some` lint

This commit is contained in:
Michael Wright 2019-11-10 15:12:05 +02:00
parent 6f9c43ddc5
commit 5817a4fa06
8 changed files with 145 additions and 2 deletions
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1
CHANGELOG.md
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@ -1203,6 +1203,7 @@ Released 2018-09-13
[`suspicious_unary_op_formatting`]: https://rust-lang.github.io/rust-clippy/master/index.html#suspicious_unary_op_formatting
[`temporary_assignment`]: https://rust-lang.github.io/rust-clippy/master/index.html#temporary_assignment
[`temporary_cstring_as_ptr`]: https://rust-lang.github.io/rust-clippy/master/index.html#temporary_cstring_as_ptr
[`to_digit_is_some`]: https://rust-lang.github.io/rust-clippy/master/index.html#to_digit_is_some
[`todo`]: https://rust-lang.github.io/rust-clippy/master/index.html#todo
[`too_many_arguments`]: https://rust-lang.github.io/rust-clippy/master/index.html#too_many_arguments
[`too_many_lines`]: https://rust-lang.github.io/rust-clippy/master/index.html#too_many_lines

2
README.md
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@ -6,7 +6,7 @@
A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
[There are 332 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
[There are 333 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:

5
clippy_lints/src/lib.rs
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@ -272,6 +272,7 @@ pub mod strings;
pub mod suspicious_trait_impl;
pub mod swap;
pub mod temporary_assignment;
pub mod to_digit_is_some;
pub mod trait_bounds;
pub mod transmute;
pub mod transmuting_null;
@ -713,6 +714,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
&swap::ALMOST_SWAPPED,
&swap::MANUAL_SWAP,
&temporary_assignment::TEMPORARY_ASSIGNMENT,
&to_digit_is_some::TO_DIGIT_IS_SOME,
&trait_bounds::TYPE_REPETITION_IN_BOUNDS,
&transmute::CROSSPOINTER_TRANSMUTE,
&transmute::TRANSMUTE_BYTES_TO_STR,
@ -944,6 +946,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
store.register_late_pass(|| box unused_self::UnusedSelf);
store.register_late_pass(|| box mutable_debug_assertion::DebugAssertWithMutCall);
store.register_late_pass(|| box exit::Exit);
store.register_late_pass(|| box to_digit_is_some::ToDigitIsSome);
store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
LintId::of(&arithmetic::FLOAT_ARITHMETIC),
@ -1238,6 +1241,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
LintId::of(&swap::ALMOST_SWAPPED),
LintId::of(&swap::MANUAL_SWAP),
LintId::of(&temporary_assignment::TEMPORARY_ASSIGNMENT),
LintId::of(&to_digit_is_some::TO_DIGIT_IS_SOME),
LintId::of(&transmute::CROSSPOINTER_TRANSMUTE),
LintId::of(&transmute::TRANSMUTE_BYTES_TO_STR),
LintId::of(&transmute::TRANSMUTE_INT_TO_BOOL),
@ -1363,6 +1367,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
LintId::of(&returns::NEEDLESS_RETURN),
LintId::of(&returns::UNUSED_UNIT),
LintId::of(&strings::STRING_LIT_AS_BYTES),
LintId::of(&to_digit_is_some::TO_DIGIT_IS_SOME),
LintId::of(&try_err::TRY_ERR),
LintId::of(&types::FN_TO_NUMERIC_CAST),
LintId::of(&types::FN_TO_NUMERIC_CAST_WITH_TRUNCATION),

92
clippy_lints/src/to_digit_is_some.rs Normal file
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@ -0,0 +1,92 @@
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;
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 use the dedicated `is_digit` method.
///
/// **Example:**
/// ```rust
/// # let x: char = 'x'
/// let is_digit = x.to_digit().is_some();
/// ```
/// can be written as:
/// ```
/// # let x: char = 'x'
/// let is_digit = x.is_digit();
/// ```
pub TO_DIGIT_IS_SOME,
style,
"`char.is_digit()` is clearer"
}
declare_lint_pass!(ToDigitIsSome => [TO_DIGIT_IS_SOME]);
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
};
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);
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,
);
}
}
}
}
}

9
src/lintlist/mod.rs
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@ -6,7 +6,7 @@ pub use lint::Lint;
pub use lint::LINT_LEVELS;
// begin lint list, do not remove this comment, it’s used in `update_lints`
pub const ALL_LINTS: [Lint; 332] = [
pub const ALL_LINTS: [Lint; 333] = [
Lint {
name: "absurd_extreme_comparisons",
group: "correctness",
@ -1876,6 +1876,13 @@ pub const ALL_LINTS: [Lint; 332] = [
deprecation: None,
module: "methods",
},
Lint {
name: "to_digit_is_some",
group: "style",
desc: "`char.is_digit()` is clearer",
deprecation: None,
module: "to_digit_is_some",
},
Lint {
name: "todo",
group: "restriction",

11
tests/ui/to_digit_is_some.fixed Normal file
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@ -0,0 +1,11 @@
//run-rustfix
#![warn(clippy::to_digit_is_some)]
fn main() {
let c = 'x';
let d = &c;
let _ = d.is_digit(10);
let _ = char::is_digit(c, 10);
}

11
tests/ui/to_digit_is_some.rs Normal file
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@ -0,0 +1,11 @@
//run-rustfix
#![warn(clippy::to_digit_is_some)]
fn main() {
let c = 'x';
let d = &c;
let _ = d.to_digit(10).is_some();
let _ = char::to_digit(c, 10).is_some();
}

16
tests/ui/to_digit_is_some.stderr Normal file
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@ -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`
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)`
error: aborting due to 2 previous errors