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Auto merge of #13334 - nyurik:ascii-str-eq, r=xFrednet
Add manual_ignore_cast_cmp lint
```rust
// bad
fn compare(a: &str, b: &str) -> bool {
a.to_ascii_lowercase() == b.to_ascii_lowercase()
|| a.to_ascii_lowercase() == "abc"
}
// good
fn compare(a: &str, b: &str) -> bool {
a.eq_ignore_ascii_case(b)
|| a.eq_ignore_ascii_case("abc")
}
```
- [x] Followed [lint naming conventions][lint_naming]
- [x] Added passing UI tests (including committed `.stderr` file)
- [x] `cargo test` passes locally
- [x] Executed `cargo dev update_lints`
- [x] Added lint documentation
- [x] Run `cargo dev fmt`
changelog: New lint: [`manual_ignore_case_cmp`] `perf`
[#13334](#13334)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,127 @@ | ||
| use crate::manual_ignore_case_cmp::MatchType::{Literal, ToAscii}; | ||
| use clippy_utils::diagnostics::span_lint_and_then; | ||
| use clippy_utils::source::snippet_with_applicability; | ||
| use clippy_utils::ty::{get_type_diagnostic_name, is_type_diagnostic_item, is_type_lang_item}; | ||
| use rustc_ast::LitKind; | ||
| use rustc_errors::Applicability; | ||
| use rustc_hir::ExprKind::{Binary, Lit, MethodCall}; | ||
| use rustc_hir::{BinOpKind, Expr, LangItem}; | ||
| use rustc_lint::{LateContext, LateLintPass}; | ||
| use rustc_middle::ty; | ||
| use rustc_middle::ty::{Ty, UintTy}; | ||
| use rustc_session::declare_lint_pass; | ||
| use rustc_span::{Span, sym}; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// ### What it does | ||
| /// Checks for manual case-insensitive ASCII comparison. | ||
| /// | ||
| /// ### Why is this bad? | ||
| /// The `eq_ignore_ascii_case` method is faster because it does not allocate | ||
| /// memory for the new strings, and it is more readable. | ||
| /// | ||
| /// ### Example | ||
| /// ```no_run | ||
| /// fn compare(a: &str, b: &str) -> bool { | ||
| /// a.to_ascii_lowercase() == b.to_ascii_lowercase() || a.to_ascii_lowercase() == "abc" | ||
| /// } | ||
| /// ``` | ||
| /// Use instead: | ||
| /// ```no_run | ||
| /// fn compare(a: &str, b: &str) -> bool { | ||
| /// a.eq_ignore_ascii_case(b) || a.eq_ignore_ascii_case("abc") | ||
| /// } | ||
| /// ``` | ||
| #[clippy::version = "1.82.0"] | ||
| pub MANUAL_IGNORE_CASE_CMP, | ||
| perf, | ||
| "manual case-insensitive ASCII comparison" | ||
| } | ||
|
|
||
| declare_lint_pass!(ManualIgnoreCaseCmp => [MANUAL_IGNORE_CASE_CMP]); | ||
|
|
||
| enum MatchType<'a, 'b> { | ||
| ToAscii(bool, Ty<'a>), | ||
| Literal(&'b LitKind), | ||
| } | ||
|
|
||
| fn get_ascii_type<'a, 'b>(cx: &LateContext<'a>, kind: rustc_hir::ExprKind<'b>) -> Option<(Span, MatchType<'a, 'b>)> { | ||
| if let MethodCall(path, expr, _, _) = kind { | ||
| let is_lower = match path.ident.name.as_str() { | ||
| "to_ascii_lowercase" => true, | ||
| "to_ascii_uppercase" => false, | ||
| _ => return None, | ||
| }; | ||
| let ty_raw = cx.typeck_results().expr_ty(expr); | ||
| let ty = ty_raw.peel_refs(); | ||
| if needs_ref_to_cmp(cx, ty) | ||
| || ty.is_str() | ||
| || ty.is_slice() | ||
| || matches!(get_type_diagnostic_name(cx, ty), Some(sym::OsStr | sym::OsString)) | ||
| { | ||
| return Some((expr.span, ToAscii(is_lower, ty_raw))); | ||
| } | ||
| } else if let Lit(expr) = kind { | ||
| return Some((expr.span, Literal(&expr.node))); | ||
| } | ||
| None | ||
| } | ||
|
|
||
| /// Returns true if the type needs to be dereferenced to be compared | ||
| fn needs_ref_to_cmp(cx: &LateContext<'_>, ty: Ty<'_>) -> bool { | ||
| ty.is_char() | ||
| || *ty.kind() == ty::Uint(UintTy::U8) | ||
| || is_type_diagnostic_item(cx, ty, sym::Vec) | ||
| || is_type_lang_item(cx, ty, LangItem::String) | ||
| } | ||
|
|
||
| impl LateLintPass<'_> for ManualIgnoreCaseCmp { | ||
| fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'_ Expr<'_>) { | ||
| // check if expression represents a comparison of two strings | ||
| // using .to_ascii_lowercase() or .to_ascii_uppercase() methods, | ||
| // or one of the sides is a literal | ||
| // Offer to replace it with .eq_ignore_ascii_case() method | ||
| if let Binary(op, left, right) = &expr.kind | ||
| && (op.node == BinOpKind::Eq || op.node == BinOpKind::Ne) | ||
| && let Some((left_span, left_val)) = get_ascii_type(cx, left.kind) | ||
| && let Some((right_span, right_val)) = get_ascii_type(cx, right.kind) | ||
| && match (&left_val, &right_val) { | ||
| (ToAscii(l_lower, ..), ToAscii(r_lower, ..)) if l_lower == r_lower => true, | ||
| (ToAscii(..), Literal(..)) | (Literal(..), ToAscii(..)) => true, | ||
| _ => false, | ||
| } | ||
| { | ||
| let deref = match right_val { | ||
| ToAscii(_, ty) if needs_ref_to_cmp(cx, ty) => "&", | ||
| ToAscii(..) => "", | ||
| Literal(ty) => { | ||
| if let LitKind::Char(_) | LitKind::Byte(_) = ty { | ||
| "&" | ||
| } else { | ||
| "" | ||
| } | ||
| }, | ||
| }; | ||
| let neg = if op.node == BinOpKind::Ne { "!" } else { "" }; | ||
| span_lint_and_then( | ||
| cx, | ||
| MANUAL_IGNORE_CASE_CMP, | ||
| expr.span, | ||
| "manual case-insensitive ASCII comparison", | ||
| |diag| { | ||
| let mut app = Applicability::MachineApplicable; | ||
| diag.span_suggestion_verbose( | ||
| expr.span, | ||
| "consider using `.eq_ignore_ascii_case()` instead", | ||
| format!( | ||
| "{neg}{}.eq_ignore_ascii_case({deref}{})", | ||
| snippet_with_applicability(cx, left_span, "_", &mut app), | ||
| snippet_with_applicability(cx, right_span, "_", &mut app) | ||
| ), | ||
| app, | ||
| ); | ||
| }, | ||
| ); | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| #![allow(clippy::all)] | ||
| #![deny(clippy::manual_ignore_case_cmp)] | ||
|
|
||
| use std::ffi::{OsStr, OsString}; | ||
|
|
||
| fn main() {} | ||
|
|
||
| fn variants(a: &str, b: &str) { | ||
| if a.eq_ignore_ascii_case(b) { | ||
| return; | ||
| } | ||
| if a.eq_ignore_ascii_case(b) { | ||
| return; | ||
| } | ||
| let r = a.eq_ignore_ascii_case(b); | ||
| let r = r || a.eq_ignore_ascii_case(b); | ||
| r && a.eq_ignore_ascii_case(&b.to_uppercase()); | ||
| // != | ||
| if !a.eq_ignore_ascii_case(b) { | ||
| return; | ||
| } | ||
| if !a.eq_ignore_ascii_case(b) { | ||
| return; | ||
| } | ||
| let r = !a.eq_ignore_ascii_case(b); | ||
| let r = r || !a.eq_ignore_ascii_case(b); | ||
| r && !a.eq_ignore_ascii_case(&b.to_uppercase()); | ||
| } | ||
|
|
||
| fn unsupported(a: char, b: char) { | ||
| // TODO:: these are rare, and might not be worth supporting | ||
| a.to_ascii_lowercase() == char::to_ascii_lowercase(&b); | ||
| char::to_ascii_lowercase(&a) == b.to_ascii_lowercase(); | ||
| char::to_ascii_lowercase(&a) == char::to_ascii_lowercase(&b); | ||
| } | ||
|
|
||
| fn char(a: char, b: char) { | ||
| a.eq_ignore_ascii_case(&b); | ||
| a.to_ascii_lowercase() == *&b.to_ascii_lowercase(); | ||
| *&a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.eq_ignore_ascii_case(&'a'); | ||
| 'a'.eq_ignore_ascii_case(&b); | ||
| } | ||
| fn u8(a: u8, b: u8) { | ||
| a.eq_ignore_ascii_case(&b); | ||
| a.eq_ignore_ascii_case(&b'a'); | ||
| b'a'.eq_ignore_ascii_case(&b); | ||
| } | ||
| fn ref_str(a: &str, b: &str) { | ||
| a.eq_ignore_ascii_case(b); | ||
| a.to_uppercase().eq_ignore_ascii_case(b); | ||
| a.eq_ignore_ascii_case("a"); | ||
| "a".eq_ignore_ascii_case(b); | ||
| } | ||
| fn ref_ref_str(a: &&str, b: &&str) { | ||
| a.eq_ignore_ascii_case(b); | ||
| a.to_uppercase().eq_ignore_ascii_case(b); | ||
| a.eq_ignore_ascii_case("a"); | ||
| "a".eq_ignore_ascii_case(b); | ||
| } | ||
| fn string(a: String, b: String) { | ||
| a.eq_ignore_ascii_case(&b); | ||
| a.eq_ignore_ascii_case("a"); | ||
| "a".eq_ignore_ascii_case(&b); | ||
| &a.to_ascii_lowercase() == &b.to_ascii_lowercase(); | ||
| &&a.to_ascii_lowercase() == &&b.to_ascii_lowercase(); | ||
| a.eq_ignore_ascii_case("a"); | ||
| "a".eq_ignore_ascii_case(&b); | ||
| } | ||
| fn ref_string(a: String, b: &String) { | ||
| a.eq_ignore_ascii_case(b); | ||
| a.eq_ignore_ascii_case("a"); | ||
| "a".eq_ignore_ascii_case(b); | ||
|
|
||
| b.eq_ignore_ascii_case(&a); | ||
| b.eq_ignore_ascii_case("a"); | ||
| "a".eq_ignore_ascii_case(&a); | ||
| } | ||
| fn string_ref_str(a: String, b: &str) { | ||
| a.eq_ignore_ascii_case(b); | ||
| a.eq_ignore_ascii_case("a"); | ||
| "a".eq_ignore_ascii_case(b); | ||
|
|
||
| b.eq_ignore_ascii_case(&a); | ||
| b.eq_ignore_ascii_case("a"); | ||
| "a".eq_ignore_ascii_case(&a); | ||
| } | ||
| fn ref_u8slice(a: &[u8], b: &[u8]) { | ||
| a.eq_ignore_ascii_case(b); | ||
| } | ||
| fn u8vec(a: Vec<u8>, b: Vec<u8>) { | ||
| a.eq_ignore_ascii_case(&b); | ||
| } | ||
| fn ref_u8vec(a: Vec<u8>, b: &Vec<u8>) { | ||
| a.eq_ignore_ascii_case(b); | ||
| b.eq_ignore_ascii_case(&a); | ||
| } | ||
| fn ref_osstr(a: &OsStr, b: &OsStr) { | ||
| a.eq_ignore_ascii_case(b); | ||
| } | ||
| fn osstring(a: OsString, b: OsString) { | ||
| a.eq_ignore_ascii_case(b); | ||
| } | ||
| fn ref_osstring(a: OsString, b: &OsString) { | ||
| a.eq_ignore_ascii_case(b); | ||
| b.eq_ignore_ascii_case(a); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| #![allow(clippy::all)] | ||
| #![deny(clippy::manual_ignore_case_cmp)] | ||
|
|
||
| use std::ffi::{OsStr, OsString}; | ||
|
|
||
| fn main() {} | ||
|
|
||
| fn variants(a: &str, b: &str) { | ||
| if a.to_ascii_lowercase() == b.to_ascii_lowercase() { | ||
| return; | ||
| } | ||
| if a.to_ascii_uppercase() == b.to_ascii_uppercase() { | ||
| return; | ||
| } | ||
| let r = a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| let r = r || a.to_ascii_uppercase() == b.to_ascii_uppercase(); | ||
| r && a.to_ascii_lowercase() == b.to_uppercase().to_ascii_lowercase(); | ||
| // != | ||
| if a.to_ascii_lowercase() != b.to_ascii_lowercase() { | ||
| return; | ||
| } | ||
| if a.to_ascii_uppercase() != b.to_ascii_uppercase() { | ||
| return; | ||
| } | ||
| let r = a.to_ascii_lowercase() != b.to_ascii_lowercase(); | ||
| let r = r || a.to_ascii_uppercase() != b.to_ascii_uppercase(); | ||
| r && a.to_ascii_lowercase() != b.to_uppercase().to_ascii_lowercase(); | ||
| } | ||
|
|
||
| fn unsupported(a: char, b: char) { | ||
| // TODO:: these are rare, and might not be worth supporting | ||
| a.to_ascii_lowercase() == char::to_ascii_lowercase(&b); | ||
| char::to_ascii_lowercase(&a) == b.to_ascii_lowercase(); | ||
| char::to_ascii_lowercase(&a) == char::to_ascii_lowercase(&b); | ||
| } | ||
|
|
||
| fn char(a: char, b: char) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_ascii_lowercase() == *&b.to_ascii_lowercase(); | ||
| *&a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_ascii_lowercase() == 'a'; | ||
| 'a' == b.to_ascii_lowercase(); | ||
| } | ||
| fn u8(a: u8, b: u8) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_ascii_lowercase() == b'a'; | ||
| b'a' == b.to_ascii_lowercase(); | ||
| } | ||
| fn ref_str(a: &str, b: &str) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_uppercase().to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_ascii_lowercase() == "a"; | ||
| "a" == b.to_ascii_lowercase(); | ||
| } | ||
| fn ref_ref_str(a: &&str, b: &&str) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_uppercase().to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_ascii_lowercase() == "a"; | ||
| "a" == b.to_ascii_lowercase(); | ||
| } | ||
| fn string(a: String, b: String) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_ascii_lowercase() == "a"; | ||
| "a" == b.to_ascii_lowercase(); | ||
| &a.to_ascii_lowercase() == &b.to_ascii_lowercase(); | ||
| &&a.to_ascii_lowercase() == &&b.to_ascii_lowercase(); | ||
| a.to_ascii_lowercase() == "a"; | ||
| "a" == b.to_ascii_lowercase(); | ||
| } | ||
| fn ref_string(a: String, b: &String) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_ascii_lowercase() == "a"; | ||
| "a" == b.to_ascii_lowercase(); | ||
|
|
||
| b.to_ascii_lowercase() == a.to_ascii_lowercase(); | ||
| b.to_ascii_lowercase() == "a"; | ||
| "a" == a.to_ascii_lowercase(); | ||
| } | ||
| fn string_ref_str(a: String, b: &str) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| a.to_ascii_lowercase() == "a"; | ||
| "a" == b.to_ascii_lowercase(); | ||
|
|
||
| b.to_ascii_lowercase() == a.to_ascii_lowercase(); | ||
| b.to_ascii_lowercase() == "a"; | ||
| "a" == a.to_ascii_lowercase(); | ||
| } | ||
| fn ref_u8slice(a: &[u8], b: &[u8]) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| } | ||
| fn u8vec(a: Vec<u8>, b: Vec<u8>) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| } | ||
| fn ref_u8vec(a: Vec<u8>, b: &Vec<u8>) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| b.to_ascii_lowercase() == a.to_ascii_lowercase(); | ||
| } | ||
| fn ref_osstr(a: &OsStr, b: &OsStr) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| } | ||
| fn osstring(a: OsString, b: OsString) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| } | ||
| fn ref_osstring(a: OsString, b: &OsString) { | ||
| a.to_ascii_lowercase() == b.to_ascii_lowercase(); | ||
| b.to_ascii_lowercase() == a.to_ascii_lowercase(); | ||
| } |
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