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needless_character_iteration
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108 changes: 108 additions & 0 deletions
108
clippy_lints/src/methods/needless_character_iteration.rs
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,108 @@ | ||
use rustc_errors::Applicability; | ||
use rustc_hir::{Closure, Expr, ExprKind, HirId, StmtKind, UnOp}; | ||
use rustc_lint::LateContext; | ||
use rustc_middle::ty; | ||
use rustc_span::Span; | ||
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||
use super::utils::get_last_chain_binding_hir_id; | ||
use super::NEEDLESS_CHARACTER_ITERATION; | ||
use clippy_utils::diagnostics::span_lint_and_sugg; | ||
use clippy_utils::source::snippet_opt; | ||
use clippy_utils::{match_def_path, path_to_local_id, peel_blocks}; | ||
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||
fn peels_expr_ref<'a, 'tcx>(mut expr: &'a Expr<'tcx>) -> &'a Expr<'tcx> { | ||
while let ExprKind::AddrOf(_, _, e) = expr.kind { | ||
expr = e; | ||
} | ||
expr | ||
} | ||
|
||
fn handle_expr( | ||
cx: &LateContext<'_>, | ||
expr: &Expr<'_>, | ||
first_param: HirId, | ||
span: Span, | ||
before_chars: Span, | ||
revert: bool, | ||
) { | ||
match expr.kind { | ||
ExprKind::MethodCall(method, receiver, [], _) => { | ||
if method.ident.name.as_str() == "is_ascii" | ||
&& path_to_local_id(receiver, first_param) | ||
&& let char_arg_ty = cx.typeck_results().expr_ty_adjusted(receiver).peel_refs() | ||
&& *char_arg_ty.kind() == ty::Char | ||
&& let Some(snippet) = snippet_opt(cx, before_chars) | ||
{ | ||
span_lint_and_sugg( | ||
cx, | ||
NEEDLESS_CHARACTER_ITERATION, | ||
span, | ||
"checking if a string is ascii using iterators", | ||
"try", | ||
format!("{}{snippet}.is_ascii()", if revert { "!" } else { "" }), | ||
Applicability::MachineApplicable, | ||
); | ||
} | ||
}, | ||
ExprKind::Block(block, _) => { | ||
if block.stmts.iter().any(|stmt| !matches!(stmt.kind, StmtKind::Let(_))) { | ||
// If there is something else than let bindings, then better not emit the lint. | ||
return; | ||
} | ||
if let Some(block_expr) = block.expr | ||
// First we ensure that this is a "binding chain" (each statement is a binding | ||
// of the previous one) and that it is a binding of the closure argument. | ||
&& let Some(last_chain_binding_id) = | ||
get_last_chain_binding_hir_id(first_param, block.stmts) | ||
{ | ||
handle_expr(cx, block_expr, last_chain_binding_id, span, before_chars, revert); | ||
} | ||
}, | ||
ExprKind::Unary(UnOp::Not, expr) => handle_expr(cx, expr, first_param, span, before_chars, !revert), | ||
ExprKind::Call(fn_path, [arg]) => { | ||
if let ExprKind::Path(path) = fn_path.kind | ||
&& let Some(fn_def_id) = cx.qpath_res(&path, fn_path.hir_id).opt_def_id() | ||
&& match_def_path(cx, fn_def_id, &["core", "char", "methods", "<impl char>", "is_ascii"]) | ||
&& path_to_local_id(peels_expr_ref(arg), first_param) | ||
&& let Some(snippet) = snippet_opt(cx, before_chars) | ||
{ | ||
span_lint_and_sugg( | ||
cx, | ||
NEEDLESS_CHARACTER_ITERATION, | ||
span, | ||
"checking if a string is ascii using iterators", | ||
"try", | ||
format!("{}{snippet}.is_ascii()", if revert { "!" } else { "" }), | ||
Applicability::MachineApplicable, | ||
); | ||
} | ||
}, | ||
_ => {}, | ||
} | ||
} | ||
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pub(super) fn check(cx: &LateContext<'_>, call_expr: &Expr<'_>, recv: &Expr<'_>, closure_arg: &Expr<'_>) { | ||
if let ExprKind::Closure(&Closure { body, .. }) = closure_arg.kind | ||
&& let body = cx.tcx.hir().body(body) | ||
&& let Some(first_param) = body.params.first() | ||
&& let ExprKind::MethodCall(method, mut recv, [], _) = recv.kind | ||
&& method.ident.name.as_str() == "chars" | ||
&& let str_ty = cx.typeck_results().expr_ty_adjusted(recv).peel_refs() | ||
&& *str_ty.kind() == ty::Str | ||
{ | ||
let expr_start = recv.span; | ||
while let ExprKind::MethodCall(_, new_recv, _, _) = recv.kind { | ||
recv = new_recv; | ||
} | ||
let body_expr = peel_blocks(body.value); | ||
|
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handle_expr( | ||
cx, | ||
body_expr, | ||
first_param.pat.hir_id, | ||
recv.span.with_hi(call_expr.span.hi()), | ||
recv.span.with_hi(expr_start.hi()), | ||
false, | ||
); | ||
} | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,51 @@ | ||
#![warn(clippy::needless_character_iteration)] | ||
#![allow(clippy::map_identity, clippy::unnecessary_operation)] | ||
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#[derive(Default)] | ||
struct S { | ||
field: &'static str, | ||
} | ||
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impl S { | ||
fn field(&self) -> &str { | ||
self.field | ||
} | ||
} | ||
|
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fn magic(_: char) {} | ||
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fn main() { | ||
"foo".is_ascii(); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
!"foo".is_ascii(); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
"foo".is_ascii(); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
!"foo".is_ascii(); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
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let s = String::new(); | ||
s.is_ascii(); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
!"foo".to_string().is_ascii(); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
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"foo".is_ascii(); | ||
!"foo".is_ascii(); | ||
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S::default().field().is_ascii(); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
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// Should not lint! | ||
"foo".chars().all(|c| { | ||
let x = c; | ||
magic(x); | ||
x.is_ascii() | ||
}); | ||
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// Should not lint! | ||
"foo".chars().all(|c| c.is_ascii() && c.is_alphabetic()); | ||
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// Should not lint! | ||
"foo".chars().map(|c| c).all(|c| !char::is_ascii(&c)); | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,59 @@ | ||
#![warn(clippy::needless_character_iteration)] | ||
#![allow(clippy::map_identity, clippy::unnecessary_operation)] | ||
|
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#[derive(Default)] | ||
struct S { | ||
field: &'static str, | ||
} | ||
|
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impl S { | ||
fn field(&self) -> &str { | ||
self.field | ||
} | ||
} | ||
|
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fn magic(_: char) {} | ||
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fn main() { | ||
"foo".chars().all(|c| c.is_ascii()); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
"foo".chars().all(|c| !c.is_ascii()); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
"foo".chars().all(|c| char::is_ascii(&c)); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
"foo".chars().all(|c| !char::is_ascii(&c)); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
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let s = String::new(); | ||
s.chars().all(|c| c.is_ascii()); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
"foo".to_string().chars().all(|c| !c.is_ascii()); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
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"foo".chars().all(|c| { | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
let x = c; | ||
x.is_ascii() | ||
}); | ||
"foo".chars().all(|c| { | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
let x = c; | ||
!x.is_ascii() | ||
}); | ||
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S::default().field().chars().all(|x| x.is_ascii()); | ||
//~^ ERROR: checking if a string is ascii using iterators | ||
|
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// Should not lint! | ||
"foo".chars().all(|c| { | ||
let x = c; | ||
magic(x); | ||
x.is_ascii() | ||
}); | ||
|
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// Should not lint! | ||
"foo".chars().all(|c| c.is_ascii() && c.is_alphabetic()); | ||
|
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// Should not lint! | ||
"foo".chars().map(|c| c).all(|c| !char::is_ascii(&c)); | ||
} |
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