75 lines
2.6 KiB
Rust
75 lines
2.6 KiB
Rust
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::msrvs::{self, Msrv};
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use clippy_utils::{is_trait_method, match_def_path, paths, peel_hir_expr_refs};
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use rustc_errors::Applicability;
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use rustc_hir::def::{DefKind, Res};
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use rustc_hir::{Expr, ExprKind, Mutability, QPath};
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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_tool_lint, impl_lint_pass};
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use rustc_span::sym;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for references on `std::path::MAIN_SEPARATOR.to_string()` used
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/// to build a `&str`.
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///
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/// ### Why is this bad?
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/// There exists a `std::path::MAIN_SEPARATOR_STR` which does not require
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/// an extra memory allocation.
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///
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/// ### Example
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/// ```rust
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/// let s: &str = &std::path::MAIN_SEPARATOR.to_string();
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/// ```
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/// Use instead:
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/// ```rust
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/// let s: &str = std::path::MAIN_SEPARATOR_STR;
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/// ```
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#[clippy::version = "1.70.0"]
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pub MANUAL_MAIN_SEPARATOR_STR,
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complexity,
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"`&std::path::MAIN_SEPARATOR.to_string()` can be replaced by `std::path::MAIN_SEPARATOR_STR`"
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}
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pub struct ManualMainSeparatorStr {
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msrv: Msrv,
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}
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impl ManualMainSeparatorStr {
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#[must_use]
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pub fn new(msrv: Msrv) -> Self {
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Self { msrv }
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}
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}
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impl_lint_pass!(ManualMainSeparatorStr => [MANUAL_MAIN_SEPARATOR_STR]);
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impl LateLintPass<'_> for ManualMainSeparatorStr {
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fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
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if self.msrv.meets(msrvs::PATH_MAIN_SEPARATOR_STR) &&
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let (target, _) = peel_hir_expr_refs(expr) &&
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is_trait_method(cx, target, sym::ToString) &&
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let ExprKind::MethodCall(path, receiver, &[], _) = target.kind &&
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path.ident.name == sym::to_string &&
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let ExprKind::Path(QPath::Resolved(None, path)) = receiver.kind &&
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let Res::Def(DefKind::Const, receiver_def_id) = path.res &&
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match_def_path(cx, receiver_def_id, &paths::PATH_MAIN_SEPARATOR) &&
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let ty::Ref(_, ty, Mutability::Not) = cx.typeck_results().expr_ty_adjusted(expr).kind() &&
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ty.is_str()
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{
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span_lint_and_sugg(
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cx,
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MANUAL_MAIN_SEPARATOR_STR,
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expr.span,
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"taking a reference on `std::path::MAIN_SEPARATOR` conversion to `String`",
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"replace with",
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"std::path::MAIN_SEPARATOR_STR".to_owned(),
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Applicability::MachineApplicable,
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);
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}
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}
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extract_msrv_attr!(LateContext);
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}
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