74 lines
2.7 KiB
Rust
74 lines
2.7 KiB
Rust
use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::ty::match_type;
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir::{BinOpKind, Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::source_map::Spanned;
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use clippy_utils::consts::{constant, Constant};
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::paths;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for calculation of subsecond microseconds or milliseconds
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/// from other `Duration` methods.
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///
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/// ### Why is this bad?
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/// It's more concise to call `Duration::subsec_micros()` or
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/// `Duration::subsec_millis()` than to calculate them.
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///
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/// ### Example
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/// ```rust
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/// # use std::time::Duration;
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/// let dur = Duration::new(5, 0);
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///
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/// // Bad
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/// let _micros = dur.subsec_nanos() / 1_000;
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/// let _millis = dur.subsec_nanos() / 1_000_000;
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///
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/// // Good
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/// let _micros = dur.subsec_micros();
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/// let _millis = dur.subsec_millis();
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/// ```
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pub DURATION_SUBSEC,
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complexity,
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"checks for calculation of subsecond microseconds or milliseconds"
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}
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declare_lint_pass!(DurationSubsec => [DURATION_SUBSEC]);
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impl<'tcx> LateLintPass<'tcx> for DurationSubsec {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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if_chain! {
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if let ExprKind::Binary(Spanned { node: BinOpKind::Div, .. }, left, right) = expr.kind;
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if let ExprKind::MethodCall(method_path, _ , args, _) = left.kind;
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if match_type(cx, cx.typeck_results().expr_ty(&args[0]).peel_refs(), &paths::DURATION);
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if let Some((Constant::Int(divisor), _)) = constant(cx, cx.typeck_results(), right);
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then {
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let suggested_fn = match (method_path.ident.as_str().as_ref(), divisor) {
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("subsec_micros", 1_000) | ("subsec_nanos", 1_000_000) => "subsec_millis",
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("subsec_nanos", 1_000) => "subsec_micros",
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_ => return,
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};
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let mut applicability = Applicability::MachineApplicable;
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span_lint_and_sugg(
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cx,
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DURATION_SUBSEC,
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expr.span,
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&format!("calling `{}()` is more concise than this calculation", suggested_fn),
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"try",
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format!(
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"{}.{}()",
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snippet_with_applicability(cx, args[0].span, "_", &mut applicability),
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suggested_fn
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),
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applicability,
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);
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}
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}
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}
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}
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