2021-03-25 18:29:11 +00:00
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use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::ty::match_type;
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2018-11-20 13:06:29 +00:00
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use if_chain::if_chain;
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2018-12-29 15:04:45 +00:00
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use rustc_errors::Applicability;
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2020-02-21 08:39:38 +00:00
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use rustc_hir::{BinOpKind, Expr, ExprKind};
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2020-01-12 06:08:41 +00:00
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use rustc_lint::{LateContext, LateLintPass};
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2020-01-11 11:37:08 +00:00
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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2020-01-04 10:00:00 +00:00
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use rustc_span::source_map::Spanned;
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2018-03-18 20:27:15 +00:00
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2021-06-03 06:41:37 +00:00
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use clippy_utils::consts::{constant, Constant};
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2021-03-25 18:29:11 +00:00
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::paths;
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2018-03-18 20:27:15 +00:00
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2018-06-09 09:04:21 +00:00
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declare_clippy_lint! {
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2021-07-29 10:16:06 +00:00
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/// ### What it does
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/// Checks for calculation of subsecond microseconds or milliseconds
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2019-03-05 16:50:33 +00:00
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/// from other `Duration` methods.
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///
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2021-07-29 10:16:06 +00:00
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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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2019-03-05 16:50:33 +00:00
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/// `Duration::subsec_millis()` than to calculate them.
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///
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2021-07-29 10:16:06 +00:00
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/// ### Example
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2019-03-05 16:50:33 +00:00
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/// ```rust
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2019-08-02 06:13:54 +00:00
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/// # use std::time::Duration;
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2019-03-05 16:50:33 +00:00
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/// let dur = Duration::new(5, 0);
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2020-06-09 14:36:01 +00:00
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///
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/// // Bad
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2019-03-05 16:50:33 +00:00
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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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2020-06-09 14:36:01 +00:00
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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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2019-03-05 16:50:33 +00:00
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/// ```
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2021-12-06 11:33:31 +00:00
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#[clippy::version = "pre 1.29.0"]
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2018-03-18 20:27:15 +00:00
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pub DURATION_SUBSEC,
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2018-06-09 09:04:21 +00:00
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complexity,
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2018-06-12 06:25:10 +00:00
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"checks for calculation of subsecond microseconds or milliseconds"
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2018-03-18 20:27:15 +00:00
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}
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2019-04-08 20:43:55 +00:00
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declare_lint_pass!(DurationSubsec => [DURATION_SUBSEC]);
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2018-03-18 20:27:15 +00:00
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2020-06-25 20:41:36 +00:00
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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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2018-03-18 20:27:15 +00:00
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if_chain! {
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2021-04-08 15:50:13 +00:00
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if let ExprKind::Binary(Spanned { node: BinOpKind::Div, .. }, left, right) = expr.kind;
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2021-12-01 17:17:50 +00:00
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if let ExprKind::MethodCall(method_path, args, _) = left.kind;
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2020-09-24 12:49:22 +00:00
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if match_type(cx, cx.typeck_results().expr_ty(&args[0]).peel_refs(), &paths::DURATION);
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2020-07-17 08:47:04 +00:00
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if let Some((Constant::Int(divisor), _)) = constant(cx, cx.typeck_results(), right);
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2018-03-18 20:27:15 +00:00
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then {
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2021-12-15 05:13:11 +00:00
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let suggested_fn = match (method_path.ident.as_str(), divisor) {
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2018-09-26 09:44:50 +00:00
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("subsec_micros", 1_000) | ("subsec_nanos", 1_000_000) => "subsec_millis",
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2018-06-12 06:25:10 +00:00
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("subsec_nanos", 1_000) => "subsec_micros",
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2018-03-18 20:27:15 +00:00
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_ => return,
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};
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2018-11-27 14:13:57 +00:00
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let mut applicability = Applicability::MachineApplicable;
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2018-03-18 20:27:15 +00:00
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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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2020-08-28 14:10:16 +00:00
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&format!("calling `{}()` is more concise than this calculation", suggested_fn),
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2018-03-18 20:27:15 +00:00
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"try",
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2018-11-27 20:14:15 +00:00
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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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2018-11-27 14:13:57 +00:00
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applicability,
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2018-03-18 20:27:15 +00:00
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);
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}
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}
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}
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}
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