76 lines
2.7 KiB
Rust
76 lines
2.7 KiB
Rust
use if_chain::if_chain;
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use rustc::hir::*;
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use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use rustc::{declare_tool_lint, lint_array};
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use rustc_errors::Applicability;
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use syntax::source_map::Spanned;
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use crate::consts::{constant, Constant};
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use crate::utils::paths;
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use crate::utils::{match_type, snippet_with_applicability, span_lint_and_sugg, walk_ptrs_ty};
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declare_clippy_lint! {
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/// **What it does:** 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?** 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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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// let dur = Duration::new(5, 0);
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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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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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#[derive(Copy, Clone)]
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pub struct DurationSubsec;
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impl LintPass for DurationSubsec {
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fn get_lints(&self) -> LintArray {
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lint_array!(DURATION_SUBSEC)
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}
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fn name(&self) -> &'static str {
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"DurationSubsec"
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DurationSubsec {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
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if_chain! {
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if let ExprKind::Binary(Spanned { node: BinOpKind::Div, .. }, ref left, ref right) = expr.node;
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if let ExprKind::MethodCall(ref method_path, _ , ref args) = left.node;
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if match_type(cx, walk_ptrs_ty(cx.tables.expr_ty(&args[0])), &paths::DURATION);
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if let Some((Constant::Int(divisor), _)) = constant(cx, cx.tables, 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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