clippy_lints/src/operators/duration_subsec.rs

   1 use clippy_utils::consts::{constant, Constant};
   2 use clippy_utils::diagnostics::span_lint_and_sugg;
   3 use clippy_utils::source::snippet_with_applicability;
   4 use clippy_utils::ty::is_type_diagnostic_item;
   5 use rustc_errors::Applicability;
   6 use rustc_hir::{BinOpKind, Expr, ExprKind};
   7 use rustc_lint::LateContext;
   8 use rustc_span::sym;
   9
  10 use super::DURATION_SUBSEC;
  11
  12 pub(crate) fn check<'tcx>(
  13     cx: &LateContext<'tcx>,
  14     expr: &'tcx Expr<'_>,
  15     op: BinOpKind,
  16     left: &'tcx Expr<'_>,
  17     right: &'tcx Expr<'_>,
  18 ) {
  19     if op == BinOpKind::Div
  20         && let ExprKind::MethodCall(method_path, self_arg, [], _) = left.kind
  21         && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(self_arg).peel_refs(), sym::Duration)
  22         && let Some((Constant::Int(divisor), _)) = constant(cx, cx.typeck_results(), right)
  23     {
  24         let suggested_fn = match (method_path.ident.as_str(), divisor) {
  25             ("subsec_micros", 1_000) | ("subsec_nanos", 1_000_000) => "subsec_millis",
  26             ("subsec_nanos", 1_000) => "subsec_micros",
  27             _ => return,
  28         };
  29         let mut applicability = Applicability::MachineApplicable;
  30         span_lint_and_sugg(
  31             cx,
  32             DURATION_SUBSEC,
  33             expr.span,
  34             &format!("calling `{}()` is more concise than this calculation", suggested_fn),
  35             "try",
  36             format!(
  37                 "{}.{}()",
  38                 snippet_with_applicability(cx, self_arg.span, "_", &mut applicability),
  39                 suggested_fn
  40             ),
  41             applicability,
  42         );
  43     }
  44 }