Move DurationSubsec into Operators lint pass

Author: Jarcho

clippy_lints/src/duration_subsec.rs

@@ -56,7 +56,6 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
     LintId::of(drop_forget_ref::FORGET_REF),
     LintId::of(drop_forget_ref::UNDROPPED_MANUALLY_DROPS),
     LintId::of(duplicate_mod::DUPLICATE_MOD),
-    LintId::of(duration_subsec::DURATION_SUBSEC),
     LintId::of(entry::MAP_ENTRY),
     LintId::of(enum_clike::ENUM_CLIKE_UNPORTABLE_VARIANT),
     LintId::of(enum_variants::ENUM_VARIANT_NAMES),
@@ -251,6 +250,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
     LintId::of(operators::ASSIGN_OP_PATTERN),
     LintId::of(operators::BAD_BIT_MASK),
     LintId::of(operators::DOUBLE_COMPARISONS),
+    LintId::of(operators::DURATION_SUBSEC),
     LintId::of(operators::INEFFECTIVE_BIT_MASK),
     LintId::of(operators::MISREFACTORED_ASSIGN_OP),
     LintId::of(option_env_unwrap::OPTION_ENV_UNWRAP),

clippy_lints/src/lib.register_all.rs

@@ -10,7 +10,6 @@ store.register_group(true, "clippy::complexity", Some("clippy_complexity"), vec!
     LintId::of(casts::UNNECESSARY_CAST),
     LintId::of(derivable_impls::DERIVABLE_IMPLS),
     LintId::of(double_parens::DOUBLE_PARENS),
-    LintId::of(duration_subsec::DURATION_SUBSEC),
     LintId::of(explicit_write::EXPLICIT_WRITE),
     LintId::of(format::USELESS_FORMAT),
     LintId::of(functions::TOO_MANY_ARGUMENTS),
@@ -68,6 +67,7 @@ store.register_group(true, "clippy::complexity", Some("clippy_complexity"), vec!
     LintId::of(no_effect::NO_EFFECT),
     LintId::of(no_effect::UNNECESSARY_OPERATION),
     LintId::of(operators::DOUBLE_COMPARISONS),
+    LintId::of(operators::DURATION_SUBSEC),
     LintId::of(overflow_check_conditional::OVERFLOW_CHECK_CONDITIONAL),
     LintId::of(partialeq_ne_impl::PARTIALEQ_NE_IMPL),
     LintId::of(precedence::PRECEDENCE),

clippy_lints/src/lib.register_complexity.rs

@@ -127,7 +127,6 @@ store.register_lints(&[
     drop_forget_ref::FORGET_REF,
     drop_forget_ref::UNDROPPED_MANUALLY_DROPS,
     duplicate_mod::DUPLICATE_MOD,
-    duration_subsec::DURATION_SUBSEC,
     else_if_without_else::ELSE_IF_WITHOUT_ELSE,
     empty_drop::EMPTY_DROP,
     empty_enum::EMPTY_ENUM,
@@ -420,6 +419,7 @@ store.register_lints(&[
     operators::ASSIGN_OP_PATTERN,
     operators::BAD_BIT_MASK,
     operators::DOUBLE_COMPARISONS,
+    operators::DURATION_SUBSEC,
     operators::FLOAT_ARITHMETIC,
     operators::INEFFECTIVE_BIT_MASK,
     operators::INTEGER_ARITHMETIC,

clippy_lints/src/lib.register_lints.rs

@@ -209,7 +209,6 @@ mod doc_link_with_quotes;
 mod double_parens;
 mod drop_forget_ref;
 mod duplicate_mod;
-mod duration_subsec;
 mod else_if_without_else;
 mod empty_drop;
 mod empty_enum;
@@ -707,7 +706,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(inherent_impl::MultipleInherentImpl));
     store.register_late_pass(|| Box::new(neg_cmp_op_on_partial_ord::NoNegCompOpForPartialOrd));
     store.register_late_pass(|| Box::new(unwrap::Unwrap));
-    store.register_late_pass(|| Box::new(duration_subsec::DurationSubsec));
     store.register_late_pass(|| Box::new(indexing_slicing::IndexingSlicing));
     store.register_late_pass(|| Box::new(non_copy_const::NonCopyConst));
     store.register_late_pass(|| Box::new(ptr_offset_with_cast::PtrOffsetWithCast));

clippy_lints/src/lib.rs

@@ -0,0 +1,44 @@
+use clippy_utils::consts::{constant, Constant};
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::snippet_with_applicability;
+use clippy_utils::ty::is_type_diagnostic_item;
+use rustc_errors::Applicability;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
+use rustc_lint::LateContext;
+use rustc_span::sym;
+
+use super::DURATION_SUBSEC;
+
+pub(crate) fn check<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx Expr<'_>,
+    op: BinOpKind,
+    left: &'tcx Expr<'_>,
+    right: &'tcx Expr<'_>,
+) {
+    if op == BinOpKind::Div
+        && let ExprKind::MethodCall(method_path, [self_arg], _) = left.kind
+        && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(self_arg).peel_refs(), sym::Duration)
+        && let Some((Constant::Int(divisor), _)) = constant(cx, cx.typeck_results(), right)
+    {
+        let suggested_fn = match (method_path.ident.as_str(), divisor) {
+            ("subsec_micros", 1_000) | ("subsec_nanos", 1_000_000) => "subsec_millis",
+            ("subsec_nanos", 1_000) => "subsec_micros",
+            _ => return,
+        };
+        let mut applicability = Applicability::MachineApplicable;
+        span_lint_and_sugg(
+            cx,
+            DURATION_SUBSEC,
+            expr.span,
+            &format!("calling `{}()` is more concise than this calculation", suggested_fn),
+            "try",
+            format!(
+                "{}.{}()",
+                snippet_with_applicability(cx, self_arg.span, "_", &mut applicability),
+                suggested_fn
+            ),
+            applicability,
+        );
+    }
+}

clippy_lints/src/operators/duration_subsec.rs

@@ -7,6 +7,7 @@ mod arithmetic;
 mod assign_op_pattern;
 mod bit_mask;
 mod double_comparison;
+mod duration_subsec;
 mod misrefactored_assign_op;
 mod verbose_bit_mask;
 
@@ -265,6 +266,34 @@ declare_clippy_lint! {
     "unnecessary double comparisons that can be simplified"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for calculation of subsecond microseconds or milliseconds
+    /// from other `Duration` methods.
+    ///
+    /// ### Why is this bad?
+    /// It's more concise to call `Duration::subsec_micros()` or
+    /// `Duration::subsec_millis()` than to calculate them.
+    ///
+    /// ### Example
+    /// ```rust
+    /// # use std::time::Duration;
+    /// let dur = Duration::new(5, 0);
+    ///
+    /// // Bad
+    /// let _micros = dur.subsec_nanos() / 1_000;
+    /// let _millis = dur.subsec_nanos() / 1_000_000;
+    ///
+    /// // Good
+    /// let _micros = dur.subsec_micros();
+    /// let _millis = dur.subsec_millis();
+    /// ```
+    #[clippy::version = "pre 1.29.0"]
+    pub DURATION_SUBSEC,
+    complexity,
+    "checks for calculation of subsecond microseconds or milliseconds"
+}
+
 pub struct Operators {
     arithmetic_context: arithmetic::Context,
     verbose_bit_mask_threshold: u64,
@@ -279,6 +308,7 @@ impl_lint_pass!(Operators => [
     INEFFECTIVE_BIT_MASK,
     VERBOSE_BIT_MASK,
     DOUBLE_COMPARISONS,
+    DURATION_SUBSEC,
 ]);
 impl Operators {
     pub fn new(verbose_bit_mask_threshold: u64) -> Self {
@@ -299,6 +329,7 @@ impl<'tcx> LateLintPass<'tcx> for Operators {
                 bit_mask::check(cx, e, op.node, lhs, rhs);
                 verbose_bit_mask::check(cx, e, op.node, lhs, rhs, self.verbose_bit_mask_threshold);
                 double_comparison::check(cx, op.node, lhs, rhs, e.span);
+                duration_subsec::check(cx, e, op.node, lhs, rhs);
             },
             ExprKind::AssignOp(op, lhs, rhs) => {
                 self.arithmetic_context.check_binary(cx, e, op.node, lhs, rhs);