diff --git a/CHANGELOG.md b/CHANGELOG.md
index f1697312d5c..6f1f73c1fd2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4428,6 +4428,7 @@ Released 2018-09-13
[`try_err`]: https://rust-lang.github.io/rust-clippy/master/index.html#try_err
[`type_complexity`]: https://rust-lang.github.io/rust-clippy/master/index.html#type_complexity
[`type_repetition_in_bounds`]: https://rust-lang.github.io/rust-clippy/master/index.html#type_repetition_in_bounds
+[`unchecked_duration_subtraction`]: https://rust-lang.github.io/rust-clippy/master/index.html#unchecked_duration_subtraction
[`undocumented_unsafe_blocks`]: https://rust-lang.github.io/rust-clippy/master/index.html#undocumented_unsafe_blocks
[`undropped_manually_drops`]: https://rust-lang.github.io/rust-clippy/master/index.html#undropped_manually_drops
[`unicode_not_nfc`]: https://rust-lang.github.io/rust-clippy/master/index.html#unicode_not_nfc
diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs
index 0ff039a4cdf..0d3fc43a644 100644
--- a/clippy_lints/src/declared_lints.rs
+++ b/clippy_lints/src/declared_lints.rs
@@ -203,6 +203,8 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
crate::inherent_to_string::INHERENT_TO_STRING_SHADOW_DISPLAY_INFO,
crate::init_numbered_fields::INIT_NUMBERED_FIELDS_INFO,
crate::inline_fn_without_body::INLINE_FN_WITHOUT_BODY_INFO,
+ crate::instant_subtraction::MANUAL_INSTANT_ELAPSED_INFO,
+ crate::instant_subtraction::UNCHECKED_DURATION_SUBTRACTION_INFO,
crate::int_plus_one::INT_PLUS_ONE_INFO,
crate::invalid_upcast_comparisons::INVALID_UPCAST_COMPARISONS_INFO,
crate::invalid_utf8_in_unchecked::INVALID_UTF8_IN_UNCHECKED_INFO,
@@ -251,7 +253,6 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
crate::manual_async_fn::MANUAL_ASYNC_FN_INFO,
crate::manual_bits::MANUAL_BITS_INFO,
crate::manual_clamp::MANUAL_CLAMP_INFO,
- crate::manual_instant_elapsed::MANUAL_INSTANT_ELAPSED_INFO,
crate::manual_is_ascii_check::MANUAL_IS_ASCII_CHECK_INFO,
crate::manual_let_else::MANUAL_LET_ELSE_INFO,
crate::manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE_INFO,
diff --git a/clippy_lints/src/instant_subtraction.rs b/clippy_lints/src/instant_subtraction.rs
new file mode 100644
index 00000000000..60754b224fc
--- /dev/null
+++ b/clippy_lints/src/instant_subtraction.rs
@@ -0,0 +1,184 @@
+use clippy_utils::{
+ diagnostics::{self, span_lint_and_sugg},
+ meets_msrv, msrvs, source,
+ sugg::Sugg,
+ ty,
+};
+use rustc_errors::Applicability;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_semver::RustcVersion;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::{source_map::Spanned, sym};
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Lints subtraction between `Instant::now()` and another `Instant`.
+ ///
+ /// ### Why is this bad?
+ /// It is easy to accidentally write `prev_instant - Instant::now()`, which will always be 0ns
+ /// as `Instant` subtraction saturates.
+ ///
+ /// `prev_instant.elapsed()` also more clearly signals intention.
+ ///
+ /// ### Example
+ /// ```rust
+ /// use std::time::Instant;
+ /// let prev_instant = Instant::now();
+ /// let duration = Instant::now() - prev_instant;
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// use std::time::Instant;
+ /// let prev_instant = Instant::now();
+ /// let duration = prev_instant.elapsed();
+ /// ```
+ #[clippy::version = "1.65.0"]
+ pub MANUAL_INSTANT_ELAPSED,
+ pedantic,
+ "subtraction between `Instant::now()` and previous `Instant`"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Lints subtraction between an [`Instant`] and a [`Duration`].
+ ///
+ /// ### Why is this bad?
+ /// Unchecked subtraction could cause underflow on certain platforms, leading to
+ /// unintentional panics.
+ ///
+ /// ### Example
+ /// ```rust
+ /// # use std::time::{Instant, Duration};
+ /// let time_passed = Instant::now() - Duration::from_secs(5);
+ /// ```
+ ///
+ /// Use instead:
+ /// ```rust
+ /// # use std::time::{Instant, Duration};
+ /// let time_passed = Instant::now().checked_sub(Duration::from_secs(5));
+ /// ```
+ ///
+ /// [`Duration`]: std::time::Duration
+ /// [`Instant::now()`]: std::time::Instant::now;
+ #[clippy::version = "1.65.0"]
+ pub UNCHECKED_DURATION_SUBTRACTION,
+ suspicious,
+ "finds unchecked subtraction of a 'Duration' from an 'Instant'"
+}
+
+pub struct InstantSubtraction {
+ msrv: Option<RustcVersion>,
+}
+
+impl InstantSubtraction {
+ #[must_use]
+ pub fn new(msrv: Option<RustcVersion>) -> Self {
+ Self { msrv }
+ }
+}
+
+impl_lint_pass!(InstantSubtraction => [MANUAL_INSTANT_ELAPSED, UNCHECKED_DURATION_SUBTRACTION]);
+
+impl LateLintPass<'_> for InstantSubtraction {
+ fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'_ Expr<'_>) {
+ if let ExprKind::Binary(
+ Spanned {
+ node: BinOpKind::Sub, ..
+ },
+ lhs,
+ rhs,
+ ) = expr.kind
+ {
+ if_chain! {
+ if is_instant_now_call(cx, lhs);
+
+ if is_an_instant(cx, rhs);
+ if let Some(sugg) = Sugg::hir_opt(cx, rhs);
+
+ then {
+ print_manual_instant_elapsed_sugg(cx, expr, sugg)
+ } else {
+ if_chain! {
+ if !expr.span.from_expansion();
+ if meets_msrv(self.msrv, msrvs::TRY_FROM);
+
+ if is_an_instant(cx, lhs);
+ if is_a_duration(cx, rhs);
+
+ then {
+ print_unchecked_duration_subtraction_sugg(cx, lhs, rhs, expr)
+ }
+ }
+ }
+ }
+ }
+ }
+
+ extract_msrv_attr!(LateContext);
+}
+
+fn is_instant_now_call(cx: &LateContext<'_>, expr_block: &'_ Expr<'_>) -> bool {
+ if let ExprKind::Call(fn_expr, []) = expr_block.kind
+ && let Some(fn_id) = clippy_utils::path_def_id(cx, fn_expr)
+ && clippy_utils::match_def_path(cx, fn_id, &clippy_utils::paths::INSTANT_NOW)
+ {
+ true
+ } else {
+ false
+ }
+}
+
+fn is_an_instant(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+ let expr_ty = cx.typeck_results().expr_ty(expr);
+
+ match expr_ty.kind() {
+ rustc_middle::ty::Adt(def, _) => clippy_utils::match_def_path(cx, def.did(), &clippy_utils::paths::INSTANT),
+ _ => false,
+ }
+}
+
+fn is_a_duration(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+ let expr_ty = cx.typeck_results().expr_ty(expr);
+ ty::is_type_diagnostic_item(cx, expr_ty, sym::Duration)
+}
+
+fn print_manual_instant_elapsed_sugg(cx: &LateContext<'_>, expr: &Expr<'_>, sugg: Sugg<'_>) {
+ span_lint_and_sugg(
+ cx,
+ MANUAL_INSTANT_ELAPSED,
+ expr.span,
+ "manual implementation of `Instant::elapsed`",
+ "try",
+ format!("{}.elapsed()", sugg.maybe_par()),
+ Applicability::MachineApplicable,
+ );
+}
+
+fn print_unchecked_duration_subtraction_sugg(
+ cx: &LateContext<'_>,
+ left_expr: &Expr<'_>,
+ right_expr: &Expr<'_>,
+ expr: &Expr<'_>,
+) {
+ let mut applicability = Applicability::MachineApplicable;
+
+ let left_expr =
+ source::snippet_with_applicability(cx, left_expr.span, "std::time::Instant::now()", &mut applicability);
+ let right_expr = source::snippet_with_applicability(
+ cx,
+ right_expr.span,
+ "std::time::Duration::from_secs(1)",
+ &mut applicability,
+ );
+
+ diagnostics::span_lint_and_sugg(
+ cx,
+ UNCHECKED_DURATION_SUBTRACTION,
+ expr.span,
+ "unchecked subtraction of a 'Duration' from an 'Instant'",
+ "try",
+ format!("{left_expr}.checked_sub({right_expr}).unwrap()"),
+ applicability,
+ );
+}
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index f847490be27..4e640d7ebf6 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -151,6 +151,7 @@ mod inherent_impl;
mod inherent_to_string;
mod init_numbered_fields;
mod inline_fn_without_body;
+mod instant_subtraction;
mod int_plus_one;
mod invalid_upcast_comparisons;
mod invalid_utf8_in_unchecked;
@@ -172,7 +173,6 @@ mod manual_assert;
mod manual_async_fn;
mod manual_bits;
mod manual_clamp;
-mod manual_instant_elapsed;
mod manual_is_ascii_check;
mod manual_let_else;
mod manual_non_exhaustive;
@@ -907,7 +907,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(move |_| Box::new(operators::Operators::new(verbose_bit_mask_threshold)));
store.register_late_pass(|_| Box::new(invalid_utf8_in_unchecked::InvalidUtf8InUnchecked));
store.register_late_pass(|_| Box::<std_instead_of_core::StdReexports>::default());
- store.register_late_pass(|_| Box::new(manual_instant_elapsed::ManualInstantElapsed));
+ store.register_late_pass(move |_| Box::new(instant_subtraction::InstantSubtraction::new(msrv)));
store.register_late_pass(|_| Box::new(partialeq_to_none::PartialeqToNone));
store.register_late_pass(move |_| Box::new(manual_clamp::ManualClamp::new(msrv)));
store.register_late_pass(|_| Box::new(manual_string_new::ManualStringNew));
diff --git a/clippy_lints/src/manual_instant_elapsed.rs b/clippy_lints/src/manual_instant_elapsed.rs
deleted file mode 100644
index 1e60aa02d3c..00000000000
--- a/clippy_lints/src/manual_instant_elapsed.rs
+++ /dev/null
@@ -1,69 +0,0 @@
-use clippy_utils::diagnostics::span_lint_and_sugg;
-use rustc_errors::Applicability;
-use rustc_hir::{BinOpKind, Expr, ExprKind};
-use rustc_lint::{LateContext, LateLintPass};
-use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::source_map::Spanned;
-
-declare_clippy_lint! {
- /// ### What it does
- /// Lints subtraction between `Instant::now()` and another `Instant`.
- ///
- /// ### Why is this bad?
- /// It is easy to accidentally write `prev_instant - Instant::now()`, which will always be 0ns
- /// as `Instant` subtraction saturates.
- ///
- /// `prev_instant.elapsed()` also more clearly signals intention.
- ///
- /// ### Example
- /// ```rust
- /// use std::time::Instant;
- /// let prev_instant = Instant::now();
- /// let duration = Instant::now() - prev_instant;
- /// ```
- /// Use instead:
- /// ```rust
- /// use std::time::Instant;
- /// let prev_instant = Instant::now();
- /// let duration = prev_instant.elapsed();
- /// ```
- #[clippy::version = "1.65.0"]
- pub MANUAL_INSTANT_ELAPSED,
- pedantic,
- "subtraction between `Instant::now()` and previous `Instant`"
-}
-
-declare_lint_pass!(ManualInstantElapsed => [MANUAL_INSTANT_ELAPSED]);
-
-impl LateLintPass<'_> for ManualInstantElapsed {
- fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'_ Expr<'_>) {
- if let ExprKind::Binary(Spanned {node: BinOpKind::Sub, ..}, lhs, rhs) = expr.kind
- && check_instant_now_call(cx, lhs)
- && let ty_resolved = cx.typeck_results().expr_ty(rhs)
- && let rustc_middle::ty::Adt(def, _) = ty_resolved.kind()
- && clippy_utils::match_def_path(cx, def.did(), &clippy_utils::paths::INSTANT)
- && let Some(sugg) = clippy_utils::sugg::Sugg::hir_opt(cx, rhs)
- {
- span_lint_and_sugg(
- cx,
- MANUAL_INSTANT_ELAPSED,
- expr.span,
- "manual implementation of `Instant::elapsed`",
- "try",
- format!("{}.elapsed()", sugg.maybe_par()),
- Applicability::MachineApplicable,
- );
- }
- }
-}
-
-fn check_instant_now_call(cx: &LateContext<'_>, expr_block: &'_ Expr<'_>) -> bool {
- if let ExprKind::Call(fn_expr, []) = expr_block.kind
- && let Some(fn_id) = clippy_utils::path_def_id(cx, fn_expr)
- && clippy_utils::match_def_path(cx, fn_id, &clippy_utils::paths::INSTANT_NOW)
- {
- true
- } else {
- false
- }
-}
diff --git a/clippy_lints/src/utils/conf.rs b/clippy_lints/src/utils/conf.rs
index 0cf49ca6d42..ab58e9b8b68 100644
--- a/clippy_lints/src/utils/conf.rs
+++ b/clippy_lints/src/utils/conf.rs
@@ -213,7 +213,7 @@ define_Conf! {
///
/// Suppress lints whenever the suggested change would cause breakage for other crates.
(avoid_breaking_exported_api: bool = true),
- /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT, DEPRECATED_CFG_ATTR, INDEX_REFUTABLE_SLICE, MAP_CLONE, BORROW_AS_PTR, MANUAL_BITS, ERR_EXPECT, CAST_ABS_TO_UNSIGNED, UNINLINED_FORMAT_ARGS, MANUAL_CLAMP, MANUAL_LET_ELSE.
+ /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT, DEPRECATED_CFG_ATTR, INDEX_REFUTABLE_SLICE, MAP_CLONE, BORROW_AS_PTR, MANUAL_BITS, ERR_EXPECT, CAST_ABS_TO_UNSIGNED, UNINLINED_FORMAT_ARGS, MANUAL_CLAMP, MANUAL_LET_ELSE, UNCHECKED_DURATION_SUBTRACTION.
///
/// The minimum rust version that the project supports
(msrv: Option<String> = None),
diff --git a/tests/ui/manual_instant_elapsed.fixed b/tests/ui/manual_instant_elapsed.fixed
index 0fa776b7b2e..85a91543c89 100644
--- a/tests/ui/manual_instant_elapsed.fixed
+++ b/tests/ui/manual_instant_elapsed.fixed
@@ -1,6 +1,7 @@
// run-rustfix
#![warn(clippy::manual_instant_elapsed)]
#![allow(clippy::unnecessary_operation)]
+#![allow(clippy::unchecked_duration_subtraction)]
#![allow(unused_variables)]
#![allow(unused_must_use)]
diff --git a/tests/ui/manual_instant_elapsed.rs b/tests/ui/manual_instant_elapsed.rs
index 5b11b84535d..c98cb15b916 100644
--- a/tests/ui/manual_instant_elapsed.rs
+++ b/tests/ui/manual_instant_elapsed.rs
@@ -1,6 +1,7 @@
// run-rustfix
#![warn(clippy::manual_instant_elapsed)]
#![allow(clippy::unnecessary_operation)]
+#![allow(clippy::unchecked_duration_subtraction)]
#![allow(unused_variables)]
#![allow(unused_must_use)]
diff --git a/tests/ui/manual_instant_elapsed.stderr b/tests/ui/manual_instant_elapsed.stderr
index 5537f5642a2..4ce1f689107 100644
--- a/tests/ui/manual_instant_elapsed.stderr
+++ b/tests/ui/manual_instant_elapsed.stderr
@@ -1,5 +1,5 @@
error: manual implementation of `Instant::elapsed`
- --> $DIR/manual_instant_elapsed.rs:17:20
+ --> $DIR/manual_instant_elapsed.rs:18:20
|
LL | let duration = Instant::now() - prev_instant;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `prev_instant.elapsed()`
@@ -7,7 +7,7 @@ LL | let duration = Instant::now() - prev_instant;
= note: `-D clippy::manual-instant-elapsed` implied by `-D warnings`
error: manual implementation of `Instant::elapsed`
- --> $DIR/manual_instant_elapsed.rs:26:5
+ --> $DIR/manual_instant_elapsed.rs:27:5
|
LL | Instant::now() - *ref_to_instant; // to ensure parens are added correctly
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(*ref_to_instant).elapsed()`
diff --git a/tests/ui/unchecked_duration_subtraction.fixed b/tests/ui/unchecked_duration_subtraction.fixed
new file mode 100644
index 00000000000..a0e49a8beb1
--- /dev/null
+++ b/tests/ui/unchecked_duration_subtraction.fixed
@@ -0,0 +1,17 @@
+// run-rustfix
+#![warn(clippy::unchecked_duration_subtraction)]
+
+use std::time::{Duration, Instant};
+
+fn main() {
+ let _first = Instant::now();
+ let second = Duration::from_secs(3);
+
+ let _ = _first.checked_sub(second).unwrap();
+
+ let _ = Instant::now().checked_sub(Duration::from_secs(5)).unwrap();
+
+ let _ = _first.checked_sub(Duration::from_secs(5)).unwrap();
+
+ let _ = Instant::now().checked_sub(second).unwrap();
+}
diff --git a/tests/ui/unchecked_duration_subtraction.rs b/tests/ui/unchecked_duration_subtraction.rs
new file mode 100644
index 00000000000..a14a7ea57cc
--- /dev/null
+++ b/tests/ui/unchecked_duration_subtraction.rs
@@ -0,0 +1,17 @@
+// run-rustfix
+#![warn(clippy::unchecked_duration_subtraction)]
+
+use std::time::{Duration, Instant};
+
+fn main() {
+ let _first = Instant::now();
+ let second = Duration::from_secs(3);
+
+ let _ = _first - second;
+
+ let _ = Instant::now() - Duration::from_secs(5);
+
+ let _ = _first - Duration::from_secs(5);
+
+ let _ = Instant::now() - second;
+}
diff --git a/tests/ui/unchecked_duration_subtraction.stderr b/tests/ui/unchecked_duration_subtraction.stderr
new file mode 100644
index 00000000000..a2e0aa1d7c0
--- /dev/null
+++ b/tests/ui/unchecked_duration_subtraction.stderr
@@ -0,0 +1,28 @@
+error: unchecked subtraction of a 'Duration' from an 'Instant'
+ --> $DIR/unchecked_duration_subtraction.rs:10:13
+ |
+LL | let _ = _first - second;
+ | ^^^^^^^^^^^^^^^ help: try: `_first.checked_sub(second).unwrap()`
+ |
+ = note: `-D clippy::unchecked-duration-subtraction` implied by `-D warnings`
+
+error: unchecked subtraction of a 'Duration' from an 'Instant'
+ --> $DIR/unchecked_duration_subtraction.rs:12:13
+ |
+LL | let _ = Instant::now() - Duration::from_secs(5);
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Instant::now().checked_sub(Duration::from_secs(5)).unwrap()`
+
+error: unchecked subtraction of a 'Duration' from an 'Instant'
+ --> $DIR/unchecked_duration_subtraction.rs:14:13
+ |
+LL | let _ = _first - Duration::from_secs(5);
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `_first.checked_sub(Duration::from_secs(5)).unwrap()`
+
+error: unchecked subtraction of a 'Duration' from an 'Instant'
+ --> $DIR/unchecked_duration_subtraction.rs:16:13
+ |
+LL | let _ = Instant::now() - second;
+ | ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Instant::now().checked_sub(second).unwrap()`
+
+error: aborting due to 4 previous errors
+