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, +} + +impl InstantSubtraction { + #[must_use] + pub fn new(msrv: Option) -> 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::::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 = 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 +