From e5ebd3edabc17436de086a7ce147983c2238939a Mon Sep 17 00:00:00 2001 From: Evan Typanski Date: Tue, 21 Jun 2022 14:13:15 -0400 Subject: [PATCH] Implement manual_rem_euclid lint --- CHANGELOG.md | 1 + clippy_lints/src/lib.register_all.rs | 1 + clippy_lints/src/lib.register_complexity.rs | 1 + clippy_lints/src/lib.register_lints.rs | 1 + clippy_lints/src/lib.rs | 2 + clippy_lints/src/manual_rem_euclid.rs | 110 ++++++++++++++++++++ clippy_utils/src/msrvs.rs | 2 +- tests/ui/manual_rem_euclid.fixed | 17 +++ tests/ui/manual_rem_euclid.rs | 17 +++ tests/ui/manual_rem_euclid.stderr | 34 ++++++ tests/ui/min_rust_version_attr.rs | 6 ++ tests/ui/min_rust_version_attr.stderr | 8 +- 12 files changed, 195 insertions(+), 5 deletions(-) create mode 100644 clippy_lints/src/manual_rem_euclid.rs create mode 100644 tests/ui/manual_rem_euclid.fixed create mode 100644 tests/ui/manual_rem_euclid.rs create mode 100644 tests/ui/manual_rem_euclid.stderr diff --git a/CHANGELOG.md b/CHANGELOG.md index d64dd772ac5..dcc96bc10b8 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -3527,6 +3527,7 @@ Released 2018-09-13 [`manual_non_exhaustive`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_non_exhaustive [`manual_ok_or`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_ok_or [`manual_range_contains`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_range_contains +[`manual_rem_euclid`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_rem_euclid [`manual_saturating_arithmetic`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_saturating_arithmetic [`manual_split_once`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_split_once [`manual_str_repeat`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_str_repeat diff --git a/clippy_lints/src/lib.register_all.rs b/clippy_lints/src/lib.register_all.rs index 7876f21f6e6..a1565255b0b 100644 --- a/clippy_lints/src/lib.register_all.rs +++ b/clippy_lints/src/lib.register_all.rs @@ -135,6 +135,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![ LintId::of(manual_async_fn::MANUAL_ASYNC_FN), LintId::of(manual_bits::MANUAL_BITS), LintId::of(manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE), + LintId::of(manual_rem_euclid::MANUAL_REM_EUCLID), LintId::of(manual_strip::MANUAL_STRIP), LintId::of(map_clone::MAP_CLONE), LintId::of(map_unit_fn::OPTION_MAP_UNIT_FN), diff --git a/clippy_lints/src/lib.register_complexity.rs b/clippy_lints/src/lib.register_complexity.rs index 4f1c3673f85..6370264a12a 100644 --- a/clippy_lints/src/lib.register_complexity.rs +++ b/clippy_lints/src/lib.register_complexity.rs @@ -24,6 +24,7 @@ store.register_group(true, "clippy::complexity", Some("clippy_complexity"), vec! LintId::of(loops::MANUAL_FLATTEN), LintId::of(loops::SINGLE_ELEMENT_LOOP), LintId::of(loops::WHILE_LET_LOOP), + LintId::of(manual_rem_euclid::MANUAL_REM_EUCLID), LintId::of(manual_strip::MANUAL_STRIP), LintId::of(map_unit_fn::OPTION_MAP_UNIT_FN), LintId::of(map_unit_fn::RESULT_MAP_UNIT_FN), diff --git a/clippy_lints/src/lib.register_lints.rs b/clippy_lints/src/lib.register_lints.rs index de22f50cf94..f706ba0620f 100644 --- a/clippy_lints/src/lib.register_lints.rs +++ b/clippy_lints/src/lib.register_lints.rs @@ -254,6 +254,7 @@ store.register_lints(&[ manual_bits::MANUAL_BITS, manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE, manual_ok_or::MANUAL_OK_OR, + manual_rem_euclid::MANUAL_REM_EUCLID, manual_strip::MANUAL_STRIP, map_clone::MAP_CLONE, map_err_ignore::MAP_ERR_IGNORE, diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index dcee11cc28c..70cf6be8b7c 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -282,6 +282,7 @@ mod manual_async_fn; mod manual_bits; mod manual_non_exhaustive; mod manual_ok_or; +mod manual_rem_euclid; mod manual_strip; mod map_clone; mod map_err_ignore; @@ -912,6 +913,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: store.register_late_pass(|| Box::new(as_underscore::AsUnderscore)); store.register_late_pass(|| Box::new(read_zero_byte_vec::ReadZeroByteVec)); store.register_late_pass(|| Box::new(default_instead_of_iter_empty::DefaultIterEmpty)); + store.register_late_pass(move || Box::new(manual_rem_euclid::ManualRemEuclid::new(msrv))); // add lints here, do not remove this comment, it's used in `new_lint` } diff --git a/clippy_lints/src/manual_rem_euclid.rs b/clippy_lints/src/manual_rem_euclid.rs new file mode 100644 index 00000000000..7ef8f78a5f6 --- /dev/null +++ b/clippy_lints/src/manual_rem_euclid.rs @@ -0,0 +1,110 @@ +use clippy_utils::consts::{constant_full_int, FullInt}; +use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::source::snippet_with_applicability; +use clippy_utils::{meets_msrv, msrvs, path_to_local}; +use if_chain::if_chain; +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}; + +declare_clippy_lint! { + /// ### What it does + /// Checks for an expression like `((x % 4) + 4) % 4` which is a common manual reimplementation + /// of `x.rem_euclid(4)`. + /// + /// ### Why is this bad? + /// It's simpler and more readable. + /// + /// ### Example + /// ```rust + /// let x = 24; + /// let rem = ((x % 4) + 4) % 4; + /// ``` + /// Use instead: + /// ```rust + /// let x = 24; + /// let rem = x.rem_euclid(4); + /// ``` + #[clippy::version = "1.63.0"] + pub MANUAL_REM_EUCLID, + complexity, + "manually reimplementing `rem_euclid`" +} + +pub struct ManualRemEuclid { + msrv: Option, +} + +impl ManualRemEuclid { + #[must_use] + pub fn new(msrv: Option) -> Self { + Self { msrv } + } +} + +impl_lint_pass!(ManualRemEuclid => [MANUAL_REM_EUCLID]); + +impl<'tcx> LateLintPass<'tcx> for ManualRemEuclid { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { + if !meets_msrv(self.msrv, msrvs::REM_EUCLID) { + return; + } + + if_chain! { + if let ExprKind::Binary(op1, ..) = expr.kind; + if op1.node == BinOpKind::Rem; + if let Some((const1, expr1)) = check_for_positive_int_constant(cx, expr); + if let ExprKind::Binary(op2, ..) = expr1.kind; + if op2.node == BinOpKind::Add; + if let Some((const2, expr2)) = check_for_positive_int_constant(cx, expr1); + if let ExprKind::Binary(op3, ..) = expr2.kind; + if op3.node == BinOpKind::Rem; + if let Some((const3, expr3)) = check_for_positive_int_constant(cx, expr2); + if const1 == const2 && const2 == const3; + if path_to_local(expr3).is_some(); + then { + let mut app = Applicability::MachineApplicable; + let rem_of = snippet_with_applicability(cx, expr3.span, "_", &mut app); + span_lint_and_sugg( + cx, + MANUAL_REM_EUCLID, + expr.span, + "manual `rem_euclid` implementation", + "consider using", + format!("{rem_of}.rem_euclid({const1})"), + app, + ); + } + } + } + + extract_msrv_attr!(LateContext); +} + +// Takes a binary expression and separates the operands into the int constant and the other +// operand. Ensures the int constant is positive. +fn check_for_positive_int_constant<'a>(cx: &'a LateContext<'_>, expr: &'a Expr<'_>) -> Option<(u128, &'a Expr<'a>)> { + let (int_const, other_op) = if let ExprKind::Binary(_, left, right) = expr.kind { + if let Some(int_const) = constant_full_int(cx, cx.typeck_results(), left) { + (int_const, right) + } else if let Some(int_const) = constant_full_int(cx, cx.typeck_results(), right) { + (int_const, left) + } else { + return None; + } + } else { + return None; + }; + + if int_const > FullInt::S(0) { + let val = match int_const { + FullInt::S(s) => s.try_into().unwrap(), + FullInt::U(u) => u, + }; + Some((val, other_op)) + } else { + None + } +} diff --git a/clippy_utils/src/msrvs.rs b/clippy_utils/src/msrvs.rs index b9ec2c19fdd..8000f9e21a1 100644 --- a/clippy_utils/src/msrvs.rs +++ b/clippy_utils/src/msrvs.rs @@ -23,7 +23,7 @@ msrv_aliases! { 1,42,0 { MATCHES_MACRO, SLICE_PATTERNS, PTR_SLICE_RAW_PARTS } 1,41,0 { RE_REBALANCING_COHERENCE, RESULT_MAP_OR_ELSE } 1,40,0 { MEM_TAKE, NON_EXHAUSTIVE, OPTION_AS_DEREF } - 1,38,0 { POINTER_CAST } + 1,38,0 { POINTER_CAST, REM_EUCLID } 1,37,0 { TYPE_ALIAS_ENUM_VARIANTS } 1,36,0 { ITERATOR_COPIED } 1,35,0 { OPTION_COPIED, RANGE_CONTAINS } diff --git a/tests/ui/manual_rem_euclid.fixed b/tests/ui/manual_rem_euclid.fixed new file mode 100644 index 00000000000..f176fc9ad12 --- /dev/null +++ b/tests/ui/manual_rem_euclid.fixed @@ -0,0 +1,17 @@ +// run-rustfix + +#![warn(clippy::manual_rem_euclid)] + +fn main() { + let value: i32 = 5; + + let _: i32 = value.rem_euclid(4); + let _: i32 = value.rem_euclid(4); + let _: i32 = value.rem_euclid(4); + let _: i32 = value.rem_euclid(4); + let _: i32 = 1 + value.rem_euclid(4); + + let _: i32 = (3 + value % 4) % 4; + let _: i32 = (-4 + value % -4) % -4; + let _: i32 = ((5 % 4) + 4) % 4; +} diff --git a/tests/ui/manual_rem_euclid.rs b/tests/ui/manual_rem_euclid.rs new file mode 100644 index 00000000000..b243065de87 --- /dev/null +++ b/tests/ui/manual_rem_euclid.rs @@ -0,0 +1,17 @@ +// run-rustfix + +#![warn(clippy::manual_rem_euclid)] + +fn main() { + let value: i32 = 5; + + let _: i32 = ((value % 4) + 4) % 4; + let _: i32 = (4 + (value % 4)) % 4; + let _: i32 = (value % 4 + 4) % 4; + let _: i32 = (4 + value % 4) % 4; + let _: i32 = 1 + (4 + value % 4) % 4; + + let _: i32 = (3 + value % 4) % 4; + let _: i32 = (-4 + value % -4) % -4; + let _: i32 = ((5 % 4) + 4) % 4; +} diff --git a/tests/ui/manual_rem_euclid.stderr b/tests/ui/manual_rem_euclid.stderr new file mode 100644 index 00000000000..7134759dcc9 --- /dev/null +++ b/tests/ui/manual_rem_euclid.stderr @@ -0,0 +1,34 @@ +error: manual `rem_euclid` implementation + --> $DIR/manual_rem_euclid.rs:8:18 + | +LL | let _: i32 = ((value % 4) + 4) % 4; + | ^^^^^^^^^^^^^^^^^^^^^ help: consider using: `value.rem_euclid(4)` + | + = note: `-D clippy::manual-rem-euclid` implied by `-D warnings` + +error: manual `rem_euclid` implementation + --> $DIR/manual_rem_euclid.rs:9:18 + | +LL | let _: i32 = (4 + (value % 4)) % 4; + | ^^^^^^^^^^^^^^^^^^^^^ help: consider using: `value.rem_euclid(4)` + +error: manual `rem_euclid` implementation + --> $DIR/manual_rem_euclid.rs:10:18 + | +LL | let _: i32 = (value % 4 + 4) % 4; + | ^^^^^^^^^^^^^^^^^^^ help: consider using: `value.rem_euclid(4)` + +error: manual `rem_euclid` implementation + --> $DIR/manual_rem_euclid.rs:11:18 + | +LL | let _: i32 = (4 + value % 4) % 4; + | ^^^^^^^^^^^^^^^^^^^ help: consider using: `value.rem_euclid(4)` + +error: manual `rem_euclid` implementation + --> $DIR/manual_rem_euclid.rs:12:22 + | +LL | let _: i32 = 1 + (4 + value % 4) % 4; + | ^^^^^^^^^^^^^^^^^^^ help: consider using: `value.rem_euclid(4)` + +error: aborting due to 5 previous errors + diff --git a/tests/ui/min_rust_version_attr.rs b/tests/ui/min_rust_version_attr.rs index f83c3e0e281..301a8e54ccf 100644 --- a/tests/ui/min_rust_version_attr.rs +++ b/tests/ui/min_rust_version_attr.rs @@ -155,6 +155,11 @@ fn cast_abs_to_unsigned() { assert_eq!(10u32, x.abs() as u32); } +fn manual_rem_euclid() { + let x: i32 = 10; + let _: i32 = ((x % 4) + 4) % 4; +} + fn main() { filter_map_next(); checked_conversion(); @@ -174,6 +179,7 @@ fn main() { int_from_bool(); err_expect(); cast_abs_to_unsigned(); + manual_rem_euclid(); } mod just_under_msrv { diff --git a/tests/ui/min_rust_version_attr.stderr b/tests/ui/min_rust_version_attr.stderr index de225eb740d..b1c23b539ff 100644 --- a/tests/ui/min_rust_version_attr.stderr +++ b/tests/ui/min_rust_version_attr.stderr @@ -1,12 +1,12 @@ error: stripping a prefix manually - --> $DIR/min_rust_version_attr.rs:198:24 + --> $DIR/min_rust_version_attr.rs:204:24 | LL | assert_eq!(s["hello, ".len()..].to_uppercase(), "WORLD!"); | ^^^^^^^^^^^^^^^^^^^^ | = note: `-D clippy::manual-strip` implied by `-D warnings` note: the prefix was tested here - --> $DIR/min_rust_version_attr.rs:197:9 + --> $DIR/min_rust_version_attr.rs:203:9 | LL | if s.starts_with("hello, ") { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -17,13 +17,13 @@ LL ~ assert_eq!(.to_uppercase(), "WORLD!"); | error: stripping a prefix manually - --> $DIR/min_rust_version_attr.rs:210:24 + --> $DIR/min_rust_version_attr.rs:216:24 | LL | assert_eq!(s["hello, ".len()..].to_uppercase(), "WORLD!"); | ^^^^^^^^^^^^^^^^^^^^ | note: the prefix was tested here - --> $DIR/min_rust_version_attr.rs:209:9 + --> $DIR/min_rust_version_attr.rs:215:9 | LL | if s.starts_with("hello, ") { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^