refactor(integer_division_remainder_used): move to under operators (#15953)

changelog: none

Author: samueltardieu

clippy_lints/src/declared_lints.rs

@@ -227,7 +227,6 @@ pub static LINTS: &[&::declare_clippy_lint::LintInfo] = &[
     crate::init_numbered_fields::INIT_NUMBERED_FIELDS_INFO,
     crate::inline_fn_without_body::INLINE_FN_WITHOUT_BODY_INFO,
     crate::int_plus_one::INT_PLUS_ONE_INFO,
-    crate::integer_division_remainder_used::INTEGER_DIVISION_REMAINDER_USED_INFO,
     crate::item_name_repetitions::ENUM_VARIANT_NAMES_INFO,
     crate::item_name_repetitions::MODULE_INCEPTION_INFO,
     crate::item_name_repetitions::MODULE_NAME_REPETITIONS_INFO,
@@ -590,6 +589,7 @@ pub static LINTS: &[&::declare_clippy_lint::LintInfo] = &[
     crate::operators::IMPOSSIBLE_COMPARISONS_INFO,
     crate::operators::INEFFECTIVE_BIT_MASK_INFO,
     crate::operators::INTEGER_DIVISION_INFO,
+    crate::operators::INTEGER_DIVISION_REMAINDER_USED_INFO,
     crate::operators::INVALID_UPCAST_COMPARISONS_INFO,
     crate::operators::MANUAL_DIV_CEIL_INFO,
     crate::operators::MANUAL_IS_MULTIPLE_OF_INFO,

clippy_lints/src/integer_division_remainder_used.rs

@@ -171,7 +171,6 @@ mod inherent_to_string;
 mod init_numbered_fields;
 mod inline_fn_without_body;
 mod int_plus_one;
-mod integer_division_remainder_used;
 mod item_name_repetitions;
 mod items_after_statements;
 mod items_after_test_module;
@@ -793,7 +792,6 @@ pub fn register_lint_passes(store: &mut rustc_lint::LintStore, conf: &'static Co
     store.register_early_pass(|| Box::new(multiple_bound_locations::MultipleBoundLocations));
     store.register_late_pass(move |_| Box::new(assigning_clones::AssigningClones::new(conf)));
     store.register_late_pass(|_| Box::new(zero_repeat_side_effects::ZeroRepeatSideEffects));
-    store.register_late_pass(|_| Box::new(integer_division_remainder_used::IntegerDivisionRemainderUsed));
     store.register_late_pass(move |_| Box::new(macro_metavars_in_unsafe::ExprMetavarsInUnsafe::new(conf)));
     store.register_late_pass(move |_| Box::new(string_patterns::StringPatterns::new(conf)));
     store.register_early_pass(|| Box::new(field_scoped_visibility_modifiers::FieldScopedVisibilityModifiers));

clippy_lints/src/lib.rs

@@ -0,0 +1,24 @@
+use clippy_utils::diagnostics::span_lint;
+use rustc_ast::BinOpKind;
+use rustc_hir::Expr;
+use rustc_lint::LateContext;
+use rustc_middle::ty;
+use rustc_span::Span;
+
+use super::INTEGER_DIVISION_REMAINDER_USED;
+
+pub(super) fn check(cx: &LateContext<'_>, op: BinOpKind, lhs: &Expr<'_>, rhs: &Expr<'_>, span: Span) {
+    if let BinOpKind::Div | BinOpKind::Rem = op
+        && let lhs_ty = cx.typeck_results().expr_ty(lhs)
+        && let rhs_ty = cx.typeck_results().expr_ty(rhs)
+        && let ty::Int(_) | ty::Uint(_) = lhs_ty.peel_refs().kind()
+        && let ty::Int(_) | ty::Uint(_) = rhs_ty.peel_refs().kind()
+    {
+        span_lint(
+            cx,
+            INTEGER_DIVISION_REMAINDER_USED,
+            span.source_callsite(),
+            format!("use of `{}` has been disallowed in this context", op.as_str()),
+        );
+    }
+}

clippy_lints/src/operators/integer_division_remainder_used.rs

@@ -11,6 +11,7 @@ mod float_cmp;
 mod float_equality_without_abs;
 mod identity_op;
 mod integer_division;
+mod integer_division_remainder_used;
 mod invalid_upcast_comparisons;
 mod manual_div_ceil;
 mod manual_is_multiple_of;
@@ -911,6 +912,29 @@ declare_clippy_lint! {
     "a comparison involving an upcast which is always true or false"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for the usage of division (`/`) and remainder (`%`) operations
+    /// when performed on any integer types using the default `Div` and `Rem` trait implementations.
+    ///
+    /// ### Why restrict this?
+    /// In cryptographic contexts, division can result in timing sidechannel vulnerabilities,
+    /// and needs to be replaced with constant-time code instead (e.g. Barrett reduction).
+    ///
+    /// ### Example
+    /// ```no_run
+    /// let my_div = 10 / 2;
+    /// ```
+    /// Use instead:
+    /// ```no_run
+    /// let my_div = 10 >> 1;
+    /// ```
+    #[clippy::version = "1.79.0"]
+    pub INTEGER_DIVISION_REMAINDER_USED,
+    restriction,
+    "use of disallowed default division and remainder operations"
+}
+
 pub struct Operators {
     arithmetic_context: numeric_arithmetic::Context,
     verbose_bit_mask_threshold: u64,
@@ -948,6 +972,7 @@ impl_lint_pass!(Operators => [
     FLOAT_EQUALITY_WITHOUT_ABS,
     IDENTITY_OP,
     INTEGER_DIVISION,
+    INTEGER_DIVISION_REMAINDER_USED,
     CMP_OWNED,
     FLOAT_CMP,
     FLOAT_CMP_CONST,
@@ -987,6 +1012,7 @@ impl<'tcx> LateLintPass<'tcx> for Operators {
                 duration_subsec::check(cx, e, op.node, lhs, rhs);
                 float_equality_without_abs::check(cx, e, op.node, lhs, rhs);
                 integer_division::check(cx, e, op.node, lhs, rhs);
+                integer_division_remainder_used::check(cx, op.node, lhs, rhs, e.span);
                 cmp_owned::check(cx, op.node, lhs, rhs);
                 float_cmp::check(cx, e, op.node, lhs, rhs);
                 modulo_one::check(cx, e, op.node, rhs);

clippy_lints/src/operators/mod.rs

@@ -1,4 +1,4 @@
-error: use of / has been disallowed in this context
+error: use of `/` has been disallowed in this context
   --> tests/ui/integer_division_remainder_used.rs:10:14
    |
 LL |         Self(self.0 / rhs.0)
@@ -7,49 +7,49 @@ LL |         Self(self.0 / rhs.0)
    = note: `-D clippy::integer-division-remainder-used` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::integer_division_remainder_used)]`
 
-error: use of % has been disallowed in this context
+error: use of `%` has been disallowed in this context
   --> tests/ui/integer_division_remainder_used.rs:18:14
    |
 LL |         Self(self.0 % rhs.0)
    |              ^^^^^^^^^^^^^^
 
-error: use of / has been disallowed in this context
+error: use of `/` has been disallowed in this context
   --> tests/ui/integer_division_remainder_used.rs:27:13
    |
 LL |     let c = a / b;
    |             ^^^^^
 
-error: use of % has been disallowed in this context
+error: use of `%` has been disallowed in this context
   --> tests/ui/integer_division_remainder_used.rs:29:13
    |
 LL |     let d = a % b;
    |             ^^^^^
 
-error: use of / has been disallowed in this context
+error: use of `/` has been disallowed in this context
   --> tests/ui/integer_division_remainder_used.rs:31:13
    |
 LL |     let e = &a / b;
    |             ^^^^^^
 
-error: use of % has been disallowed in this context
+error: use of `%` has been disallowed in this context
   --> tests/ui/integer_division_remainder_used.rs:33:13
    |
 LL |     let f = a % &b;
    |             ^^^^^^
 
-error: use of / has been disallowed in this context
+error: use of `/` has been disallowed in this context
   --> tests/ui/integer_division_remainder_used.rs:35:13
    |
 LL |     let g = &a / &b;
    |             ^^^^^^^
 
-error: use of % has been disallowed in this context
+error: use of `%` has been disallowed in this context
   --> tests/ui/integer_division_remainder_used.rs:37:13
    |
 LL |     let h = &10 % b;
    |             ^^^^^^^
 
-error: use of / has been disallowed in this context
+error: use of `/` has been disallowed in this context
   --> tests/ui/integer_division_remainder_used.rs:39:13
    |
 LL |     let i = a / &4;