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Auto merge of #10309 - c410-f3r:arith, r=giraffate

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[arithmetic_side_effects] Fix #10252

Fix #10252

At least for integers, shifts are already handled by the compiler.

----

changelog: [`arithmetic_side_effects`]: No longer lints on right or left shifts with constant integers, as the compiler warns about them.
[#10309](https://github.com/rust-lang/rust-clippy/pull/10309)
<!-- changelog_checked-->
This commit is contained in:
bors 2023-03-09 13:30:11 +00:00
commit ea4ebed2ed
3 changed files with 206 additions and 123 deletions
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13
clippy_lints/src/operators/arithmetic_side_effects.rs
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@ -143,6 +143,10 @@ impl ArithmeticSideEffects {
return;
}
let has_valid_op = if Self::is_integral(lhs_ty) && Self::is_integral(rhs_ty) {
if let hir::BinOpKind::Shl | hir::BinOpKind::Shr = op.node {
// At least for integers, shifts are already handled by the CTFE
return;
}
let (actual_lhs, lhs_ref_counter) = peel_hir_expr_refs(lhs);
let (actual_rhs, rhs_ref_counter) = peel_hir_expr_refs(rhs);
match (
@ -151,10 +155,13 @@ impl ArithmeticSideEffects {
) {
(None, None) => false,
(None, Some(n)) | (Some(n), None) => match (&op.node, n) {
(hir::BinOpKind::Div | hir::BinOpKind::Rem, 0) => false,
// Division and module are always valid if applied to non-zero integers
(hir::BinOpKind::Div | hir::BinOpKind::Rem, local_n) if local_n != 0 => true,
// Addition or subtracting zeros is always a no-op
(hir::BinOpKind::Add | hir::BinOpKind::Sub, 0)
| (hir::BinOpKind::Div | hir::BinOpKind::Rem, _)
| (hir::BinOpKind::Mul, 0 | 1) => true,
// Multiplication by 1 or 0 will never overflow
| (hir::BinOpKind::Mul, 0 | 1)
=> true,
_ => false,
},
(Some(_), Some(_)) => {