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Fix subtraction overflow in cast_possible_truncation

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This commit is contained in:
Alex Macleod 2022-04-11 18:54:44 +01:00
parent c7e6863843
commit 4a21082da2
3 changed files with 33 additions and 15 deletions
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20
clippy_lints/src/casts/cast_possible_truncation.rs
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@ -29,21 +29,19 @@ fn apply_reductions(cx: &LateContext<'_>, nbits: u64, expr: &Expr<'_>, signed: b
ExprKind::Block(block, _) => block.expr.map_or(nbits, |e| apply_reductions(cx, nbits, e, signed)),
ExprKind::Binary(op, left, right) => match op.node {
BinOpKind::Div => {
apply_reductions(cx, nbits, left, signed)
- (if signed {
0 // let's be conservative here
} else {
// by dividing by 1, we remove 0 bits, etc.
get_constant_bits(cx, right).map_or(0, |b| b.saturating_sub(1))
})
apply_reductions(cx, nbits, left, signed).saturating_sub(if signed {
// let's be conservative here
0
} else {
// by dividing by 1, we remove 0 bits, etc.
get_constant_bits(cx, right).map_or(0, |b| b.saturating_sub(1))
})
},
BinOpKind::Rem | BinOpKind::BitAnd => get_constant_bits(cx, right)
.unwrap_or(u64::max_value())
.min(apply_reductions(cx, nbits, left, signed)),
BinOpKind::Shr => {
apply_reductions(cx, nbits, left, signed)
- constant_int(cx, right).map_or(0, |s| u64::try_from(s).expect("shift too high"))
},
BinOpKind::Shr => apply_reductions(cx, nbits, left, signed)
.saturating_sub(constant_int(cx, right).map_or(0, |s| u64::try_from(s).expect("shift too high"))),
_ => nbits,
},
ExprKind::MethodCall(method, [left, right], _) => {