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Use the visitor pattern instead of recusive functions

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teor 2024-01-16 18:56:51 +10:00
parent 4ab2ed33a0
commit 740441fd98
1 changed files with 18 additions and 12 deletions
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30
clippy_lints/src/casts/cast_sign_loss.rs
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@ -1,5 +1,8 @@
use std::ops::ControlFlow;
use clippy_utils::consts::{constant, Constant};
use clippy_utils::diagnostics::span_lint;
use clippy_utils::visitors::{for_each_expr, Descend};
use clippy_utils::{method_chain_args, sext};
use rustc_hir::{BinOpKind, Expr, ExprKind};
use rustc_lint::LateContext;
@ -216,34 +219,37 @@ fn expr_muldiv_sign(cx: &LateContext<'_>, expr: &Expr<'_>) -> Sign {
///
/// Expressions using other operators are preserved, so we can try to evaluate them later.
fn exprs_with_muldiv_binop_peeled<'e>(expr: &'e Expr<'_>) -> Vec<&'e Expr<'e>> {
#[inline]
fn collect_operands<'e>(expr: &'e Expr<'e>, operands: &mut Vec<&'e Expr<'e>>) {
match expr.kind {
ExprKind::Binary(op, lhs, rhs) => {
let mut res = vec![];
for_each_expr(expr, |sub_expr| {
match sub_expr.kind {
ExprKind::Binary(op, lhs, _rhs) => {
if matches!(op.node, BinOpKind::Mul | BinOpKind::Div) {
// For binary operators which both contribute to the sign of the result,
// collect all their operands, recursively. This ignores overflow.
collect_operands(lhs, operands);
collect_operands(rhs, operands);
ControlFlow::Continue(Descend::Yes)
} else if matches!(op.node, BinOpKind::Rem) {
// For binary operators where the left hand side determines the sign of the result,
// only collect that side, recursively. Overflow panics, so this always holds.
//
// > Given remainder = dividend % divisor, the remainder will have the same sign as the dividend
// https://doc.rust-lang.org/reference/expressions/operator-expr.html#arithmetic-and-logical-binary-operators
collect_operands(lhs, operands);
res.push(lhs);
ControlFlow::Break(())
} else {
// The sign of the result of other binary operators depends on the values of the operands,
// so try to evaluate the expression.
operands.push(expr);
res.push(expr);
ControlFlow::Continue(Descend::No)
}
},
// For other expressions, including unary operators and constants, try to evaluate the expression.
_ => operands.push(expr),
_ => {
res.push(expr);
ControlFlow::Continue(Descend::No)
},
}
}
});
let mut res = vec![];
collect_operands(expr, &mut res);
res
}