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|
#![allow(
// False positive
clippy::match_same_arms
)]
use super::ARITHMETIC;
use clippy_utils::{consts::constant_simple, diagnostics::span_lint};
use rustc_data_structures::fx::FxHashSet;
use rustc_hir as hir;
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::impl_lint_pass;
use rustc_span::source_map::Span;
const HARD_CODED_ALLOWED: &[&str] = &["std::num::Saturating", "std::string::String", "std::num::Wrapping"];
#[derive(Debug)]
pub struct Arithmetic {
allowed: FxHashSet<String>,
// Used to check whether expressions are constants, such as in enum discriminants and consts
const_span: Option<Span>,
expr_span: Option<Span>,
}
impl_lint_pass!(Arithmetic => [ARITHMETIC]);
impl Arithmetic {
#[must_use]
pub fn new(mut allowed: FxHashSet<String>) -> Self {
allowed.extend(HARD_CODED_ALLOWED.iter().copied().map(String::from));
Self {
allowed,
const_span: None,
expr_span: None,
}
}
/// Checks if the given `expr` has any of the inner `allowed` elements.
fn is_allowed_ty(&self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
self.allowed.contains(
cx.typeck_results()
.expr_ty(expr)
.to_string()
.split('<')
.next()
.unwrap_or_default(),
)
}
fn issue_lint(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
span_lint(cx, ARITHMETIC, expr.span, "arithmetic detected");
self.expr_span = Some(expr.span);
}
}
impl<'tcx> LateLintPass<'tcx> for Arithmetic {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
if self.expr_span.is_some() {
return;
}
if let Some(span) = self.const_span && span.contains(expr.span) {
return;
}
match &expr.kind {
hir::ExprKind::Binary(op, lhs, rhs) | hir::ExprKind::AssignOp(op, lhs, rhs) => {
let (
hir::BinOpKind::Add
| hir::BinOpKind::Sub
| hir::BinOpKind::Mul
| hir::BinOpKind::Div
| hir::BinOpKind::Rem
| hir::BinOpKind::Shl
| hir::BinOpKind::Shr
) = op.node else {
return;
};
if self.is_allowed_ty(cx, lhs) || self.is_allowed_ty(cx, rhs) {
return;
}
self.issue_lint(cx, expr);
},
hir::ExprKind::Unary(hir::UnOp::Neg, _) => {
// CTFE already takes care of things like `-1` that do not overflow.
if constant_simple(cx, cx.typeck_results(), expr).is_none() {
self.issue_lint(cx, expr);
}
},
_ => {},
}
}
fn check_body(&mut self, cx: &LateContext<'_>, body: &hir::Body<'_>) {
let body_owner = cx.tcx.hir().body_owner_def_id(body.id());
match cx.tcx.hir().body_owner_kind(body_owner) {
hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => {
let body_span = cx.tcx.def_span(body_owner);
if let Some(span) = self.const_span && span.contains(body_span) {
return;
}
self.const_span = Some(body_span);
},
hir::BodyOwnerKind::Closure | hir::BodyOwnerKind::Fn => {},
}
}
fn check_body_post(&mut self, cx: &LateContext<'_>, body: &hir::Body<'_>) {
let body_owner = cx.tcx.hir().body_owner(body.id());
let body_span = cx.tcx.hir().span(body_owner);
if let Some(span) = self.const_span && span.contains(body_span) {
return;
}
self.const_span = None;
}
fn check_expr_post(&mut self, _: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
if Some(expr.span) == self.expr_span {
self.expr_span = None;
}
}
}
|
