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use crate::consts::constant_simple;
use crate::utils::span_lint;
use rustc_hir as hir;
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::source_map::Span;
declare_clippy_lint! {
/// **What it does:** Checks for plain integer arithmetic.
///
/// **Why is this bad?** This is only checked against overflow in debug builds.
/// In some applications one wants explicitly checked, wrapping or saturating
/// arithmetic.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # let a = 0;
/// a + 1;
/// ```
pub INTEGER_ARITHMETIC,
restriction,
"any integer arithmetic statement"
}
declare_clippy_lint! {
/// **What it does:** Checks for float arithmetic.
///
/// **Why is this bad?** For some embedded systems or kernel development, it
/// can be useful to rule out floating-point numbers.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # let a = 0.0;
/// a + 1.0;
/// ```
pub FLOAT_ARITHMETIC,
restriction,
"any floating-point arithmetic statement"
}
#[derive(Copy, Clone, Default)]
pub struct Arithmetic {
expr_span: Option<Span>,
/// This field is used to check whether expressions are constants, such as in enum discriminants
/// and consts
const_span: Option<Span>,
}
impl_lint_pass!(Arithmetic => [INTEGER_ARITHMETIC, FLOAT_ARITHMETIC]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Arithmetic {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr<'_>) {
if self.expr_span.is_some() {
return;
}
if let Some(span) = self.const_span {
if span.contains(expr.span) {
return;
}
}
match &expr.kind {
hir::ExprKind::Binary(op, l, r) | hir::ExprKind::AssignOp(op, l, r) => {
match op.node {
hir::BinOpKind::And
| hir::BinOpKind::Or
| hir::BinOpKind::BitAnd
| hir::BinOpKind::BitOr
| hir::BinOpKind::BitXor
| hir::BinOpKind::Shl
| hir::BinOpKind::Shr
| hir::BinOpKind::Eq
| hir::BinOpKind::Lt
| hir::BinOpKind::Le
| hir::BinOpKind::Ne
| hir::BinOpKind::Ge
| hir::BinOpKind::Gt => return,
_ => (),
}
let (l_ty, r_ty) = (cx.tables.expr_ty(l), cx.tables.expr_ty(r));
if l_ty.is_integral() && r_ty.is_integral() {
span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
self.expr_span = Some(expr.span);
} else if l_ty.is_floating_point() && r_ty.is_floating_point() {
span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected");
self.expr_span = Some(expr.span);
}
},
hir::ExprKind::Unary(hir::UnOp::UnNeg, arg) => {
let ty = cx.tables.expr_ty(arg);
if constant_simple(cx, cx.tables, expr).is_none() {
if ty.is_integral() {
span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
self.expr_span = Some(expr.span);
} else if ty.is_floating_point() {
span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected");
self.expr_span = Some(expr.span);
}
}
},
_ => (),
}
}
fn check_expr_post(&mut self, _: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr<'_>) {
if Some(expr.span) == self.expr_span {
self.expr_span = None;
}
}
fn check_body(&mut self, cx: &LateContext<'_, '_>, body: &hir::Body<'_>) {
let body_owner = cx.tcx.hir().body_owner(body.id());
match cx.tcx.hir().body_owner_kind(body_owner) {
hir::BodyOwnerKind::Static(_) | hir::BodyOwnerKind::Const => {
let body_span = cx.tcx.hir().span(body_owner);
if let Some(span) = self.const_span {
if span.contains(body_span) {
return;
}
}
self.const_span = Some(body_span);
},
hir::BodyOwnerKind::Fn | hir::BodyOwnerKind::Closure => (),
}
}
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 {
if span.contains(body_span) {
return;
}
}
self.const_span = None;
}
}
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