//! lint on indexing and slicing operations
use crate::consts::{constant, Constant};
-use crate::utils;
-use crate::utils::higher;
-use crate::utils::higher::Range;
-use rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::ty;
-use rustc::{declare_tool_lint, lint_array};
-use syntax::ast::RangeLimits;
+use crate::utils::{higher, span_lint, span_lint_and_help};
+use rustc_ast::ast::RangeLimits;
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
-/// **What it does:** Checks for out of bounds array indexing with a constant
-/// index.
-///
-/// **Why is this bad?** This will always panic at runtime.
-///
-/// **Known problems:** Hopefully none.
-///
-/// **Example:**
-/// ```rust
-/// let x = [1, 2, 3, 4];
-///
-/// // Bad
-/// x[9];
-/// &x[2..9];
-///
-/// // Good
-/// x[0];
-/// x[3];
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for out of bounds array indexing with a constant
+ /// index.
+ ///
+ /// **Why is this bad?** This will always panic at runtime.
+ ///
+ /// **Known problems:** Hopefully none.
+ ///
+ /// **Example:**
+ /// ```no_run
+ /// # #![allow(const_err)]
+ /// let x = [1, 2, 3, 4];
+ ///
+ /// // Bad
+ /// x[9];
+ /// &x[2..9];
+ ///
+ /// // Good
+ /// x[0];
+ /// x[3];
+ /// ```
pub OUT_OF_BOUNDS_INDEXING,
correctness,
"out of bounds constant indexing"
}
-/// **What it does:** Checks for usage of indexing or slicing. Arrays are special cased, this lint
-/// does report on arrays if we can tell that slicing operations are in bounds and does not
-/// lint on constant `usize` indexing on arrays because that is handled by rustc's `const_err` lint.
-///
-/// **Why is this bad?** Indexing and slicing can panic at runtime and there are
-/// safe alternatives.
-///
-/// **Known problems:** Hopefully none.
-///
-/// **Example:**
-/// ```rust
-/// // Vector
-/// let x = vec![0; 5];
-///
-/// // Bad
-/// x[2];
-/// &x[2..100];
-/// &x[2..];
-/// &x[..100];
-///
-/// // Good
-/// x.get(2);
-/// x.get(2..100);
-/// x.get(2..);
-/// x.get(..100);
-///
-/// // Array
-/// let y = [0, 1, 2, 3];
-///
-/// // Bad
-/// &y[10..100];
-/// &y[10..];
-/// &y[..100];
-///
-/// // Good
-/// &y[2..];
-/// &y[..2];
-/// &y[0..3];
-/// y.get(10);
-/// y.get(10..100);
-/// y.get(10..);
-/// y.get(..100);
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for usage of indexing or slicing. Arrays are special cases, this lint
+ /// does report on arrays if we can tell that slicing operations are in bounds and does not
+ /// lint on constant `usize` indexing on arrays because that is handled by rustc's `const_err` lint.
+ ///
+ /// **Why is this bad?** Indexing and slicing can panic at runtime and there are
+ /// safe alternatives.
+ ///
+ /// **Known problems:** Hopefully none.
+ ///
+ /// **Example:**
+ /// ```rust,no_run
+ /// // Vector
+ /// let x = vec![0; 5];
+ ///
+ /// // Bad
+ /// x[2];
+ /// &x[2..100];
+ /// &x[2..];
+ /// &x[..100];
+ ///
+ /// // Good
+ /// x.get(2);
+ /// x.get(2..100);
+ /// x.get(2..);
+ /// x.get(..100);
+ ///
+ /// // Array
+ /// let y = [0, 1, 2, 3];
+ ///
+ /// // Bad
+ /// &y[10..100];
+ /// &y[10..];
+ /// &y[..100];
+ ///
+ /// // Good
+ /// &y[2..];
+ /// &y[..2];
+ /// &y[0..3];
+ /// y.get(10);
+ /// y.get(10..100);
+ /// y.get(10..);
+ /// y.get(..100);
+ /// ```
pub INDEXING_SLICING,
restriction,
"indexing/slicing usage"
}
-#[derive(Copy, Clone)]
-pub struct IndexingSlicing;
-
-impl LintPass for IndexingSlicing {
- fn get_lints(&self) -> LintArray {
- lint_array!(INDEXING_SLICING, OUT_OF_BOUNDS_INDEXING)
- }
-
- fn name(&self) -> &'static str {
- "IndexSlicing"
- }
-}
+declare_lint_pass!(IndexingSlicing => [INDEXING_SLICING, OUT_OF_BOUNDS_INDEXING]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IndexingSlicing {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
- if let ExprKind::Index(ref array, ref index) = &expr.node {
- let ty = cx.tables.expr_ty(array);
+ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
+ if let ExprKind::Index(ref array, ref index) = &expr.kind {
+ let ty = cx.tables().expr_ty(array);
if let Some(range) = higher::range(cx, index) {
- // Ranged indexes, i.e. &x[n..m], &x[n..], &x[..n] and &x[..]
- if let ty::Array(_, s) = ty.sty {
- let size: u128 = s.assert_usize(cx.tcx).unwrap().into();
+ // Ranged indexes, i.e., &x[n..m], &x[n..], &x[..n] and &x[..]
+ if let ty::Array(_, s) = ty.kind {
+ let size: u128 = if let Some(size) = s.try_eval_usize(cx.tcx, cx.param_env) {
+ size.into()
+ } else {
+ return;
+ };
let const_range = to_const_range(cx, range, size);
if let (Some(start), _) = const_range {
if start > size {
- utils::span_lint(
+ span_lint(
cx,
OUT_OF_BOUNDS_INDEXING,
range.start.map_or(expr.span, |start| start.span),
if let (_, Some(end)) = const_range {
if end > size {
- utils::span_lint(
+ span_lint(
cx,
OUT_OF_BOUNDS_INDEXING,
range.end.map_or(expr.span, |end| end.span),
(None, None) => return, // [..] is ok.
};
- utils::span_help_and_lint(cx, INDEXING_SLICING, expr.span, "slicing may panic.", help_msg);
+ span_lint_and_help(cx, INDEXING_SLICING, expr.span, "slicing may panic.", None, help_msg);
} else {
- // Catchall non-range index, i.e. [n] or [n << m]
- if let ty::Array(..) = ty.sty {
+ // Catchall non-range index, i.e., [n] or [n << m]
+ if let ty::Array(..) = ty.kind {
// Index is a constant uint.
- if let Some(..) = constant(cx, cx.tables, index) {
+ if let Some(..) = constant(cx, cx.tables(), index) {
// Let rustc's `const_err` lint handle constant `usize` indexing on arrays.
return;
}
}
- utils::span_help_and_lint(
+ span_lint_and_help(
cx,
INDEXING_SLICING,
expr.span,
"indexing may panic.",
+ None,
"Consider using `.get(n)` or `.get_mut(n)` instead",
);
}
/// the range. If the start or end is not constant, None is returned.
fn to_const_range<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
- range: Range<'_>,
+ range: higher::Range<'_>,
array_size: u128,
) -> (Option<u128>, Option<u128>) {
- let s = range.start.map(|expr| constant(cx, cx.tables, expr).map(|(c, _)| c));
+ let s = range.start.map(|expr| constant(cx, cx.tables(), expr).map(|(c, _)| c));
let start = match s {
Some(Some(Constant::Int(x))) => Some(x),
Some(_) => None,
None => Some(0),
};
- let e = range.end.map(|expr| constant(cx, cx.tables, expr).map(|(c, _)| c));
+ let e = range.end.map(|expr| constant(cx, cx.tables(), expr).map(|(c, _)| c));
let end = match e {
Some(Some(Constant::Int(x))) => {
if range.limits == RangeLimits::Closed {
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