This commit removes the logic in this PR that linted out-of-bounds constant `usize` indexing on arrays. That case is already handled by rustc's `const_err` lint. Beyond removing the linting logic, the test file and its associated stderr were updated to verify that const `usize` indexing operations on arrays are no longer handled by this `indexing_slicing` lint.
"out of bounds constant indexing"
}
-/// **What it does:** Checks for usage of indexing or slicing. Does not report
-/// on arrays if we can tell that the indexing or slicing operations are in
-/// bounds.
+/// **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.
/// let y = [0, 1, 2, 3];
///
/// // Bad
-/// y[10];
/// &y[10..100];
/// &y[10..];
/// &y[..100];
///
/// // Good
-/// y[2];
/// &y[2..];
/// &y[..2];
/// &y[0..3];
);
} else {
// Catchall non-range index, i.e. [n] or [n << m]
- if let ty::TyArray(_, s) = ty.sty {
- let size: u128 = s.assert_usize(cx.tcx).unwrap().into();
+ if let ty::TyArray(..) = ty.sty {
// Index is a constant uint.
- if let Some((Constant::Int(const_index), _)) = constant(cx, cx.tables, index) {
- if size <= const_index {
- utils::span_lint(
- cx,
- OUT_OF_BOUNDS_INDEXING,
- expr.span,
- "const index is out of bounds",
- );
- }
- // Else index is in bounds, ok.
-
+ if let Some(..) = constant(cx, cx.tables, index) {
+ // Let rustc's `const_err` lint handle constant `usize` indexing on arrays.
return;
}
}
&x[..index];
&x[index_from..index_to];
&x[index_from..][..index_to]; // Two lint reports, one for [index_from..] and another for [..index_to].
- x[4];
- x[1 << 3];
+ x[4]; // Ok, let rustc's `const_err` lint handle `usize` indexing on arrays.
+ x[1 << 3]; // Ok, let rustc's `const_err` lint handle `usize` indexing on arrays.
&x[..=4];
&x[1..5];
&x[5..][..10]; // Two lint reports, one for [5..] and another for [..10].
&y[..]; // Ok, should not produce stderr.
let empty: [i8; 0] = [];
- empty[0];
+ empty[0]; // Ok, let rustc's `const_err` lint handle `usize` indexing on arrays.
&empty[1..5];
&empty[0..=4];
&empty[..=4];
const N: usize = 15; // Out of bounds
const M: usize = 3; // In bounds
- x[N];
+ x[N]; // Ok, let rustc's `const_err` lint handle `usize` indexing on arrays.
x[M]; // Ok, should not produce stderr.
v[N];
v[M];
|
= help: Consider using `.get(n..)` or .get_mut(n..)` instead
-error: const index is out of bounds
- --> $DIR/indexing_slicing.rs:16:5
- |
-16 | x[4];
- | ^^^^
- |
- = note: `-D out-of-bounds-indexing` implied by `-D warnings`
-
-error: const index is out of bounds
- --> $DIR/indexing_slicing.rs:17:5
- |
-17 | x[1 << 3];
- | ^^^^^^^^^
-
error: range is out of bounds
--> $DIR/indexing_slicing.rs:18:6
|
18 | &x[..=4];
| ^^^^^^^
+ |
+ = note: `-D out-of-bounds-indexing` implied by `-D warnings`
error: range is out of bounds
--> $DIR/indexing_slicing.rs:19:6
|
= help: Consider using `.get(..n)`or `.get_mut(..n)` instead
-error: const index is out of bounds
- --> $DIR/indexing_slicing.rs:47:5
- |
-47 | empty[0];
- | ^^^^^^^^
-
error: range is out of bounds
--> $DIR/indexing_slicing.rs:48:6
|
|
= help: Consider using `.get(..n)`or `.get_mut(..n)` instead
-error: const index is out of bounds
- --> $DIR/indexing_slicing.rs:78:5
- |
-78 | x[N];
- | ^^^^
-
error: indexing may panic.
--> $DIR/indexing_slicing.rs:80:5
|
|
= help: Consider using `.get(n)` or `.get_mut(n)` instead
-error: aborting due to 41 previous errors
+error: aborting due to 37 previous errors