diff --git a/clippy_lints/src/indexing_slicing.rs b/clippy_lints/src/indexing_slicing.rs index b4e6414195e..7dd72a5383c 100644 --- a/clippy_lints/src/indexing_slicing.rs +++ b/clippy_lints/src/indexing_slicing.rs @@ -34,9 +34,9 @@ declare_clippy_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. @@ -64,13 +64,11 @@ declare_clippy_lint! { /// 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]; @@ -132,20 +130,10 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IndexingSlicing { ); } 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; } } diff --git a/tests/ui/indexing_slicing.rs b/tests/ui/indexing_slicing.rs index 301658415d6..e39dc92367c 100644 --- a/tests/ui/indexing_slicing.rs +++ b/tests/ui/indexing_slicing.rs @@ -13,8 +13,8 @@ fn main() { &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]. @@ -44,7 +44,7 @@ fn main() { &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]; @@ -75,7 +75,7 @@ fn main() { 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]; diff --git a/tests/ui/indexing_slicing.stderr b/tests/ui/indexing_slicing.stderr index 2546d62bfc6..ee11dce6d1c 100644 --- a/tests/ui/indexing_slicing.stderr +++ b/tests/ui/indexing_slicing.stderr @@ -47,25 +47,13 @@ error: slicing may panic. | = 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 @@ -159,12 +147,6 @@ error: slicing may panic. | = 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 | @@ -269,12 +251,6 @@ error: slicing may panic. | = 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 | @@ -291,5 +267,5 @@ error: indexing may panic. | = help: Consider using `.get(n)` or `.get_mut(n)` instead -error: aborting due to 41 previous errors +error: aborting due to 37 previous errors