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Removing lint for constant usize array indexing

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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.
This commit is contained in:
Shea Newton 2018-06-19 21:30:43 +00:00
parent e63f5dfedb
commit c479b3bc28
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GPG key ID: 17EB9122DC958643
3 changed files with 13 additions and 49 deletions
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24
clippy_lints/src/indexing_slicing.rs
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@ -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;
}
}