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Add check for illegal accessing known length array with a constant index

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This commit is contained in:
cocodery 2023-12-22 20:17:43 +08:00
parent 7e650b7610
commit d020196dc0
1 changed files with 17 additions and 1 deletions
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18
clippy_lints/src/indexing_slicing.rs
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@ -170,7 +170,23 @@ impl<'tcx> LateLintPass<'tcx> for IndexingSlicing {
return;
}
// Index is a constant uint.
if constant(cx, cx.typeck_results(), index).is_some() {
if let Some(constant) = constant(cx, cx.typeck_results(), index) {
// only `usize` index is legal in rust array index
// leave other type to rustc
if let Constant::Int(off) = constant
&& let ty::Uint(utype) = cx.typeck_results().expr_ty(index).kind()
&& *utype == ty::UintTy::Usize
&& let ty::Array(_, s) = ty.kind()
&& let Some(size) = s.try_eval_target_usize(cx.tcx, cx.param_env)
{
// get constant offset and check whether it is in bounds
let off = usize::try_from(off).unwrap();
let size = usize::try_from(size).unwrap();
if off >= size {
span_lint(cx, OUT_OF_BOUNDS_INDEXING, expr.span, "index is out of bounds");
}
}
// Let rustc's `const_err` lint handle constant `usize` indexing on arrays.
return;
}