74 lines
2.4 KiB
Rust
74 lines
2.4 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_help;
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use clippy_utils::source::snippet;
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use rustc_hir::{Expr, ExprKind, Item, ItemKind, Node};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty::layout::LayoutOf;
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use rustc_middle::ty::{self, ConstKind};
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for local arrays that may be too large.
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///
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/// ### Why is this bad?
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/// Large local arrays may cause stack overflow.
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///
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/// ### Example
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/// ```rust,ignore
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/// let a = [0u32; 1_000_000];
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/// ```
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#[clippy::version = "1.41.0"]
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pub LARGE_STACK_ARRAYS,
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pedantic,
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"allocating large arrays on stack may cause stack overflow"
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}
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pub struct LargeStackArrays {
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maximum_allowed_size: u128,
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}
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impl LargeStackArrays {
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#[must_use]
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pub fn new(maximum_allowed_size: u128) -> Self {
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Self { maximum_allowed_size }
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}
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}
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impl_lint_pass!(LargeStackArrays => [LARGE_STACK_ARRAYS]);
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impl<'tcx> LateLintPass<'tcx> for LargeStackArrays {
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fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
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if let ExprKind::Repeat(_, _) | ExprKind::Array(_) = expr.kind
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&& let ty::Array(element_type, cst) = cx.typeck_results().expr_ty(expr).kind()
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&& let ConstKind::Value(ty::ValTree::Leaf(element_count)) = cst.kind()
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&& let Ok(element_count) = element_count.try_to_target_usize(cx.tcx)
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&& let Ok(element_size) = cx.layout_of(*element_type).map(|l| l.size.bytes())
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&& !cx.tcx.hir().parent_iter(expr.hir_id).any(|(_, node)| {
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matches!(
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node,
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Node::Item(Item {
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kind: ItemKind::Static(..),
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..
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})
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)
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})
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&& self.maximum_allowed_size < u128::from(element_count) * u128::from(element_size)
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{
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span_lint_and_help(
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cx,
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LARGE_STACK_ARRAYS,
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expr.span,
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&format!(
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"allocating a local array larger than {} bytes",
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self.maximum_allowed_size
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),
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None,
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&format!(
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"consider allocating on the heap with `vec!{}.into_boxed_slice()`",
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snippet(cx, expr.span, "[...]")
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),
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);
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}
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}
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}
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