1 use rustc_hir::{Expr, ExprKind};
2 use rustc_lint::{LateContext, LateLintPass};
3 use rustc_middle::mir::interpret::ConstValue;
4 use rustc_middle::ty::{self, ConstKind};
5 use rustc_session::{declare_tool_lint, impl_lint_pass};
7 use if_chain::if_chain;
9 use crate::rustc_target::abi::LayoutOf;
10 use crate::utils::{snippet, span_lint_and_help};
12 declare_clippy_lint! {
13 /// **What it does:** Checks for local arrays that may be too large.
15 /// **Why is this bad?** Large local arrays may cause stack overflow.
17 /// **Known problems:** None.
21 /// let a = [0u32; 1_000_000];
23 pub LARGE_STACK_ARRAYS,
25 "allocating large arrays on stack may cause stack overflow"
28 pub struct LargeStackArrays {
29 maximum_allowed_size: u64,
32 impl LargeStackArrays {
34 pub fn new(maximum_allowed_size: u64) -> Self {
35 Self { maximum_allowed_size }
39 impl_lint_pass!(LargeStackArrays => [LARGE_STACK_ARRAYS]);
41 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeStackArrays {
42 fn check_expr(&mut self, cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
44 if let ExprKind::Repeat(_, _) = expr.kind;
45 if let ty::Array(element_type, cst) = cx.tables.expr_ty(expr).kind;
46 if let ConstKind::Value(val) = cst.val;
47 if let ConstValue::Scalar(element_count) = val;
48 if let Ok(element_count) = element_count.to_machine_usize(&cx.tcx);
49 if let Ok(element_size) = cx.layout_of(element_type).map(|l| l.size.bytes());
50 if self.maximum_allowed_size < element_count * element_size;
57 "allocating a local array larger than {} bytes",
58 self.maximum_allowed_size
62 "consider allocating on the heap with `vec!{}.into_boxed_slice()`",
63 snippet(cx, expr.span, "[...]")