| use rustc_hir::{Expr, ExprKind}; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_middle::mir::interpret::ConstValue; |
| use rustc_middle::ty::{self, ConstKind}; |
| use rustc_session::{declare_tool_lint, impl_lint_pass}; |
| |
| use if_chain::if_chain; |
| |
| use crate::rustc_target::abi::LayoutOf; |
| use crate::utils::{snippet, span_lint_and_help}; |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for local arrays that may be too large. |
| /// |
| /// **Why is this bad?** Large local arrays may cause stack overflow. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust,ignore |
| /// let a = [0u32; 1_000_000]; |
| /// ``` |
| pub LARGE_STACK_ARRAYS, |
| pedantic, |
| "allocating large arrays on stack may cause stack overflow" |
| } |
| |
| pub struct LargeStackArrays { |
| maximum_allowed_size: u64, |
| } |
| |
| impl LargeStackArrays { |
| #[must_use] |
| pub fn new(maximum_allowed_size: u64) -> Self { |
| Self { maximum_allowed_size } |
| } |
| } |
| |
| impl_lint_pass!(LargeStackArrays => [LARGE_STACK_ARRAYS]); |
| |
| impl<'tcx> LateLintPass<'tcx> for LargeStackArrays { |
| fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) { |
| if_chain! { |
| if let ExprKind::Repeat(_, _) = expr.kind; |
| if let ty::Array(element_type, cst) = cx.tables().expr_ty(expr).kind; |
| if let ConstKind::Value(val) = cst.val; |
| if let ConstValue::Scalar(element_count) = val; |
| if let Ok(element_count) = element_count.to_machine_usize(&cx.tcx); |
| if let Ok(element_size) = cx.layout_of(element_type).map(|l| l.size.bytes()); |
| if self.maximum_allowed_size < element_count * element_size; |
| then { |
| span_lint_and_help( |
| cx, |
| LARGE_STACK_ARRAYS, |
| expr.span, |
| &format!( |
| "allocating a local array larger than {} bytes", |
| self.maximum_allowed_size |
| ), |
| None, |
| &format!( |
| "consider allocating on the heap with `vec!{}.into_boxed_slice()`", |
| snippet(cx, expr.span, "[...]") |
| ), |
| ); |
| } |
| } |
| } |
| } |