1 use clippy_utils::diagnostics::span_lint_and_help;
2 use clippy_utils::path_res;
3 use clippy_utils::ty::is_type_lang_item;
4 use rustc_hir::{lang_items, Expr, ExprKind};
5 use rustc_lint::{LateContext, LateLintPass};
6 use rustc_session::{declare_lint_pass, declare_tool_lint};
11 /// Prevents the safe `std::mem::drop` function from being called on `std::mem::ManuallyDrop`.
13 /// ### Why is this bad?
14 /// The safe `drop` function does not drop the inner value of a `ManuallyDrop`.
16 /// ### Known problems
17 /// Does not catch cases if the user binds `std::mem::drop`
18 /// to a different name and calls it that way.
23 /// drop(std::mem::ManuallyDrop::new(S));
29 /// std::mem::ManuallyDrop::drop(&mut std::mem::ManuallyDrop::new(S));
32 #[clippy::version = "1.49.0"]
33 pub UNDROPPED_MANUALLY_DROPS,
35 "use of safe `std::mem::drop` function to drop a std::mem::ManuallyDrop, which will not drop the inner value"
38 declare_lint_pass!(UndroppedManuallyDrops => [UNDROPPED_MANUALLY_DROPS]);
40 impl<'tcx> LateLintPass<'tcx> for UndroppedManuallyDrops {
41 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
43 if let ExprKind::Call(fun, [arg_0, ..]) = expr.kind;
44 if path_res(cx, fun).opt_def_id() == cx.tcx.get_diagnostic_item(sym::mem_drop);
45 let ty = cx.typeck_results().expr_ty(arg_0);
46 if is_type_lang_item(cx, ty, lang_items::LangItem::ManuallyDrop);
50 UNDROPPED_MANUALLY_DROPS,
52 "the inner value of this ManuallyDrop will not be dropped",
54 "to drop a `ManuallyDrop<T>`, use std::mem::ManuallyDrop::drop",