rust/clippy_lints/src/mem_forget.rs
2018-03-28 15:24:26 +02:00

51 lines
1.5 KiB
Rust

use rustc::lint::*;
use rustc::hir::{Expr, ExprCall, ExprPath};
use utils::{match_def_path, opt_def_id, paths, span_lint};
/// **What it does:** Checks for usage of `std::mem::forget(t)` where `t` is
/// `Drop`.
///
/// **Why is this bad?** `std::mem::forget(t)` prevents `t` from running its
/// destructor, possibly causing leaks.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// mem::forget(Rc::new(55)))
/// ```
declare_clippy_lint! {
pub MEM_FORGET,
restriction,
"`mem::forget` usage on `Drop` types, likely to cause memory leaks"
}
pub struct MemForget;
impl LintPass for MemForget {
fn get_lints(&self) -> LintArray {
lint_array![MEM_FORGET]
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MemForget {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
if let ExprCall(ref path_expr, ref args) = e.node {
if let ExprPath(ref qpath) = path_expr.node {
if let Some(def_id) = opt_def_id(cx.tables.qpath_def(qpath, path_expr.hir_id)) {
if match_def_path(cx.tcx, def_id, &paths::MEM_FORGET) {
let forgot_ty = cx.tables.expr_ty(&args[0]);
if match forgot_ty.ty_adt_def() {
Some(def) => def.has_dtor(cx.tcx),
_ => false,
} {
span_lint(cx, MEM_FORGET, e.span, "usage of mem::forget on Drop type");
}
}
}
}
}
}
}