1 use clippy_utils::diagnostics::span_lint_and_then;
2 use clippy_utils::{match_def_path, paths};
3 use rustc_data_structures::fx::FxHashMap;
4 use rustc_hir::def_id::DefId;
5 use rustc_hir::{def::Res, AsyncGeneratorKind, Body, BodyId, GeneratorKind};
6 use rustc_lint::{LateContext, LateLintPass};
7 use rustc_middle::ty::GeneratorInteriorTypeCause;
8 use rustc_session::{declare_tool_lint, impl_lint_pass};
11 use crate::utils::conf::DisallowedType;
13 declare_clippy_lint! {
15 /// Checks for calls to await while holding a non-async-aware MutexGuard.
17 /// ### Why is this bad?
18 /// The Mutex types found in std::sync and parking_lot
19 /// are not designed to operate in an async context across await points.
21 /// There are two potential solutions. One is to use an async-aware Mutex
22 /// type. Many asynchronous foundation crates provide such a Mutex type. The
23 /// other solution is to ensure the mutex is unlocked before calling await,
24 /// either by introducing a scope or an explicit call to Drop::drop.
26 /// ### Known problems
27 /// Will report false positive for explicitly dropped guards
28 /// ([#6446](https://github.com/rust-lang/rust-clippy/issues/6446)). A workaround for this is
29 /// to wrap the `.lock()` call in a block instead of explicitly dropping the guard.
33 /// # use std::sync::Mutex;
34 /// # async fn baz() {}
35 /// async fn foo(x: &Mutex<u32>) {
36 /// let mut guard = x.lock().unwrap();
41 /// async fn bar(x: &Mutex<u32>) {
42 /// let mut guard = x.lock().unwrap();
44 /// drop(guard); // explicit drop
51 /// # use std::sync::Mutex;
52 /// # async fn baz() {}
53 /// async fn foo(x: &Mutex<u32>) {
55 /// let mut guard = x.lock().unwrap();
61 /// async fn bar(x: &Mutex<u32>) {
63 /// let mut guard = x.lock().unwrap();
65 /// } // guard dropped here at end of scope
69 #[clippy::version = "1.45.0"]
70 pub AWAIT_HOLDING_LOCK,
72 "inside an async function, holding a `MutexGuard` while calling `await`"
75 declare_clippy_lint! {
77 /// Checks for calls to await while holding a `RefCell` `Ref` or `RefMut`.
79 /// ### Why is this bad?
80 /// `RefCell` refs only check for exclusive mutable access
81 /// at runtime. Holding onto a `RefCell` ref across an `await` suspension point
82 /// risks panics from a mutable ref shared while other refs are outstanding.
84 /// ### Known problems
85 /// Will report false positive for explicitly dropped refs
86 /// ([#6353](https://github.com/rust-lang/rust-clippy/issues/6353)). A workaround for this is
87 /// to wrap the `.borrow[_mut]()` call in a block instead of explicitly dropping the ref.
91 /// # use std::cell::RefCell;
92 /// # async fn baz() {}
93 /// async fn foo(x: &RefCell<u32>) {
94 /// let mut y = x.borrow_mut();
99 /// async fn bar(x: &RefCell<u32>) {
100 /// let mut y = x.borrow_mut();
102 /// drop(y); // explicit drop
109 /// # use std::cell::RefCell;
110 /// # async fn baz() {}
111 /// async fn foo(x: &RefCell<u32>) {
113 /// let mut y = x.borrow_mut();
119 /// async fn bar(x: &RefCell<u32>) {
121 /// let mut y = x.borrow_mut();
123 /// } // y dropped here at end of scope
127 #[clippy::version = "1.49.0"]
128 pub AWAIT_HOLDING_REFCELL_REF,
130 "inside an async function, holding a `RefCell` ref while calling `await`"
133 declare_clippy_lint! {
135 /// Allows users to configure types which should not be held across `await`
136 /// suspension points.
138 /// ### Why is this bad?
139 /// There are some types which are perfectly "safe" to be used concurrently
140 /// from a memory access perspective but will cause bugs at runtime if they
141 /// are held in such a way.
143 /// ### Known problems
148 /// await-holding-invalid-types = [
149 /// # You can specify a type name
150 /// "CustomLockType",
151 /// # You can (optionally) specify a reason
152 /// { type = "OtherCustomLockType", reason = "Relies on a thread local" }
157 /// # async fn baz() {}
158 /// struct CustomLockType;
159 /// struct OtherCustomLockType;
161 /// let _x = CustomLockType;
162 /// let _y = CustomLockType;
163 /// baz().await; // Lint violation
166 #[clippy::version = "1.49.0"]
167 pub AWAIT_HOLDING_INVALID_TYPE,
169 "holding a type across an await point which is not allowed to be held as per the configuration"
172 impl_lint_pass!(AwaitHolding => [AWAIT_HOLDING_LOCK, AWAIT_HOLDING_REFCELL_REF, AWAIT_HOLDING_INVALID_TYPE]);
175 pub struct AwaitHolding {
176 conf_invalid_types: Vec<DisallowedType>,
177 def_ids: FxHashMap<DefId, DisallowedType>,
181 pub(crate) fn new(conf_invalid_types: Vec<DisallowedType>) -> Self {
184 def_ids: FxHashMap::default(),
189 impl LateLintPass<'_> for AwaitHolding {
190 fn check_crate(&mut self, cx: &LateContext<'_>) {
191 for conf in &self.conf_invalid_types {
192 let path = match conf {
193 DisallowedType::Simple(path) | DisallowedType::WithReason { path, .. } => path,
195 let segs: Vec<_> = path.split("::").collect();
196 if let Res::Def(_, id) = clippy_utils::def_path_res(cx, &segs) {
197 self.def_ids.insert(id, conf.clone());
202 fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) {
203 use AsyncGeneratorKind::{Block, Closure, Fn};
204 if let Some(GeneratorKind::Async(Block | Closure | Fn)) = body.generator_kind {
205 let body_id = BodyId {
206 hir_id: body.value.hir_id,
208 let typeck_results = cx.tcx.typeck_body(body_id);
209 self.check_interior_types(
211 typeck_results.generator_interior_types.as_ref().skip_binder(),
219 fn check_interior_types(&self, cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
220 for ty_cause in ty_causes {
221 if let rustc_middle::ty::Adt(adt, _) = ty_cause.ty.kind() {
222 if is_mutex_guard(cx, adt.did()) {
227 "this `MutexGuard` is held across an `await` point",
230 "consider using an async-aware `Mutex` type or ensuring the \
231 `MutexGuard` is dropped before calling await",
234 ty_cause.scope_span.unwrap_or(span),
235 "these are all the `await` points this lock is held through",
239 } else if is_refcell_ref(cx, adt.did()) {
242 AWAIT_HOLDING_REFCELL_REF,
244 "this `RefCell` reference is held across an `await` point",
246 diag.help("ensure the reference is dropped before calling `await`");
248 ty_cause.scope_span.unwrap_or(span),
249 "these are all the `await` points this reference is held through",
253 } else if let Some(disallowed) = self.def_ids.get(&adt.did()) {
254 emit_invalid_type(cx, ty_cause.span, disallowed);
261 fn emit_invalid_type(cx: &LateContext<'_>, span: Span, disallowed: &DisallowedType) {
262 let (type_name, reason) = match disallowed {
263 DisallowedType::Simple(path) => (path, &None),
264 DisallowedType::WithReason { path, reason } => (path, reason),
269 AWAIT_HOLDING_INVALID_TYPE,
271 &format!("`{type_name}` may not be held across an `await` point per `clippy.toml`",),
273 if let Some(reason) = reason {
274 diag.note(reason.clone());
280 fn is_mutex_guard(cx: &LateContext<'_>, def_id: DefId) -> bool {
281 match_def_path(cx, def_id, &paths::MUTEX_GUARD)
282 || match_def_path(cx, def_id, &paths::RWLOCK_READ_GUARD)
283 || match_def_path(cx, def_id, &paths::RWLOCK_WRITE_GUARD)
284 || match_def_path(cx, def_id, &paths::PARKING_LOT_MUTEX_GUARD)
285 || match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_READ_GUARD)
286 || match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_WRITE_GUARD)
289 fn is_refcell_ref(cx: &LateContext<'_>, def_id: DefId) -> bool {
290 match_def_path(cx, def_id, &paths::REFCELL_REF) || match_def_path(cx, def_id, &paths::REFCELL_REFMUT)