rust-clippy/clippy_lints/src/await_holding_invalid.rs

150 lines
5.2 KiB
Rust
Raw Normal View History

use crate::utils::{match_def_path, paths, span_lint_and_note};
use rustc_hir::def_id::DefId;
use rustc_hir::{AsyncGeneratorKind, Body, BodyId, GeneratorKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::GeneratorInteriorTypeCause;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::Span;
declare_clippy_lint! {
/// **What it does:** Checks for calls to await while holding a
/// non-async-aware MutexGuard.
///
/// **Why is this bad?** The Mutex types found in std::sync and parking_lot
/// are not designed to operate in an async context across await points.
///
/// There are two potential solutions. One is to use an asynx-aware Mutex
/// type. Many asynchronous foundation crates provide such a Mutex type. The
/// other solution is to ensure the mutex is unlocked before calling await,
/// either by introducing a scope or an explicit call to Drop::drop.
///
/// **Known problems:** None.
///
/// **Example:**
///
2020-04-10 05:12:34 +00:00
/// ```rust,ignore
/// use std::sync::Mutex;
///
/// async fn foo(x: &Mutex<u32>) {
/// let guard = x.lock().unwrap();
/// *guard += 1;
/// bar.await;
/// }
/// ```
///
/// Use instead:
2020-04-10 05:12:34 +00:00
/// ```rust,ignore
/// use std::sync::Mutex;
///
/// async fn foo(x: &Mutex<u32>) {
/// {
/// let guard = x.lock().unwrap();
/// *guard += 1;
/// }
/// bar.await;
/// }
/// ```
pub AWAIT_HOLDING_LOCK,
pedantic,
"Inside an async function, holding a MutexGuard while calling await"
}
declare_clippy_lint! {
/// **What it does:** Checks for calls to await while holding a
/// `RefCell` `Ref` or `RefMut`.
///
/// **Why is this bad?** `RefCell` refs only check for exclusive mutable access
/// at runtime. Holding onto a `RefCell` ref across an `await` suspension point
/// risks panics from a mutable ref shared while other refs are outstanding.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust,ignore
/// use std::cell::RefCell;
///
/// async fn foo(x: &RefCell<u32>) {
/// let mut y = x.borrow_mut();
/// *y += 1;
/// bar.await;
/// }
/// ```
///
/// Use instead:
/// ```rust,ignore
/// use std::cell::RefCell;
///
/// async fn foo(x: &RefCell<u32>) {
/// {
/// let mut y = x.borrow_mut();
/// *y += 1;
/// }
/// bar.await;
/// }
/// ```
pub AWAIT_HOLDING_REFCELL_REF,
pedantic,
"Inside an async function, holding a RefCell ref while calling await"
}
declare_lint_pass!(AwaitHolding => [AWAIT_HOLDING_LOCK, AWAIT_HOLDING_REFCELL_REF]);
impl LateLintPass<'_> for AwaitHolding {
fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) {
use AsyncGeneratorKind::{Block, Closure, Fn};
if let Some(GeneratorKind::Async(Block | Closure | Fn)) = body.generator_kind {
let body_id = BodyId {
hir_id: body.value.hir_id,
};
let def_id = cx.tcx.hir().body_owner_def_id(body_id);
2020-07-17 08:47:04 +00:00
let typeck_results = cx.tcx.typeck(def_id);
check_interior_types(
cx,
&typeck_results.generator_interior_types.as_ref().skip_binder(),
body.value.span,
);
}
}
}
fn check_interior_types(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
for ty_cause in ty_causes {
if let rustc_middle::ty::Adt(adt, _) = ty_cause.ty.kind() {
if is_mutex_guard(cx, adt.did) {
span_lint_and_note(
cx,
AWAIT_HOLDING_LOCK,
ty_cause.span,
"this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.",
ty_cause.scope_span.or(Some(span)),
"these are all the await points this lock is held through",
);
}
if is_refcell_ref(cx, adt.did) {
span_lint_and_note(
cx,
AWAIT_HOLDING_REFCELL_REF,
ty_cause.span,
"this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.",
ty_cause.scope_span.or(Some(span)),
"these are all the await points this ref is held through",
);
}
}
}
}
fn is_mutex_guard(cx: &LateContext<'_>, def_id: DefId) -> bool {
match_def_path(cx, def_id, &paths::MUTEX_GUARD)
|| match_def_path(cx, def_id, &paths::RWLOCK_READ_GUARD)
|| match_def_path(cx, def_id, &paths::RWLOCK_WRITE_GUARD)
|| match_def_path(cx, def_id, &paths::PARKING_LOT_MUTEX_GUARD)
|| match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_READ_GUARD)
|| match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_WRITE_GUARD)
}
fn is_refcell_ref(cx: &LateContext<'_>, def_id: DefId) -> bool {
match_def_path(cx, def_id, &paths::REFCELL_REF) || match_def_path(cx, def_id, &paths::REFCELL_REFMUT)
}