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Auto merge of #6029 - Daniel-B-Smith:refcell_ref_await, r=flip1995

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Add lint for holding RefCell Ref across an await

Fixes #6008

This introduces the lint await_holding_refcell_ref. For async functions, we iterate
over all types in generator_interior_types and look for `core::cell::Ref` or `core::cell::RefMut`. If we find one then we emit a lint.

Heavily cribs from: https://github.com/rust-lang/rust-clippy/pull/5439

changelog: introduce the await_holding_refcell_ref lint
This commit is contained in:
bors 2020-10-25 08:54:27 +00:00
commit a675778cfb
7 changed files with 257 additions and 9 deletions
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1
CHANGELOG.md
View file

@ -1632,6 +1632,7 @@ Released 2018-09-13
[`assign_ops`]: https://rust-lang.github.io/rust-clippy/master/index.html#assign_ops
[`async_yields_async`]: https://rust-lang.github.io/rust-clippy/master/index.html#async_yields_async
[`await_holding_lock`]: https://rust-lang.github.io/rust-clippy/master/index.html#await_holding_lock
[`await_holding_refcell_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#await_holding_refcell_ref
[`bad_bit_mask`]: https://rust-lang.github.io/rust-clippy/master/index.html#bad_bit_mask
[`bind_instead_of_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#bind_instead_of_map
[`blacklisted_name`]: https://rust-lang.github.io/rust-clippy/master/index.html#blacklisted_name

59
clippy_lints/src/await_holding_lock.rs → clippy_lints/src/await_holding_invalid.rs
View file

@ -45,13 +45,52 @@ declare_clippy_lint! {
/// }
/// ```
pub AWAIT_HOLDING_LOCK,
pedantic,
correctness,
"Inside an async function, holding a MutexGuard while calling await"
}
declare_lint_pass!(AwaitHoldingLock => [AWAIT_HOLDING_LOCK]);
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 b = x.borrow_mut()();
/// *ref += 1;
/// bar.await;
/// }
/// ```
///
/// Use instead:
/// ```rust,ignore
/// use std::cell::RefCell;
///
/// async fn foo(x: &RefCell<u32>) {
/// {
/// let b = x.borrow_mut();
/// *ref += 1;
/// }
/// bar.await;
/// }
/// ```
pub AWAIT_HOLDING_REFCELL_REF,
correctness,
"Inside an async function, holding a RefCell ref while calling await"
}
impl LateLintPass<'_> for AwaitHoldingLock {
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 {
@ -78,6 +117,16 @@ fn check_interior_types(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorType
"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",
);
}
}
}
}
@ -90,3 +139,7 @@ fn is_mutex_guard(cx: &LateContext<'_>, def_id: DefId) -> bool {
|| 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)
}

12
clippy_lints/src/lib.rs
View file

@ -160,7 +160,7 @@ mod assign_ops;
mod async_yields_async;
mod atomic_ordering;
mod attrs;
mod await_holding_lock;
mod await_holding_invalid;
mod bit_mask;
mod blacklisted_name;
mod blocks_in_if_conditions;
@ -509,7 +509,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&attrs::MISMATCHED_TARGET_OS,
&attrs::UNKNOWN_CLIPPY_LINTS,
&attrs::USELESS_ATTRIBUTE,
&await_holding_lock::AWAIT_HOLDING_LOCK,
&await_holding_invalid::AWAIT_HOLDING_LOCK,
&await_holding_invalid::AWAIT_HOLDING_REFCELL_REF,
&bit_mask::BAD_BIT_MASK,
&bit_mask::INEFFECTIVE_BIT_MASK,
&bit_mask::VERBOSE_BIT_MASK,
@ -906,7 +907,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
]);
// end register lints, do not remove this comment, it’s used in `update_lints`
store.register_late_pass(|| box await_holding_lock::AwaitHoldingLock);
store.register_late_pass(|| box await_holding_invalid::AwaitHolding);
store.register_late_pass(|| box serde_api::SerdeAPI);
store.register_late_pass(|| box utils::internal_lints::CompilerLintFunctions::new());
store.register_late_pass(|| box utils::internal_lints::LintWithoutLintPass::default());
@ -1190,7 +1191,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_group(true, "clippy::pedantic", Some("clippy_pedantic"), vec![
LintId::of(&attrs::INLINE_ALWAYS),
LintId::of(&await_holding_lock::AWAIT_HOLDING_LOCK),
LintId::of(&bit_mask::VERBOSE_BIT_MASK),
LintId::of(&checked_conversions::CHECKED_CONVERSIONS),
LintId::of(&copies::MATCH_SAME_ARMS),
@ -1290,6 +1290,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&attrs::MISMATCHED_TARGET_OS),
LintId::of(&attrs::UNKNOWN_CLIPPY_LINTS),
LintId::of(&attrs::USELESS_ATTRIBUTE),
LintId::of(&await_holding_invalid::AWAIT_HOLDING_LOCK),
LintId::of(&await_holding_invalid::AWAIT_HOLDING_REFCELL_REF),
LintId::of(&bit_mask::BAD_BIT_MASK),
LintId::of(&bit_mask::INEFFECTIVE_BIT_MASK),
LintId::of(&blacklisted_name::BLACKLISTED_NAME),
@ -1736,6 +1738,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&attrs::DEPRECATED_SEMVER),
LintId::of(&attrs::MISMATCHED_TARGET_OS),
LintId::of(&attrs::USELESS_ATTRIBUTE),
LintId::of(&await_holding_invalid::AWAIT_HOLDING_LOCK),
LintId::of(&await_holding_invalid::AWAIT_HOLDING_REFCELL_REF),
LintId::of(&bit_mask::BAD_BIT_MASK),
LintId::of(&bit_mask::INEFFECTIVE_BIT_MASK),
LintId::of(&booleans::LOGIC_BUG),

2
clippy_lints/src/utils/paths.rs
View file

@ -93,6 +93,8 @@ pub const RANGE_ARGUMENT_TRAIT: [&str; 3] = ["core", "ops", "RangeBounds"];
pub const RC: [&str; 3] = ["alloc", "rc", "Rc"];
pub const RC_PTR_EQ: [&str; 4] = ["alloc", "rc", "Rc", "ptr_eq"];
pub const RECEIVER: [&str; 4] = ["std", "sync", "mpsc", "Receiver"];
pub const REFCELL_REF: [&str; 3] = ["core", "cell", "Ref"];
pub const REFCELL_REFMUT: [&str; 3] = ["core", "cell", "RefMut"];
pub const REGEX_BUILDER_NEW: [&str; 5] = ["regex", "re_builder", "unicode", "RegexBuilder", "new"];
pub const REGEX_BYTES_BUILDER_NEW: [&str; 5] = ["regex", "re_builder", "bytes", "RegexBuilder", "new"];
pub const REGEX_BYTES_NEW: [&str; 4] = ["regex", "re_bytes", "Regex", "new"];

11
src/lintlist/mod.rs
View file

@ -62,10 +62,17 @@ vec![
},
Lint {
name: "await_holding_lock",
group: "pedantic",
group: "correctness",
desc: "Inside an async function, holding a MutexGuard while calling await",
deprecation: None,
module: "await_holding_lock",
module: "await_holding_invalid",
},
Lint {
name: "await_holding_refcell_ref",
group: "correctness",
desc: "Inside an async function, holding a RefCell ref while calling await",
deprecation: None,
module: "await_holding_invalid",
},
Lint {
name: "bad_bit_mask",

86
tests/ui/await_holding_refcell_ref.rs Normal file
View file

@ -0,0 +1,86 @@
// edition:2018
#![warn(clippy::await_holding_refcell_ref)]
use std::cell::RefCell;
async fn bad(x: &RefCell<u32>) -> u32 {
let b = x.borrow();
baz().await
}
async fn bad_mut(x: &RefCell<u32>) -> u32 {
let b = x.borrow_mut();
baz().await
}
async fn good(x: &RefCell<u32>) -> u32 {
{
let b = x.borrow_mut();
let y = *b + 1;
}
baz().await;
let b = x.borrow_mut();
47
}
async fn baz() -> u32 {
42
}
async fn also_bad(x: &RefCell<u32>) -> u32 {
let first = baz().await;
let b = x.borrow_mut();
let second = baz().await;
let third = baz().await;
first + second + third
}
async fn less_bad(x: &RefCell<u32>) -> u32 {
let first = baz().await;
let b = x.borrow_mut();
let second = baz().await;
drop(b);
let third = baz().await;
first + second + third
}
async fn not_good(x: &RefCell<u32>) -> u32 {
let first = baz().await;
let second = {
let b = x.borrow_mut();
baz().await
};
let third = baz().await;
first + second + third
}
#[allow(clippy::manual_async_fn)]
fn block_bad(x: &RefCell<u32>) -> impl std::future::Future<Output = u32> + '_ {
async move {
let b = x.borrow_mut();
baz().await
}
}
fn main() {
let rc = RefCell::new(100);
good(&rc);
bad(&rc);
bad_mut(&rc);
also_bad(&rc);
less_bad(&rc);
not_good(&rc);
block_bad(&rc);
}

95
tests/ui/await_holding_refcell_ref.stderr Normal file
View file

@ -0,0 +1,95 @@
error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
--> $DIR/await_holding_refcell_ref.rs:7:9
|
LL | let b = x.borrow();
| ^
|
= note: `-D clippy::await-holding-refcell-ref` implied by `-D warnings`
note: these are all the await points this ref is held through
--> $DIR/await_holding_refcell_ref.rs:7:5
|
LL | / let b = x.borrow();
LL | | baz().await
LL | | }
| |_^
error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
--> $DIR/await_holding_refcell_ref.rs:12:9
|
LL | let b = x.borrow_mut();
| ^
|
note: these are all the await points this ref is held through
--> $DIR/await_holding_refcell_ref.rs:12:5
|
LL | / let b = x.borrow_mut();
LL | | baz().await
LL | | }
| |_^
error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
--> $DIR/await_holding_refcell_ref.rs:33:9
|
LL | let b = x.borrow_mut();
| ^
|
note: these are all the await points this ref is held through
--> $DIR/await_holding_refcell_ref.rs:33:5
|
LL | / let b = x.borrow_mut();
LL | |
LL | | let second = baz().await;
LL | |
... |
LL | | first + second + third
LL | | }
| |_^
error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
--> $DIR/await_holding_refcell_ref.rs:45:9
|
LL | let b = x.borrow_mut();
| ^
|
note: these are all the await points this ref is held through
--> $DIR/await_holding_refcell_ref.rs:45:5
|
LL | / let b = x.borrow_mut();
LL | |
LL | | let second = baz().await;
LL | |
... |
LL | | first + second + third
LL | | }
| |_^
error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
--> $DIR/await_holding_refcell_ref.rs:60:13
|
LL | let b = x.borrow_mut();
| ^
|
note: these are all the await points this ref is held through
--> $DIR/await_holding_refcell_ref.rs:60:9
|
LL | / let b = x.borrow_mut();
LL | | baz().await
LL | | };
| |_____^
error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
--> $DIR/await_holding_refcell_ref.rs:72:13
|
LL | let b = x.borrow_mut();
| ^
|
note: these are all the await points this ref is held through
--> $DIR/await_holding_refcell_ref.rs:72:9
|
LL | / let b = x.borrow_mut();
LL | | baz().await
LL | | }
| |_____^
error: aborting due to 6 previous errors