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Move mutex_integer to restriction and improve mutex_{integer,atomic} docs (#14110)

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Similar to https://github.com/rust-lang/rust-clippy/pull/10115 (for
`mutex_atomic`), but for `mutex_integer`.

This also improve docs of `mutex_integer`/`mutex_atomic` (extend known
problems section to mention condvar issue
(https://github.com/rust-lang/rust-clippy/issues/1516) and portability
issue).

changelog: Moved [`mutex_integer`] to `restriction`
This commit is contained in:
Jason Newcomb 2025-02-04 10:44:57 +00:00 • committed by GitHub
commit 75e3a2e905
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1 changed files with 21 additions and 9 deletions
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30
clippy_lints/src/mutex_atomic.rs
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@ -18,11 +18,14 @@ declare_clippy_lint! {
///
/// On the other hand, `Mutex`es are, in general, easier to
/// verify correctness. An atomic does not behave the same as
/// an equivalent mutex. See [this issue](https://github.com/rust-lang/rust-clippy/issues/4295)'s commentary for more details.
/// an equivalent mutex. See [this issue](https://github.com/rust-lang/rust-clippy/issues/4295)'s
/// commentary for more details.
///
/// ### Known problems
/// This lint cannot detect if the mutex is actually used
/// for waiting before a critical section.
/// * This lint cannot detect if the mutex is actually used
/// for waiting before a critical section.
/// * This lint has a false positive that warns without considering the case
/// where `Mutex` is used together with `Condvar`.
///
/// ### Example
/// ```no_run
@ -48,14 +51,23 @@ declare_clippy_lint! {
/// Checks for usage of `Mutex<X>` where `X` is an integral
/// type.
///
/// ### Why is this bad?
/// ### Why restrict this?
/// Using a mutex just to make access to a plain integer
/// sequential is
/// shooting flies with cannons. `std::sync::atomic::AtomicUsize` is leaner and faster.
///
/// On the other hand, `Mutex`es are, in general, easier to
/// verify correctness. An atomic does not behave the same as
/// an equivalent mutex. See [this issue](https://github.com/rust-lang/rust-clippy/issues/4295)'s
/// commentary for more details.
///
/// ### Known problems
/// This lint cannot detect if the mutex is actually used
/// for waiting before a critical section.
/// * This lint cannot detect if the mutex is actually used
/// for waiting before a critical section.
/// * This lint has a false positive that warns without considering the case
/// where `Mutex` is used together with `Condvar`.
/// * This lint suggest using `AtomicU64` instead of `Mutex<u64>`, but
/// `AtomicU64` is not available on some 32-bit platforms.
///
/// ### Example
/// ```no_run
@ -70,7 +82,7 @@ declare_clippy_lint! {
/// ```
#[clippy::version = "pre 1.29.0"]
pub MUTEX_INTEGER,
nursery,
restriction,
"using a mutex for an integer type"
}
@ -108,7 +120,7 @@ fn get_atomic_name(ty: Ty<'_>) -> Option<&'static str> {
UintTy::U32 => Some("AtomicU32"),
UintTy::U64 => Some("AtomicU64"),
UintTy::Usize => Some("AtomicUsize"),
// There's no `AtomicU128`.
// `AtomicU128` is unstable and only available on a few platforms: https://github.com/rust-lang/rust/issues/99069
UintTy::U128 => None,
}
},
@ -119,7 +131,7 @@ fn get_atomic_name(ty: Ty<'_>) -> Option<&'static str> {
IntTy::I32 => Some("AtomicI32"),
IntTy::I64 => Some("AtomicI64"),
IntTy::Isize => Some("AtomicIsize"),
// There's no `AtomicI128`.
// `AtomicU128` is unstable and only available on a few platforms: https://github.com/rust-lang/rust/issues/99069
IntTy::I128 => None,
}
},