69 lines
2.3 KiB
Rust
69 lines
2.3 KiB
Rust
use crate::utils::{is_type_diagnostic_item, span_lint_and_sugg};
|
|
use if_chain::if_chain;
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir::{Expr, ExprKind, Mutability};
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_middle::ty;
|
|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `&mut Mutex::lock` calls
|
|
///
|
|
/// **Why is this bad?** `Mutex::lock` is less efficient than
|
|
/// calling `Mutex::get_mut`. In addition you also have a statically
|
|
/// guarantee that the mutex isn't locked, instead of just a runtime
|
|
/// guarantee.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// use std::sync::{Arc, Mutex};
|
|
///
|
|
/// let mut value_rc = Arc::new(Mutex::new(42_u8));
|
|
/// let value_mutex = Arc::get_mut(&mut value_rc).unwrap();
|
|
///
|
|
/// let mut value = value_mutex.lock().unwrap();
|
|
/// *value += 1;
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// use std::sync::{Arc, Mutex};
|
|
///
|
|
/// let mut value_rc = Arc::new(Mutex::new(42_u8));
|
|
/// let value_mutex = Arc::get_mut(&mut value_rc).unwrap();
|
|
///
|
|
/// let value = value_mutex.get_mut().unwrap();
|
|
/// *value += 1;
|
|
/// ```
|
|
pub MUT_MUTEX_LOCK,
|
|
style,
|
|
"`&mut Mutex::lock` does unnecessary locking"
|
|
}
|
|
|
|
declare_lint_pass!(MutMutexLock => [MUT_MUTEX_LOCK]);
|
|
|
|
impl<'tcx> LateLintPass<'tcx> for MutMutexLock {
|
|
fn check_expr(&mut self, cx: &LateContext<'tcx>, ex: &'tcx Expr<'tcx>) {
|
|
if_chain! {
|
|
if let ExprKind::MethodCall(path, method_span, args, _) = &ex.kind;
|
|
if path.ident.name == sym!(lock);
|
|
let ty = cx.typeck_results().expr_ty(&args[0]);
|
|
if let ty::Ref(_, inner_ty, Mutability::Mut) = ty.kind();
|
|
if is_type_diagnostic_item(cx, inner_ty, sym!(mutex_type));
|
|
then {
|
|
span_lint_and_sugg(
|
|
cx,
|
|
MUT_MUTEX_LOCK,
|
|
*method_span,
|
|
"calling `&mut Mutex::lock` unnecessarily locks an exclusive (mutable) reference",
|
|
"change this to",
|
|
"get_mut".to_owned(),
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|