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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /src/tools/clippy/clippy_lints/src/mut_mutex_lock.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/tools/clippy/clippy_lints/src/mut_mutex_lock.rs')
-rw-r--r-- | src/tools/clippy/clippy_lints/src/mut_mutex_lock.rs | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/mut_mutex_lock.rs b/src/tools/clippy/clippy_lints/src/mut_mutex_lock.rs new file mode 100644 index 000000000..b7f981faa --- /dev/null +++ b/src/tools/clippy/clippy_lints/src/mut_mutex_lock.rs @@ -0,0 +1,70 @@ +use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::ty::is_type_diagnostic_item; +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}; +use rustc_span::sym; + +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. + /// + /// ### 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; + /// ``` + #[clippy::version = "1.49.0"] + 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, [self_arg, ..], _) = &ex.kind; + if path.ident.name == sym!(lock); + let ty = cx.typeck_results().expr_ty(self_arg); + if let ty::Ref(_, inner_ty, Mutability::Mut) = ty.kind(); + if is_type_diagnostic_item(cx, *inner_ty, sym::Mutex); + then { + span_lint_and_sugg( + cx, + MUT_MUTEX_LOCK, + path.ident.span, + "calling `&mut Mutex::lock` unnecessarily locks an exclusive (mutable) reference", + "change this to", + "get_mut".to_owned(), + Applicability::MaybeIncorrect, + ); + } + } + } +} |