//!
//! This lint is **warn** by default
-use crate::utils::{match_type, paths, span_lint};
-use rustc::hir::Expr;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::ty::{self, Ty};
-use rustc::{declare_tool_lint, lint_array};
-use syntax::ast;
+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::ty::is_type_diagnostic_item;
+use rustc_hir::Expr;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::{self, Ty};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::sym;
-/// **What it does:** Checks for usages of `Mutex<X>` where an atomic will do.
-///
-/// **Why is this bad?** Using a mutex just to make access to a plain bool or
-/// reference sequential is shooting flies with cannons.
-/// `std::sync::atomic::AtomicBool` and `std::sync::atomic::AtomicPtr` are leaner and
-/// faster.
-///
-/// **Known problems:** This lint cannot detect if the mutex is actually used
-/// for waiting before a critical section.
-///
-/// **Example:**
-/// ```rust
-/// let x = Mutex::new(&y);
-/// ```
declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for usages of `Mutex<X>` where an atomic will do.
+ ///
+ /// ### Why is this bad?
+ /// Using a mutex just to make access to a plain bool or
+ /// reference sequential is shooting flies with cannons.
+ /// `std::sync::atomic::AtomicBool` and `std::sync::atomic::AtomicPtr` are leaner and
+ /// faster.
+ ///
+ /// ### Known problems
+ /// This lint cannot detect if the mutex is actually used
+ /// for waiting before a critical section.
+ ///
+ /// ### Example
+ /// ```rust
+ /// # let y = true;
+ ///
+ /// // Bad
+ /// # use std::sync::Mutex;
+ /// let x = Mutex::new(&y);
+ ///
+ /// // Good
+ /// # use std::sync::atomic::AtomicBool;
+ /// let x = AtomicBool::new(y);
+ /// ```
pub MUTEX_ATOMIC,
perf,
"using a mutex where an atomic value could be used instead"
}
-/// **What it does:** Checks for usages of `Mutex<X>` where `X` is an integral
-/// type.
-///
-/// **Why is this bad?** 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.
-///
-/// **Known problems:** This lint cannot detect if the mutex is actually used
-/// for waiting before a critical section.
-///
-/// **Example:**
-/// ```rust
-/// let x = Mutex::new(0usize);
-/// ```
declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for usages of `Mutex<X>` where `X` is an integral
+ /// type.
+ ///
+ /// ### Why is this bad?
+ /// 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.
+ ///
+ /// ### Known problems
+ /// This lint cannot detect if the mutex is actually used
+ /// for waiting before a critical section.
+ ///
+ /// ### Example
+ /// ```rust
+ /// # use std::sync::Mutex;
+ /// let x = Mutex::new(0usize);
+ ///
+ /// // Good
+ /// # use std::sync::atomic::AtomicUsize;
+ /// let x = AtomicUsize::new(0usize);
+ /// ```
pub MUTEX_INTEGER,
nursery,
"using a mutex for an integer type"
}
-impl LintPass for MutexAtomic {
- fn get_lints(&self) -> LintArray {
- lint_array!(MUTEX_ATOMIC, MUTEX_INTEGER)
- }
-
- fn name(&self) -> &'static str {
- "Mutex"
- }
-}
-
-pub struct MutexAtomic;
+declare_lint_pass!(Mutex => [MUTEX_ATOMIC, MUTEX_INTEGER]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutexAtomic {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
- let ty = cx.tables.expr_ty(expr);
- if let ty::Adt(_, subst) = ty.sty {
- if match_type(cx, ty, &paths::MUTEX) {
+impl<'tcx> LateLintPass<'tcx> for Mutex {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+ let ty = cx.typeck_results().expr_ty(expr);
+ if let ty::Adt(_, subst) = ty.kind() {
+ if is_type_diagnostic_item(cx, ty, sym::Mutex) {
let mutex_param = subst.type_at(0);
if let Some(atomic_name) = get_atomic_name(mutex_param) {
let msg = format!(
- "Consider using an {} instead of a Mutex here. If you just want the locking \
- behaviour and not the internal type, consider using Mutex<()>.",
+ "consider using an `{}` instead of a `Mutex` here; if you just want the locking \
+ behavior and not the internal type, consider using `Mutex<()>`",
atomic_name
);
- match mutex_param.sty {
- ty::Uint(t) if t != ast::UintTy::Usize => span_lint(cx, MUTEX_INTEGER, expr.span, &msg),
- ty::Int(t) if t != ast::IntTy::Isize => span_lint(cx, MUTEX_INTEGER, expr.span, &msg),
+ match *mutex_param.kind() {
+ ty::Uint(t) if t != ty::UintTy::Usize => span_lint(cx, MUTEX_INTEGER, expr.span, &msg),
+ ty::Int(t) if t != ty::IntTy::Isize => span_lint(cx, MUTEX_INTEGER, expr.span, &msg),
_ => span_lint(cx, MUTEX_ATOMIC, expr.span, &msg),
};
}
}
}
-fn get_atomic_name(ty: Ty<'_>) -> Option<(&'static str)> {
- match ty.sty {
+fn get_atomic_name(ty: Ty<'_>) -> Option<&'static str> {
+ match ty.kind() {
ty::Bool => Some("AtomicBool"),
ty::Uint(_) => Some("AtomicUsize"),
ty::Int(_) => Some("AtomicIsize"),