Rollup merge of #88860 - nbdd0121:panic, r=m-ou-se

[rust.git] / clippy_lints / src / mutex_atomic.rs

diff --git a/clippy_lints/src/mutex_atomic.rs b/clippy_lints/src/mutex_atomic.rs
index 6800e4295f5702b9449e50ab20aa97dd79454129..5feddcbfc61042c6eeecd73900de7354a172519c 100644 (file)
--- a/clippy_lints/src/mutex_atomic.rs
+++ b/clippy_lints/src/mutex_atomic.rs
@@ -2,27 +2,39 @@
 //!
 //! 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;
 
 declare_clippy_lint! {
-    /// **What it does:** Checks for usages of `Mutex<X>` where an atomic will do.
+    /// ### 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
+    /// ### 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
+    /// ### Known problems
+    /// This lint cannot detect if the mutex is actually used
     /// for waiting before a critical section.
     ///
-    /// **Example:**
+    /// ### 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,
@@ -30,52 +42,50 @@
 }
 
 declare_clippy_lint! {
-    /// **What it does:** Checks for usages of `Mutex<X>` where `X` is an integral
+    /// ### 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
+    /// ### 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
+    /// ### Known problems
+    /// This lint cannot detect if the mutex is actually used
     /// for waiting before a critical section.
     ///
-    /// **Example:**
+    /// ### 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),
                     };
                 }
@@ -84,8 +94,8 @@ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
     }
 }
 
-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"),