Auto merge of #9148 - arieluy:then_some_unwrap_or, r=Jarcho

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

diff --git a/clippy_lints/src/let_underscore.rs b/clippy_lints/src/let_underscore.rs
index 89146b4dd2c9bd5f58b61a89a2cab4b61f7b6d76..176787497ebf2e655f93ba77b15e1c41436aa87a 100644 (file)
--- a/clippy_lints/src/let_underscore.rs
+++ b/clippy_lints/src/let_underscore.rs
@@ -10,12 +10,11 @@
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks for `let _ = <expr>`
-    /// where expr is #[must_use]
+    /// Checks for `let _ = <expr>` where expr is `#[must_use]`
     ///
     /// ### Why is this bad?
-    /// It's better to explicitly
-    /// handle the value of a #[must_use] expr
+    /// It's better to explicitly handle the value of a `#[must_use]`
+    /// expr
     ///
     /// ### Example
     /// ```rust
@@ -27,6 +26,7 @@
     /// // is_ok() is marked #[must_use]
     /// let _ = f().is_ok();
     /// ```
+    #[clippy::version = "1.42.0"]
     pub LET_UNDERSCORE_MUST_USE,
     restriction,
     "non-binding let on a `#[must_use]` expression"
@@ -34,7 +34,8 @@
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks for `let _ = sync_lock`
+    /// Checks for `let _ = sync_lock`.
+    /// This supports `mutex` and `rwlock` in `std::sync` and `parking_lot`.
     ///
     /// ### Why is this bad?
     /// This statement immediately drops the lock instead of
@@ -44,16 +45,15 @@
     /// `std::mem::drop` conveys your intention better and is less error-prone.
     ///
     /// ### Example
-    ///
-    /// Bad:
     /// ```rust,ignore
     /// let _ = mutex.lock();
     /// ```
     ///
-    /// Good:
+    /// Use instead:
     /// ```rust,ignore
     /// let _lock = mutex.lock();
     /// ```
+    #[clippy::version = "1.43.0"]
     pub LET_UNDERSCORE_LOCK,
     correctness,
     "non-binding let on a synchronization lock"
@@ -73,28 +73,25 @@
     /// better and is less error-prone.
     ///
     /// ### Example
-    ///
-    /// Bad:
-    /// ```rust,ignore
-    /// struct Droppable;
-    /// impl Drop for Droppable {
-    ///     fn drop(&mut self) {}
-    /// }
+    /// ```rust
+    /// # struct DroppableItem;
     /// {
-    ///     let _ = Droppable;
-    ///     //               ^ dropped here
+    ///     let _ = DroppableItem;
+    ///     //                   ^ dropped here
     ///     /* more code */
     /// }
     /// ```
     ///
-    /// Good:
-    /// ```rust,ignore
+    /// Use instead:
+    /// ```rust
+    /// # struct DroppableItem;
     /// {
-    ///     let _droppable = Droppable;
+    ///     let _droppable = DroppableItem;
     ///     /* more code */
     ///     // dropped at end of scope
     /// }
     /// ```
+    #[clippy::version = "1.50.0"]
     pub LET_UNDERSCORE_DROP,
     pedantic,
     "non-binding let on a type that implements `Drop`"
@@ -102,10 +99,13 @@
 
 declare_lint_pass!(LetUnderscore => [LET_UNDERSCORE_MUST_USE, LET_UNDERSCORE_LOCK, LET_UNDERSCORE_DROP]);
 
-const SYNC_GUARD_PATHS: [&[&str]; 3] = [
+const SYNC_GUARD_PATHS: [&[&str]; 6] = [
     &paths::MUTEX_GUARD,
     &paths::RWLOCK_READ_GUARD,
     &paths::RWLOCK_WRITE_GUARD,
+    &paths::PARKING_LOT_MUTEX_GUARD,
+    &paths::PARKING_LOT_RWLOCK_READ_GUARD,
+    &paths::PARKING_LOT_RWLOCK_WRITE_GUARD,
 ];
 
 impl<'tcx> LateLintPass<'tcx> for LetUnderscore {
@@ -119,7 +119,7 @@ fn check_local(&mut self, cx: &LateContext<'_>, local: &Local<'_>) {
             if let Some(init) = local.init;
             then {
                 let init_ty = cx.typeck_results().expr_ty(init);
-                let contains_sync_guard = init_ty.walk(cx.tcx).any(|inner| match inner.unpack() {
+                let contains_sync_guard = init_ty.walk().any(|inner| match inner.unpack() {
                     GenericArgKind::Type(inner_ty) => {
                         SYNC_GUARD_PATHS.iter().any(|path| match_type(cx, inner_ty, path))
                     },