`redundant_pattern_matching` fix inverted boolean when missing `Drop` trait # Please enter the commit message for your changes. Lines starting # with '#' will be ignored, and an empty message aborts the commit. # # Date: Fri Apr 2 19:04:45 2021 -0400 # # On branch redundant_pattern_matching # Your branch is ahead of 'origin/redundant_pattern_matching' by 1 commit. # (use "git push" to publish your local commits) # # Changes to be committed: # modified: clippy_lints/src/matches.rs # # Please enter the commit message for your changes. Lines starting # with '#' will be ignored, and an empty message aborts the commit. # # Date: Fri Apr 2 19:04:45 2021 -0400 # # interactive rebase in progress; onto ebc64690d # Last commands done (6 commands done): # pick 25d211ad8 Code cleanup and additional std types checked # r 0c71ce56f `redundant_pattern_matching` fix inverted boolean when missing `Drop` trait # No commands remaining. # You are currently editing a commit while rebasing branch 'redundant_pattern_matching' on 'ebc64690d'. # # Changes to be committed: # modified: clippy_lints/src/matches.rs #

1 files changed, 5 insertions, 3 deletions

diff --git a/clippy_lints/src/matches.rs b/clippy_lints/src/matches.rs
index dc5232085ed..ddfc27e8460 100644
--- a/clippy_lints/src/matches.rs
+++ b/clippy_lints/src/matches.rs
@@ -1733,15 +1733,17 @@ mod redundant_pattern_match {
         }
     }
 
-    // Check if the drop order for a type matters
+    /// Checks if the drop order for a type matters. Some std types implement drop solely to
+    /// deallocate memory. For these types, and composites containing them, changing the drop order
+    /// won't result in any observable side effects.
     fn type_needs_ordered_drop(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
         if !ty.needs_drop(cx.tcx, cx.param_env) {
             false
-        } else if cx
+        } else if !cx
             .tcx
             .lang_items()
             .drop_trait()
-            .map_or(false, |id| !implements_trait(cx, ty, id, &[]))
+            .map_or(false, |id| implements_trait(cx, ty, id, &[]))
         {
             // This type doesn't implement drop, so no side effects here.
             // Check if any component type has any.