std::thread: add SAFETY comment

rust-lang · Oct 27, 2023 · ccb36a6 · ccb36a6
1 parent 95f6a01
commit ccb36a6
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
@@ -546,6 +546,8 @@ impl Builder {
         }
 
         let main = Box::new(main);
+        // SAFETY: dynamic size and alignment of the Box remain the same. See below for why the
+        // lifetime change is justified.
         #[cfg(bootstrap)]
         let main =
             unsafe { mem::transmute::<Box<dyn FnOnce() + 'a>, Box<dyn FnOnce() + 'static>>(main) };