Rollup merge of #63546 - lzutao:clouldabi-maybeuninit, r=RalfJung

Remove uses of `mem::uninitialized()` from cloudabi

This PR removes uses of `mem::uninitialized` from `cloudabi` module,
excluding the layout test in `src/libstd/sys/cloudabi/abi/cloudabi.rs`.

r? @RalfJung
cc @EdSchouten
cc #62397

1 files changed, 4 insertions, 3 deletions

diff --git a/src/libstd/sys/cloudabi/thread.rs b/src/libstd/sys/cloudabi/thread.rs
index 7da16c4d247..240b6ea9e57 100644
--- a/src/libstd/sys/cloudabi/thread.rs
+++ b/src/libstd/sys/cloudabi/thread.rs
@@ -72,10 +72,11 @@ impl Thread {
                 },
                 ..mem::zeroed()
             };
-            let mut event: abi::event = mem::uninitialized();
-            let mut nevents: usize = mem::uninitialized();
-            let ret = abi::poll(&subscription, &mut event, 1, &mut nevents);
+            let mut event = mem::MaybeUninit::<abi::event>::uninit();
+            let mut nevents = mem::MaybeUninit::<usize>::uninit();
+            let ret = abi::poll(&subscription, event.as_mut_ptr(), 1, nevents.as_mut_ptr());
             assert_eq!(ret, abi::errno::SUCCESS);
+            let event = event.assume_init();
             assert_eq!(event.error, abi::errno::SUCCESS);
         }
     }