Prefer ManuallyDrop::{take,new} over ptr::{read,write}

Author: oli-obk

src/libstd/lib.rs

@@ -275,6 +275,7 @@
 #![feature(link_args)]
 #![feature(linkage)]
 #![feature(log_syntax)]
+#![feature(manually_drop_take)]
 #![feature(maybe_uninit_ref)]
 #![feature(maybe_uninit_slice)]
 #![feature(mem_take)]

src/libstd/panicking.rs

@@ -13,7 +13,6 @@ use crate::any::Any;
 use crate::fmt;
 use crate::intrinsics;
 use crate::mem::{self, ManuallyDrop};
-use crate::ptr;
 use crate::raw;
 use crate::sync::atomic::{AtomicBool, Ordering};
 use crate::sys::stdio::panic_output;
@@ -283,8 +282,9 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
     fn do_call<F: FnOnce() -> R, R>(data: *mut u8) {
         unsafe {
             let data = data as *mut Data<F, R>;
-            let f = ptr::read(&mut *(*data).f);
-            ptr::write(&mut *(*data).r, f());
+            let data = &mut (*data);
+            let f = ManuallyDrop::take(&mut data.f);
+            data.r = ManuallyDrop::new(f());
         }
     }
 }