fix(visit): Improve Map implementation for Box

crates/swc_visit/src/util/map.rs

@@ -1,4 +1,4 @@
-use std::{mem, ptr};
+use std::ptr;
 
 /// Copied from `syntax::ptr::P` of rustc.
 pub trait Map<T> {
@@ -13,17 +13,15 @@ pub trait Map<T> {
 }
 
 impl<T> Map<T> for Box<T> {
-    fn map<F>(mut self, f: F) -> Self
+    fn map<F>(self, f: F) -> Self
     where
         F: FnOnce(T) -> T,
     {
-        let p: *mut T = &mut *self;
-
         // Leak self in case of panic.
         // FIXME(eddyb) Use some sort of "free guard" that
         // only deallocates, without dropping the pointee,
         // in case the call the `f` below ends in a panic.
-        mem::forget(self);
+        let p = Box::into_raw(self);
 
         unsafe {
             ptr::write(p, f(ptr::read(p)));