[GitHub] [arrow] andygrove commented on a change in pull request #7061: ARROW-8629: [Rust] Eliminate indirection of zero sized allocations

[GitBox <gi...@apache.org>]

andygrove commented on a change in pull request #7061:
URL: https://github.com/apache/arrow/pull/7061#discussion_r417658203



##########
File path: rust/arrow/src/memory.rs
##########
@@ -20,34 +20,56 @@
 
 use std::alloc::Layout;
 use std::mem::align_of;
+use std::ptr::NonNull;
 
 pub const ALIGNMENT: usize = 64;
 
+///
+/// As you can see this is global and lives as long as the program lives.
+/// Be careful to not write anything to this pointer in any scenario.
+/// If you use allocation methods shown here you won't have any problems.
+const BYPASS_PTR: NonNull<u8> = unsafe { NonNull::new_unchecked(0xDEADBEEF as *mut u8) };
+
 pub fn allocate_aligned(size: usize) -> *mut u8 {
     unsafe {

Review comment:
       I'm not familiar with the use case of calling this with zero. Should that even be allowed?




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