Use memoffset::offset_of instead of homegrown macro

The homegrown macro was fine in 2016, but at some point it technically
became UB.  The memoffset crate does the same thing, but avoids UB when
using rustc 1.51.0 or later.

Fixes #1415

1 files changed, 0 insertions, 13 deletions

diff --git a/src/macros.rs b/src/macros.rs
index feb02ea7..7d6ac8df 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -203,16 +203,3 @@ macro_rules! libc_enum {
         }
     };
 }
-
-/// A Rust version of the familiar C `offset_of` macro.  It returns the byte
-/// offset of `field` within struct `ty`
-#[cfg(not(target_os = "redox"))]
-macro_rules! offset_of {
-    ($ty:ty, $field:ident) => {{
-        // Safe because we don't actually read from the dereferenced pointer
-        #[allow(unused_unsafe)] // for when the macro is used in an unsafe block
-        unsafe {
-            &(*(ptr::null() as *const $ty)).$field as *const _ as usize
-        }
-    }}
-}